{"id":18218,"date":"2020-06-27T11:08:05","date_gmt":"2020-06-27T11:08:05","guid":{"rendered":"https:\/\/www.radiation-dosimetry.org\/o-que-e-radiacao-beta-definicao\/"},"modified":"2020-07-24T10:23:28","modified_gmt":"2020-07-24T10:23:28","slug":"o-que-e-radiacao-beta-definicao","status":"publish","type":"post","link":"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/","title":{"rendered":"O que \u00e9 radia\u00e7\u00e3o beta &#8211; Defini\u00e7\u00e3o"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-u-clearfix su-u-trim\">A radia\u00e7\u00e3o beta consiste em el\u00e9trons livres ou p\u00f3sitrons em velocidades relativ\u00edsticas.\u00a0Essas part\u00edculas s\u00e3o conhecidas como part\u00edculas beta.\u00a0Qual \u00e9 a radia\u00e7\u00e3o beta.\u00a0Dosimetria de Radia\u00e7\u00e3o<\/div>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2>Formas de radia\u00e7\u00e3o ionizante<\/h2>\n<figure id=\"attachment_317\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-317\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Alfa_beta_gamma_neutron_radiation.png\"><img loading=\"lazy\" class=\"size-medium wp-image-317 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Alfa_beta_gamma_neutron_radiation-174x300.png\" alt=\"Intera\u00e7\u00e3o da radia\u00e7\u00e3o com a mat\u00e9ria\" width=\"174\" height=\"300\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Alfa_beta_gamma_neutron_radiation-174x300.png\" \/><\/a><figcaption id=\"caption-attachment-317\" class=\"wp-caption-text\">Intera\u00e7\u00e3o da radia\u00e7\u00e3o com a mat\u00e9ria<\/figcaption><\/figure>\n<p><strong>A radia\u00e7\u00e3o ionizante<\/strong>\u00a0\u00e9 categorizada pela natureza das part\u00edculas ou ondas eletromagn\u00e9ticas que criam o efeito ionizante.\u00a0Essas\u00a0<strong>part\u00edculas \/ ondas<\/strong>\u00a0t\u00eam diferentes mecanismos de ioniza\u00e7\u00e3o e podem ser agrupadas como:<\/p>\n<ul>\n<li><strong>Ionizante direto<\/strong>\u00a0.\u00a0Part\u00edculas carregadas (\u00a0<strong>n\u00facleos at\u00f4micos, el\u00e9trons, p\u00f3sitrons, pr\u00f3tons, m\u00faons etc.<\/strong>\u00a0) podem ionizar \u00e1tomos diretamente por intera\u00e7\u00e3o fundamental atrav\u00e9s da for\u00e7a de Coulomb, se transportarem energia cin\u00e9tica suficiente.\u00a0Essas part\u00edculas devem estar se movendo em velocidades relativ\u00edsticas para alcan\u00e7ar a energia cin\u00e9tica necess\u00e1ria.\u00a0Mesmo os f\u00f3tons (raios gama e raios X) podem ionizar \u00e1tomos diretamente (apesar de serem eletricamente neutros) atrav\u00e9s do efeito Fotoel\u00e9trico e do efeito Compton, mas a ioniza\u00e7\u00e3o secund\u00e1ria (indireta) \u00e9 muito mais significativa.\n<ul>\n<li><strong>Radia\u00e7\u00e3o alfa<\/strong>\u00a0.\u00a0A radia\u00e7\u00e3o alfa consiste em\u00a0<a title=\"Alpha Particle\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/alpha-particle\/\">part\u00edculas alfa<\/a>\u00a0em alta energia \/ velocidade.\u00a0A produ\u00e7\u00e3o de part\u00edculas alfa \u00e9 denominada decaimento alfa.\u00a0As part\u00edculas alfa consistem em dois pr\u00f3tons e dois n\u00eautrons unidos em uma part\u00edcula id\u00eantica a um n\u00facleo de h\u00e9lio.\u00a0As part\u00edculas alfa s\u00e3o relativamente grandes e carregam uma carga positiva dupla.