{"id":1672,"date":"2017-10-27T16:32:39","date_gmt":"2017-10-27T16:32:39","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/chapter\/nuclear-radioactivity\/"},"modified":"2017-11-08T03:27:47","modified_gmt":"2017-11-08T03:27:47","slug":"nuclear-radioactivity","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/chapter\/nuclear-radioactivity\/","title":{"raw":"Nuclear Radioactivity","rendered":"Nuclear Radioactivity"},"content":{"raw":"\n<div class=\"textbox learning-objectives\">\n<h3 itemprop=\"educationalUse\">Learning Objectives<\/h3>\n<ul>\n<li>Explain nuclear radiation.<\/li>\n<li>Explain the types of radiation\u2014alpha emission, beta emission, and gamma emission.<\/li>\n<li>Explain the ionization of radiation in an atom.<\/li>\n<li>Define the range of radiation.<\/li>\n<\/ul>\n<\/div>\n<p id=\"import-auto-id2382456\">The discovery and study of nuclear radioactivity quickly revealed evidence of revolutionary new physics. In addition, uses for nuclear radiation also emerged quickly\u2014for example, people such as Ernest Rutherford used it to determine the size of the nucleus and devices were painted with radon-doped paint to make them glow in the dark (see <a href=\"#import-auto-id3209830\" class=\"autogenerated-content\">(Figure)<\/a>). We therefore begin our study of nuclear physics with the discovery and basic features of nuclear radioactivity.<\/p>\n<div class=\"bc-figure figure\">\n<div class=\"bc-figcaption figcaption\">The dials of this World War II aircraft glow in the dark, because they are painted with radium-doped phosphorescent paint. It is a poignant reminder of the dual nature of radiation. Although radium paint dials are conveniently visible day and night, they emit radon, a radioactive gas that is hazardous and is not directly sensed. (credit: U.S. Air Force Photo)<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id3076369\" data-alt=\"The image shows an aircraft panel with lots of dial indicators, some levers and two wheels.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_01a.jpg\" data-media-type=\"image\/png\" alt=\"The image shows an aircraft panel with lots of dial indicators, some levers and two wheels.\" width=\"250\"><\/span><\/p><\/div>\n<div class=\"bc-section section\" data-depth=\"1\" id=\"fs-id1448851\">\n<h1 data-type=\"title\">Discovery of Nuclear Radioactivity<\/h1>\n<p id=\"import-auto-id1177617\">In 1896, the French physicist Antoine Henri Becquerel (1852\u20131908) accidentally found that a uranium-rich mineral called pitchblende emits invisible, penetrating rays that can darken a photographic plate enclosed in an opaque envelope. The rays therefore carry energy; but amazingly, the pitchblende emits them continuously without any energy input. This is an apparent violation of the law of conservation of energy, one that we now understand is due to the conversion of a small amount of mass into energy, as related in Einstein\u2019s famous equation [latex]\\mathit{E}={\\mathit{mc}}^{2}[\/latex]. It was soon evident that Becquerel\u2019s rays originate in the nuclei of the atoms and have other unique characteristics. The emission of these rays is called <strong>nuclear radioactivity<\/strong> or simply <span data-type=\"term\">radioactivity<\/span>. The rays themselves are called <span data-type=\"term\">nuclear radiation<\/span>. A nucleus that spontaneously destroys part of its mass to emit radiation is said to <span data-type=\"term\">decay<\/span> (a term also used to describe the emission of radiation by atoms in excited states). A substance or object that emits nuclear radiation is said to be <span data-type=\"term\">radioactive<\/span>.<\/p>\n<p id=\"import-auto-id1514494\">Two types of experimental evidence imply that Becquerel\u2019s rays originate deep in the heart (or nucleus) of an atom. First, the radiation is found to be associated with certain elements, such as uranium. Radiation does not vary with chemical state\u2014that is, uranium is radioactive whether it is in the form of an element or compound. In addition, radiation does not vary with temperature, pressure, or ionization state of the uranium atom. Since all of these factors affect electrons in an atom, the radiation cannot come from electron transitions, as atomic spectra do. The huge energy emitted during each event is the second piece of evidence that the radiation cannot be atomic. Nuclear radiation has energies of the order of [latex]{\\text{10}}^{6}\\phantom{\\rule{0.25em}{0ex}}\\text{eV}[\/latex] per event, which is much greater than the typical atomic energies (a few [latex]\\text{eV}[\/latex]), such as that observed in spectra and chemical reactions, and more than ten times as high as the most energetic characteristic x rays. Becquerel did not vigorously pursue his discovery for very long. In 1898, Marie Curie (1867\u20131934), then a graduate student married the already well-known French physicist Pierre Curie (1859\u20131906), began her doctoral study of Becquerel\u2019s rays. She and her husband soon discovered two new radioactive elements, which she named <em data-effect=\"italics\"><em data-effect=\"italics\">polonium<\/em><\/em> (after her native land) and <em data-effect=\"italics\"><em data-effect=\"italics\">radium<\/em><\/em> (because it radiates). These two new elements filled holes in the periodic table and, further, displayed much higher levels of radioactivity per gram of material than uranium. Over a period of four years, working under poor conditions and spending their own funds, the Curies processed more than a ton of uranium ore to isolate a gram of radium salt. Radium became highly sought after, because it was about two million times as radioactive as uranium. Curie\u2019s radium salt glowed visibly from the radiation that took its toll on them and other unaware researchers. Shortly after completing her Ph.D., both Curies and Becquerel shared the 1903 Nobel Prize in physics for their work on radioactivity. Pierre was killed in a horse cart accident in 1906, but Marie continued her study of radioactivity for nearly 30 more years. Awarded the 1911 Nobel Prize in chemistry for her discovery of two new elements, she remains the only person to win Nobel Prizes in physics and chemistry. Marie\u2019s radioactive fingerprints on some pages of her notebooks can still expose film, and she suffered from radiation-induced lesions. She died of leukemia likely caused by radiation, but she was active in research almost until her death in 1934. The following year, her daughter and son-in-law, Irene and Frederic Joliot-Curie, were awarded the Nobel Prize in chemistry for their discovery of artificially induced radiation, adding to a remarkable family legacy.<\/p>\n<\/div>\n<div class=\"bc-section section\" data-depth=\"1\" id=\"fs-id2407919\">\n<h1 data-type=\"title\">Alpha, Beta, and Gamma<\/h1>\n<p id=\"import-auto-id3422619\">Research begun by people such as New Zealander Ernest Rutherford soon after the discovery of nuclear radiation indicated that different types of rays are emitted. Eventually, three types were distinguished and named <span data-type=\"term\" id=\"import-auto-id1427002\">alpha<\/span>[latex]\\left(\\alpha \\right)[\/latex], <span data-type=\"term\" id=\"import-auto-id1517480\">beta<\/span>[latex]\\left(\\beta \\right)[\/latex], and <span data-type=\"term\" id=\"import-auto-id1472534\">gamma<\/span>[latex]\\left(\\gamma \\right)[\/latex], because, like x-rays, their identities were initially unknown. <a href=\"#import-auto-id2600407\" class=\"autogenerated-content\">(Figure)<\/a> shows what happens if the rays are passed through a magnetic field. The [latex]\\gamma [\/latex]s are unaffected, while the [latex]\\alpha [\/latex] s and [latex]\\beta [\/latex] s are deflected in opposite directions, indicating the [latex]\\alpha [\/latex] s are positive, the [latex]\\beta [\/latex] s negative, and the [latex]\\gamma [\/latex] s uncharged. Rutherford used both magnetic and electric fields to show that [latex]\\alpha [\/latex] s have a positive charge twice the magnitude of an electron, or [latex]+2\\mid {q}_{e}\\mid [\/latex]. In the process, he found the [latex]\\alpha [\/latex] s charge to mass ratio to be several thousand times smaller than the electron\u2019s. Later on, Rutherford collected [latex]\\alpha [\/latex] s from a radioactive source and passed an electric discharge through them, obtaining the spectrum of recently discovered helium gas. Among many important discoveries made by Rutherford and his collaborators was the proof that [latex]\\alpha [\/latex] <em data-effect=\"italics\">radiation is the emission of a helium nucleus<\/em>. Rutherford won the Nobel Prize in chemistry in 1908 for his early work. He continued to make important contributions until his death in 1934.<\/p>\n<div class=\"bc-figure figure\" id=\"import-auto-id2600407\">\n<div class=\"bc-figcaption figcaption\">Alpha, beta, and gamma rays are passed through a magnetic field on the way to a phosphorescent screen. The [latex]\\alpha [\/latex] s and [latex]\\beta [\/latex] s bend in opposite directions, while the [latex]\\gamma [\/latex] s are unaffected, indicating a positive charge for [latex]\\alpha [\/latex] s, negative for [latex]\\beta [\/latex] s, and neutral for [latex]\\gamma [\/latex] s. Consistent results are obtained with electric fields. Collection of the radiation offers further confirmation from the direct measurement of excess charge.