{"id":25049,"date":"2019-08-15T07:37:16","date_gmt":"2019-08-15T07:37:16","guid":{"rendered":"http:\/\/sitepourvtc.com\/?page_id=25049"},"modified":"2023-06-10T06:13:05","modified_gmt":"2023-06-10T06:13:05","slug":"beta-decay-beta-radioactivity","status":"publish","type":"page","link":"https:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radioactive-decay\/beta-decay-beta-radioactivity\/","title":{"rendered":"Beta Decay &#8211; Beta Radioactivity"},"content":{"rendered":"<div   id="8n9s8rpp6h"    class=\"su-quote su-quote-style-default\"><div   id="8n9s8rpp6h"    class=\"su-quote-inner su-u-clearfix su-u-trim\"><strong>Beta decay<\/strong> or <strong>\u03b2 decay<\/strong> represents the disintegration of a parent nucleus to a daughter through the emission of the beta particle. <strong>Beta-decay<\/strong> is governed by <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-interactions-fundamental-forces\/weak-interaction-weak-force\/\">weak interaction<\/a>. During beta decay, one of two down <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/quarks\/\">quarks<\/a> changes into an up quark by emitting a W<sup>\u2013<\/sup> boson (carries away a negative charge).<\/div><\/div>\n<p>This transition (<strong>\u03b2<\/strong><strong><sup>&#8211;<\/sup><\/strong><strong> decay<\/strong>) can be characterized as:<\/p>\n<p><a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/Beta-Decay-Beta-Radioactivity-definition.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25037\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/Beta-Decay-Beta-Radioactivity-definition.png\" alt=\"Beta Decay - Beta Radioactivity - definition\" width=\"388\" height=\"150\" srcset=\"https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/Beta-Decay-Beta-Radioactivity-definition.png 388w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/Beta-Decay-Beta-Radioactivity-definition-300x116.png 300w\" sizes=\"(max-width: 388px) 100vw, 388px\" \/><\/a><\/p>\n<p>If a <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/atom-properties-of-atoms\/atomic-nucleus\/\">nucleus<\/a> emits a beta particle, it loses an electron (or positron). In this case, the mass number of the daughter nucleus remains the same, but the daughter nucleus will form a different element.<\/p>\n<p><a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\">Beta particles<\/a> are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles have a <strong>greater range<\/strong> of penetration than alpha particles but still much less than <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">gamma rays<\/a>. The beta particles emitted are a form of <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/\">ionizing radiation<\/a> known as beta rays. There are the following forms of beta decay:<\/p>\n<ul>\n<li><strong>Negative Beta Decay &#8211; Electron Decay. <\/strong>In electron decay, a neutron-rich nucleus emits a high-energy electron (\u03b2<sup>&#8211;<\/sup> particle). The electrons are negatively charged almost massless particles. Due to the law of conservation of electric charge, the nuclear charge must increase by one unit. In this case, the process can be represented by: <a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/negative-beta-decay-definition.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25046\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/negative-beta-decay-definition.png\" alt=\"\" width=\"370\" height=\"43\" srcset=\"https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/negative-beta-decay-definition.png 370w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/negative-beta-decay-definition-300x35.png 300w\" sizes=\"(max-width: 370px) 100vw, 370px\" \/><\/a><\/li>\n<li><strong>Positive Beta Decay &#8211; Positron Decay. <\/strong>In positron decay, a proton-rich nucleus emits a positron (positrons are antiparticles of electrons and have the same mass as electrons but positive electric charge), thereby reducing the nuclear charge by one unit. In this case, the process can be represented by: An annihilation occurs when a low-energy positron collides with a low-energy electron. <a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/positive-beta-decay-definition.