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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Alpha particle</span></span>

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</style><table class="infobox"><caption class="infobox-title">Alpha particle</caption><tbody><tr><td colspan="2" class="infobox-image"><div class="infobox-caption"><a href="Alpha_decay" title="Alpha decay">Alpha decay</a></div></td></tr><tr><th scope="row" class="infobox-label"><a href="Particle#Composition" title="Particle">Composition</a></th><td class="infobox-data">2 protons, 2 neutrons</td></tr><tr><th scope="row" class="infobox-label"><a href="Particle_statistics" title="Particle statistics">Statistics</a></th><td class="infobox-data"><a href="Boson" title="Boson">Bosonic</a></td></tr><tr><th scope="row" class="infobox-label">Symbol</th><td class="infobox-data">α, α<sup>2+</sup>, He<sup>2+</sup></td></tr><tr><th scope="row" class="infobox-label"><a href="Invariant_mass" title="Invariant mass">Mass</a></th><td class="infobox-data"><span class="nowrap">6.644<span style="margin-left:.25em;">657</span><span style="margin-left:.25em;">3450</span>(21)<span style="margin-left:0.25em;margin-right:0.15em;">×</span>10<sup>−27</sup> kg</span><span style="visibility:hidden; color:transparent; padding-left:2px">‍</span><sup id="cite_ref-physconst-malpha_1-0" class="reference"><a href="#cite_note-physconst-malpha-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><br><span class="nowrap">4.001<span style="margin-left:.25em;">506</span><span style="margin-left:.25em;">179</span><span style="margin-left:.25em;">129</span>(62) Da</span><span style="visibility:hidden; color:transparent; padding-left:2px">‍</span><sup id="cite_ref-physconst-malphaDa_2-0" class="reference"><a href="#cite_note-physconst-malphaDa-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><br><span class="nowrap">3.727<span style="margin-left:.25em;">379</span><span style="margin-left:.25em;">4118</span>(11) <span class="nowrap"><a href="Electronvolt#Mass" title="Electronvolt">GeV/<i>c</i><sup>2</sup></a></span></span><span style="visibility:hidden; color:transparent; padding-left:2px">‍</span><sup id="cite_ref-physconst-malphac2GeV_3-0" class="reference"><a href="#cite_note-physconst-malphac2GeV-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup></td></tr><tr><th scope="row" class="infobox-label"><a href="Electric_charge" title="Electric charge">Electric charge</a></th><td class="infobox-data">+2 <a href="Elementary_charge" title="Elementary charge"><i>e</i></a></td></tr><tr><th scope="row" class="infobox-label"><a href="Spin_(physics)" title="Spin (physics)">Spin</a></th><td class="infobox-data">0 <a href="Reduced_Planck_constant" class="mw-redirect" title="Reduced Planck constant"><i>ħ</i></a><sup id="cite_ref-Krane_4-0" class="reference"><a href="#cite_note-Krane-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup></td></tr></tbody></table>

<p><b>Alpha particles</b>, also called <b>alpha rays</b> or <b>alpha radiation</b>, consist of two <a href="Proton" title="Proton">protons</a> and two <a href="Neutron" title="Neutron">neutrons</a> bound together into a <a href="Particle" title="Particle">particle</a> identical to a <a href="Helium-4" title="Helium-4">helium-4</a> <a href="Atomic_nucleus" title="Atomic nucleus">nucleus</a>.<sup id="cite_ref-:02_5-0" class="reference"><a href="#cite_note-:02-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> They are generally produced in the process of <a href="Alpha_decay" title="Alpha decay">alpha decay</a> but may also be produced in different ways. Alpha particles are named after the first letter in the <a href="Greek_alphabet" title="Greek alphabet">Greek alphabet</a>, <a href="Alpha" title="Alpha">α</a>. The symbol for the alpha particle is α or α<sup>2+</sup>. Because they are identical to helium nuclei, they are also sometimes written as He<sup>2+</sup> or <span class="chemf nowrap"><span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:right"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sup><br><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">2</sub></span></span>He</span><sup>2+</sup> indicating a helium <a href="Ion" title="Ion">ion</a> with a +2 charge (missing its two <a href="Electron" title="Electron">electrons</a>). Once the ion gains electrons from its environment, the alpha particle becomes a normal (electrically neutral) helium atom <span class="chemf nowrap"><span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:right"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sup><br><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">2</sub></span></span>He</span>.

</p><p>Alpha particles have a net spin of zero. When produced in standard alpha <a href="Radioactive_decay" title="Radioactive decay">radioactive decay</a>, alpha particles generally have a <a href="Kinetic_energy" title="Kinetic energy">kinetic energy</a> of about 5 <a href="MeV" class="mw-redirect" title="MeV">MeV</a> and a <a href="Velocity" title="Velocity">velocity</a> in the vicinity of 4% of the <a href="Speed_of_light" title="Speed of light">speed of light</a>. They are a highly <a href="Ionizing_radiation" title="Ionizing radiation">ionizing</a> form of <a href="Particle_radiation" title="Particle radiation">particle radiation</a>, with low <a href="Penetration_depth" title="Penetration depth">penetration depth</a> (stopped by a few centimetres of <a href="Air" class="mw-redirect" title="Air">air</a>, or by the <a href="Skin" title="Skin">skin</a>).

</p><p>However, so-called <a href="Long-range_alpha" class="mw-redirect" title="Long-range alpha">long-range alpha</a> particles from <a href="Ternary_fission" title="Ternary fission">ternary fission</a> are three times as energetic and penetrate three times as far. The helium nuclei that form 10–12% of <a href="Cosmic_ray" title="Cosmic ray">cosmic rays</a> are also usually of much higher energy than those produced by nuclear decay processes, and thus may be highly penetrating and able to traverse the human body and also many metres of dense solid shielding, depending on their energy. To a lesser extent, this is also true of very high-energy helium nuclei produced by particle accelerators.

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<p>The term "alpha particle" was coined by <a href="Ernest_Rutherford" title="Ernest Rutherford">Ernest Rutherford</a> in reporting his studies of the properties of uranium radiation.<sup id="cite_ref-RutherfordAlpha_6-0" class="reference"><a href="#cite_note-RutherfordAlpha-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The radiation appeared to have two different characters, the first he called "<span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \alpha }">

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</math></span><img src="./7ed48a5e36207156fb792fa79d29925d2f7901e8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.332ex; height:2.509ex;" alt="{\displaystyle \beta }" loading="lazy"></span> radiation". After five years of additional experimental work, Rutherford and <a href="Hans_Geiger" title="Hans Geiger">Hans Geiger</a> determined that "the alpha particle, after it has lost its positive charge, is a Helium atom".<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-PaisInward_9-0" class="reference"><a href="#cite_note-PaisInward-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 61">: 61 </span></sup>

Alpha radiation consists of particles equivalent to <i>doubly-ionized helium nuclei</i> (He<sup>2+</sup>) which can gain electrons from passing through matter. This mechanism is the origin of terrestrial helium gas.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="Sources">Sources</h2></div>

<div class="mw-heading mw-heading3"><h3 id="Alpha_decay">Alpha decay</h3></div>

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</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Alpha_decay" title="Alpha decay">Alpha decay</a></div>

<p>The best-known source of alpha particles is <a href="Alpha_decay" title="Alpha decay">alpha decay</a> of heavier (mass number of at least 104) atoms. When an <a href="Atom" title="Atom">atom</a> emits an alpha particle in alpha decay, the atom's <a href="Mass_number" title="Mass number">mass number</a> decreases by four due to the loss of the four <a href="Nucleon" title="Nucleon">nucleons</a> in the alpha particle. The <a href="Atomic_number" title="Atomic number">atomic number</a> of the atom goes down by two, as a result of the loss of two protons – the atom becomes a new element. Examples of this sort of <a href="Nuclear_transmutation" title="Nuclear transmutation">nuclear transmutation</a> by alpha decay are the decay of <a href="Uranium" title="Uranium">uranium</a> to <a href="Thorium" title="Thorium">thorium</a>, and that of <a href="Radium" title="Radium">radium</a> to <a href="Radon" title="Radon">radon</a>.