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1889078\" data-alt=\"The figure shows north and south poles of a magnet through which three rays labeled as alpha beta and gamma are passed. After passing through a magnetic field the alpha ray is slightly deflected toward the right. The beta ray is deflected toward the left and the gamma ray is not deflected.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_02a.jpg\" data-media-type=\"image\/jpg\" alt=\"The figure shows north and south poles of a magnet through which three rays labeled as alpha beta and gamma are passed. After passing through a magnetic field the alpha ray is slightly deflected toward the right. The beta ray is deflected toward the left and the gamma ray is not deflected.\" width=\"300\"><\/span><\/p><\/div>\n<p id=\"import-auto-id1514401\">Other researchers had already proved that [latex]\\beta [\/latex] s are negative and have the same mass and same charge-to-mass ratio as the recently discovered electron. By 1902, it was recognized that [latex]\\beta [\/latex] <em data-effect=\"italics\">radiation is the emission of an electron<\/em>. Although [latex]\\beta [\/latex] s are electrons, they do not exist in the nucleus before it decays and are not ejected atomic electrons\u2014the electron is created in the nucleus at the instant of decay.<\/p>\n<p id=\"import-auto-id1435020\">Since [latex]\\gamma [\/latex] s remain unaffected by electric and magnetic fields, it is natural to think they might be photons. Evidence for this grew, but it was not until 1914 that this was proved by Rutherford and collaborators. By scattering [latex]\\gamma [\/latex] radiation from a crystal and observing interference, they demonstrated that <strong data-effect=\"bold\">[latex]\\gamma [\/latex] <em data-effect=\"italics\">radiation is the emission of a high-energy photon by a nucleus<\/em>. In fact, [latex]\\gamma [\/latex] radiation comes from the de-excitation of a nucleus, just as an x ray comes from the de-excitation of an atom. The names \"[latex]\\gamma [\/latex] ray\" and \"x ray\" identify the source of the radiation. At the same energy, [latex]\\gamma [\/latex] rays and x rays are otherwise identical.<\/strong><\/p>\n<table id=\"import-auto-id1888293\" summary=\"Types of radiation are listed in column 1. The range for each type is in column 2.\">\n<caption><span data-type=\"title\">Properties of Nuclear Radiation<\/span><\/caption>\n<thead>\n<tr>\n<th>\n              Type of Radiation\n            <\/th>\n<th>\n              Range\n            <\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>[latex]\\alpha [\/latex]-Particles<\/td>\n<td>A sheet of paper, a few cm of air, fractions of a mm of tissue<\/td>\n<\/tr>\n<tr>\n<td>[latex]\\beta [\/latex]-Particles<\/td>\n<td>A thin aluminum plate, or tens of cm of tissue<\/td>\n<\/tr>\n<tr>\n<td>[latex]\\gamma [\/latex] Rays<\/td>\n<td>Several cm of lead or meters of concrete<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"bc-section section\" data-depth=\"1\" id=\"fs-id3226082\">\n<h1 data-type=\"title\">Ionization and Range<\/h1>\n<p id=\"import-auto-id969060\">Two of the most important characteristics of [latex]\\alpha [\/latex], [latex]\\beta [\/latex], and [latex]\\gamma [\/latex] rays were recognized very early. All three types of nuclear radiation produce <em data-effect=\"italics\"><em data-effect=\"italics\">ionization<\/em><\/em> in materials, but they penetrate different distances in materials\u2014that is, they have different <em data-effect=\"italics\"><em data-effect=\"italics\">ranges<\/em><\/em>. Let us examine why they have these characteristics and what are some of the consequences.<\/p>\n<p id=\"import-auto-id1901135\">Like x rays, nuclear radiation in the form of [latex]\\alpha [\/latex] s, [latex]\\beta [\/latex] s, and [latex]\\gamma [\/latex] s has enough energy per event to ionize atoms and molecules in any material. The energy emitted in various nuclear decays ranges from a few [latex]\\text{keV}[\/latex] to more than [latex]\\text{10&nbsp;MeV}[\/latex], while only a few [latex]\\text{eV}[\/latex] are needed to produce ionization. The effects of x rays and nuclear radiation on biological tissues and other materials, such as solid state electronics, are directly related to the ionization they produce. All of them, for example, can damage electronics or kill cancer cells. In addition, methods for detecting x rays and nuclear radiation are based on ionization, directly or indirectly. All of them can ionize the air between the plates of a capacitor, for example, causing it to discharge. This is the basis of inexpensive personal radiation monitors, such as pictured in <a href=\"#import-auto-id1900612\" class=\"autogenerated-content\">(Figure)<\/a>. Apart from [latex]\\alpha [\/latex], [latex]\\beta [\/latex], and [latex]\\gamma [\/latex], there are other forms of nuclear radiation as well, and these also produce ionization with similar effects. We define <span data-type=\"term\" id=\"import-auto-id2968914\">ionizing radiation<\/span><strong data-effect=\"bold\"> as any form of radiation that produces ionization whether nuclear in origin or not, since the effects and detection of the radiation are related to ionization.<\/strong><\/p>\n<div class=\"bc-figure figure\">\n<div class=\"bc-figcaption figcaption\">These dosimeters (literally, dose meters) are personal radiation monitors that detect the amount of radiation by the discharge of a rechargeable internal capacitor. The amount of discharge is related to the amount of ionizing radiation encountered, a measurement of dose. One dosimeter is shown in the charger. Its scale is read through an eyepiece on the top. (credit: L. Chang, Wikimedia Commons)<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1871385\" data-alt=\"Image shows a person\u2019s hand holding a cylindrical object placed near a small piece of radioactive material. A dial indicator is connected to the cylindrical radiation detector.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_03a.jpg\" data-media-type=\"image\/png\" alt=\"Image shows a person\u2019s hand holding a cylindrical object placed near a small piece of radioactive material. A dial indicator is connected to the cylindrical radiation detector.\" width=\"250\"><\/span><\/p><\/div>\n<p>The <span data-type=\"term\" id=\"import-auto-id1587169\">range of radiation<\/span> is defined to be the distance it can travel through a material. Range is related to several factors, including the energy of the radiation, the material encountered, and the type of radiation (see <a href=\"#import-auto-id3385282\" class=\"autogenerated-content\">(Figure)<\/a>). The higher the <em data-effect=\"italics\"><em data-effect=\"italics\">energy<\/em><\/em>, the greater the range, all other factors being the same. This makes good sense, since radiation loses its energy in materials primarily by producing ionization in them, and each ionization of an atom or a molecule requires energy that is removed from the radiation. The amount of ionization is, thus, directly proportional to the energy of the particle of radiation, as is its range.<\/p>\n<p id=\"import-auto-id1405600\">\n<\/p><div class=\"bc-figure figure\" id=\"import-auto-id3385282\">\n<div class=\"bc-figcaption figcaption\">The penetration or range of radiation depends on its energy, the material it encounters, and the type of radiation. (a) Greater energy means greater range. (b) Radiation has a smaller range in materials with high electron density. (c) Alphas have the smallest range, betas have a greater range, and gammas penetrate the farthest.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1514585\" data-alt=\"Three cases of range of radiation are shown. The first case shows that higher energy has greater range than lower energy. The second case shows that, for same energy material having high electron density will have lower range. The third case shows that among alpha beta and gamma rays for the same energy alphas have the smallest range betas have a greater range and gammas penetrate the farthest.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_04a.jpg\" data-media-type=\"image\/jpg\" alt=\"Three cases of range of radiation are shown. The first case shows that higher energy has greater range than lower energy. The second case shows that, for same energy material having high electron density will have lower range. The third case shows that among alpha beta and gamma rays for the same energy alphas have the smallest range betas have a greater range and gammas penetrate the farthest.\" width=\"550\"><\/span><\/p><\/div>\n<p>Radiation can be absorbed or shielded by materials, such as the lead aprons dentists drape on us when taking x rays. Lead is a particularly effective shield compared with other materials, such as plastic or air. How does the range of radiation depend on <em data-effect=\"italics\"><em data-effect=\"italics\">material<\/em><\/em>? Ionizing radiation interacts best with charged particles in a material. Since electrons have small masses, they most readily absorb the energy of the radiation in collisions. The greater the density of a material and, in particular, the greater the density of electrons within a material, the smaller the range of radiation.