{"id":1677,"date":"2017-10-27T16:32:40","date_gmt":"2017-10-27T16:32:40","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/chapter\/radiation-detection-and-detectors\/"},"modified":"2017-11-08T03:27:48","modified_gmt":"2017-11-08T03:27:48","slug":"radiation-detection-and-detectors","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/chapter\/radiation-detection-and-detectors\/","title":{"raw":"Radiation Detection and Detectors","rendered":"Radiation Detection and Detectors"},"content":{"raw":"\n<div class=\"textbox learning-objectives\">\n<h3 itemprop=\"educationalUse\">Learning Objectives<\/h3>\n<ul>\n<li>Explain the working principle of a Geiger tube.<\/li>\n<li>Define and discuss radiation detectors.<\/li>\n<\/ul>\n<\/div>\n<p id=\"import-auto-id3022820\">It is well known that ionizing radiation affects us but does not trigger nerve impulses. Newspapers carry stories about unsuspecting victims of radiation poisoning who fall ill with radiation sickness, such as burns and blood count changes, but who never felt the radiation directly. This makes the detection of radiation by instruments more than an important research tool. This section is a brief overview of radiation detection and some of its applications.<\/p>\n<div class=\"bc-section section\" data-depth=\"1\" id=\"fs-id3017872\">\n<h1 data-type=\"title\">Human Application<\/h1>\n<p id=\"import-auto-id3165264\">The first direct detection of radiation was Becquerel\u2019s fogged photographic plate. Photographic film is still the most common detector of ionizing radiation, being used routinely in medical and dental x rays. Nuclear radiation is also captured on film, such as seen in <a href=\"#import-auto-id3076369\" class=\"autogenerated-content\">(Figure)<\/a>. The mechanism for film exposure by ionizing radiation is similar to that by photons. A quantum of energy interacts with the emulsion and alters it chemically, thus exposing the film. The quantum  come from an [latex]\\alpha [\/latex]-particle, [latex]\\beta [\/latex]-particle, or photon, provided it has more than the few eV of energy needed to induce the chemical change (as does all ionizing radiation). The process is not 100% efficient, since not all incident radiation interacts and not all interactions produce the chemical change. The amount of film darkening is related to exposure, but the darkening also depends on the type of radiation, so that absorbers and other devices must be used to obtain energy, charge, and particle-identification information.<\/p>\n<div class=\"bc-figure figure\">\n<div class=\"bc-figcaption figcaption\">Film badges contain film similar to that used in  this dental x-ray film and is sandwiched between various absorbers to determine the penetrating ability of the radiation as well as the amount. (credit: Werneuchen, Wikimedia Commons)<\/div>\n<p><span data-type=\"media\" data-alt=\"Image shows fingers holding a black strip of film on a radioactive rock.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_02_01a.jpg\" data-media-type=\"image\/png\" alt=\"Image shows fingers holding a black strip of film on a radioactive rock.\" width=\"250\"><\/span><\/p><\/div>\n<p id=\"import-auto-id2056101\">Another very common <span data-type=\"term\" id=\"import-auto-id2017624\">radiation detector<\/span> is the <span data-type=\"term\" id=\"import-auto-id3177120\">Geiger tube<\/span>. The clicking and buzzing sound we hear in dramatizations and documentaries, as well as in our own physics labs, is usually an audio output of events detected by a Geiger counter. These relatively inexpensive radiation detectors are based on the simple and sturdy Geiger tube, shown schematically in <a href=\"#import-auto-id3027822\" class=\"autogenerated-content\">(Figure)<\/a>(b). A conducting cylinder with a wire along its axis is filled with an insulating gas so that a voltage applied between the cylinder and wire produces almost no current. Ionizing radiation passing through the tube produces free ion pairs that are attracted to the wire and cylinder, forming a current that is detected as a count. The word count implies that there is no information on energy, charge, or type of radiation with a simple Geiger counter. They do not detect every particle, since some radiation can pass through without producing enough ionization to be detected. However, Geiger counters are very useful in producing a prompt output that reveals the existence and relative intensity of ionizing radiation.