</p><p>Alpha particles are commonly emitted by all of the larger <a href="Radioactive" class="mw-redirect" title="Radioactive">radioactive</a> nuclei such as <a href="Uranium" title="Uranium">uranium</a>, <a href="Thorium" title="Thorium">thorium</a>, <a href="Actinium" title="Actinium">actinium</a>, and <a href="Radium" title="Radium">radium</a>, as well as the <a href="Transuranic" class="mw-redirect" title="Transuranic">transuranic</a> elements. Unlike other types of decay, alpha decay as a process must have a minimum-size atomic nucleus that can support it. The smallest nuclei that have to date been found to be capable of alpha emission are <a href="Beryllium-8" title="Beryllium-8">beryllium-8</a> and <a href="Tellurium-104" class="mw-redirect" title="Tellurium-104">tellurium-104</a>, not counting beta-delayed alpha emission of some lighter elements. The alpha decay sometimes leaves the parent nucleus in an excited state; the emission of a <a href="Gamma_ray" title="Gamma ray">gamma ray</a> then removes the excess <a href="Energy" title="Energy">energy</a>.

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<div class="mw-heading mw-heading4"><h4 id="Mechanism_of_production_in_alpha_decay">Mechanism of production in alpha decay</h4></div>

<p>In contrast to <a href="Beta_decay" title="Beta decay">beta decay</a>, the <a href="Fundamental_interaction" title="Fundamental interaction">fundamental interactions</a> responsible for alpha decay are a balance between the <a href="Electromagnetic_force" class="mw-redirect" title="Electromagnetic force">electromagnetic force</a> and <a href="Nuclear_force" title="Nuclear force">nuclear force</a>. Alpha decay results from the <a href="Coulomb's_law" title="Coulomb's law">Coulomb repulsion</a><sup id="cite_ref-Krane_4-1" class="reference"><a href="#cite_note-Krane-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> between the alpha particle and the rest of the nucleus, which both have a positive <a href="Electric_charge" title="Electric charge">electric charge</a>, but which is kept in check by the <a href="Nuclear_force" title="Nuclear force">nuclear force</a>. In <a href="Physics_in_the_Classical_Limit" class="mw-redirect" title="Physics in the Classical Limit">classical physics</a>, alpha particles do not have enough energy to escape the <a href="Potential_well" title="Potential well">potential well</a> from the strong force inside the nucleus (this well involves escaping the strong force to go up one side of the well, which is followed by the electromagnetic force causing a repulsive push-off down the other side).

</p><p>However, the <a href="Quantum_tunneling" class="mw-redirect" title="Quantum tunneling">quantum tunnelling</a> effect allows alphas to escape even though they do not have enough energy to overcome the <a href="Nuclear_force" title="Nuclear force">nuclear force</a>. This is allowed by the wave nature of matter, which allows the alpha particle to spend some of its time in a region so far from the nucleus that the potential from the repulsive electromagnetic force has fully compensated for the attraction of the nuclear force. From this point, alpha particles can escape.

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<div class="mw-heading mw-heading3"><h3 id="Ternary_fission">Ternary fission</h3></div>

<p>Especially energetic alpha particles deriving from a nuclear process are produced in the relatively rare (one in a few hundred) <a href="Nuclear_fission" title="Nuclear fission">nuclear fission</a> process of <a href="Ternary_fission" title="Ternary fission">ternary fission</a>. In this process, three charged particles are produced from the event instead of the normal two, with the smallest of the charged particles most probably (90% probability) being an alpha particle. Such alpha particles are termed "long range alphas" since at their typical energy of 16 MeV, they are at far higher energy than is ever produced by alpha decay. Ternary fission happens in both neutron-induced fission (the <a href="Nuclear_reaction" title="Nuclear reaction">nuclear reaction</a> that happens in a nuclear reactor), and also when <a href="Fissionable" class="mw-redirect" title="Fissionable">fissionable</a> and <a href="Fissile" class="mw-redirect" title="Fissile">fissile</a> <a href="Actinide" title="Actinide">actinides</a> nuclides (i.e., heavy atoms capable of fission) undergo <a href="Spontaneous_fission" title="Spontaneous fission">spontaneous fission</a> as a form of radioactive decay. In both induced and spontaneous fission, the higher energies available in heavy nuclei result in long range alphas of higher energy than those from alpha decay.

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<div class="mw-heading mw-heading3"><h3 id="Accelerators">Accelerators</h3></div>

<p>Energetic helium nuclei (helium ions) may be produced by <a href="Cyclotron" title="Cyclotron">cyclotrons</a>, <a href="Synchrotron" title="Synchrotron">synchrotrons</a>, and other <a href="Particle_accelerator" title="Particle accelerator">particle accelerators</a>. Convention is that they are not normally referred to as "alpha particles".

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<div class="mw-heading mw-heading3"><h3 id="Solar_core_reactions">Solar core reactions</h3></div>

<p>Helium nuclei may participate in nuclear reactions in stars, and occasionally and historically these have been referred to as alpha reactions (see <a href="Triple-alpha_process" title="Triple-alpha process">triple-alpha process</a> and <a href="Alpha_process" title="Alpha process">alpha process</a>).

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<div class="mw-heading mw-heading3"><h3 id="Cosmic_rays">Cosmic rays</h3></div>

<p>In addition, extremely high energy helium nuclei sometimes referred to as alpha particles make up about 10 to 12% of <a href="Cosmic_ray" title="Cosmic ray">cosmic rays</a>. The mechanisms of cosmic ray production continue to be debated.

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<div class="mw-heading mw-heading2"><h2 id="Energy_and_absorption">Energy and absorption</h2></div>

<p>The energy of the alpha particle emitted in <a href="Alpha_decay" title="Alpha decay">alpha decay</a> is mildly dependent on the half-life for the emission process, with many orders of magnitude differences in half-life being associated with energy changes of less than 50%, shown by the <a href="Geiger%E2%80%93Nuttall_law" title="Geiger–Nuttall law">Geiger–Nuttall law</a>.