<\/p>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" id=\"fs-id3139051\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">Collisions<\/div>\n<p id=\"import-auto-id2680091\">Conservation of energy and momentum often results in energy transfer to a less massive object in a collision. This was discussed in detail in <a href=\"\/contents\/643b6e4a-de21-4a14-a677-b0d4c5ddb2d5@2\">Work, Energy, and Energy Resources<\/a>, for example.<\/p>\n<\/div>\n<p id=\"import-auto-id3077371\">Different <em data-effect=\"italics\"><em data-effect=\"italics\">types<\/em><\/em> of radiation have different ranges when compared at the same energy and in the same material. Alphas have the shortest range, betas penetrate farther, and gammas have the greatest range. This is directly related to charge and speed of the particle or type of radiation. At a given energy, each<br>\n[latex]\\alpha [\/latex],<br>\n[latex]\\beta [\/latex], or<br>\n[latex]\\gamma [\/latex] will produce the same number of ionizations in a material (each ionization requires a certain amount of energy on average). The more readily the particle produces ionization, the more quickly it will lose its energy. The effect of <em data-effect=\"italics\"><em data-effect=\"italics\">charge<\/em><\/em> is as follows: The [latex]\\alpha [\/latex] has a charge of [latex]+{2q}_{e}[\/latex] , the [latex]\\beta [\/latex] has a charge of [latex]-{q}_{e}[\/latex] , and the [latex]\\gamma [\/latex] is uncharged. The electromagnetic force exerted by the [latex]\\alpha [\/latex] is thus twice as strong as that exerted by the [latex]\\beta [\/latex] and it is more likely to produce ionization. Although chargeless, the [latex]\\gamma [\/latex] does interact weakly because it is an electromagnetic wave, but it is less likely to produce ionization in any encounter. More quantitatively, the change in momentum [latex]\\Delta p[\/latex] given to a particle in the material is [latex]\\Delta p=F\\Delta t[\/latex], where [latex]F[\/latex] is the force the<br>\n[latex]\\alpha [\/latex],<br>\n[latex]\\beta [\/latex], or<br>\n[latex]\\gamma [\/latex] exerts over a time<br>\n[latex]\\Delta t[\/latex]. The smaller the charge, the smaller is [latex]F[\/latex] and the smaller is the momentum (and energy) lost. Since the speed of alphas is about 5% to 10% of the speed of light, classical (non-relativistic) formulas apply.<\/p>\n<p>The <em data-effect=\"italics\"><em data-effect=\"italics\">speed<\/em><\/em> at which they travel is the other major factor affecting the range of [latex]\\alpha [\/latex] s, [latex]\\beta [\/latex] s, and [latex]\\gamma [\/latex] s. The faster they move, the less time they spend in the vicinity of an atom or a molecule, and the less likely they are to interact. Since [latex]\\alpha [\/latex] s and [latex]\\beta [\/latex] s are particles with mass (helium nuclei and electrons, respectively), their energy is kinetic, given classically by [latex]\\frac{1}{2}{\\text{mv}}^{2}[\/latex]. The mass of the [latex]\\beta [\/latex] particle is thousands of times less than that of the [latex]\\alpha [\/latex] s, so that [latex]\\beta [\/latex] s must travel much faster than [latex]\\alpha [\/latex] s to have the same energy. Since [latex]\\beta [\/latex] s move faster (most at relativistic speeds), they have less time to interact than [latex]\\alpha [\/latex] s. Gamma rays are photons, which must travel at the speed of light. They are even less likely to interact than a [latex]\\beta [\/latex], since they spend even less time near a given atom (and they have no charge). The range of [latex]\\gamma [\/latex] s is thus greater than the range of [latex]\\beta [\/latex] s.<\/p>\n<p id=\"import-auto-id3253816\">Alpha radiation from radioactive sources has a range much less than a millimeter of biological tissues, usually not enough to even penetrate the dead layers of our skin. On the other hand, the same [latex]\\alpha [\/latex] radiation can penetrate a few centimeters of air, so mere distance from a source prevents [latex]\\alpha [\/latex] radiation from reaching us. This makes [latex]\\alpha [\/latex] radiation relatively safe for our body compared to [latex]\\beta [\/latex] and [latex]\\gamma [\/latex] radiation. Typical [latex]\\beta [\/latex] radiation can penetrate a few millimeters of tissue or about a meter of air. Beta radiation is thus hazardous even when not ingested. The range of [latex]\\beta [\/latex] s in lead is about a millimeter, and so it is easy to store  [latex]\\beta [\/latex] sources in lead radiation-proof containers. Gamma rays have a much greater range than either [latex]\\alpha [\/latex]s or [latex]\\beta [\/latex]s. In fact, if a given thickness of material, like a lead brick, absorbs 90% of the [latex]\\gamma [\/latex]s, then a second lead brick will only absorb 90% of what got through the first. Thus, [latex]\\gamma [\/latex]s do not have a well-defined range; we can only cut down the amount that gets through. Typically, [latex]\\gamma [\/latex]s can penetrate many meters of air, go right through our bodies, and are effectively shielded (that is, reduced in intensity to acceptable levels) by many centimeters of lead. One benefit of [latex]\\gamma [\/latex]s is that they can be used as radioactive tracers (see <a href=\"#import-auto-id2589483\" class=\"autogenerated-content\">(Figure)<\/a>).<\/p>\n<div class=\"bc-figure figure\" id=\"import-auto-id2589483\">\n<div class=\"bc-figcaption figcaption\">This image of the concentration of a radioactive tracer in a patient\u2019s body reveals where the most active bone cells are, an indication of bone cancer. A short-lived radioactive substance that locates itself selectively is given to the patient, and the radiation is measured with an external detector. The emitted [latex]\\gamma [\/latex] radiation has a sufficient range to leave the body\u2014the range of [latex]\\alpha [\/latex] s and [latex]\\beta [\/latex] s is too small for them to be observed outside the patient. (credit: Kieran Maher, Wikimedia Commons)<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2402987\" data-alt=\"This figure shows four images of a skeleton of a human. Different parts of the body show bright spots wherever the bone cells are most active, indicating bone cancer.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_05a.jpg\" data-media-type=\"image\/png\" alt=\"This figure shows four images of a skeleton of a human. Different parts of the body show bright spots wherever the bone cells are most active, indicating bone cancer.\" width=\"250\"><\/span><\/p><\/div>\n<\/div>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">PhET Explorations: Beta Decay<\/div>\n<p id=\"eip-id1705720\">Watch beta decay occur for a collection of nuclei or for an individual nucleus.<\/p>\n<div class=\"bc-figure figure\" id=\"eip-id2686793\">\n<div class=\"bc-figcaption figcaption\"><a href=\"\/resources\/9ebd8ca8827071f35e8580ea6d2a7f92d83a0b2c\/beta-decay_en.jar\">Beta Decay<\/a><\/div>\n<p><span data-type=\"media\" id=\"Phet_module_32.1\" data-alt=\"\"><a href=\"\/resources\/9ebd8ca8827071f35e8580ea6d2a7f92d83a0b2c\/beta-decay_en.jar\" data-type=\"image\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/PhET_Icon.png\" data-media-type=\"image\/png\" alt=\"\" data-print=\"false\" width=\"450\"><\/a><span data-media-type=\"image\/png\" data-print=\"true\" data-src=\"\/resources\/075500ad9f71890a85fe3f7a4137ac08e2b7907c\/PhET_Icon.png\" data-type=\"image\"><\/span><\/span><\/p><\/div>\n<\/div>\n<div class=\"section-summary\" data-depth=\"1\">\n<h1 data-type=\"title\">Section Summary<\/h1>\n<ul id=\"fs-id2070975\">\n<li>Some nuclei are radioactive\u2014they spontaneously decay destroying some part of their mass and emitting energetic rays, a process called nuclear radioactivity.<\/li>\n<li id=\"import-auto-id3094443\">Nuclear radiation, like x rays, is ionizing radiation, because energy sufficient to ionize matter is emitted in each decay.<\/li>\n<li id=\"import-auto-id2381952\">The range (or distance traveled in a material) of ionizing radiation is directly related to the charge of the emitted particle and its energy, with greater-charge and lower-energy particles having the shortest ranges.<\/li>\n<li id=\"import-auto-id1916326\">Radiation detectors are based directly or indirectly upon the ionization created by radiation, as are the effects of radiation on living and inert materials.<\/li>\n<\/ul>\n<\/div>\n<div class=\"conceptual-questions\" data-depth=\"1\" id=\"fs-id3162312\" data-element-type=\"conceptual-questions\">\n<h1 data-type=\"title\">Conceptual Questions<\/h1>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id1575916\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\">\n<p id=\"import-auto-id2415626\">Suppose the range for [latex]5\\text{.}\\text{0&nbsp;MeV}\\alpha [\/latex] ray is known to be 2.0 mm in a certain material. Does this mean that every [latex]5\\text{.}\\text{0&nbsp;MeV}\\alpha [\/latex] a ray that strikes this material travels 2.0 mm, or does the range have an average value with some statistical fluctuations in the distances traveled? Explain.