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25048\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/positive-beta-decay-definition.png\" alt=\"\" width=\"350\" height=\"49\" srcset=\"https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/positive-beta-decay-definition.png 350w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/positive-beta-decay-definition-300x42.png 300w\" sizes=\"(max-width: 350px) 100vw, 350px\" \/><\/a><\/li>\n<li><strong>Inverse Beta Decay &#8211; Electron Capture<\/strong><strong>. Electron capture<\/strong>, also known as inverse beta decay, is sometimes included as a type of beta decay because the basic nuclear process, mediated by the weak interaction, is the same. In this process, a proton-rich nucleus can also reduce its nuclear charge by one unit by absorbing an atomic electron. <a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/electron-capture-definition.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25047\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/electron-capture-definition.png\" alt=\"\" width=\"277\" height=\"42\" \/><\/a><\/li>\n<\/ul>\n<p>The emission of electrons was among the earliest observed decay phenomena. The inverse process, <strong>electron capture<\/strong>, was first observed by Luis Alvarez in vanadium 48, and he reported it in a 1937 paper in Physical Review.<\/p>\n<figure id=\"attachment_12115\" aria-describedby=\"caption-attachment-12115\" style=\"width: 290px\" class=\"wp-caption alignright\"><a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/05\/uranium-238-decay.png\"><img loading=\"lazy\" class=\"size-medium wp-image-12115\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/05\/uranium-238-decay-300x174.png\" alt=\"Uranium 238 decay.\" width=\"300\" height=\"174\" srcset=\"https:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/05\/uranium-238-decay-300x174.png 300w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/05\/uranium-238-decay-1024x594.png 1024w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/05\/uranium-238-decay.png 1449w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-12115\" class=\"wp-caption-text\">Uranium 238 decay chain comprises alpha and beta decays.<\/figcaption><\/figure>\n<p>A <a href=\"http:\/\/sitepourvtc.com\/nuclear-power-plant\/what-is-nuclear-reactor\/\">nuclear reactor<\/a> occurs especially the \u03b2\u2212 decay because the common feature of the <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/fission\/fission-fragments\/\">fission products<\/a> is an excess of neutrons (see <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/nuclear-stability\/\">Nuclear Stability<\/a>). An unstable fission fragment with excess <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/\">neutrons<\/a> undergoes \u03b2\u2212 decay, where the neutron is converted into a proton, an electron, and an <strong>electron antineutrino<\/strong>. A <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/free-neutron\/\">free neutron<\/a> also undergoes this type of decay. A free neutron will decay with a half-life of <strong>about 611 seconds<\/strong> (10.3 minutes) into a proton, an electron, and an antineutrino (the <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/what-is-antimatter\/\">antimatter<\/a> counterpart of the <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutrino\/\">neutrino<\/a>, a particle with no charge and little or no mass).<\/p>\n<div   id="8n9s8rpp6h"    class=\"collapsible-container\">\n<h2>Theory of Beta Decay &#8211; Weak Interaction<\/h2>\n<p><strong>Beta-decay<\/strong> is governed by <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-interactions-fundamental-forces\/weak-interaction-weak-force\/\">weak interaction<\/a>. During beta decay, one of two down <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/quarks\/\">quarks<\/a> changes into an up quark by emitting a W<sup>\u2013<\/sup> boson (carries away a negative charge). The W<sup>\u2013<\/sup> boson then decays into a<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\"> beta particle<\/a> and an<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/antineutrino\/\"> antineutrino<\/a>. This process is equivalent to the process in which a neutrino interacts with a neutron.