\u00a0Eles n\u00e3o s\u00e3o muito penetrantes e um peda\u00e7o de papel pode det\u00ea-los.\u00a0Eles viajam apenas alguns cent\u00edmetros, mas depositam todas as suas energias por seus caminhos curtos.<\/li>\n<li><strong>Radia\u00e7\u00e3o beta<\/strong>\u00a0.\u00a0A radia\u00e7\u00e3o beta consiste em el\u00e9trons livres ou p\u00f3sitrons em velocidades relativ\u00edsticas.\u00a0<a title=\"Part\u00edcula Beta\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\">As part\u00edculas beta<\/a>\u00a0(el\u00e9trons) s\u00e3o muito menores que as part\u00edculas alfa.\u00a0Eles carregam uma \u00fanica carga negativa.\u00a0Eles s\u00e3o mais penetrantes que as part\u00edculas alfa, mas o metal fino de alum\u00ednio pode det\u00ea-las.\u00a0Eles podem percorrer v\u00e1rios metros, mas depositam menos energia em qualquer ponto do caminho do que as part\u00edculas alfa.<\/li>\n<\/ul>\n<\/li>\n<li><strong>Ionizando indiretamente<\/strong>\u00a0.\u00a0A radia\u00e7\u00e3o ionizante indireta \u00e9 part\u00edculas eletricamente neutras e, portanto, n\u00e3o interage fortemente com a mat\u00e9ria.\u00a0A maior parte dos efeitos de ioniza\u00e7\u00e3o \u00e9 devida a ioniza\u00e7\u00f5es secund\u00e1rias.\n<ul>\n<li><strong>Radia\u00e7\u00e3o de f\u00f3tons<\/strong>\u00a0(\u00a0<a title=\"Raios gama \/ radia\u00e7\u00e3o gama\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">raios gama<\/a>\u00a0ou\u00a0<a title=\"Raios gama \/ radia\u00e7\u00e3o gama\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">raios<\/a>\u00a0X).\u00a0A radia\u00e7\u00e3o de f\u00f3tons consiste em\u00a0<a title=\"F\u00f3ton - Part\u00edcula Fundamental\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/\">f\u00f3tons<\/a>\u00a0de alta energia\u00a0.\u00a0Esses f\u00f3tons s\u00e3o part\u00edculas \/ ondas (Dualidade de Part\u00edculas de Onda) sem massa de repouso ou carga el\u00e9trica.\u00a0Eles podem viajar 10 metros ou mais no ar.\u00a0Esta \u00e9 uma longa dist\u00e2ncia em compara\u00e7\u00e3o com part\u00edculas alfa ou beta.\u00a0No entanto, os raios gama depositam menos energia ao longo de seus caminhos.\u00a0Chumbo, \u00e1gua e concreto impedem a radia\u00e7\u00e3o gama.\u00a0Os f\u00f3tons (raios gama e raios X) podem ionizar \u00e1tomos diretamente atrav\u00e9s do efeito Fotoel\u00e9trico e do efeito Compton, onde o el\u00e9tron relativamente energ\u00e9tico \u00e9 produzido.\u00a0O el\u00e9tron secund\u00e1rio continuar\u00e1 produzindo\u00a0<strong>m\u00faltiplos<\/strong>\u00a0eventos de\u00a0<strong>ioniza\u00e7\u00e3o<\/strong>\u00a0; portanto, a\u00a0<strong>ioniza\u00e7\u00e3o<\/strong>\u00a0secund\u00e1ria (indireta) \u00e9 muito mais significativa.<\/li>\n<li><strong>Radia\u00e7\u00e3o de n\u00eautrons<\/strong>\u00a0.\u00a0A radia\u00e7\u00e3o de\u00a0<a title=\"N\u00eautron gr\u00e1tis\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/free-neutron\/\" target=\"_blank\" rel=\"noopener noreferrer\">n\u00eautrons<\/a>\u00a0consiste em\u00a0<a title=\"N\u00eautron gr\u00e1tis\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/free-neutron\/\" target=\"_blank\" rel=\"noopener noreferrer\">n\u00eautrons livres<\/a>\u00a0em qualquer energia \/ velocidade.