<\/p>\n<div class=\"bc-figure figure\" id=\"import-auto-id3027822\">\n<div class=\"bc-figcaption figcaption\">(a) Geiger counters such as this one are used for prompt monitoring of radiation levels, generally giving only relative intensity and not identifying the type or energy of the radiation. (credit: TimVickers, Wikimedia Commons) (b) Voltage applied between the cylinder and wire in a Geiger tube causes ions and electrons produced by radiation passing through the gas-filled cylinder to move towards them. The resulting current is detected and registered as a count.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2453959\" data-alt=\"Image of Geiger counter and its working principle is shown. A small detector with handle is attached to a voltage dial indicator. Voltage applied between the cylinder and wire in a Geiger tube causes ions and electrons produced by incoming radiation passing through the gas-filled cylinder to move towards them.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_02_02a.jpg\" data-media-type=\"image\/png\" alt=\"Image of Geiger counter and its working principle is shown. A small detector with handle is attached to a voltage dial indicator. Voltage applied between the cylinder and wire in a Geiger tube causes ions and electrons produced by incoming radiation passing through the gas-filled cylinder to move towards them.\" width=\"400\"><\/span><\/p><\/div>\n<p>Another radiation detection method records light produced when radiation interacts with materials. The energy of the radiation is sufficient to excite atoms in a material that may fluoresce, such as the phosphor used by Rutherford\u2019s group. Materials called <span data-type=\"term\">scintillators<\/span> use a more complex collaborative process to convert radiation energy into light. Scintillators may be liquid or solid, and they can be very efficient. Their light output can provide information about the energy, charge, and type of radiation. Scintillator light flashes are very brief in duration, enabling the detection of a huge number of particles in short periods of time. Scintillator detectors are used in a variety of research and diagnostic applications. Among these are the detection by satellite-mounted equipment of the radiation from distant galaxies, the analysis of radiation from a person indicating body burdens, and the detection of exotic particles in accelerator laboratories.<\/p>\n<p id=\"import-auto-id3234433\">Light from a scintillator is converted into electrical signals by devices such as the <span data-type=\"term\" id=\"import-auto-id2929794\">photomultiplier<\/span> tube shown schematically in <a href=\"#import-auto-id3089405\" class=\"autogenerated-content\">(Figure)<\/a>. These tubes are based on the photoelectric effect, which is multiplied in stages into a cascade of electrons, hence the name photomultiplier. Light entering the photomultiplier strikes a metal plate, ejecting an electron that is attracted by a positive potential difference to the next plate, giving it enough energy to eject two or more electrons, and so on. The final output current can be made proportional to the energy of the light entering the tube, which is in turn proportional to the energy deposited in the scintillator. Very sophisticated information can be obtained with scintillators, including energy, charge, particle identification, direction of motion, and so on.<\/p>\n<div class=\"bc-figure figure\" id=\"import-auto-id3089405\">\n<div class=\"bc-figcaption figcaption\">Photomultipliers use the photoelectric effect on the photocathode to convert the light output of a scintillator into an electrical signal. Each successive dynode has a more-positive potential than the last and attracts the ejected electrons, giving them more energy. The number of electrons is thus multiplied at each dynode, resulting in an easily detected output current.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2051574\" data-alt=\"A cylindrical tube contains several curved plates labeled dynodes. Incoming radiation passes through a scintillating material at the top of the cylindrical tube. The photon thus produced generates a photoelectron at the photocathode and the photoelectron is then multiplied by collisions at the several successive dynodes, creating a sizable output electric pulse.