<\/p>\n<p><a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/theory-of-beta-decay-weak-interaction.png\"><img loading=\"lazy\" class=\"aligncenter size-large wp-image-25042\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/theory-of-beta-decay-weak-interaction-1024x262.png\" alt=\"theory of beta decay - weak interaction\" width=\"1024\" height=\"262\" srcset=\"https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/theory-of-beta-decay-weak-interaction-1024x262.png 1024w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/theory-of-beta-decay-weak-interaction-300x77.png 300w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/theory-of-beta-decay-weak-interaction-768x196.png 768w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/theory-of-beta-decay-weak-interaction.png 1111w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/a><\/p>\n<p>As can be seen from the figure, the <strong>weak interaction<\/strong> changes one flavor of quark into another. Note that<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/the-standard-model\/\">\u00a0the Standard Model<\/a> counts six flavors of quarks and six flavors of leptons. The <strong>weak interaction<\/strong> is the only process in which a quark can change to another quark or a lepton to another lepton (flavor change). Neither the <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-interactions-fundamental-forces\/strong-interaction-strong-force\/\">strong interaction<\/a> nor <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-interactions-fundamental-forces\/electromagnetic-interaction-electromagnetic-force\/\">electromagnetic<\/a> permit flavor changing. This fact is crucial in many decays of nuclear particles. In the fusion process, which, for example, powers the Sun, two protons interact via the weak force to form a deuterium nucleus, which reacts further to generate helium. Without the weak interaction, the diproton would decay back into two hydrogen-1 unbound protons through proton emission. As a result, the sun would not burn without it since the weak interaction causes the transmutation p -&gt; n.<\/p>\n<p>In contrast to <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radioactive-decay\/alpha-decay-alpha-radioactivity\/\">alpha decay<\/a>, neither the beta particle nor its associated neutrino exist within the nucleus prior to beta decay but are created in the decay process. Through this process, unstable atoms obtain a more stable ratio of protons to neutrons. The probability of a nuclide decaying due to beta and other forms of decay is determined by its nuclear binding energy. The energy release (see below) or Q value must be positive for either electron or positron emission to be energetically possible.<\/p>\n<div   id="8n9s8rpp6h"    class=\"su-divider su-divider-style-dotted\" style=\"margin:15px 0;border-width:2px;border-color:#999999\"><\/div>\n<h2>Example of Beta Decay<\/h2>\n<div   id="8n9s8rpp6h"    class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\" data-scroll-offset=\"0\"><div   id="8n9s8rpp6h"    class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span class=\"su-spoiler-icon\"><\/span>Free Neutron<\/div><div   id="8n9s8rpp6h"    class=\"su-spoiler-content su-u-clearfix su-u-trim\">\n<p><strong>A free neutron<\/strong> is a neutron that is not bounded in a nucleus. Unlike a bounded neutron, the free neutron is subject to <strong>radioactive beta decay<\/strong>.<\/p>\n<figure id=\"attachment_11524\" aria-describedby=\"caption-attachment-11524\" style=\"width: 290px\" class=\"wp-caption alignright\"><a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/01\/free_neutron.png\"><img loading=\"lazy\" class=\"size-medium wp-image-11524\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/01\/free_neutron-300x200.png\" alt=\"Free Neutron\" width=\"300\" height=\"200\" srcset=\"https:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/01\/free_neutron-300x200.png 300w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/01\/free_neutron.png 400w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-11524\" class=\"wp-caption-text\">The free neutron decays into a proton, an electron, and an antineutrino with a half-life of about 611 seconds (10.3 minutes).