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2968914\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id3063012\">\n<p id=\"import-auto-id3359300\">What is the difference between <strong data-effect=\"bold\">[latex]\\gamma [\/latex]<\/strong> rays and characteristic x rays? Is either necessarily more energetic than the other? Which can be the most energetic?<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id2398885\">\n<p id=\"import-auto-id2044545\">Ionizing radiation interacts with matter by scattering from electrons and nuclei in the substance. Based on the law of conservation of momentum and energy, explain why electrons tend to absorb more energy than nuclei in these interactions.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\">\n<p id=\"import-auto-id2669079\">What characteristics of radioactivity show it to be nuclear in origin and not atomic?<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2392575\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id3006575\">\n<p id=\"import-auto-id3081359\">What is the source of the energy emitted in radioactive decay? Identify an earlier conservation law, and describe how it was modified to take such processes into account.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2397625\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id2628800\">\n<p id=\"import-auto-id1402635\">Consider <a href=\"#import-auto-id2600407\" class=\"autogenerated-content\">(Figure)<\/a>. If an electric field is substituted for the magnetic field with positive charge instead of the north pole and negative charge instead of the south pole, in which directions will the [latex]\\alpha [\/latex], [latex]\\beta [\/latex] , and [latex]\\gamma [\/latex] rays bend?<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id3007938\">\n<p id=\"import-auto-id3104414\">Explain how an [latex]\\alpha [\/latex] particle can have a larger range in air than a [latex]\\beta [\/latex] particle with the same energy in lead.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2621936\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id2405734\">\n<p id=\"import-auto-id3138305\">Arrange the following according to their ability to act as radiation shields, with the best first and worst last. Explain your ordering in terms of how radiation loses its energy in matter.<\/p>\n<p>(a) A solid material with low density composed of low-mass atoms.<\/p>\n<p id=\"import-auto-id2025977\">(b) A gas composed of high-mass atoms.<\/p>\n<p id=\"import-auto-id1514269\">(c) A gas composed of low-mass atoms.<\/p>\n<p id=\"import-auto-id2407944\">(d) A solid with high density composed of high-mass atoms.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id1548218\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id2067290\">\n<p id=\"fs-id1491342\">Often, when people have to work around radioactive materials spills, we see them wearing white coveralls (usually a plastic material). What types of radiation (if any) do you think these suits protect the worker from, and how?<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div data-type=\"glossary\" class=\"textbox shaded\">\n<h2 data-type=\"glossary-title\">Glossary<\/h2>\n<dl class=\"definition\" id=\"import-auto-id1609258\">\n<dt>alpha rays<\/dt>\n<dd id=\"fs-id2953612\">one of the types of rays emitted from the nucleus of an atom<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id1128778\">\n<dt>beta rays<\/dt>\n<dd id=\"fs-id2661356\">one of the types of rays emitted from the nucleus of an atom<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id3154827\">\n<dt>gamma rays<\/dt>\n<dd id=\"fs-id3226093\">one of the types of rays emitted from the nucleus of an atom<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id1420343\">\n<dt>ionizing radiation<\/dt>\n<dd>radiation (whether nuclear in origin or not) that produces ionization whether nuclear in origin or not<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id1586620\">\n<dt>nuclear radiation<\/dt>\n<dd id=\"fs-id2397219\"> rays that originate in the nuclei of atoms, the first examples of which were discovered by Becquerel<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id2436703\">\n<dt>radioactivity<\/dt>\n<dd id=\"fs-id1326421\">the emission of rays from the nuclei of atoms<\/dd>\n<\/dl>\n<dl class=\"definition\">\n<dt>radioactive<\/dt>\n<dd id=\"fs-id2598327\">a substance or object that emits nuclear radiation<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id3035538\">\n<dt>range of radiation<\/dt>\n<dd>the distance that the radiation can travel through a material<\/dd>\n<\/dl>\n<\/div>\n\n","rendered":"<div class=\"textbox learning-objectives\">\n<h3 itemprop=\"educationalUse\">Learning Objectives<\/h3>\n<ul>\n<li>Explain nuclear radiation.<\/li>\n<li>Explain the types of radiation\u2014alpha emission, beta emission, and gamma emission.<\/li>\n<li>Explain the ionization of radiation in an atom.<\/li>\n<li>Define the range of radiation.<\/li>\n<\/ul>\n<\/div>\n<p id=\"import-auto-id2382456\">The discovery and study of nuclear radioactivity quickly revealed evidence of revolutionary new physics. In addition, uses for nuclear radiation also emerged quickly\u2014for example, people such as Ernest Rutherford used it to determine the size of the nucleus and devices were painted with radon-doped paint to make them glow in the dark (see <a href=\"#import-auto-id3209830\" class=\"autogenerated-content\">(Figure)<\/a>). We therefore begin our study of nuclear physics with the discovery and basic features of nuclear radioactivity.<\/p>\n<div class=\"bc-figure figure\">\n<div class=\"bc-figcaption figcaption\">The dials of this World War II aircraft glow in the dark, because they are painted with radium-doped phosphorescent paint. It is a poignant reminder of the dual nature of radiation. Although radium paint dials are conveniently visible day and night, they emit radon, a radioactive gas that is hazardous and is not directly sensed. (credit: U.S. Air Force Photo)<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id3076369\" data-alt=\"The image shows an aircraft panel with lots of dial indicators, some levers and two wheels.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_01a.jpg\" data-media-type=\"image\/png\" alt=\"The image shows an aircraft panel with lots of dial indicators, some levers and two wheels.\" width=\"250\" \/><\/span><\/p>\n<\/div>\n<div class=\"bc-section section\" data-depth=\"1\" id=\"fs-id1448851\">\n<h1 data-type=\"title\">Discovery of Nuclear Radioactivity<\/h1>\n<p id=\"import-auto-id1177617\">In 1896, the French physicist Antoine Henri Becquerel (1852\u20131908) accidentally found that a uranium-rich mineral called pitchblende emits invisible, penetrating rays that can darken a photographic plate enclosed in an opaque envelope. The rays therefore carry energy; but amazingly, the pitchblende emits them continuously without any energy input. This is an apparent violation of the law of conservation of energy, one that we now understand is due to the conversion of a small amount of mass into energy, as related in Einstein\u2019s famous equation <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-ce3218fc87dd2f76cb174155609fe6f6_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#109;&#97;&#116;&#104;&#105;&#116;&#123;&#69;&#125;&#61;&#123;&#92;&#109;&#97;&#116;&#104;&#105;&#116;&#123;&#109;&#99;&#125;&#125;&#94;&#123;&#50;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"15\" width=\"67\" style=\"vertical-align: 0px;\" \/>. It was soon evident that Becquerel\u2019s rays originate in the nuclei of the atoms and have other unique characteristics. The emission of these rays is called <strong>nuclear radioactivity<\/strong> or simply <span data-type=\"term\">radioactivity<\/span>. The rays themselves are called <span data-type=\"term\">nuclear radiation<\/span>. A nucleus that spontaneously destroys part of its mass to emit radiation is said to <span data-type=\"term\">decay<\/span> (a term also used to describe the emission of radiation by atoms in excited states). A substance or object that emits nuclear radiation is said to be <span data-type=\"term\">radioactive<\/span>.