http://debianws.lexgopc.com/wiki143/index.php?action=history&feed=atom&title=Geiger%E2%80%93M%C3%BCller_tubeGeiger–Müller tube - Revision history2026-05-30T18:29:59ZRevision history for this page on the wikiMediaWiki 1.43.1http://debianws.lexgopc.com/wiki143/index.php?title=Geiger%E2%80%93M%C3%BCller_tube&diff=4380554&oldid=previmported>Neon coyote: /* growthexperiments-addlink-summary-summary:2|1|0 */2025-12-19T21:42:03Z<p><span class="autocomment">growthexperiments-addlink-summary-summary:2|1|0</span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 21:42, 19 December 2025</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Gas mixtures==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Gas mixtures==</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The components of the gas mixture are vital to the operation and application of a G-M tube. The mixture is composed of an inert gas such as [[helium]], [[argon]] or [[neon]] which is ionized by incident radiation, and a "quench" gas of 5–10% of an organic vapor or a halogen gas to prevent spurious pulsing by quenching the electron avalanches.<ref name="knoll"/> This combination of gases is known as a [[Penning mixture]] and makes use of the [[Penning ionization]] effect.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The components of the gas mixture are vital to the operation and application of a G-M tube. The mixture is composed of an <ins style="font-weight: bold; text-decoration: none;">[[</ins>inert gas<ins style="font-weight: bold; text-decoration: none;">]] </ins>such as [[helium]], [[argon]] or [[neon]] which is ionized by incident radiation, and a "quench" gas of 5–10% of an organic vapor or a halogen gas to prevent spurious pulsing by quenching the electron avalanches.<ref name="knoll"/> This combination of gases is known as a [[Penning mixture]] and makes use of the [[Penning ionization]] effect.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The modern halogen-filled G–M tube was invented by [[Sidney H. Liebson]] in 1947 and has several advantages over the older tubes with organic mixtures.<ref>{{cite journal |first=S. H. |last=Liebson |year=1947 |title=The discharge mechanism of self-quenching Geiger–Mueller counters |journal=Physical Review |volume=72 |issue=7 |pages=602–608 |doi=10.1103/physrev.72.602|bibcode = 1947PhRv...72..602L |hdl=1903/17793 |url=http://drum.lib.umd.edu/bitstream/1903/17793/1/DP70461.pdf |hdl-access=free }}</ref> The halogen tube discharge takes advantage of a [[metastable]] state of the inert gas atom to more-readily ionize a halogen molecule than an organic vapor, enabling the tube to operate at much lower voltages, typically 400–600 volts instead of 900–1200 volts. While halogen-quenched tubes have greater plateau voltage slopes compared to organic-quenched tubes (an undesirable quality), they have a vastly longer life than tubes quenched with organic compounds. This is because an organic vapor is gradually destroyed by the discharge process, giving organic-quenched tubes a useful life of around 10<sup>9</sup> events. However, halogen ions can recombine over time, giving halogen-quenched tubes an effectively unlimited lifetime for most uses, although they will still eventually fail at some point due to other ionization-initiated processes that limit the lifetime of all Geiger tubes. For these reasons, the halogen-quenched tube is now the most common.<ref name="knoll"/></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The modern halogen-filled G–M tube was invented by [[Sidney H. Liebson]] in 1947 and has several advantages over the older tubes with organic mixtures.<ref>{{cite journal |first=S. H. |last=Liebson |year=1947 |title=The discharge mechanism of self-quenching Geiger–Mueller counters |journal=Physical Review |volume=72 |issue=7 |pages=602–608 |doi=10.1103/physrev.72.602|bibcode = 1947PhRv...72..602L |hdl=1903/17793 |url=http://drum.lib.umd.edu/bitstream/1903/17793/1/DP70461.pdf |hdl-access=free }}</ref> The halogen tube discharge takes advantage of a [[metastable]] state of the inert gas atom to more-readily ionize a halogen molecule than an organic vapor, enabling the tube to operate at much lower voltages, typically 400–600 volts instead of 900–1200 volts. While halogen-quenched tubes have greater plateau voltage slopes compared to organic-quenched tubes (an undesirable quality), they have a vastly longer life than tubes quenched with organic compounds. This is because an organic vapor is gradually destroyed by the discharge process, giving organic-quenched tubes a useful life of around 10<sup>9</sup> events. However, halogen ions can recombine over time, giving halogen-quenched tubes an effectively unlimited lifetime for most uses, although they will still eventually fail at some point due to other ionization-initiated processes that limit the lifetime of all Geiger tubes. For these reasons, the halogen-quenched tube is now the most common.<ref name="knoll"/></div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Pure noble gases exhibit threshold voltages increasing with increasing atomic weight. Addition of polyatomic organic quenchers increases threshold voltage, due to dissipation of large percentage of collisions energy in molecular vibrations. Argon with alcohol vapors was one of the most common fills of early tubes. As little as 1 ppm of impurities (argon, mercury, and krypton in neon) can significantly lower the threshold voltage. Admixture of chlorine or bromine provides quenching and stability to low-voltage neon-argon mixtures, with wide temperature range. Lower operating voltages lead to longer rise times of pulses, without appreciably changing the dead times.