<br \/>Source: scienceblogs.com<\/figcaption><\/figure>\n<p>It decays into a proton, an electron, and an antineutrino (the antimatter counterpart of the neutrino, a particle with no charge and little or no mass). A free neutron will decay with a half-life of <strong>about 611 seconds<\/strong> (10.3 minutes). This decay involves\u00a0<strong>the weak interaction<\/strong> and is associated with a quark transformation (a down quark is converted to an up quark). The decay of the neutron is a good example of the observations that led to the discovery of <strong>the neutrino<\/strong>. Because it decays in this manner, the neutron does not exist in nature in its free state, except among other highly energetic particles in cosmic rays. Since free neutrons are <strong>electrically neutral<\/strong>, they pass through the electrical fields within atoms without any interaction. They interact with matter almost exclusively through relatively rare collisions with atomic nuclei.<\/p>\n<p><span style=\"font-weight: 400;\">It must be noted that a <strong>proton cannot decay in free space, and a<\/strong>\u00a0proton can undergo decay, but only inside a nucleus. It is due to <\/span><span style=\"font-weight: 400;\">the conservation of the baryon number that has been established as a basic principle of physics. This principle provides a basis for the <\/span><b>stability of the proton<\/b><span style=\"font-weight: 400;\">. Since the proton is the lightest particle among all baryons, the hypothetical products of its decay would have to be non-baryons.<\/span><\/p>\n<p>See also:<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/what-is-proton-properties-of-proton\/stability-of-proton\/\"> Stability of Proton<\/a><\/p>\n<\/div><\/div>\n<div   id="8n9s8rpp6h"    class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\" data-scroll-offset=\"0\"><div   id="8n9s8rpp6h"    class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span class=\"su-spoiler-icon\"><\/span>Discovery of Neutrino<\/div><div   id="8n9s8rpp6h"    class=\"su-spoiler-content su-u-clearfix su-u-trim\">\n<p>The study of beta decay provided the first physical evidence for the\u00a0<strong>existence of the neutrino<\/strong>. The <strong>discovery of the neutrino<\/strong>\u00a0is based on the\u00a0<strong>law of conservation of energy<\/strong>\u00a0during the process of beta decay.<\/p>\n<p>See also: <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutrino\/\">Discovery of Neutrino<\/a><\/p>\n<\/div><\/div>\n<div   id="8n9s8rpp6h"    class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\" data-scroll-offset=\"0\"><div   id="8n9s8rpp6h"    class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span class=\"su-spoiler-icon\"><\/span>Beta Decay of Tritium<\/div><div   id="8n9s8rpp6h"    class=\"su-spoiler-content su-u-clearfix su-u-trim\">\n<p><a href=\"http:\/\/sitepourvtc.com\/glossary\/tritium\/\"><strong>Tritium<\/strong><\/a> is a radioactive isotope, but it emits a very weak form of radiation, a low-energy<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\"> beta particle<\/a> similar to an electron. It is a pure beta emitter (i.e., beta emitter without accompanying<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\"> gamma radiation<\/a>). The electron\u2019s kinetic energy varies, with an average of 5.7 keV, while the nearly undetectable electron <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/antineutrino\/\">antineutrino<\/a> carries off the remaining energy. Such a very low energy of electron causes that the electron cannot penetrate the skin or even does not travel very far in the air. Beta particles from tritium can penetrate only about 6.0 mm of air.<\/p>\n<p>Tritium decays via negative beta decay into helium-3 with a half-life of <strong>12.3 years<\/strong>.<\/p>\n<p><a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/11\/Tritium-Decay.