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_02_04a.jpg\" data-media-type=\"image\/jpg\" alt=\"A cylindrical tube contains several curved plates labeled dynodes. Incoming radiation passes through a scintillating material at the top of the cylindrical tube. The photon thus produced generates a photoelectron at the photocathode and the photoelectron is then multiplied by collisions at the several successive dynodes, creating a sizable output electric pulse.\" width=\"300\"><\/span><\/p><\/div>\n<p id=\"import-auto-id1817248\"><span data-type=\"term\" id=\"import-auto-id2589898\">Solid-state radiation detectors<\/span> convert ionization produced in a semiconductor (like those found in computer chips) directly into an electrical signal. Semiconductors can be constructed that do not conduct current in one particular direction. When a voltage is applied in that direction, current flows only when ionization is produced by radiation, similar to what happens in a Geiger tube. Further, the amount of current in a solid-state detector is closely related to the energy deposited and, since the detector is solid, it can have a high efficiency (since ionizing radiation is stopped in a shorter distance in solids fewer particles escape detection). As with scintillators, very sophisticated information can be obtained from solid-state detectors.<\/p>\n<\/div>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">PhET Explorations: Radioactive Dating Game<\/div>\n<p id=\"eip-id1190954\">Learn about different types of radiometric dating, such as carbon dating. Understand how decay and half life work to enable radiometric dating to work. Play a game that tests your ability to match the percentage of the dating element that remains to the age of the object. <\/p>\n<div class=\"bc-figure figure\" id=\"fs-id1942522\">\n<div class=\"bc-figcaption figcaption\"><a href=\"\/resources\/05aca8e9759894c05372dc7d2495a1a8d555adbf\/radioactive-dating-game_en.jar\">Radioactive Dating Game<\/a><\/div>\n<p><span data-type=\"media\" id=\"fs-id1992725\" data-alt=\"\"><a href=\"\/resources\/05aca8e9759894c05372dc7d2495a1a8d555adbf\/radioactive-dating-game_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\" id=\"fs-id2969225\">\n<h1 data-type=\"title\">Section Summary<\/h1>\n<ul id=\"fs-id1587135\">\n<li>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-id2042988\" data-element-type=\"conceptual-questions\">\n<h1 data-type=\"title\">Conceptual Questions<\/h1>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id1517480\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id1446888\">\n<p id=\"import-auto-id1568371\"> Is it possible for light emitted by a scintillator to be too low in frequency to be used in a photomultiplier tube? Explain.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"problems-exercises\" data-depth=\"1\" id=\"fs-id1967602\" data-element-type=\"problems-exercises\">\n<h1 data-type=\"title\">Problems &amp; Exercises<\/h1>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2437827\" data-element-type=\"problems-exercises\">\n<div data-type=\"problem\" class=\"problem\">\n<p id=\"import-auto-id1823725\">The energy of 30.0 [latex]\\text{eV}[\/latex] is required to ionize a molecule of the gas inside a Geiger tube, thereby producing an ion pair. Suppose a particle of ionizing radiation deposits 0.500 MeV of energy in this Geiger tube. What maximum number of ion pairs can it create?<\/p>\n<\/div>\n<div data-type=\"solution\" class=\"solution\" id=\"fs-id1864068\">\n[latex]1.67\u00d7{\\text{10}}^{4}[\/latex]\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"problems-exercises\">\n<div data-type=\"problem\" class=\"problem\">\n<p id=\"eip-437\">A particle of ionizing radiation creates 4000 ion pairs in the gas inside a Geiger tube as it passes through. What minimum energy was deposited, if 30.0 [latex]\\text{eV}[\/latex]  is required to create each ion pair?\n  <\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"eip-811\" data-element-type=\"problems-exercises\">\n<div data-type=\"problem\" class=\"problem\">\n<p>(a) Repeat <a href=\"#eip-144\" class=\"autogenerated-content\">(Figure)<\/a>, and convert the energy to joules or calories. (b) If all of this energy is converted to thermal energy in the gas, what is its temperature increase, assuming [latex]\\text{50.0 c}{\\text{m}}^{3}[\/latex]  of ideal gas at 0.250-atm pressure? (The small answer is consistent with the fact that the energy is large on a quantum mechanical scale but small on a macroscopic scale.)