</p><p>The energy of alpha particles emitted varies, with higher energy alpha particles being emitted from larger nuclei, but most alpha particles have energies of between 3 and 7 <a href="MeV" class="mw-redirect" title="MeV">MeV</a> (mega-electron-volts), corresponding to extremely long and extremely short half-lives of alpha-emitting nuclides, respectively. The energies and ratios are often distinct and can be used to identify specific nuclides as in <a href="Alpha-particle_spectroscopy" title="Alpha-particle spectroscopy">alpha spectrometry</a>.

</p><p>With a typical kinetic energy of 5 MeV; the speed of emitted alpha particles is 15,000 km/s, which is 5% of the speed of light. This energy is a substantial amount of energy for a single particle, but their high mass means alpha particles have a lower speed than any other common type of radiation, e.g. <a href="Beta_particle" title="Beta particle">β particles</a>, <a href="Neutron_radiation" title="Neutron radiation">neutrons</a>.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup>

</p><p>Because of their charge and large mass, alpha particles are easily absorbed by materials, and they can travel only a few centimetres in air. They can be absorbed by tissue paper or by the outer layers of human skin. They typically penetrate skin about 40 <a href="Micrometre" title="Micrometre">micrometres</a>, equivalent to a few <a href="Cell_(biology)" title="Cell (biology)">cells</a> deep.

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<div class="mw-heading mw-heading2"><h2 id="Biological_effects">Biological effects</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Relative_biological_effectiveness" title="Relative biological effectiveness">Relative biological effectiveness</a></div>

<p>Due to the short range of absorption and inability to penetrate the outer layers of skin, alpha particles are not, in general, dangerous to life unless the source is ingested or inhaled.<sup id="cite_ref-Christensen2014_13-0" class="reference"><a href="#cite_note-Christensen2014-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Because of this high mass and strong absorption, if alpha-emitting radionuclides do enter the body (upon being inhaled, ingested, or injected, as with the use of <a href="Thorotrast" title="Thorotrast">Thorotrast</a> for high-quality X-ray images prior to the 1950s), alpha radiation is the most destructive form of <a href="Ionizing_radiation" title="Ionizing radiation">ionizing radiation</a>. It is the most strongly ionizing, and with large enough doses can cause any or all of the symptoms of <a href="Radiation_poisoning" class="mw-redirect" title="Radiation poisoning">radiation poisoning</a>. It is estimated that <a href="Chromosome" title="Chromosome">chromosome</a> damage from alpha particles is anywhere from 10 to 1000<sup id="cite_ref-LittleKennedy1985_14-0" class="reference"><a href="#cite_note-LittleKennedy1985-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> times greater than that caused by an equivalent amount of gamma or beta radiation, with the average being set at 20 times. A study of European nuclear workers exposed internally to alpha radiation from plutonium and uranium found that when relative biological effectiveness is considered to be 20, the carcinogenic potential (in terms of lung cancer) of alpha radiation appears to be consistent with that reported for doses of external gamma radiation i.e. a given dose of alpha-particles inhaled presents the same risk as a 20-times higher dose of gamma radiation.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> The powerful alpha emitter <a href="Polonium-210" title="Polonium-210">polonium-210</a> (a milligram of <sup>210</sup>Po emits as many alpha particles per second as 4.215 grams of <a href="Radium-226" title="Radium-226"><sup>226</sup>Ra</a>) is suspected of playing a role in <a href="Lung_cancer" title="Lung cancer">lung cancer</a> and <a href="Bladder_cancer" title="Bladder cancer">bladder cancer</a> related to <a href="Tobacco_and_health" class="mw-redirect" title="Tobacco and health">tobacco smoking</a>.<sup id="cite_ref-Science_v143_no3603_16-0" class="reference"><a href="#cite_note-Science_v143_no3603-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> <sup>210</sup>Po was used to kill Russian dissident and ex-<a href="Federal_Security_Service_of_the_Russian_Federation" class="mw-redirect" title="Federal Security Service of the Russian Federation">FSB</a> officer <a href="Alexander_Litvinenko" title="Alexander Litvinenko">Alexander V. Litvinenko</a> in 2006.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="History_of_discovery_and_use">History of discovery and use</h2></div>

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</style><div class="thumb tmulti tright"><div class="thumbinner multiimageinner" style="width:592px;max-width:592px"><div class="trow"><div class="tsingle" style="width:379px;max-width:379px"><div class="thumbimage" style="height:221px;overflow:hidden"><span typeof="mw:File"></span></div></div><div class="tsingle" style="width:209px;max-width:209px"><div class="thumbimage" style="height:221px;overflow:hidden"><span typeof="mw:File"></span></div></div></div><div class="trow" style="display:flex"><div class="thumbcaption">Figure 1 and 2 from Rutherford's 1899 paper on uranium radiation.<sup id="cite_ref-Rutherford1899_18-0" class="reference"><a href="#cite_note-Rutherford1899-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> The uranium radiation ionized the air between the electrodes A and B, creating a current. At first the current steadily dropped as Rutherford placed layer after layer of aluminium foil over the uranium, but past 20 micrometers of thickness the current remained more or less the same.</div></div></div></div>

<p>In 1896, <a href="Henri_Becquerel" title="Henri Becquerel">Henri Becquerel</a> discovered that <a href="Uranium" title="Uranium">uranium</a> emits an invisible radiation that can darken photographic plates, and that this mystery radiation wasn't <a href="Phosphorescence" title="Phosphorescence">phosphorescence</a>.<sup id="cite_ref-PaisInward_9-1" class="reference"><a href="#cite_note-PaisInward-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 49">: 49 </span></sup> In 1898, <a href="Marie_Curie" title="Marie Curie">Marie Curie</a> showed that this phenomenon, which she called "radioactivity", was not unique to uranium and was a property of individual atoms.<sup id="cite_ref-PaisInward_9-2" class="reference"><a href="#cite_note-PaisInward-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 55">: 55 </span></sup> <a href="Ernest_Rutherford" title="Ernest Rutherford">Ernest Rutherford</a> studied uranium radiation and discovered that it could ionize gas particles.<sup id="cite_ref-Whittaker_19-0" class="reference"><a href="#cite_note-Whittaker-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 2">: 2 </span></sup>

</p><p>In 1899, Rutherford discovered that uranium radiation is a mixture of two types of radiation.<sup id="cite_ref-PaisInward_9-3" class="reference"><a href="#cite_note-PaisInward-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 60">: 60 </span></sup> He performed an experiment which involved two electrodes separated by 4 cm of air. He placed some uranium on the bottom electrode, and the radiation from the uranium ionized the air between the electrodes, creating a current. Rutherford then placed an aluminium foil (5 micrometers thick) over the uranium and noticed that the current dropped a bit, indicating that the foil was absorbing some of the uranium's radiation. Rutherford placed a few more foils over the uranium and found that, for the first four foils, the current steadily decreased at a geometric rate. However, after the fourth layer of foil over the uranium, the current didn't drop anymore and remained more or less level for up to twelve layers of foil. This result indicated that uranium radiation has two components. Rutherford dubbed one component "alpha radiation" which was fully absorbed by just a few layers of foil, and what was left was a second component that could penetrate many layers of foil, and he dubbed the latter "<a href="Beta_radiation" class="mw-redirect" title="Beta radiation">beta radiation</a>".<sup id="cite_ref-Rutherford1899_18-1" class="reference"><a href="#cite_note-Rutherford1899-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup>