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Pure noble gases exhibit threshold voltages increasing with increasing atomic weight. Addition of polyatomic organic quenchers increases threshold voltage, due to dissipation of large percentage of collisions energy in molecular vibrations. Argon with alcohol vapors was one of the most common fills of early tubes. As little as 1 ppm of impurities (argon, mercury, and krypton in neon) can significantly lower the threshold voltage. Admixture of chlorine or bromine provides quenching and stability to low-voltage neon-argon mixtures, with wide temperature range. Lower operating voltages lead to longer rise times of pulses, without appreciably changing the dead times.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Spurious pulses are caused mostly by secondary electrons emitted by the cathode due to positive ion bombardment. The resulting spurious pulses have the nature of a relaxation oscillator and show uniform spacing, dependent on the tube fill gas and overvoltage. At high enough overvoltages, but still below the onset of continuous corona discharges, sequences of thousands of pulses can be produced. Such spurious counts can be suppressed by coating the cathode with higher [[work function]] materials, chemical passivation, lacquer coating, etc.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Spurious pulses are caused mostly by secondary electrons emitted by the cathode due to positive ion bombardment. The resulting spurious pulses have the nature of a <ins style="font-weight: bold; text-decoration: none;">[[</ins>relaxation oscillator<ins style="font-weight: bold; text-decoration: none;">]] </ins>and show uniform spacing, dependent on the tube fill gas and overvoltage. At high enough overvoltages, but still below the onset of continuous corona discharges, sequences of thousands of pulses can be produced. Such spurious counts can be suppressed by coating the cathode with higher [[work function]] materials, chemical passivation, lacquer coating, etc.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The organic quenchers can decompose to smaller molecules (ethyl alcohol and ethyl acetate) or polymerize into solid deposits (typical for methane). Degradation products of organic molecules may or may not have quenching properties. Larger molecules degrade to more quenching products than small ones; tubes quenched with amyl acetate tend to have ten times higher lifetime than ethanol ones. Tubes quenched with hydrocarbons often fail due to coating of the electrodes with polymerization products, before the gas itself can be depleted; simple gas refill won't help, washing the electrodes to remove the deposits is necessary. Low ionization efficiency is sometimes deliberately sought; mixtures of low pressure hydrogen or helium with organic quenchers are used in some cosmic rays experiments, to detect heavily ionizing muons and electrons.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The organic quenchers can decompose to smaller molecules (ethyl alcohol and ethyl acetate) or polymerize into solid deposits (typical for methane). Degradation products of organic molecules may or may not have quenching properties. Larger molecules degrade to more quenching products than small ones; tubes quenched with amyl acetate tend to have ten times higher lifetime than ethanol ones. Tubes quenched with hydrocarbons often fail due to coating of the electrodes with polymerization products, before the gas itself can be depleted; simple gas refill won't help, washing the electrodes to remove the deposits is necessary. Low ionization efficiency is sometimes deliberately sought; mixtures of low pressure hydrogen or helium with organic quenchers are used in some cosmic rays experiments, to detect heavily ionizing muons and electrons.</div></td></tr>
</table>imported>Neon coyotehttp://debianws.lexgopc.com/wiki143/index.php?title=Geiger%E2%80%93M%C3%BCller_tube&diff=3239401&oldid=previmported>Rowing007: Fixed per MOS2025-11-12T13:59:23Z<p>Fixed per MOS</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 13:59, 12 November 2025</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{short description|Part of a Geiger counter}}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{short description|Part of a Geiger counter}}</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[File:Geiger counter.jpg|thumb|right| A complete Geiger counter, with the Geiger–Müller tube mounted in a cylindrical enclosure connected by a cable to the instrument<del style="font-weight: bold; text-decoration: none;">.</del>]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[File:Geiger counter.jpg|thumb|right| A complete Geiger counter, with the Geiger–Müller tube mounted in a cylindrical enclosure connected by a cable to the instrument]]</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''Geiger–Müller tube''' or '''G–M tube''' is the sensing element of the [[Geiger counter]] instrument used for the detection of [[ionizing radiation]]. It is named after [[Hans Geiger]], who invented the principle in 1908,<ref>{{cite journal |first1=E. |last1=Rutherford |author1-link=Ernest Rutherford |first2=H. |last2=Geiger |year=1908 |author2-link=Hans Geiger |title=An electrical method of counting the number of α particles from radioactive substances |journal=Proceedings of the Royal Society |location=London |series=Series A |volume=81 |issue=546 |pages=141–161 |doi=10.1098/rspa.1908.0065|bibcode = 1908RSPSA..81..141R |doi-access=free }}</ref> and [[Walther Müller]], who collaborated with Geiger in developing the technique further in 1928 to produce a practical tube that could detect a number of different radiation types.