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-13228\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/11\/Tritium-Decay.png\" alt=\"Decay of Tritium\" width=\"295\" height=\"79\" \/><\/a><\/p>\n<\/div><\/div>\n<div   id="8n9s8rpp6h"    class=\"su-divider su-divider-style-dotted\" style=\"margin:15px 0;border-width:2px;border-color:#999999\"><\/div>\n<h2>Energy Spectrum of Beta Decay<\/h2>\n<p>In <a href=\"http:\/\/www.personal-dosimeter.com\/ionizing-radiation\/alpha-decay\/\">alpha<\/a>\u00a0and\u00a0<a href=\"http:\/\/www.personal-dosimeter.com\/ionizing-radiation\/gamma-decay\/\">gamma decay<\/a>, the resulting particle (<a title=\"Alpha Particle\" href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/alpha-particle\/\">alpha particle<\/a>\u00a0or\u00a0<a title=\"Photon \u2013 Fundamental Particle\" href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/\">photon<\/a>) has a\u00a0<strong>narrow energy distribution<\/strong> since the particle carries the energy from the difference between the initial and final nuclear states. For example, in the case of alpha decay, when a parent nucleus breaks down spontaneously to yield a daughter nucleus and an alpha particle, the sum of the mass of the two products does not quite equal the mass of the original nucleus (see <a title=\"Mass Defect\" href=\"http:\/\/sitepourvtc.com\/nuclear-power\/nuclear-energy\/mass-defect\/\">Mass Defect<\/a>). As a result of the law of conservation of energy, this difference appears in the form of the<strong>\u00a0kinetic energy of the alpha particle<\/strong>. Since the same particles appear as products at every breakdown of a particular parent nucleus, the mass difference should <strong>always be the same<\/strong>, and the<strong>\u00a0<a href=\"http:\/\/sitepourvtc.com\/nuclear-engineering\/thermodynamics\/what-is-energy-physics\/what-is-kinetic-energy\/\">kinetic energy<\/a><\/strong> of the alpha particles should also always be the same. In other words, the beam of alpha particles should be\u00a0<strong>monoenergetic<\/strong>.<\/p>\n<p>It was expected that the same considerations would hold for a parent nucleus breaking down to a daughter nucleus and\u00a0<strong>a beta particle<\/strong>. Because only the electron and the recoiling daughter nucleus were observed in beta decay, the process was initially <strong>assumed to be a two-body process<\/strong>, much like alpha decay. It would seem reasonable to suppose that the beta particles also form a <strong>monoenergetic beam<\/strong>.<\/p>\n<p>To demonstrate the energetics of two-body beta decay, consider the beta decay in which an electron is emitted and the parent nucleus is at rest. <strong><a href=\"http:\/\/sitepourvtc.com\/laws-of-conservation\/law-of-conservation-of-energy\/\">Conservation<\/a><a href=\"http:\/\/sitepourvtc.com\/laws-of-conservation\/law-of-conservation-of-energy\/\"><strong>\u00a0<\/strong>of energy<\/a><\/strong>\u00a0requires:<\/p>\n<p><a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2016\/11\/conservation-of-energy-beta-decay.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-15817 lazy-loaded\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2016\/11\/conservation-of-energy-beta-decay.png\" sizes=\"(max-width: 436px) 100vw, 436px\" srcset=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2016\/11\/conservation-of-energy-beta-decay.png 436w, http:\/\/sitepourvtc.com\/wp-content\/uploads\/2016\/11\/conservation-of-energy-beta-decay-300x153.png 300w\" alt=\"conservation-of-energy-beta-decay\" width=\"436\" height=\"222\" data-lazy-type=\"image\" data-src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2016\/11\/conservation-of-energy-beta-decay.png\" data-srcset=\"\" \/><\/a><\/p>\n<p>Since the electron is a much lighter particle, it was expected to carry away most of the released energy, which would have a unique value <strong>T<\/strong><strong><sub>e-<\/sub><\/strong>.<\/p>\n<figure id=\"attachment_11708\" aria-describedby=\"caption-attachment-11708\" style=\"width: 334px\" class=\"wp-caption alignright\"><a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/03\/beta-decay-spectrum.gif\"><img loading=\"lazy\" class=\"size-full wp-image-11708\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2015\/03\/beta-decay-spectrum.gif\" alt=\"Energy spectrum of beta decay\" width=\"344\" height=\"274\" \/><\/a><figcaption id=\"caption-attachment-11708\" class=\"wp-caption-text\">The shape of this energy curve depends on what fraction of the reaction energy (Q value-the amount of energy released by the reaction) is carried by the electron or neutrino.