<\/p>\n<p id=\"import-auto-id1514494\">Two types of experimental evidence imply that Becquerel\u2019s rays originate deep in the heart (or nucleus) of an atom. First, the radiation is found to be associated with certain elements, such as uranium. Radiation does not vary with chemical state\u2014that is, uranium is radioactive whether it is in the form of an element or compound. In addition, radiation does not vary with temperature, pressure, or ionization state of the uranium atom. Since all of these factors affect electrons in an atom, the radiation cannot come from electron transitions, as atomic spectra do. The huge energy emitted during each event is the second piece of evidence that the radiation cannot be atomic. Nuclear radiation has energies of the order of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-5e8fa32913a91293612b089aea565706_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#123;&#92;&#116;&#101;&#120;&#116;&#123;&#49;&#48;&#125;&#125;&#94;&#123;&#54;&#125;&#92;&#112;&#104;&#97;&#110;&#116;&#111;&#109;&#123;&#92;&#114;&#117;&#108;&#101;&#123;&#48;&#46;&#50;&#53;&#101;&#109;&#125;&#123;&#48;&#101;&#120;&#125;&#125;&#92;&#116;&#101;&#120;&#116;&#123;&#101;&#86;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"50\" style=\"vertical-align: -1px;\" \/> per event, which is much greater than the typical atomic energies (a few <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-df5b51e6a4c2654e1fab00740dbd3964_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#116;&#101;&#120;&#116;&#123;&#101;&#86;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"13\" width=\"21\" style=\"vertical-align: 0px;\" \/>), such as that observed in spectra and chemical reactions, and more than ten times as high as the most energetic characteristic x rays. Becquerel did not vigorously pursue his discovery for very long. In 1898, Marie Curie (1867\u20131934), then a graduate student married the already well-known French physicist Pierre Curie (1859\u20131906), began her doctoral study of Becquerel\u2019s rays. She and her husband soon discovered two new radioactive elements, which she named <em data-effect=\"italics\"><em data-effect=\"italics\">polonium<\/em><\/em> (after her native land) and <em data-effect=\"italics\"><em data-effect=\"italics\">radium<\/em><\/em> (because it radiates). These two new elements filled holes in the periodic table and, further, displayed much higher levels of radioactivity per gram of material than uranium. Over a period of four years, working under poor conditions and spending their own funds, the Curies processed more than a ton of uranium ore to isolate a gram of radium salt. Radium became highly sought after, because it was about two million times as radioactive as uranium. Curie\u2019s radium salt glowed visibly from the radiation that took its toll on them and other unaware researchers. Shortly after completing her Ph.D., both Curies and Becquerel shared the 1903 Nobel Prize in physics for their work on radioactivity. Pierre was killed in a horse cart accident in 1906, but Marie continued her study of radioactivity for nearly 30 more years. Awarded the 1911 Nobel Prize in chemistry for her discovery of two new elements, she remains the only person to win Nobel Prizes in physics and chemistry. Marie\u2019s radioactive fingerprints on some pages of her notebooks can still expose film, and she suffered from radiation-induced lesions. She died of leukemia likely caused by radiation, but she was active in research almost until her death in 1934. The following year, her daughter and son-in-law, Irene and Frederic Joliot-Curie, were awarded the Nobel Prize in chemistry for their discovery of artificially induced radiation, adding to a remarkable family legacy.<\/p>\n<\/div>\n<div class=\"bc-section section\" data-depth=\"1\" id=\"fs-id2407919\">\n<h1 data-type=\"title\">Alpha, Beta, and Gamma<\/h1>\n<p id=\"import-auto-id3422619\">Research begun by people such as New Zealander Ernest Rutherford soon after the discovery of nuclear radiation indicated that different types of rays are emitted. Eventually, three types were distinguished and named <span data-type=\"term\" id=\"import-auto-id1427002\">alpha<\/span><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-7a47ed793062f8fc5f69175611356c25_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#108;&#101;&#102;&#116;&#40;&#92;&#97;&#108;&#112;&#104;&#97;&#32;&#92;&#114;&#105;&#103;&#104;&#116;&#41;\" title=\"Rendered by QuickLaTeX.com\" height=\"18\" width=\"23\" style=\"vertical-align: -4px;\" \/>, <span data-type=\"term\" id=\"import-auto-id1517480\">beta<\/span><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4179749bf5340ad49f3415d91732e03b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#108;&#101;&#102;&#116;&#40;&#92;&#98;&#101;&#116;&#97;&#32;&#92;&#114;&#105;&#103;&#104;&#116;&#41;\" title=\"Rendered by QuickLaTeX.com\" height=\"18\" width=\"23\" style=\"vertical-align: -4px;\" \/>, and <span data-type=\"term\" id=\"import-auto-id1472534\">gamma<\/span><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-c60d1c626d991f2c014fb1e98cbe7ef1_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#108;&#101;&#102;&#116;&#40;&#92;&#103;&#97;&#109;&#109;&#97;&#32;&#92;&#114;&#105;&#103;&#104;&#116;&#41;\" title=\"Rendered by QuickLaTeX.com\" height=\"18\" width=\"22\" style=\"vertical-align: -4px;\" \/>, because, like x-rays, their identities were initially unknown. <a href=\"#import-auto-id2600407\" class=\"autogenerated-content\">(Figure)<\/a> shows what happens if the rays are passed through a magnetic field. The <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/>s are unaffected, while the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s are deflected in opposite directions, indicating the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s are positive, the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s negative, and the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> s uncharged. Rutherford used both magnetic and electric fields to show that <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s have a positive charge twice the magnitude of an electron, or <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-d92aaef9af7c6c2adacd4b12d7e0e9de_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#43;&#50;&#92;&#109;&#105;&#100;&#32;&#123;&#113;&#125;&#95;&#123;&#101;&#125;&#92;&#109;&#105;&#100;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"18\" width=\"60\" style=\"vertical-align: -4px;\" \/>. In the process, he found the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s charge to mass ratio to be several thousand times smaller than the electron\u2019s. Later on, Rutherford collected <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s from a radioactive source and passed an electric discharge through them, obtaining the spectrum of recently discovered helium gas. Among many important discoveries made by Rutherford and his collaborators was the proof that <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> <em data-effect=\"italics\">radiation is the emission of a helium nucleus<\/em>. Rutherford won the Nobel Prize in chemistry in 1908 for his early work. He continued to make important contributions until his death in 1934.<\/p>\n<div class=\"bc-figure figure\" id=\"import-auto-id2600407\">\n<div class=\"bc-figcaption figcaption\">Alpha, beta, and gamma rays are passed through a magnetic field on the way to a phosphorescent screen. The <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s bend in opposite directions, while the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> s are unaffected, indicating a positive charge for <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s, negative for <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s, and neutral for <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> s. Consistent results are obtained with electric fields. Collection of the radiation offers further confirmation from the direct measurement of excess charge.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1889078\" data-alt=\"The figure shows north and south poles of a magnet through which three rays labeled as alpha beta and gamma are passed. After passing through a magnetic field the alpha ray is slightly deflected toward the right. The beta ray is deflected toward the left and the gamma ray is not deflected.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_02a.jpg\" data-media-type=\"image\/jpg\" alt=\"The figure shows north and south poles of a magnet through which three rays labeled as alpha beta and gamma are passed. After passing through a magnetic field the alpha ray is slightly deflected toward the right. The beta ray is deflected toward the left and the gamma ray is not deflected.\" width=\"300\" \/><\/span><\/p>\n<\/div>\n<p id=\"import-auto-id1514401\">Other researchers had already proved that <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s are negative and have the same mass and same charge-to-mass ratio as the recently discovered electron. By 1902, it was recognized that <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> <em data-effect=\"italics\">radiation is the emission of an electron<\/em>. Although <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s are electrons, they do not exist in the nucleus before it decays and are not ejected atomic electrons\u2014the electron is created in the nucleus at the instant of decay.<\/p>\n<p id=\"import-auto-id1435020\">Since <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> s remain unaffected by electric and magnetic fields, it is natural to think they might be photons. Evidence for this grew, but it was not until 1914 that this was proved by Rutherford and collaborators. By scattering <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> radiation from a crystal and observing interference, they demonstrated that <strong data-effect=\"bold\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> <em data-effect=\"italics\">radiation is the emission of a high-energy photon by a nucleus<\/em>. In fact, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> radiation comes from the de-excitation of a nucleus, just as an x ray comes from the de-excitation of an atom. The names &#8220;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> ray&#8221; and &#8220;x ray&#8221; identify the source of the radiation. At the same energy, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> rays and x rays are otherwise identical.