<ref>{{cite journal</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The '''Geiger–Müller tube''' or '''G–M tube''' is the sensing element of the [[Geiger counter]] instrument used for the detection of [[ionizing radiation]]. It is named after [[Hans Geiger]], who invented the principle in 1908,<ref>{{cite journal |first1=E. |last1=Rutherford |author1-link=Ernest Rutherford |first2=H. |last2=Geiger |year=1908 |author2-link=Hans Geiger |title=An electrical method of counting the number of α particles from radioactive substances |journal=Proceedings of the Royal Society |location=London |series=Series A |volume=81 |issue=546 |pages=141–161 |doi=10.1098/rspa.1908.0065|bibcode = 1908RSPSA..81..141R |doi-access=free }}</ref> and [[Walther Müller]], who collaborated with Geiger in developing the technique further in 1928 to produce a practical tube that could detect a number of different radiation types.<ref>{{cite journal</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> | title = Elektronenzählrohr zur Messung schwächster Aktivitäten |trans-title=Electron counting tube for measurement of weakest radioactivities |language=de</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> | title = Elektronenzählrohr zur Messung schwächster Aktivitäten |trans-title=Electron counting tube for measurement of weakest radioactivities |language=de</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A G-M tube consists of a chamber filled with a gas mixture at a low pressure of about 0.1 [[Atmosphere (unit)|atmosphere]]. The chamber contains two electrodes, between which there is a potential difference of several hundred [[volt]]s. The walls of the tube are either metal or have their inside surface coated with a conducting material or a spiral wire to form the [[cathode]], while the [[anode]] is a [[wire]] mounted axially in the center of the chamber.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A G-M tube consists of a chamber filled with a gas mixture at a low pressure of about 0.1 [[Atmosphere (unit)|atmosphere]]. The chamber contains two electrodes, between which there is a potential difference of several hundred [[volt]]s. The walls of the tube are either metal or have their inside surface coated with a conducting material or a spiral wire to form the [[cathode]], while the [[anode]] is a [[wire]] mounted axially in the center of the chamber.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>When [[ionizing radiation]] strikes the tube, some molecules of the fill gas are ionized directly by the incident radiation, and if the tube cathode is an electrical conductor, such as stainless steel, indirectly by means of secondary electrons produced in the walls of the tube, which migrate into the gas. This creates positively charged [[ion]]s and free [[electron]]s, known as [[Ionization|ion pairs]], in the gas. The strong electric field created by the voltage across the tube's electrodes accelerates the positive ions towards the cathode and the electrons towards the anode. Close to the anode in the "avalanche region" where the electric field strength rises inversely proportional to radial distance as the anode is approached, free electrons gain sufficient energy to ionize additional gas molecules by collision and create a large number of [[Townsend discharge|electron avalanches]]. These spread along the anode and effectively throughout the avalanche region. This is the "gas multiplication" effect which gives the tube its key characteristic of being able to produce a significant output pulse from a single original ionizing event.<ref name="knoll">Glenn F Knoll. ''Radiation Detection and Measurement'', third edition 2000. John Wiley and sons, {{ISBN|0-471-07338-5}}</ref></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>When [[ionizing radiation]] strikes the tube, some molecules of the fill gas are ionized directly by the incident radiation, and if the tube cathode is an electrical conductor, such as stainless steel, indirectly by means of secondary electrons produced in the walls of the tube, which migrate into the gas. This creates positively charged [[ion]]s and free [[electron]]s, known as [[Ionization|ion pairs]], in the gas. The strong <ins style="font-weight: bold; text-decoration: none;">[[</ins>electric field<ins style="font-weight: bold; text-decoration: none;">]] </ins>created by the voltage across the tube's electrodes accelerates the positive ions towards the cathode and the electrons towards the anode. Close to the anode in the "avalanche region" where the electric field strength rises inversely proportional to radial distance as the anode is approached, free electrons gain sufficient energy to ionize additional gas molecules by collision and create a large number of [[Townsend discharge|electron avalanches]]. These spread along the anode and effectively throughout the avalanche region. This is the "gas multiplication" effect which gives the tube its key characteristic of being able to produce a significant output pulse from a single original ionizing event.<ref name="knoll">Glenn F Knoll. ''Radiation Detection and Measurement'', third edition 2000. John Wiley and sons, {{ISBN|0-471-07338-5}}</ref></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>If there were to be only one avalanche per original ionizing event, then the number of excited molecules would be in the order of 10<sup>6</sup> to 10<sup>8</sup>. However the production of ''multiple avalanches'' results in an increased multiplication factor which can produce 10<sup>9</sup> to 10<sup>10</sup> ion pairs.<ref name="knoll"/> The creation of multiple avalanches is due to the production of UV photons in the original avalanche, which are not affected by the electric field and move laterally to the axis of the anode to instigate further ionizing events by collision with gas molecules. These collisions produce further avalanches, which in turn produce more photons, and thereby more avalanches in a chain reaction which spreads laterally through the fill gas, and envelops the anode wire. The accompanying diagram shows this graphically. The speed of propagation of the avalanches is typically 2–4&nbsp;cm per microsecond, so that for common sizes of tubes the complete ionization of the gas around the anode takes just a few microseconds.