<\/figcaption><\/figure>\n<p><strong>But the reality was different<\/strong>. The spectrum of beta particles measured by Lise Meitner and Otto Hahn in 1911 and by Jean Danysz in 1913 showed multiple lines on a diffuse background. Moreover, virtually all of the emitted beta particles have energies below that predicted by energy conservation in two-body decays. <strong>The electrons emitted in\u00a0<a title=\"Spectrum of Beta Particles\" href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/spectrum-beta-particles\/\">beta decay have a continuous<\/a> rather than a discrete spectrum <\/strong>that appears to contradict the conservation of energy, under the then-current assumption that beta decay is the simple emission of an electron from a nucleus. When this was first observed, <strong>it appeared to threaten the survival of one of the most important conservation laws in physics<\/strong>!<\/p>\n<p>To account for this energy release,\u00a0<strong>Pauli proposed<\/strong>\u00a0(in 1931) that there was emitted in the decay process\u00a0<strong>another particle<\/strong>, later named by Fermi the<strong>\u00a0neutrino<\/strong>. It was clear that this particle must be highly penetrating and that the conservation of electric charge requires the neutrino to be electrically neutral. This would explain why it was so hard to detect this particle. The term neutrino comes from Italian, meaning \u201clittle neutral one,\u201d and neutrinos are denoted by the Greek letter<strong>\u00a0\u03bd (nu)<\/strong>. In the process of beta decay, the neutrino carries the missing energy, and also, in this process, the law of <strong>conservation of energy remains valid<\/strong>.<\/p>\n<h2>Conservation Laws in Beta Decay<\/h2>\n<p>In analyzing<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/nuclear-reactions\/\"> nuclear reactions<\/a>, we apply the <strong>many <a href=\"http:\/\/sitepourvtc.com\/laws-of-conservation\/\">conservation laws<\/a><\/strong>. <strong>Nuclear reactions<\/strong> are subject to classical <strong>conservation laws for the charge, momentum, angular momentum, and energy <\/strong>(including rest energies). Additional conservation laws not anticipated by classical physics are:<\/p>\n<ul>\n<li><a href=\"http:\/\/sitepourvtc.com\/laws-of-conservation\/law-conservation-lepton-number\/\">Law of Conservation of Lepton Number<\/a><\/li>\n<li><a href=\"http:\/\/sitepourvtc.com\/laws-of-conservation\/law-conservation-baryon-number\/\">Law of Conservation of Baryon Number<\/a><\/li>\n<li><a href=\"http:\/\/sitepourvtc.com\/laws-of-conservation\/law-conservation-electric-charge\/\">Law of Conservation of Electric Charge<\/a><\/li>\n<\/ul>\n<p>Certain of these laws are obeyed under all circumstances, and others are not. We have accepted the conservation of energy and momentum. In all the examples, we assume that the number of protons and neutrons is separately conserved. We shall find circumstances and conditions in which this rule is not true. Where we are considering non-relativistic nuclear reactions, it is essentially true. However, when considering relativistic nuclear energies or those involving weak interactions, we shall find that these principles must be extended.<\/p>\n<p>Some conservation principles have arisen from theoretical considerations, and others are just empirical relationships. Notwithstanding, any reaction not expressly forbidden by the conservation laws will generally occur, perhaps at a slow rate. This expectation is based on quantum mechanics. Unless the barrier between the initial and final states is infinitely high, there is always a <strong>non-zero probability<\/strong> that a system will make the transition between them.<\/p>\n<p>For purposes of analyzing non-relativistic reactions, it is sufficient to note four of the fundamental laws governing these reactions.<\/p>\n<ol>\n<li><strong>Conservation of nucleons<\/strong>. The total number of nucleons before and after a reaction are the same.<\/li>\n<li><strong>Conservation of charge<\/strong>. The sum of the charges on all the particles before and after a reaction are the same.<\/li>\n<li><strong>Conservation of momentum<\/strong>. The total momentum of the interacting particles before and after a reaction is the same.<\/li>\n<li><strong>Conservation of energy<\/strong>. Energy, including rest mass energy, is conserved in nuclear reactions.