\n  <\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"problems-exercises\">\n<div data-type=\"problem\" class=\"problem\">\n<p>Suppose a particle of ionizing radiation deposits 1.0 MeV in the gas of a Geiger tube, all of which goes to creating ion pairs. Each ion pair requires 30.0 eV of energy. (a) The applied voltage sweeps the ions out of the gas in  [latex]\\text{1.00}\\phantom{\\rule{0.25em}{0ex}}\\mu \\text{s}[\/latex]. What is the current? (b) This current is smaller than the actual current since the applied voltage in the Geiger tube accelerates the separated ions, which then create other ion pairs in subsequent collisions. What is the current if this last effect multiplies the number of ion pairs by 900?<\/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-id3037273\">\n<dt>Geiger tube<\/dt>\n<dd id=\"fs-id3379134\">a very common radiation detector that usually gives an audio output<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id2681604\">\n<dt>photomultiplier<\/dt>\n<dd id=\"fs-id3079793\">a device that converts light into electrical signals<\/dd>\n<\/dl>\n<dl class=\"definition\">\n<dt>radiation detector<\/dt>\n<dd id=\"fs-id3079442\">a device that is used to detect and track the radiation from a radioactive reaction<\/dd>\n<\/dl>\n<dl class=\"definition\">\n<dt>scintillators<\/dt>\n<dd id=\"fs-id1842845\">a radiation detection method that  records light produced when radiation interacts with materials<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id1401769\">\n<dt>solid-state radiation detectors<\/dt>\n<dd id=\"fs-id1848799\">semiconductors fabricated to directly convert incident radiation into electrical current<\/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 the working principle of a Geiger tube.<\/li>\n<li>Define and discuss radiation detectors.<\/li>\n<\/ul>\n<\/div>\n<p id=\"import-auto-id3022820\">It is well known that ionizing radiation affects us but does not trigger nerve impulses. Newspapers carry stories about unsuspecting victims of radiation poisoning who fall ill with radiation sickness, such as burns and blood count changes, but who never felt the radiation directly. This makes the detection of radiation by instruments more than an important research tool. This section is a brief overview of radiation detection and some of its applications.<\/p>\n<div class=\"bc-section section\" data-depth=\"1\" id=\"fs-id3017872\">\n<h1 data-type=\"title\">Human Application<\/h1>\n<p id=\"import-auto-id3165264\">The first direct detection of radiation was Becquerel\u2019s fogged photographic plate. Photographic film is still the most common detector of ionizing radiation, being used routinely in medical and dental x rays. Nuclear radiation is also captured on film, such as seen in <a href=\"#import-auto-id3076369\" class=\"autogenerated-content\">(Figure)<\/a>. The mechanism for film exposure by ionizing radiation is similar to that by photons. A quantum of energy interacts with the emulsion and alters it chemically, thus exposing the film. The quantum  come from 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, <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, or photon, provided it has more than the few eV of energy needed to induce the chemical change (as does all ionizing radiation). The process is not 100% efficient, since not all incident radiation interacts and not all interactions produce the chemical change. The amount of film darkening is related to exposure, but the darkening also depends on the type of radiation, so that absorbers and other devices must be used to obtain energy, charge, and particle-identification information.<\/p>\n<div class=\"bc-figure figure\">\n<div class=\"bc-figcaption figcaption\">Film badges contain film similar to that used in  this dental x-ray film and is sandwiched between various absorbers to determine the penetrating ability of the radiation as well as the amount. (credit: Werneuchen, Wikimedia Commons)<\/div>\n<p><span data-type=\"media\" data-alt=\"Image shows fingers holding a black strip of film on a radioactive rock.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_02_01a.jpg\" data-media-type=\"image\/png\" alt=\"Image shows fingers holding a black strip of film on a radioactive rock.