<\/strong><\/p>\n<table id=\"import-auto-id1888293\" summary=\"Types of radiation are listed in column 1. The range for each type is in column 2.\">\n<caption><span data-type=\"title\">Properties of Nuclear Radiation<\/span><\/caption>\n<thead>\n<tr>\n<th>\n              Type of Radiation\n            <\/th>\n<th>\n              Range\n            <\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/>-Particles<\/td>\n<td>A sheet of paper, a few cm of air, fractions of a mm of tissue<\/td>\n<\/tr>\n<tr>\n<td><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/>-Particles<\/td>\n<td>A thin aluminum plate, or tens of cm of tissue<\/td>\n<\/tr>\n<tr>\n<td><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> Rays<\/td>\n<td>Several cm of lead or meters of concrete<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"bc-section section\" data-depth=\"1\" id=\"fs-id3226082\">\n<h1 data-type=\"title\">Ionization and Range<\/h1>\n<p id=\"import-auto-id969060\">Two of the most important characteristics of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/>, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/>, and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> rays were recognized very early. All three types of nuclear radiation produce <em data-effect=\"italics\"><em data-effect=\"italics\">ionization<\/em><\/em> in materials, but they penetrate different distances in materials\u2014that is, they have different <em data-effect=\"italics\"><em data-effect=\"italics\">ranges<\/em><\/em>. Let us examine why they have these characteristics and what are some of the consequences.<\/p>\n<p id=\"import-auto-id1901135\">Like x rays, nuclear radiation in the form of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s, and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> s has enough energy per event to ionize atoms and molecules in any material. The energy emitted in various nuclear decays ranges from a few <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-90adde6b62192844d6d1bd7b4091d00d_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#116;&#101;&#120;&#116;&#123;&#107;&#101;&#86;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"13\" width=\"30\" style=\"vertical-align: 0px;\" \/> to more than <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-e56d4c210566b80c7746e987e29b4255_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#116;&#101;&#120;&#116;&#123;&#49;&#48;&#32;&#77;&#101;&#86;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"14\" width=\"60\" style=\"vertical-align: -1px;\" \/>, while only a few <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-df5b51e6a4c2654e1fab00740dbd3964_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#116;&#101;&#120;&#116;&#123;&#101;&#86;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"13\" width=\"21\" style=\"vertical-align: 0px;\" \/> are needed to produce ionization. The effects of x rays and nuclear radiation on biological tissues and other materials, such as solid state electronics, are directly related to the ionization they produce. All of them, for example, can damage electronics or kill cancer cells. In addition, methods for detecting x rays and nuclear radiation are based on ionization, directly or indirectly. All of them can ionize the air between the plates of a capacitor, for example, causing it to discharge. This is the basis of inexpensive personal radiation monitors, such as pictured in <a href=\"#import-auto-id1900612\" class=\"autogenerated-content\">(Figure)<\/a>. Apart from <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/>, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/>, and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/>, there are other forms of nuclear radiation as well, and these also produce ionization with similar effects. We define <span data-type=\"term\" id=\"import-auto-id2968914\">ionizing radiation<\/span><strong data-effect=\"bold\"> as any form of radiation that produces ionization whether nuclear in origin or not, since the effects and detection of the radiation are related to ionization.<\/strong><\/p>\n<div class=\"bc-figure figure\">\n<div class=\"bc-figcaption figcaption\">These dosimeters (literally, dose meters) are personal radiation monitors that detect the amount of radiation by the discharge of a rechargeable internal capacitor. The amount of discharge is related to the amount of ionizing radiation encountered, a measurement of dose. One dosimeter is shown in the charger. Its scale is read through an eyepiece on the top. (credit: L. Chang, Wikimedia Commons)<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1871385\" data-alt=\"Image shows a person\u2019s hand holding a cylindrical object placed near a small piece of radioactive material. A dial indicator is connected to the cylindrical radiation detector.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_03a.jpg\" data-media-type=\"image\/png\" alt=\"Image shows a person\u2019s hand holding a cylindrical object placed near a small piece of radioactive material. A dial indicator is connected to the cylindrical radiation detector.\" width=\"250\" \/><\/span><\/p>\n<\/div>\n<p>The <span data-type=\"term\" id=\"import-auto-id1587169\">range of radiation<\/span> is defined to be the distance it can travel through a material. Range is related to several factors, including the energy of the radiation, the material encountered, and the type of radiation (see <a href=\"#import-auto-id3385282\" class=\"autogenerated-content\">(Figure)<\/a>). The higher the <em data-effect=\"italics\"><em data-effect=\"italics\">energy<\/em><\/em>, the greater the range, all other factors being the same. This makes good sense, since radiation loses its energy in materials primarily by producing ionization in them, and each ionization of an atom or a molecule requires energy that is removed from the radiation. The amount of ionization is, thus, directly proportional to the energy of the particle of radiation, as is its range.<\/p>\n<p id=\"import-auto-id1405600\">\n<div class=\"bc-figure figure\" id=\"import-auto-id3385282\">\n<div class=\"bc-figcaption figcaption\">The penetration or range of radiation depends on its energy, the material it encounters, and the type of radiation. (a) Greater energy means greater range. (b) Radiation has a smaller range in materials with high electron density. (c) Alphas have the smallest range, betas have a greater range, and gammas penetrate the farthest.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1514585\" data-alt=\"Three cases of range of radiation are shown. The first case shows that higher energy has greater range than lower energy. The second case shows that, for same energy material having high electron density will have lower range. The third case shows that among alpha beta and gamma rays for the same energy alphas have the smallest range betas have a greater range and gammas penetrate the farthest.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_04a.jpg\" data-media-type=\"image\/jpg\" alt=\"Three cases of range of radiation are shown. The first case shows that higher energy has greater range than lower energy. The second case shows that, for same energy material having high electron density will have lower range. The third case shows that among alpha beta and gamma rays for the same energy alphas have the smallest range betas have a greater range and gammas penetrate the farthest.\" width=\"550\" \/><\/span><\/p>\n<\/div>\n<p>Radiation can be absorbed or shielded by materials, such as the lead aprons dentists drape on us when taking x rays. Lead is a particularly effective shield compared with other materials, such as plastic or air. How does the range of radiation depend on <em data-effect=\"italics\"><em data-effect=\"italics\">material<\/em><\/em>? Ionizing radiation interacts best with charged particles in a material. Since electrons have small masses, they most readily absorb the energy of the radiation in collisions. The greater the density of a material and, in particular, the greater the density of electrons within a material, the smaller the range of radiation.<\/p>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" id=\"fs-id3139051\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">Collisions<\/div>\n<p id=\"import-auto-id2680091\">Conservation of energy and momentum often results in energy transfer to a less massive object in a collision. This was discussed in detail in <a href=\"\/contents\/643b6e4a-de21-4a14-a677-b0d4c5ddb2d5@2\">Work, Energy, and Energy Resources<\/a>, for example.