</p><p>In 1900, <a href="Marie_Curie" title="Marie Curie">Marie Curie</a> noticed that the absorption coefficient of alpha rays seemed to increase the thicker the barrier she placed in their path. This suggested that alpha radiation is not a form of light but made of particles that lose kinetic energy as they pass through barriers. In 1902, Rutherford found that he could deflect alpha rays with a magnetic field and an electric field, showing that alpha radiation is composed of electrically charged particles. The direction in which the alpha particles were deflected was the opposite of cathode rays, which showed that they are positively charged.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup>

</p><p>In 1906, Rutherford made some more precise measurements of the charge-to-mass ratio of alpha particles. Firstly, he found that the ratio was more or less the same whether the source was <a href="Radium" title="Radium">radium</a> or <a href="Actinium" title="Actinium">actinium</a>, showing that alpha particles are the same regardless of the source. Secondly, he found the charge-to-mass ratio of alpha particles to be half that of the hydrogen ion. Rutherford proposed three explanations: 1) an alpha particle is a hydrogen molecule (H<sub>2</sub>) with a charge of 1 <i>e</i>; 2) an alpha particle is an atom of helium with a charge of 2 <i>e</i>; 3) an alpha particle is half a helium atom with a charge of 1 <i>e</i>. At that time in history, scientists knew that hydrogen ions have an atomic weight of 1 and a charge of 1 <i>e</i>, and that helium has an atomic weight of 4. Nobody knew exactly how many electrons were in an atom. Protons and neutrons had not yet been discovered. Rutherford decided the second explanation was the most plausible because it is the simplest and sizeable deposits of helium were commonly found underground next to deposits of radioactive elements. His explanation was that as alpha particles are emitted by underground radioactive elements, they become trapped in the rock strata and acquire electrons, becoming helium atoms.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> Therefore an alpha particle is essentially a helium atom stripped of two electrons.

</p><p>In 1909, <a href="Ernest_Rutherford" title="Ernest Rutherford">Ernest Rutherford</a> and <a href="Thomas_Royds" title="Thomas Royds">Thomas Royds</a> finally proved that alpha particles were indeed helium ions.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> To do this they collected and purified the gas emitted by radium, a known alpha particle emitter, in a glass tube. An <a href="Electric_spark" title="Electric spark">electric spark</a> discharge inside the tube produced light. Subsequent study of the spectrum of this light showed that the gas was helium and thus the alpha particles were indeed the helium ions.<sup id="cite_ref-PaisInward_9-4" class="reference"><a href="#cite_note-PaisInward-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 61">: 61 </span></sup>

</p><p>In 1911, Rutherford used alpha particle scattering data to argue that the positive charge of an atom is concentrated in a tiny nucleus. In 1913, <a href="Antonius_van_den_Broek" title="Antonius van den Broek">Antonius van den Broek</a> suggested that the nuclear charge in an atom, and by extension the number of electrons, is equal to its <a href="Atomic_number" title="Atomic number">atomic number</a>.<sup id="cite_ref-PaisInward_9-5" class="reference"><a href="#cite_note-PaisInward-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 228">: 228 </span></sup><sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> Therefore a helium atom has two electrons, and an alpha particle is essentially a helium nucleus. In 1920, Rutherford deduced the existence of the <a href="Proton" title="Proton">proton</a> as the source of positive charge in the atom. In 1932, James Chadwick discovered the <a href="Neutron" title="Neutron">neutron</a>. Thereafter it was known that an alpha particle is an agglomeration of two protons and two neutrons.

</p>

<div class="mw-heading mw-heading2"><h2 id="Anti-alpha_particle">Anti-alpha particle</h2></div>

<p>While antimatter equivalents for helium-3 have been known since 1970,

it took until 2010 for members of the international <a href="STAR_collaboration" class="mw-redirect" title="STAR collaboration">STAR collaboration</a> using the <a href="Relativistic_Heavy_Ion_Collider" title="Relativistic Heavy Ion Collider">Relativistic Heavy Ion Collider</a> at the <a href="U.S._Department_of_Energy" class="mw-redirect" title="U.S. Department of Energy">U.S. Department of Energy</a>'s <a href="Brookhaven_National_Laboratory" title="Brookhaven National Laboratory">Brookhaven National Laboratory</a> to detect the <a href="Antimatter" title="Antimatter">antimatter</a> partner of the helium-4 nucleus.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> Like the <a href="Rutherford_scattering_experiments" title="Rutherford scattering experiments">Rutherford scattering experiments</a>, the antimatter experiment used gold. This time the gold ions moving at nearly the speed of light and colliding head on to produce the antiparticle, also dubbed "anti-alpha" particle.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="Applications">Applications</h2></div>

<div class="mw-heading mw-heading3"><h3 id="Devices">Devices</h3></div>

<ul><li>Some <a href="Smoke_detector" title="Smoke detector">smoke detectors</a> contain a small amount of the alpha emitter <a href="Americium-241" title="Americium-241">americium-241</a>.<sup id="cite_ref-EPAAmericium_28-0" class="reference"><a href="#cite_note-EPAAmericium-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> The alpha particles <a href="Ionization" title="Ionization">ionize</a> air within a small gap. A small <a href="Electric_current" title="Electric current">current</a> is passed through that ionized air. Smoke particles from fire that enter the air gap reduce the current flow, sounding the alarm. The isotope is extremely dangerous if inhaled or ingested, but the danger is minimal if the source is kept sealed. Many municipalities have established programs to collect and dispose of old smoke detectors, to keep them out of the general waste stream. However the US EPA says they "may be thrown away with household garbage".<sup id="cite_ref-EPAAmericium_28-1" class="reference"><a href="#cite_note-EPAAmericium-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup></li>

<li>Alpha decay can provide a relatively safe power source for <a href="Radioisotope_thermoelectric_generator" title="Radioisotope thermoelectric generator">radioisotope thermoelectric generators</a><sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> used for <a href="Space_probe" class="mw-redirect" title="Space probe">space probes</a>. Alpha decay is much more easily shielded against than other forms of radioactive decay. <a href="Plutonium-238" title="Plutonium-238">Plutonium-238</a>, a source of alpha particles, requires only 2.5 mm of <a href="Lead" title="Lead">lead</a> shielding to protect against unwanted radiation.</li>

<li><a href="Antistatic_devices" class="mw-redirect" title="Antistatic devices">Static eliminators</a> typically use <a href="Polonium-210" title="Polonium-210">polonium-210</a>, an alpha emitter, to ionize air, allowing the "<a href="Static_cling" title="Static cling">static cling</a>" to more rapidly dissipate.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup></li></ul>

<div class="mw-heading mw-heading3"><h3 id="Cancer_treatment">Cancer treatment</h3></div>

<p>Alpha-emitting <a href="Radionuclides" class="mw-redirect" title="Radionuclides">radionuclides</a> are presently being used in three different ways to eradicate cancerous tumors: as an infusible radioactive treatment targeted to specific tissues (radium-223), as a source of radiation inserted directly into solid tumors (radium-224), and as an attachment to a tumor-targeting molecule, such as an antibody to a tumor-associated antigen.