<\/li>\n<\/ol>\n<p>Reference: Lamarsh, John R. Introduction to Nuclear engineering 2nd Edition<\/p>\n<h2>Beta Decay &#8211; Q-value<\/h2>\n<p>In nuclear and particle physics, the <strong>energetics of nuclear reactions<\/strong> is determined by the <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/nuclear-reactions\/q-value-energetics-nuclear-reactions\/\"><strong>Q-value<\/strong><\/a> of that reaction. The <strong>Q-value<\/strong> of the reaction is defined as the <strong>difference<\/strong> between the sum of the<strong> rest<\/strong> <strong>masses<\/strong> of the <strong>initial reactants<\/strong> and the sum of the <strong>masses<\/strong> of the <strong>final products<\/strong>\u00a0in energy units (usually in MeV).<\/p>\n<p>Consider a typical reaction in which the projectile a and the target A give place to two products, B and b. This can also be expressed in the notation we have used so far, <strong>a + A \u2192 B + b<\/strong>, or even in a more compact notation, <strong>A(a,b)B<\/strong>.<\/p>\n<p>See also: <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/nuclear-energy\/emc2-meaning\/\">E=mc2<\/a><\/p>\n<p>The <strong>Q-value<\/strong> of this reaction is given by:<\/p>\n<p><strong>Q = [ma + mA \u2013 (mb + mB)]c<sup>2<\/sup><\/strong><\/p>\n<p>When describing beta decay (reaction without projectile), the disintegrating nucleus is usually referred to as the parent nucleus and the nucleus remaining after the event as the daughter nucleus. The emission of a beta particle, either an electron, \u03b2<sup>&#8211;<\/sup>, or a positron, \u03b2<sup>+<\/sup>, changes the atomic number of the nucleus without affecting its mass number. The total rest mass of the daughter nucleus and the nuclear radiation released in a beta disintegration, m<sub>Daughter<\/sub> + m<sub>Radiation<\/sub>, is always less than that of the parent nucleus, m<sub>parent<\/sub>.<\/p>\n<p>The mass-energy difference,<\/p>\n<p><strong>Q = [m<sub>parent<\/sub> \u2013 (m<sub>Daughter<\/sub> + m<sub>Radiation<\/sub>)]c<sup>2<\/sup><\/strong><\/p>\n<p>appears as the disintegration energy, liberated in the process. For example, the Q-value of typical beta decay is:<\/p>\n<p><a href=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/beta-decay-q-value-example.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25036\" src=\"http:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/beta-decay-q-value-example.png\" alt=\"beta decay - q-value\" width=\"500\" height=\"155\" srcset=\"https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/beta-decay-q-value-example.png 500w, https:\/\/sitepourvtc.com\/wp-content\/uploads\/2018\/08\/beta-decay-q-value-example-300x93.png 300w\" sizes=\"(max-width: 500px) 100vw, 500px\" \/><\/a><\/p>\n<p>In the process of beta decay, either an electron or a positron is emitted. This emission is accompanied by the emission of <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/antineutrino\/\"><strong>antineutrino<\/strong><\/a> (\u03b2- decay) or<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutrino\/\"><strong> neutrino<\/strong><\/a> (\u03b2+ decay), which share the energy and momentum of the decay. The beta emission has a characteristic spectrum. This characteristic <a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/spectrum-beta-particles\/\">spectrum<\/a> is caused by the fact that either a neutrino or an antineutrino is emitted with the emission of a beta particle. The shape of this energy curve depends on what fraction of the reaction energy (<strong>Q value<\/strong>-the amount of energy released by the reaction) is carried by the massive particle. Beta particles can therefore be emitted with any kinetic energy ranging from <strong>0 to Q<\/strong>. After an alpha or beta decay, the daughter nucleus is often left in an excited energy state. To stabilize itself, it subsequently emits high-energy photons, \u03b3-rays.<\/p>\n<\/div>\n<div   id="8n9s8rpp6h"    class=\"su-divider su-divider-style-dotted\" style=\"margin:20px 0;border-width:2px;border-color:#999999\"><\/div>\n<div   id="8n9s8rpp6h"     class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights \"><div   id="8n9s8rpp6h"     class=\"inside-grid-column\"><div   id="8n9s8rpp6h"    class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\" data-scroll-offset=\"0\"><div   id="8n9s8rpp6h"    class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span class=\"su-spoiler-icon\"><\/span>References:<\/div><div   id="8n9s8rpp6h"    class=\"su-spoiler-content su-u-clearfix su-u-trim\">\n<p><strong>Radiation Protection:<\/strong><\/p>\n<ol>\n<li>Knoll, Glenn F., Radiation Detection and Measurement 4th Edition, Wiley, 8\/2010. ISBN-13: 978-0470131480.