<ref name="knoll"/></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>If there were to be only one avalanche per original ionizing event, then the number of excited molecules would be in the order of 10<sup>6</sup> to 10<sup>8</sup>. However the production of ''multiple avalanches'' results in an increased multiplication factor which can produce 10<sup>9</sup> to 10<sup>10</sup> ion pairs.<ref name="knoll"/> The creation of multiple avalanches is due to the production of UV photons in the original avalanche, which are not affected by the electric field and move laterally to the axis of the anode to instigate further ionizing events by collision with gas molecules. These collisions produce further avalanches, which in turn produce more photons, and thereby more avalanches in a chain reaction which spreads laterally through the fill gas, and envelops the anode wire. The accompanying diagram shows this graphically. The speed of propagation of the avalanches is typically 2–4&nbsp;cm per microsecond, so that for common sizes of tubes the complete ionization of the gas around the anode takes just a few microseconds.<ref name="knoll"/></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This short, intense pulse of current can be measured as a ''count event'' in the form of a voltage pulse developed across an external electrical resistor. This can be in the order of volts, thus making further electronic processing simple.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>This short, intense pulse of current can be measured as a ''count event'' in the form of a voltage pulse developed across an external electrical resistor. This can be in the order of volts, thus making further electronic processing simple.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The discharge is terminated by the collective effect of the positive ions created by the avalanches. These ions have lower mobility than the free electrons due to their higher mass and move slowly from the vicinity of the anode wire. This creates a "space charge" which counteracts the electric field that is necessary for continued avalanche generation. For a particular tube geometry and operating voltage this termination always occurs when a certain number of avalanches has been created, therefore the pulses from the tube are always of the same magnitude regardless of the energy of the initiating particle. Consequently, there is no radiation energy information in the pulses<ref name="knoll"/> which means the Geiger–Müller tube cannot be used to generate spectral information about the incident radiation. In practice the termination of the avalanche is improved by the use of "quenching" techniques (see later).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The discharge is terminated by the collective effect of the positive ions created by the avalanches. These ions have lower mobility than the free electrons due to their higher mass and move slowly from the vicinity of the anode wire. This creates a "<ins style="font-weight: bold; text-decoration: none;">[[</ins>space charge<ins style="font-weight: bold; text-decoration: none;">]]</ins>" which counteracts the electric field that is necessary for continued avalanche generation. For a particular tube geometry and operating voltage this termination always occurs when a certain number of avalanches has been created, therefore the pulses from the tube are always of the same magnitude regardless of the energy of the initiating particle. Consequently, there is no radiation energy information in the pulses<ref name="knoll"/> which means the Geiger–Müller tube cannot be used to generate spectral information about the incident radiation. In practice the termination of the avalanche is improved by the use of "quenching" techniques (see later).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Pressure of the fill gas is important in the generation of avalanches. Too low a pressure and the efficiency of interaction with incident radiation is reduced. Too high a pressure, and the <del style="font-weight: bold; text-decoration: none;">“mean </del>free <del style="font-weight: bold; text-decoration: none;">path” </del>for collisions between accelerated electrons and the fill gas is too small, and the electrons cannot gather enough energy between each collision to cause ionization of the gas. The energy gained by electrons is proportional to the ratio “e/p”, where “e” is the electric field strength at that point in the gas, and “p” is the gas pressure.<ref name="knoll"/></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Pressure of the fill gas is important in the generation of avalanches. Too low a pressure and the efficiency of interaction with incident radiation is reduced. Too high a pressure, and the <ins style="font-weight: bold; text-decoration: none;">“[[mean </ins>free <ins style="font-weight: bold; text-decoration: none;">path]]” </ins>for collisions between accelerated electrons and the fill gas is too small, and the electrons cannot gather enough energy between each collision to cause ionization of the gas. The energy gained by electrons is proportional to the ratio “e/p”, where “e” is the electric field strength at that point in the gas, and “p” is the gas pressure.<ref name="knoll"/></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Types of tube==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Types of tube==</div></td></tr>
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