</p><p><a href="Radium-223" title="Radium-223">Radium-223</a> is an alpha emitter that is naturally attracted to the bone because it is a <a href="Calcium" title="Calcium">calcium</a> mimetic. Radium-223 (as radium-223 dichloride) can be infused into a cancer patient's veins, after which it migrates to parts of the bone where there is rapid turnover of cells due to the presence of metastasized tumors. Once within the bone, Ra-223 emits alpha radiation that can destroy tumor cells within a 100-micron distance. This approach has been in use since 2013 to treat <a href="Prostate_cancer" title="Prostate cancer">prostate cancer</a> which has metastasized to the bone.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> Radionuclides infused into the circulation are able to reach sites that are accessible to blood vessels. This means, however, that the interior of a large tumor that is not vascularized (i.e. is not well penetrated by blood vessels) may not be effectively eradicated by the radioactivity.

</p><p>Radium-224 is a radioactive atom that is utilized as a source of alpha radiation in a cancer treatment device called DaRT (<a href="Diffusing_alpha_emitters_radiation_therapy" title="Diffusing alpha emitters radiation therapy">diffusing alpha emitters radiation therapy</a>). Each radium-224 atom undergoes a decay process producing 6 daughter atoms. During this process, 4 alpha particles are emitted. The range of an alpha particle—up to 100 microns—is insufficient to cover the width of many tumors. However, radium-224's daughter atoms can diffuse up to 2–3 mm in the tissue, thus creating a "kill region" with enough radiation to potentially destroy an entire tumor, if the seeds are placed appropriately.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> Radium-224's half-life is short enough at 3.6 days to produce a rapid clinical effect while avoiding the risk of radiation damage due to overexposure. At the same time, the half-life is long enough to allow for handling and shipping the seeds to a cancer treatment center at any location across the globe.

</p><p>Targeted alpha therapy for solid tumors involves attaching an alpha-particle-emitting radionuclide to a tumor-targeting molecule such as an antibody, that can be delivered by intravenous administration to a cancer patient.<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="Alpha_radiation_and_DRAM_errors">Alpha radiation and DRAM errors</h2></div>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Soft_error#Alpha_particles_from_package_decay" title="Soft error">Soft error § Alpha particles from package decay</a></div>

<p>In computer technology, <a href="Dynamic_random_access_memory" class="mw-redirect" title="Dynamic random access memory">dynamic random access memory</a> (DRAM) "<a href="Soft_error" title="Soft error">soft errors</a>" were linked to alpha particles in 1978 in <a href="Intel" title="Intel">Intel</a>'s DRAM chips. The discovery led to strict control of radioactive elements in the packaging of semiconductor materials, and the problem is largely considered to be solved.<sup id="cite_ref-may79softerrors_35-0" class="reference"><a href="#cite_note-may79softerrors-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup>

</p>

<ul><li><a href="Alpha_nuclide" title="Alpha nuclide">Alpha nuclide</a></li>

<li><a href="Alpha_process" title="Alpha process">Alpha process</a> (also known as alpha-capture, or the alpha-ladder)</li>

<li><a href="Beta_particle" title="Beta particle">Beta particle</a></li>

<li><a href="Cosmic_ray" title="Cosmic ray">Cosmic rays</a></li>

<li><a href="Helion_(chemistry)" title="Helion (chemistry)">Helion</a>, the nucleus of <a href="Helium-3" title="Helium-3">helium-3</a> rather than <a href="Helium-4" title="Helium-4">helium-4</a></li>

<li><a href="List_of_alpha-emitting_nuclides" title="List of alpha-emitting nuclides">List of alpha-emitting nuclides</a></li>

<li><a href="Nuclear_physics" title="Nuclear physics">Nuclear physics</a></li>

<li><a href="Particle_physics" title="Particle physics">Particle physics</a></li>

<li><a href="Radionuclide" title="Radionuclide">Radioactive isotope</a></li>

<li>Rays:

<li>γ <a href="Gamma_ray" title="Gamma ray">Gamma ray</a></li>

<li>δ <a href="Delta_ray" title="Delta ray">Delta ray</a></li>

<li>ε <a href="Epsilon_radiation" class="mw-redirect" title="Epsilon radiation">Epsilon radiation</a></li></ul></li>

<li><a href="Rutherford_scattering" class="mw-redirect" title="Rutherford scattering">Rutherford scattering</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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<li id="cite_note-:02-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-:02_5-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFBohanDinwiddieChallonerStuart2016" class="citation book cs1">Bohan, Elise; Dinwiddie, Robert; Challoner, Jack; Stuart, Colin; Harvey, Derek; <a href="Rebecca_Wragg_Sykes" title="Rebecca Wragg Sykes">Wragg-Sykes, Rebecca</a>; <a href="Peter_Chrisp" title="Peter Chrisp">Chrisp, Peter</a>; Hubbard, Ben; Parker, Phillip; et al. (Writers) (February 2016). <i>Big History</i>. Foreword by <a href="David_Christian_(historian)" title="David Christian (historian)">David Christian</a> (1st American ed.). <a href="New_York_City" title="New York City">New York</a>: <a href="DK_(publisher)" title="DK (publisher)">DK</a>. p. 58. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-4654-5443-0</bdi>. <a href="OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/940282526">940282526</a>.</cite></span>

</li>

<li id="cite_note-RutherfordAlpha-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-RutherfordAlpha_6-0">^</a></b></span> <span class="reference-text">Rutherford distinguished and named α and β rays on page 116 of: E. Rutherford (1899) <a rel="nofollow" class="external text" href="https://books.google.com/books?id=ipMOAAAAIAAJ&pg=PA109">"Uranium radiation and the electrical conduction produced by it"</a>, <i>Philosophical Magazine</i>, Series 5, vol. 47, no. 284, pages 109–163. Rutherford named γ rays on page 177 of: E. Rutherford (1903) <a rel="nofollow" class="external text" href="https://books.google.com/books?id=otXPAAAAMAAJ&pg=PA177">"The magnetic and electric deviation of the easily absorbed rays from radium"</a>, <i>Philosophical Magazine</i>, Series 6, vol. 5, no. 26, pages 177–187.</span>

</li>

<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><cite id="CITEREFRutherfordGeiger2014" class="citation book cs1">Rutherford, Ernest; Geiger, Hans (2014). "The Charge and Nature of the α-Particle". <i>The Collected Papers of Lord Rutherford of Nelson</i>. Routledge. pp. <span class="nowrap">109–</span>120.</cite></span>