<\/p>\n<\/div>\n<p id=\"import-auto-id3077371\">Different <em data-effect=\"italics\"><em data-effect=\"italics\">types<\/em><\/em> of radiation have different ranges when compared at the same energy and in the same material. Alphas have the shortest range, betas penetrate farther, and gammas have the greatest range. This is directly related to charge and speed of the particle or type of radiation. At a given energy, each<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/>,<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/>, or<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> will produce the same number of ionizations in a material (each ionization requires a certain amount of energy on average). The more readily the particle produces ionization, the more quickly it will lose its energy. The effect of <em data-effect=\"italics\"><em data-effect=\"italics\">charge<\/em><\/em> is as follows: The <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> has a charge of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-eb2d2af57a78cfbb88acf6d9ca4c420c_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#43;&#123;&#50;&#113;&#125;&#95;&#123;&#101;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"37\" style=\"vertical-align: -4px;\" \/> , the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> has a charge of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-d75ef3133f65dcc5ce2320fffcea4410_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#45;&#123;&#113;&#125;&#95;&#123;&#101;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"27\" style=\"vertical-align: -4px;\" \/> , and the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> is uncharged. The electromagnetic force exerted by the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> is thus twice as strong as that exerted by the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> and it is more likely to produce ionization. Although chargeless, the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> does interact weakly because it is an electromagnetic wave, but it is less likely to produce ionization in any encounter. More quantitatively, the change in momentum <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-125a21e735bc4d008977a427433b1f51_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#68;&#101;&#108;&#116;&#97;&#32;&#112;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"24\" style=\"vertical-align: -4px;\" \/> given to a particle in the material is <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-fe7d67a704cd2dfebaaee6933895ad87_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#68;&#101;&#108;&#116;&#97;&#32;&#112;&#61;&#70;&#92;&#68;&#101;&#108;&#116;&#97;&#32;&#116;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"82\" style=\"vertical-align: -4px;\" \/>, where <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-2510519bbe1660dfdffb4195c7287343_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#70;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"14\" style=\"vertical-align: 0px;\" \/> is the force the<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/>,<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/>, or<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> exerts over a time<br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-0714636704a254c71bede042781bc57a_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#68;&#101;&#108;&#116;&#97;&#32;&#116;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"21\" style=\"vertical-align: 0px;\" \/>. The smaller the charge, the smaller is <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-2510519bbe1660dfdffb4195c7287343_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#70;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"14\" style=\"vertical-align: 0px;\" \/> and the smaller is the momentum (and energy) lost. Since the speed of alphas is about 5% to 10% of the speed of light, classical (non-relativistic) formulas apply.<\/p>\n<p>The <em data-effect=\"italics\"><em data-effect=\"italics\">speed<\/em><\/em> at which they travel is the other major factor affecting the range of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s, and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> s. The faster they move, the less time they spend in the vicinity of an atom or a molecule, and the less likely they are to interact. Since <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s are particles with mass (helium nuclei and electrons, respectively), their energy is kinetic, given classically by <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-14f1547faf0d8f6e115b7bbdaaa5d4c0_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#102;&#114;&#97;&#99;&#123;&#49;&#125;&#123;&#50;&#125;&#123;&#92;&#116;&#101;&#120;&#116;&#123;&#109;&#118;&#125;&#125;&#94;&#123;&#50;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"22\" width=\"39\" style=\"vertical-align: -6px;\" \/>. The mass of the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> particle is thousands of times less than that of the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s, so that <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s must travel much faster than <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s to have the same energy. Since <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s move faster (most at relativistic speeds), they have less time to interact than <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s. Gamma rays are photons, which must travel at the speed of light. They are even less likely to interact than a <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/>, since they spend even less time near a given atom (and they have no charge). The range of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> s is thus greater than the range of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s.<\/p>\n<p id=\"import-auto-id3253816\">Alpha radiation from radioactive sources has a range much less than a millimeter of biological tissues, usually not enough to even penetrate the dead layers of our skin. On the other hand, the same <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> radiation can penetrate a few centimeters of air, so mere distance from a source prevents <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> radiation from reaching us. This makes <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> radiation relatively safe for our body compared to <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> radiation. Typical <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> radiation can penetrate a few millimeters of tissue or about a meter of air. Beta radiation is thus hazardous even when not ingested. The range of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s in lead is about a millimeter, and so it is easy to store  <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> sources in lead radiation-proof containers. Gamma rays have a much greater range than either <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/>s or <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/>s. In fact, if a given thickness of material, like a lead brick, absorbs 90% of the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/>s, then a second lead brick will only absorb 90% of what got through the first. Thus, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/>s do not have a well-defined range; we can only cut down the amount that gets through. Typically, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/>s can penetrate many meters of air, go right through our bodies, and are effectively shielded (that is, reduced in intensity to acceptable levels) by many centimeters of lead. One benefit of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/>s is that they can be used as radioactive tracers (see <a href=\"#import-auto-id2589483\" class=\"autogenerated-content\">(Figure)<\/a>).<\/p>\n<div class=\"bc-figure figure\" id=\"import-auto-id2589483\">\n<div class=\"bc-figcaption figcaption\">This image of the concentration of a radioactive tracer in a patient\u2019s body reveals where the most active bone cells are, an indication of bone cancer. A short-lived radioactive substance that locates itself selectively is given to the patient, and the radiation is measured with an external detector. The emitted <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> radiation has a sufficient range to leave the body\u2014the range of <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> s and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> s is too small for them to be observed outside the patient. (credit: Kieran Maher, Wikimedia Commons)<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2402987\" data-alt=\"This figure shows four images of a skeleton of a human. Different parts of the body show bright spots wherever the bone cells are most active, indicating bone cancer.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_01_05a.jpg\" data-media-type=\"image\/png\" alt=\"This figure shows four images of a skeleton of a human. Different parts of the body show bright spots wherever the bone cells are most active, indicating bone cancer.\" width=\"250\" \/><\/span><\/p>\n<\/div>\n<\/div>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">PhET Explorations: Beta Decay<\/div>\n<p id=\"eip-id1705720\">Watch beta decay occur for a collection of nuclei or for an individual nucleus.