\" width=\"250\" \/><\/span><\/p>\n<\/div>\n<p id=\"import-auto-id2056101\">Another very common <span data-type=\"term\" id=\"import-auto-id2017624\">radiation detector<\/span> is the <span data-type=\"term\" id=\"import-auto-id3177120\">Geiger tube<\/span>. The clicking and buzzing sound we hear in dramatizations and documentaries, as well as in our own physics labs, is usually an audio output of events detected by a Geiger counter. These relatively inexpensive radiation detectors are based on the simple and sturdy Geiger tube, shown schematically in <a href=\"#import-auto-id3027822\" class=\"autogenerated-content\">(Figure)<\/a>(b). A conducting cylinder with a wire along its axis is filled with an insulating gas so that a voltage applied between the cylinder and wire produces almost no current. Ionizing radiation passing through the tube produces free ion pairs that are attracted to the wire and cylinder, forming a current that is detected as a count. The word count implies that there is no information on energy, charge, or type of radiation with a simple Geiger counter. They do not detect every particle, since some radiation can pass through without producing enough ionization to be detected. However, Geiger counters are very useful in producing a prompt output that reveals the existence and relative intensity of ionizing radiation.<\/p>\n<div class=\"bc-figure figure\" id=\"import-auto-id3027822\">\n<div class=\"bc-figcaption figcaption\">(a) Geiger counters such as this one are used for prompt monitoring of radiation levels, generally giving only relative intensity and not identifying the type or energy of the radiation. (credit: TimVickers, Wikimedia Commons) (b) Voltage applied between the cylinder and wire in a Geiger tube causes ions and electrons produced by radiation passing through the gas-filled cylinder to move towards them. The resulting current is detected and registered as a count.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2453959\" data-alt=\"Image of Geiger counter and its working principle is shown. A small detector with handle is attached to a voltage dial indicator. Voltage applied between the cylinder and wire in a Geiger tube causes ions and electrons produced by incoming radiation passing through the gas-filled cylinder to move towards them.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_02_02a.jpg\" data-media-type=\"image\/png\" alt=\"Image of Geiger counter and its working principle is shown. A small detector with handle is attached to a voltage dial indicator. Voltage applied between the cylinder and wire in a Geiger tube causes ions and electrons produced by incoming radiation passing through the gas-filled cylinder to move towards them.\" width=\"400\" \/><\/span><\/p>\n<\/div>\n<p>Another radiation detection method records light produced when radiation interacts with materials. The energy of the radiation is sufficient to excite atoms in a material that may fluoresce, such as the phosphor used by Rutherford\u2019s group. Materials called <span data-type=\"term\">scintillators<\/span> use a more complex collaborative process to convert radiation energy into light. Scintillators may be liquid or solid, and they can be very efficient. Their light output can provide information about the energy, charge, and type of radiation. Scintillator light flashes are very brief in duration, enabling the detection of a huge number of particles in short periods of time. Scintillator detectors are used in a variety of research and diagnostic applications. Among these are the detection by satellite-mounted equipment of the radiation from distant galaxies, the analysis of radiation from a person indicating body burdens, and the detection of exotic particles in accelerator laboratories.<\/p>\n<p id=\"import-auto-id3234433\">Light from a scintillator is converted into electrical signals by devices such as the <span data-type=\"term\" id=\"import-auto-id2929794\">photomultiplier<\/span> tube shown schematically in <a href=\"#import-auto-id3089405\" class=\"autogenerated-content\">(Figure)<\/a>. These tubes are based on the photoelectric effect, which is multiplied in stages into a cascade of electrons, hence the name photomultiplier. Light entering the photomultiplier strikes a metal plate, ejecting an electron that is attracted by a positive potential difference to the next plate, giving it enough energy to eject two or more electrons, and so on. The final output current can be made proportional to the energy of the light entering the tube, which is in turn proportional to the energy deposited in the scintillator. Very sophisticated information can be obtained with scintillators, including energy, charge, particle identification, direction of motion, and so on.