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<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><cite id="CITEREFRutherfordGeiger1908" class="citation journal cs1">Rutherford, E.; Geiger, Hans (1908). <a rel="nofollow" class="external text" href="https://doi.org/10.1098%2Frspa.1908.0066">"The Charge and Nature of the α-Particle"</a>. <i>Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character</i>. <b>81</b> (546): <span class="nowrap">162–</span>173. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1908RSPSA..81..162R">1908RSPSA..81..162R</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1098%2Frspa.1908.0066">10.1098/rspa.1908.0066</a></span>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0950-1207">0950-1207</a>. <a href="JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/92981">92981</a>.</cite></span>

</li>

<li id="cite_note-PaisInward-9"><span class="mw-cite-backlink">^ <a href="#cite_ref-PaisInward_9-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-PaisInward_9-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-PaisInward_9-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-PaisInward_9-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-PaisInward_9-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-PaisInward_9-5"><sup><i><b>f</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFPais2002" class="citation book cs1">Pais, Abraham (2002). <i>Inward bound: of matter and forces in the physical world</i> (Reprint ed.). Oxford: Clarendon Press [u.a.] <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-19-851997-3</bdi>.</cite></span>

</li>

<li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><cite id="CITEREFMorrisonPine1955" class="citation journal cs1">Morrison, P.; Pine, J. (1955). <span class="id-lock-subscription" title="Paid subscription required"><a rel="nofollow" class="external text" href="https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.1955.tb35366.x">"Radiogenic Origin of the Helium Isotopes in Rock"</a></span>. <i>Annals of the New York Academy of Sciences</i>. <b>62</b> (3): <span class="nowrap">71–</span>92. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1955NYASA..62...71M">1955NYASA..62...71M</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1111%2Fj.1749-6632.1955.tb35366.x">10.1111/j.1749-6632.1955.tb35366.x</a>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0077-8923">0077-8923</a>.</cite></span>

</li>

<li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><cite id="CITEREFFirestoneBaglin1999" class="citation book cs1">Firestone, Richard B.; Baglin, Coral M. (1999). <i>Table of isotopes</i> (8th ed.). New York: Wiley. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-471-35633-6</bdi>. <a href="OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/43118182">43118182</a>.</cite></span>

</li>

<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text">N.B. Since gamma rays are <a href="Electromagnetic" class="mw-redirect" title="Electromagnetic">electromagnetic</a> (<a href="Light" title="Light">light</a>) they move at the speed of light (<i>c</i>). Beta particles often move at a large fraction of <i>c</i>, and exceed 60% <i>c</i> whenever their energy is > 64 keV, which it commonly is. Neutron velocity from nuclear reactions ranges from about 6% <i>c</i> for fission to as much as 17% <i>c</i> for fusion.</span>

</li>

<cite id="CITEREFChristensenIddinsSugarman2014" class="citation journal cs1">Christensen, D. M.; Iddins, C. J.; Sugarman, S. L. (2014). "Ionizing radiation injuries and illnesses". <i>Emergency Medicine Clinics of North America</i>. <b>32</b> (1): <span class="nowrap">245–</span>65. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.emc.2013.10.002">10.1016/j.emc.2013.10.002</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/24275177">24275177</a>.</cite></span>

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<cite id="CITEREFLittleKennedyMcGandy1985" class="citation journal cs1">Little, John B.; Kennedy, Ann R.; McGandy, Robert B. (1985). "Effect of Dose Rate on the Induction of Experimental Lung Cancer in Hamsters by α Radiation". <i>Radiation Research</i>. <b>103</b> (2): <span class="nowrap">293–</span>9. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1985RadR..103..293L">1985RadR..103..293L</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2307%2F3576584">10.2307/3576584</a>. <a href="JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/3576584">3576584</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/4023181">4023181</a>.</cite></span>

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<cite id="CITEREFGrellier2017" class="citation journal cs1">Grellier, James; et al. (2017). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5540354">"Risk of lung cancer mortality in nuclear workers from internal exposure to alpha particle-emitting radionuclides"</a>. <i>Epidemiology</i>. <b>28</b> (5): <span class="nowrap">675–</span>684. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1097%2FEDE.0000000000000684">10.1097/EDE.0000000000000684</a>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5540354">5540354</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/28520643">28520643</a>.</cite></span>

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<cite id="CITEREFRadfordHunt1964" class="citation journal cs1">Radford, Edward P.; Hunt, Vilma R. (1964). "Polonium-210: A Volatile Radioelement in Cigarettes". <i><a href="Science_(journal)" title="Science (journal)">Science</a></i>. <b>143</b> (3603): <span class="nowrap">247–</span>249. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1964Sci...143..247R">1964Sci...143..247R</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1126%2Fscience.143.3603.247">10.1126/science.143.3603.247</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/14078362">14078362</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:23455633">23455633</a>.</cite></span>

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<cite id="CITEREFCowell2006" class="citation news cs1">Cowell, Alan (24 November 2006). <a rel="nofollow" class="external text" href="https://www.nytimes.com/2006/11/24/world/europe/25spycnd.html">"Radiation Poisoning Killed Ex-Russian Spy"</a>. <i>The New York Times</i><span class="reference-accessdate">. Retrieved <span class="nowrap">15 September</span> 2011</span>.</cite></span>

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<li id="cite_note-Rutherford1899-18"><span class="mw-cite-backlink">^ <a href="#cite_ref-Rutherford1899_18-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Rutherford1899_18-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFErnest_Rutherford1899" class="citation journal cs1">Ernest Rutherford (1899). <a rel="nofollow" class="external text" href="https://archive.org/details/londonedinburgh5471899lon/page/108/mode/2up">"Uranium Radiation and the Electrical conduction Produced by it"</a>. <i>Philosophical Magazine</i>. <b>47</b> (284): <span class="nowrap">109–</span>163.</cite></span>

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<li id="cite_note-Whittaker-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-Whittaker_19-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFWhittaker1989" class="citation book cs1">Whittaker, Edmund T. (1989). <i>A history of the theories of aether & electricity. II: The modern theories</i> (Repr ed.). New York: Dover Publ. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-486-26126-3</bdi>.</cite></span>

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<li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><cite id="CITEREFErnest_Rutherford1903" class="citation journal cs1">Ernest Rutherford (1903). <a rel="nofollow" class="external text" href="https://archive.org/details/londonedinburgh651903lond/page/176/mode/2up">"XV. The Magnetic and Electric Deviation of the easily absorbed Rays from Radium"</a>. <i>Philosophical Magazine</i>. 6. <b>5</b>: 177-187.</cite></span>

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<li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text">Heilbron (1968), pp. 252-254</span>

</li>

<li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text"><cite id="refRutherford1906" class="citation journal cs1">Ernest Rutherford (1906). <a rel="nofollow" class="external text" href="https://zenodo.org/record/1430814">"The Mass and Velocity of the α particles expelled from Radium and Actinium"</a>. <i>Philosophical Magazine</i>. Series 6. <b>12</b> (70): <span class="nowrap">348–</span>371. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F14786440609463549">10.1080/14786440609463549</a>.</cite><br></span>

</li>

<li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text"><cite id="CITEREFErnest_RutherfordThomas_Royds1909" class="citation journal cs1">Ernest Rutherford; Thomas Royds (1909). <a rel="nofollow" class="external text" href="https://archive.org/details/londonedinburg6171909lond/page/280/mode/2up">"XXI. The nature of the α particle from radioactive substances"</a>. <i>The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science</i>. <b>17</b> (98): <span class="nowrap">281–</span>286. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F14786440208636599">10.1080/14786440208636599</a>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1941-5982">1941-5982</a>.</cite></span>