<\/li>\n<li>Stabin, Michael G., Radiation Protection and Dosimetry: An Introduction to Health Physics, Springer, 10\/2010. ISBN-13: 978-1441923912.<\/li>\n<li>Martin, James E., Physics for Radiation Protection 3rd Edition, Wiley-VCH, 4\/2013. ISBN-13: 978-3527411764.<\/li>\n<li>U.S.NRC, NUCLEAR REACTOR CONCEPTS<\/li>\n<li>U.S. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993.<\/li>\n<\/ol>\n<p><strong>Nuclear and Reactor Physics:<\/strong><\/p>\n<ol>\n<li>J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).<\/li>\n<li>J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.<\/li>\n<li>W. M. Stacey, Nuclear Reactor Physics, John Wiley &amp; Sons, 2001, ISBN: 0- 471-39127-1.<\/li>\n<li>Glasstone, Sesonske. Nuclear Reactor Engineering: Reactor Systems Engineering, Springer; 4th edition, 1994, ISBN: 978-0412985317<\/li>\n<li>W.S.C. Williams. Nuclear and Particle Physics. Clarendon Press; 1 edition, 1991, ISBN: 978-0198520467<\/li>\n<li>G.R.Keepin. Physics of Nuclear Kinetics. Addison-Wesley Pub. Co; 1st edition, 1965<\/li>\n<li>Robert Reed Burn, Introduction to Nuclear Reactor Operation, 1988.<\/li>\n<li>U.S. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993.<\/li>\n<li>Paul Reuss, Neutron Physics. EDP Sciences, 2008. ISBN: 978-2759800414.<\/li>\n<\/ol>\n<\/div><\/div><div   id="8n9s8rpp6h"    class=\"su-divider su-divider-style-dotted\" style=\"margin:15px 0;border-width:2px;border-color:#999999\"><\/div><\/div><\/div>\n<div   id="8n9s8rpp6h"     class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights \"><div   id="8n9s8rpp6h"     class=\"inside-grid-column\"><\/div><\/div><div   id="8n9s8rpp6h"     class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights \"><div   id="8n9s8rpp6h"     class=\"inside-grid-column\">\n<h2>See above:<\/h2>\n<p>Radioactive Decay<a href=\"http:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radioactive-decay\/\" class=\"su-button su-button-style-flat\" style=\"color:#606060;background-color:#ffffff;border-color:#cccccc;border-radius:10px;-moz-border-radius:10px;-webkit-border-radius:10px\" target=\"_self\"><span style=\"color:#606060;padding:7px 20px;font-size:16px;line-height:24px;border-color:#ffffff;border-radius:10px;-moz-border-radius:10px;-webkit-border-radius:10px;text-shadow:0px 0px 0px #000000;-moz-text-shadow:0px 0px 0px #000000;-webkit-text-shadow:0px 0px 0px #000000\"><i class=\"sui sui-link\" style=\"font-size:16px;color:#5d5d5d\"><\/i> <\/span><\/a><\/p><\/div><\/div><div   id="8n9s8rpp6h"     class=\"lgc-column lgc-grid-parent lgc-grid-33 lgc-tablet-grid-33 lgc-mobile-grid-100 lgc-equal-heights \"><div   id="8n9s8rpp6h"     class=\"inside-grid-column\"><\/div><\/div>\n","protected":false},"excerpt":{"rendered":"<p>This transition (\u03b2&#8211; decay) can be characterized as: If a nucleus emits a beta particle, it loses an electron (or positron). In this case, the mass number of the daughter nucleus remains the same, but the daughter nucleus will form a different element. Beta particles are high-energy, high-speed electrons or positrons emitted by certain types &#8230; <a title=\"Beta Decay &#8211; Beta Radioactivity\" class=\"read-more\" href=\"https:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radioactive-decay\/beta-decay-beta-radioactivity\/\" aria-label=\"More on Beta Decay &#8211; Beta Radioactivity\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":11374,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"generate_page_header":""},"_links":{"self":[{"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages\/25049"}],"collection":[{"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/comments?post=25049"}],"version-history":[{"count":3,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages\/25049\/revisions"}],"predecessor-version":[{"id":37773,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages\/25049\/revisions\/37773"}],"up":[{"embeddable":true,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages\/11374"}],"wp:attachment":[{"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/media?parent=25049"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}