<\/p>\n<div class=\"bc-figure figure\" id=\"import-auto-id3089405\">\n<div class=\"bc-figcaption figcaption\">Photomultipliers use the photoelectric effect on the photocathode to convert the light output of a scintillator into an electrical signal. Each successive dynode has a more-positive potential than the last and attracts the ejected electrons, giving them more energy. The number of electrons is thus multiplied at each dynode, resulting in an easily detected output current.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2051574\" data-alt=\"A cylindrical tube contains several curved plates labeled dynodes. Incoming radiation passes through a scintillating material at the top of the cylindrical tube. The photon thus produced generates a photoelectron at the photocathode and the photoelectron is then multiplied by collisions at the several successive dynodes, creating a sizable output electric pulse.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_32_02_04a.jpg\" data-media-type=\"image\/jpg\" alt=\"A cylindrical tube contains several curved plates labeled dynodes. Incoming radiation passes through a scintillating material at the top of the cylindrical tube. The photon thus produced generates a photoelectron at the photocathode and the photoelectron is then multiplied by collisions at the several successive dynodes, creating a sizable output electric pulse.\" width=\"300\" \/><\/span><\/p>\n<\/div>\n<p id=\"import-auto-id1817248\"><span data-type=\"term\" id=\"import-auto-id2589898\">Solid-state radiation detectors<\/span> convert ionization produced in a semiconductor (like those found in computer chips) directly into an electrical signal. Semiconductors can be constructed that do not conduct current in one particular direction. When a voltage is applied in that direction, current flows only when ionization is produced by radiation, similar to what happens in a Geiger tube. Further, the amount of current in a solid-state detector is closely related to the energy deposited and, since the detector is solid, it can have a high efficiency (since ionizing radiation is stopped in a shorter distance in solids fewer particles escape detection). As with scintillators, very sophisticated information can be obtained from solid-state detectors.<\/p>\n<\/div>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">PhET Explorations: Radioactive Dating Game<\/div>\n<p id=\"eip-id1190954\">Learn about different types of radiometric dating, such as carbon dating. Understand how decay and half life work to enable radiometric dating to work. Play a game that tests your ability to match the percentage of the dating element that remains to the age of the object. <\/p>\n<div class=\"bc-figure figure\" id=\"fs-id1942522\">\n<div class=\"bc-figcaption figcaption\"><a href=\"\/resources\/05aca8e9759894c05372dc7d2495a1a8d555adbf\/radioactive-dating-game_en.jar\">Radioactive Dating Game<\/a><\/div>\n<p><span data-type=\"media\" id=\"fs-id1992725\" data-alt=\"\"><a href=\"\/resources\/05aca8e9759894c05372dc7d2495a1a8d555adbf\/radioactive-dating-game_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\" id=\"fs-id2969225\">\n<h1 data-type=\"title\">Section Summary<\/h1>\n<ul id=\"fs-id1587135\">\n<li>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-id2042988\" data-element-type=\"conceptual-questions\">\n<h1 data-type=\"title\">Conceptual Questions<\/h1>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id1517480\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id1446888\">\n<p id=\"import-auto-id1568371\"> Is it possible for light emitted by a scintillator to be too low in frequency to be used in a photomultiplier tube? Explain.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"problems-exercises\" data-depth=\"1\" id=\"fs-id1967602\" data-element-type=\"problems-exercises\">\n<h1 data-type=\"title\">Problems &amp; Exercises<\/h1>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id2437827\" data-element-type=\"problems-exercises\">\n<div data-type=\"problem\" class=\"problem\">\n<p id=\"import-auto-id1823725\">The energy of 30.0 <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;\" \/> is required to ionize a molecule of the gas inside a Geiger tube, thereby producing an ion pair. Suppose a particle of ionizing radiation deposits 0.500 MeV of energy in this Geiger tube. What maximum number of ion pairs can it create?