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<li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><cite id="CITEREFErnest_Rutherford1914" class="citation journal cs1">Ernest Rutherford (March 1914). <a rel="nofollow" class="external text" href="https://www.chemteam.info/Chem-History/Rutherford-1914.html">"The Structure of the Atom"</a>. <i>Philosophical Magazine</i>. 6. <b>27</b>: <span class="nowrap">488–</span>498. <q>It is obvious from the consideration of the cases of hydrogen and helium, where hydrogen has one electron and helium two, that the number of electrons cannot be exactly half the atomic weight in all cases. This has led to an interesting suggestion by van den Broek that the number of units of charge on the nucleus, and consequently the number of external electrons, may be equal to the number of the elements when arranged in order of increasing atomic weight.</q></cite></span>

</li>

<li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><cite id="CITEREFErnest_Rutherford1913" class="citation journal cs1">Ernest Rutherford (11 December 1913). "The Structure of the Atom". <i>Nature</i>. <b>92</b> (423). <q>The original suggestion of van der Broek that the charge on the nucleus is equal to the atomic number and not to half the atomic weight seems to me very promising.</q></cite></span>

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<cite id="CITEREFAgakishievet_al._(STAR_collaboration)2011" class="citation journal cs1">Agakishiev, H.; <i>et al.</i> (<a href="STAR_collaboration" class="mw-redirect" title="STAR collaboration">STAR collaboration</a>) (2011). "Observation of the antimatter helium-4 nucleus". <i><a href="Nature_(journal)" title="Nature (journal)">Nature</a></i>. <b>473</b> (7347): <span class="nowrap">353–</span>6. <a href="ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://arxiv.org/abs/1103.3312">1103.3312</a></span>. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2011Natur.473..353S">2011Natur.473..353S</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1038%2Fnature10079">10.1038/nature10079</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/21516103">21516103</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:118484566">118484566</a>.</cite>. See also <cite class="citation journal cs1">"Erratum". <i><a href="Nature_(journal)" title="Nature (journal)">Nature</a></i>. <b>475</b> (7356): 412. 2011. <a href="ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://arxiv.org/abs/1103.3312">1103.3312</a></span>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1038%2Fnature10264">10.1038/nature10264</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:4359058">4359058</a>.</cite></span>

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<cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.physorg.com/news/2011-04-antihelium-physicists-nab-heaviest-antimatter.html">"Antihelium-4: Physicists nab new record for heaviest antimatter"</a>. <a href="PhysOrg" class="mw-redirect" title="PhysOrg">PhysOrg</a>. 24 April 2011<span class="reference-accessdate">. Retrieved <span class="nowrap">15 November</span> 2011</span>.</cite></span>

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<li id="cite_note-EPAAmericium-28"><span class="mw-cite-backlink">^ <a href="#cite_ref-EPAAmericium_28-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-EPAAmericium_28-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.epa.gov/radtown/americium-ionization-smoke-detectors">"Americium in Ionization Smoke Detectors"</a>. <i>U.S. Environmental Protection Agency</i>. 27 November 2018. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20230927112506/https://www.epa.gov/radtown/americium-ionization-smoke-detectors">Archived</a> from the original on 27 September 2023<span class="reference-accessdate">. Retrieved <span class="nowrap">30 December</span> 2023</span>.</cite></span>

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<li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text">Schulman, Fred. "Isotopes and Isotope Thermoelectric Generators." Space Power Systems Advanced Technology Conference. No. N67-10265. 1966.</span>

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<li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://orau.org/health-physics-museum/collection/consumer/miscellaneous/static-eliminators.html">"Static Eliminators (1960s and 1980s)"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">30 December</span> 2023</span>.</cite></span>

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<li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text">Silson, John E. "Hazards in the use of radioactive static eliminators and their control." American Journal of Public Health and the Nation's Health 40.8 (1950): 943-952.</span>

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<li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text"><cite id="CITEREFParkerNilssonHeinrich2013" class="citation journal cs1">Parker, C.; Nilsson, S.; Heinrich, D. (18 July 2013). <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/?term=Parker+C&cauthor_id=23863050">"Alpha emitter radium-223 and survival in metastatic prostate cancer"</a>. <i>New England Journal of Medicine</i>. <b>369</b> (3): <span class="nowrap">213–</span>223. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1056%2FNEJMoa1213755">10.1056/NEJMoa1213755</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/23863050">23863050</a>.</cite></span>

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<li id="cite_note-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-33">^</a></b></span> <span class="reference-text"><cite id="CITEREFAraziCooksSchmidtKeisari2007" class="citation journal cs1">Arazi, L.; Cooks, T.; Schmidt, M.; Keisari, Y.; Kelson, I. (21 August 2007). "Treatment of solid tumors by interstitial release of recoiling short-lived alpha emitters". <i>Physics in Medicine and Biology</i>. <b>52</b> (16): <span class="nowrap">5025–</span>42. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2007PMB....52.5025A">2007PMB....52.5025A</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1088%2F0031-9155%2F52%2F16%2F021">10.1088/0031-9155/52/16/021</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/17671351">17671351</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:1585204">1585204</a>.</cite></span>

</li>

<li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text"><cite id="CITEREFTafreshiDoligalskiTichacekPandya2019" class="citation journal cs1">Tafreshi, Narges K.; Doligalski, Michael L.; Tichacek, Christopher J.; Pandya, Darpan N.; Budzevich, Mikalai M.; El-Haddad, Ghassan; Khushalani, Nikhil I.; Moros, Eduardo G.; McLaughlin, Mark L.; Wadas, Thaddeus J.; Morse, David L. (26 November 2019). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6930656">"Development of Targeted Alpha Particle Therapy for Solid Tumors"</a>. <i>Molecules</i>. <b>24</b> (23): 4314. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.3390%2Fmolecules24234314">10.3390/molecules24234314</a></span>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1420-3049">1420-3049</a>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6930656">6930656</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/31779154">31779154</a>.</cite></span>

</li>

<li id="cite_note-may79softerrors-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-may79softerrors_35-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFMayWoods1979" class="citation journal cs1">May, T. C.; Woods, M. H. (1979). "Alpha-particle-induced soft errors in dynamic memories". <i><a href="IEEE_Transactions_on_Electron_Devices" title="IEEE Transactions on Electron Devices">IEEE Transactions on Electron Devices</a></i>. <b>26</b> (1): <span class="nowrap">2–</span>9. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1979ITED...26....2M">1979ITED...26....2M</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FT-ED.1979.19370">10.1109/T-ED.1979.19370</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:43748644">43748644</a>.</cite></span>