<\/p>\n<div class=\"bc-figure figure\" id=\"eip-id2686793\">\n<div class=\"bc-figcaption figcaption\"><a href=\"\/resources\/9ebd8ca8827071f35e8580ea6d2a7f92d83a0b2c\/beta-decay_en.jar\">Beta Decay<\/a><\/div>\n<p><span data-type=\"media\" id=\"Phet_module_32.1\" data-alt=\"\"><a href=\"\/resources\/9ebd8ca8827071f35e8580ea6d2a7f92d83a0b2c\/beta-decay_en.jar\" data-type=\"image\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/PhET_Icon.png\" data-media-type=\"image\/png\" alt=\"\" data-print=\"false\" width=\"450\" \/><\/a><span data-media-type=\"image\/png\" data-print=\"true\" data-src=\"\/resources\/075500ad9f71890a85fe3f7a4137ac08e2b7907c\/PhET_Icon.png\" data-type=\"image\"><\/span><\/span><\/p>\n<\/div>\n<\/div>\n<div class=\"section-summary\" data-depth=\"1\">\n<h1 data-type=\"title\">Section Summary<\/h1>\n<ul id=\"fs-id2070975\">\n<li>Some nuclei are radioactive\u2014they spontaneously decay destroying some part of their mass and emitting energetic rays, a process called nuclear radioactivity.<\/li>\n<li id=\"import-auto-id3094443\">Nuclear radiation, like x rays, is ionizing radiation, because energy sufficient to ionize matter is emitted in each decay.<\/li>\n<li id=\"import-auto-id2381952\">The range (or distance traveled in a material) of ionizing radiation is directly related to the charge of the emitted particle and its energy, with greater-charge and lower-energy particles having the shortest ranges.<\/li>\n<li id=\"import-auto-id1916326\">Radiation detectors are based directly or indirectly upon the ionization created by radiation, as are the effects of radiation on living and inert materials.<\/li>\n<\/ul>\n<\/div>\n<div class=\"conceptual-questions\" data-depth=\"1\" id=\"fs-id3162312\" data-element-type=\"conceptual-questions\">\n<h1 data-type=\"title\">Conceptual Questions<\/h1>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id1575916\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\">\n<p id=\"import-auto-id2415626\">Suppose the range for <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-e83adf302a47ad1200b4539824784c25_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#53;&#92;&#116;&#101;&#120;&#116;&#123;&#46;&#125;&#92;&#116;&#101;&#120;&#116;&#123;&#48;&#32;&#77;&#101;&#86;&#125;&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"14\" width=\"77\" style=\"vertical-align: -1px;\" \/> ray is known to be 2.0 mm in a certain material. Does this mean that every <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-e83adf302a47ad1200b4539824784c25_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#53;&#92;&#116;&#101;&#120;&#116;&#123;&#46;&#125;&#92;&#116;&#101;&#120;&#116;&#123;&#48;&#32;&#77;&#101;&#86;&#125;&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"14\" width=\"77\" style=\"vertical-align: -1px;\" \/> a ray that strikes this material travels 2.0 mm, or does the range have an average value with some statistical fluctuations in the distances traveled? Explain.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2968914\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id3063012\">\n<p id=\"import-auto-id3359300\">What is the difference between <strong data-effect=\"bold\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/><\/strong> rays and characteristic x rays? Is either necessarily more energetic than the other? Which can be the most energetic?<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id2398885\">\n<p id=\"import-auto-id2044545\">Ionizing radiation interacts with matter by scattering from electrons and nuclei in the substance. Based on the law of conservation of momentum and energy, explain why electrons tend to absorb more energy than nuclei in these interactions.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\">\n<p id=\"import-auto-id2669079\">What characteristics of radioactivity show it to be nuclear in origin and not atomic?<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2392575\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id3006575\">\n<p id=\"import-auto-id3081359\">What is the source of the energy emitted in radioactive decay? Identify an earlier conservation law, and describe how it was modified to take such processes into account.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2397625\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id2628800\">\n<p id=\"import-auto-id1402635\">Consider <a href=\"#import-auto-id2600407\" class=\"autogenerated-content\">(Figure)<\/a>. If an electric field is substituted for the magnetic field with positive charge instead of the north pole and negative charge instead of the south pole, in which directions will the <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/>, <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> , and <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-4dfd339d0f13026ff7af56aa6f129380_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#103;&#97;&#109;&#109;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"12\" width=\"10\" style=\"vertical-align: -4px;\" \/> rays bend?<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id3007938\">\n<p id=\"import-auto-id3104414\">Explain how an <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-946f8144d4e3d460c8621773145884d3_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#97;&#108;&#112;&#104;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"8\" width=\"11\" style=\"vertical-align: 0px;\" \/> particle can have a larger range in air than a <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-39ffee81b79fbfa10c128d48495e8b8b_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#98;&#101;&#116;&#97;&#32;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"11\" style=\"vertical-align: -4px;\" \/> particle with the same energy in lead.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2621936\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id2405734\">\n<p id=\"import-auto-id3138305\">Arrange the following according to their ability to act as radiation shields, with the best first and worst last. Explain your ordering in terms of how radiation loses its energy in matter.<\/p>\n<p>(a) A solid material with low density composed of low-mass atoms.<\/p>\n<p id=\"import-auto-id2025977\">(b) A gas composed of high-mass atoms.<\/p>\n<p id=\"import-auto-id1514269\">(c) A gas composed of low-mass atoms.<\/p>\n<p id=\"import-auto-id2407944\">(d) A solid with high density composed of high-mass atoms.<\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id1548218\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id2067290\">\n<p id=\"fs-id1491342\">Often, when people have to work around radioactive materials spills, we see them wearing white coveralls (usually a plastic material). What types of radiation (if any) do you think these suits protect the worker from, and how?<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div data-type=\"glossary\" class=\"textbox shaded\">\n<h2 data-type=\"glossary-title\">Glossary<\/h2>\n<dl class=\"definition\" id=\"import-auto-id1609258\">\n<dt>alpha rays<\/dt>\n<dd id=\"fs-id2953612\">one of the types of rays emitted from the nucleus of an atom<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id1128778\">\n<dt>beta rays<\/dt>\n<dd id=\"fs-id2661356\">one of the types of rays emitted from the nucleus of an atom<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id3154827\">\n<dt>gamma rays<\/dt>\n<dd id=\"fs-id3226093\">one of the types of rays emitted from the nucleus of an atom<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id1420343\">\n<dt>ionizing radiation<\/dt>\n<dd>radiation (whether nuclear in origin or not) that produces ionization whether nuclear in origin or not<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id1586620\">\n<dt>nuclear radiation<\/dt>\n<dd id=\"fs-id2397219\"> rays that originate in the nuclei of atoms, the first examples of which were discovered by Becquerel<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id2436703\">\n<dt>radioactivity<\/dt>\n<dd id=\"fs-id1326421\">the emission of rays from the nuclei of atoms<\/dd>\n<\/dl>\n<dl class=\"definition\">\n<dt>radioactive<\/dt>\n<dd id=\"fs-id2598327\">a substance or object that emits nuclear radiation<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id3035538\">\n<dt>range of radiation<\/dt>\n<dd>the distance that the radiation can travel through a material<\/dd>\n<\/dl>\n<\/div>\n","protected":false},"author":211,"menu_order":1,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":"all-rights-reserved"},"chapter-type":[],"contributor":[],"license":[56],"class_list":["post-1672","chapter","type-chapter","status-publish","hentry","license-all-rights-reserved"],"part":1663,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1672","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/users\/211"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1672\/revisions"}],"predecessor-version":[{"id":1673,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1672\/revisions\/1673"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/parts\/1663"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1672\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/media?parent=1672"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapter-type?post=1672"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/contributor?post=1672"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/license?post=1672"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}