<\/p>\n<\/div>\n<div data-type=\"solution\" class=\"solution\" id=\"fs-id1864068\">\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-a5154e74846eb2a8ae5db7cc4ea5c4ce_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#49;&#46;&#54;&#55;&times;&#123;&#92;&#116;&#101;&#120;&#116;&#123;&#49;&#48;&#125;&#125;&#94;&#123;&#52;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"55\" style=\"vertical-align: -1px;\" \/>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"problems-exercises\">\n<div data-type=\"problem\" class=\"problem\">\n<p id=\"eip-437\">A particle of ionizing radiation creates 4000 ion pairs in the gas inside a Geiger tube as it passes through. What minimum energy was deposited, if 30.0 <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;\" \/>  is required to create each ion pair?\n  <\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" id=\"eip-811\" data-element-type=\"problems-exercises\">\n<div data-type=\"problem\" class=\"problem\">\n<p>(a) Repeat <a href=\"#eip-144\" class=\"autogenerated-content\">(Figure)<\/a>, and convert the energy to joules or calories. (b) If all of this energy is converted to thermal energy in the gas, what is its temperature increase, assuming <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-72ec8b97245b8bf57d9ae11b5da079b7_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#116;&#101;&#120;&#116;&#123;&#53;&#48;&#46;&#48;&#32;&#99;&#125;&#123;&#92;&#116;&#101;&#120;&#116;&#123;&#109;&#125;&#125;&#94;&#123;&#51;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"15\" width=\"67\" style=\"vertical-align: 0px;\" \/>  of ideal gas at 0.250-atm pressure? (The small answer is consistent with the fact that the energy is large on a quantum mechanical scale but small on a macroscopic scale.)\n  <\/p>\n<\/div>\n<\/div>\n<div data-type=\"exercise\" class=\"exercise\" data-element-type=\"problems-exercises\">\n<div data-type=\"problem\" class=\"problem\">\n<p>Suppose a particle of ionizing radiation deposits 1.0 MeV in the gas of a Geiger tube, all of which goes to creating ion pairs. Each ion pair requires 30.0 eV of energy. (a) The applied voltage sweeps the ions out of the gas in  <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-content\/ql-cache\/quicklatex.com-9684b7fb806be1a6ed7beddade6a5401_l3.png\" class=\"ql-img-inline-formula quicklatex-auto-format\" alt=\"&#92;&#116;&#101;&#120;&#116;&#123;&#49;&#46;&#48;&#48;&#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;&#109;&#117;&#32;&#92;&#116;&#101;&#120;&#116;&#123;&#115;&#125;\" title=\"Rendered by QuickLaTeX.com\" height=\"16\" width=\"53\" style=\"vertical-align: -4px;\" \/>. What is the current? (b) This current is smaller than the actual current since the applied voltage in the Geiger tube accelerates the separated ions, which then create other ion pairs in subsequent collisions. What is the current if this last effect multiplies the number of ion pairs by 900?<\/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-id3037273\">\n<dt>Geiger tube<\/dt>\n<dd id=\"fs-id3379134\">a very common radiation detector that usually gives an audio output<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id2681604\">\n<dt>photomultiplier<\/dt>\n<dd id=\"fs-id3079793\">a device that converts light into electrical signals<\/dd>\n<\/dl>\n<dl class=\"definition\">\n<dt>radiation detector<\/dt>\n<dd id=\"fs-id3079442\">a device that is used to detect and track the radiation from a radioactive reaction<\/dd>\n<\/dl>\n<dl class=\"definition\">\n<dt>scintillators<\/dt>\n<dd id=\"fs-id1842845\">a radiation detection method that  records light produced when radiation interacts with materials<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id1401769\">\n<dt>solid-state radiation detectors<\/dt>\n<dd id=\"fs-id1848799\">semiconductors fabricated to directly convert incident radiation into electrical current<\/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-1677","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\/1677","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\/1677\/revisions"}],"predecessor-version":[{"id":1678,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1677\/revisions\/1678"}],"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\/1677\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/media?parent=1677"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapter-type?post=1677"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/contributor?post=1677"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/license?post=1677"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}