</li>

</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2></div>

<ul><li><cite id="CITEREFTiplerLlewellyn2002" class="citation book cs1">Tipler, Paul; Llewellyn, Ralph (2002). <i>Modern Physics</i> (4th ed.). <a href="W._H._Freeman" class="mw-redirect" title="W. H. Freeman">W. H. Freeman</a>. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-7167-4345-3</bdi>.</cite></li></ul>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<p><span class="noviewer" typeof="mw:File"></span> Media related to <a href="https://commons.wikimedia.org/wiki/Category:Alpha_particles" class="extiw external" title="commons:Category:Alpha particles">Alpha particles</a> at Wikimedia Commons

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</style><div id="Radiation_(physics_and_health)439" style="font-size:114%;margin:0 4em"><a href="Radiation" title="Radiation">Radiation</a> (physics and health)</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Main articles</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Non-ionizing_radiation" title="Non-ionizing radiation">Non-ionizing radiation</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Acoustic_radiation_force" title="Acoustic radiation force">Acoustic radiation force</a></li>

<li><a href="Infrared" title="Infrared">Infrared</a></li>

<li><a href="Light" title="Light">Light</a></li>

<li><a href="Starlight" title="Starlight">Starlight</a></li>

<li><a href="Sunlight" title="Sunlight">Sunlight</a></li>

<li><a href="Microwave" title="Microwave">Microwave</a></li>

<li><a href="Radio_wave" title="Radio wave">Radio waves</a></li>

<li><a href="Ultraviolet" title="Ultraviolet">Ultraviolet</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Ionizing_radiation" title="Ionizing radiation">Ionizing radiation</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Radioactive_decay" title="Radioactive decay">Radioactive decay</a></li>

<li><a href="Cluster_decay" title="Cluster decay">Cluster decay</a></li>

<li><a href="Background_radiation" title="Background radiation">Background radiation</a></li>

<li><a href="Beta_particle" title="Beta particle">Beta particle</a></li>

<li><a href="Gamma_ray" title="Gamma ray">Gamma ray</a></li>

<li><a href="Cosmic_ray" title="Cosmic ray">Cosmic ray</a></li>

<li><a href="Neutron_radiation" title="Neutron radiation">Neutron radiation</a></li>

<li><a href="Nuclear_fission" title="Nuclear fission">Nuclear fission</a></li>

<li><a href="Nuclear_fusion" title="Nuclear fusion">Nuclear fusion</a></li>

<li><a href="Nuclear_reactor" title="Nuclear reactor">Nuclear reactors</a></li>

<li><a href="Nuclear_weapon" title="Nuclear weapon">Nuclear weapons</a></li>

<li><a href="Particle_accelerator" title="Particle accelerator">Particle accelerators</a></li>

<li><a href="Radionuclide" title="Radionuclide">Radioactive materials</a></li>

</div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Earth's_energy_budget" title="Earth's energy budget">Earth's energy budget</a></li>

<li><a href="Electromagnetic_radiation" title="Electromagnetic radiation">Electromagnetic radiation</a></li>

<li><a href="Synchrotron_radiation" title="Synchrotron radiation">Synchrotron radiation</a></li>

<li><a href="Thermal_radiation" title="Thermal radiation">Thermal radiation</a></li>

<li><a href="Black-body_radiation" title="Black-body radiation">Black-body radiation</a></li>

<li><a href="Particle_radiation" title="Particle radiation">Particle radiation</a></li>

<li><a href="Gravitational_radiation" class="mw-redirect" title="Gravitational radiation">Gravitational radiation</a></li>

<li><a href="Cosmic_background_radiation" title="Cosmic background radiation">Cosmic background radiation</a></li>

<li><a href="Cherenkov_radiation" title="Cherenkov radiation">Cherenkov radiation</a></li>

<li><a href="Askaryan_radiation" title="Askaryan radiation">Askaryan radiation</a></li>

<li><a href="Bremsstrahlung" title="Bremsstrahlung">Bremsstrahlung</a></li>

<li><a href="Unruh_radiation" class="mw-redirect" title="Unruh radiation">Unruh radiation</a></li>

<li><a href="Dark_radiation" title="Dark radiation">Dark radiation</a></li>

<li><a href="Radiation_exposure" title="Radiation exposure">Radiation exposure</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Radiation <br>and health</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li>Radiation syndrome

<ul><li><a href="Acute_radiation_syndrome" title="Acute radiation syndrome">acute</a></li>

<li><a href="Chronic_radiation_syndrome" title="Chronic radiation syndrome">chronic</a></li></ul></li>

<li><a href="Health_physics" title="Health physics">Health physics</a></li>

<li><a href="Dosimetry" title="Dosimetry">Dosimetry</a></li>

<li><a href="Electromagnetic_radiation_and_health" title="Electromagnetic radiation and health">Electromagnetic radiation and health</a></li>

<li><a href="Laser_safety" title="Laser safety">Laser safety</a></li>

<li><a href="Lasers_and_aviation_safety" title="Lasers and aviation safety">Lasers and aviation safety</a></li>

<li><a href="Medical_radiography" class="mw-redirect" title="Medical radiography">Medical radiography</a></li>

<li><a href="Radiation_protection" title="Radiation protection">Radiation protection</a></li>

<li><a href="Radiation_therapy" title="Radiation therapy">Radiation therapy</a></li>

<li><a href="Radiation_damage" title="Radiation damage">Radiation damage</a></li>

<li><a href="Radioactivity_in_the_life_sciences" title="Radioactivity in the life sciences">Radioactivity in the life sciences</a></li>

<li><a href="Radioactive_contamination" title="Radioactive contamination">Radioactive contamination</a></li>

<li><a href="Radiobiology" title="Radiobiology">Radiobiology</a></li>

<li><a href="Sievert" title="Sievert">Biological dose units and quantities</a></li>

<li><a href="Wireless_device_radiation_and_health" title="Wireless device radiation and health">Wireless device radiation and health</a></li>

<li><a href="Wireless_electronic_devices_and_health" class="mw-redirect" title="Wireless electronic devices and health">Wireless electronic devices and health</a></li>

<li><a href="Heat_transfer" title="Heat transfer">Radiation heat-transfer</a></li>

<li><a href="Linear_energy_transfer" title="Linear energy transfer">Linear energy transfer</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Radiation incidents</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="List_of_civilian_radiation_accidents" title="List of civilian radiation accidents">List of civilian radiation accidents</a></li>

<li><a href="1996_San_Juan_de_Dios_radiotherapy_accident" title="1996 San Juan de Dios radiotherapy accident">1996 Costa Rica accident</a></li>

<li><a href="Goi%C3%A2nia_accident" title="Goiânia accident">1987 Goiânia accident</a></li>

<li><a href="1984_Moroccan_radiation_accident" title="1984 Moroccan radiation accident">1984 Moroccan accident</a></li>

<li><a href="1990_Clinic_of_Zaragoza_radiotherapy_accident" class="mw-redirect" title="1990 Clinic of Zaragoza radiotherapy accident">1990 Zaragoza accident</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related articles</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Nuclear_physics" title="Nuclear physics">Nuclear physics</a></li>

<li><a href="Radioactive_source" title="Radioactive source">Radioactive source</a></li>

<li><a href="Radiation_hardening" title="Radiation hardening">Radiation hardening</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div></div></td></tr></tbody></table></div>

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