\u00a0<a title=\"N\u00eautron\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/\" target=\"_blank\" rel=\"noopener noreferrer\">Os n\u00eautrons<\/a>\u00a0podem ser emitidos por\u00a0<a title=\"Fic\u00e3o nuclear\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/fission\/\" target=\"_blank\" rel=\"noopener noreferrer\">fiss\u00e3o nuclear<\/a>\u00a0ou pelo\u00a0<a title=\"Decaimento radioativo - Decaimento nuclear\" href=\"https:\/\/www.nuclear-power.com\/radioactive-decay\/\" target=\"_blank\" rel=\"noopener noreferrer\">decaimento<\/a>\u00a0de alguns \u00e1tomos radioativos.\u00a0Os n\u00eautrons t\u00eam carga el\u00e9trica nula e n\u00e3o podem causar ioniza\u00e7\u00e3o diretamente.\u00a0Os n\u00eautrons ionizam a mat\u00e9ria\u00a0<strong>apenas indiretamente<\/strong>\u00a0.\u00a0Por exemplo, quando n\u00eautrons atingem os n\u00facleos de hidrog\u00eanio, ocorre radia\u00e7\u00e3o de pr\u00f3tons (pr\u00f3tons r\u00e1pidos).\u00a0Os n\u00eautrons podem variar de part\u00edculas de alta velocidade e alta energia a part\u00edculas de baixa velocidade e baixa energia (chamados n\u00eautrons t\u00e9rmicos).\u00a0Os n\u00eautrons podem viajar centenas de p\u00e9s no ar sem nenhuma intera\u00e7\u00e3o.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<h2><span>Radia\u00e7\u00e3o Beta<\/span><\/h2>\n<p><strong><span>A radia\u00e7\u00e3o beta<\/span><\/strong><span>\u00a0consiste em el\u00e9trons livres ou p\u00f3sitrons em velocidades relativ\u00edsticas.\u00a0Essas part\u00edculas s\u00e3o conhecidas como part\u00edculas beta.\u00a0<\/span><strong><span>As part\u00edculas beta<\/span><\/strong><span>\u00a0s\u00e3o\u00a0<\/span><strong><span>el\u00e9trons ou p\u00f3sitrons de<\/span><\/strong><span>\u00a0alta energia e alta velocidade\u00a0emitidos por certos\u00a0<\/span><a title=\"Fragmentos de fiss\u00e3o\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/fission\/fission-fragments\/\"><span>fragmentos de fiss\u00e3o<\/span><\/a><span>\u00a0ou por certos n\u00facleos radioativos primordiais, como o pot\u00e1ssio-40.\u00a0As part\u00edculas beta s\u00e3o uma\u00a0<\/span><a title=\"Formas de radia\u00e7\u00e3o ionizante\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/forms-ionizing-radiation\/\"><span>forma de radia\u00e7\u00e3o ionizante<\/span><\/a><span>\u00a0tamb\u00e9m conhecida como raios beta.\u00a0A produ\u00e7\u00e3o de part\u00edculas beta \u00e9 denominada\u00a0<\/span><strong><span>decaimento beta<\/span><\/strong><span>\u00a0.\u00a0Existem duas formas de decaimento beta,\u00a0<\/span><strong><span>o decaimento de el\u00e9trons (decaimento \u03b2)<\/span><\/strong><span>\u00a0e o\u00a0<\/span><strong><span>decaimento de p\u00f3sitrons (\u03b2 + decaimento)<\/span><\/strong><span>\u00a0.\u00a0Em um\u00a0<\/span><a title=\"Reator nuclear\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/\"><span>reator nuclear<\/span><\/a><span>ocorre especialmente o decaimento \u03b2, porque a caracter\u00edstica comum dos produtos de fiss\u00e3o \u00e9 um\u00a0<\/span><strong><span>excesso de\u00a0<\/span><a title=\"N\u00eautron\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/\"><span>n\u00eautrons<\/span><\/a><\/strong><span>\u00a0(\u00a0<\/span><a title=\"Estabilidade nuclear\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/nuclear-stability\/\"><span>consulte Estabilidade nuclear<\/span><\/a><span>\u00a0).\u00a0Um fragmento de fiss\u00e3o inst\u00e1vel com excesso de n\u00eautrons sofre \u03b2-decaimento, onde o n\u00eautron \u00e9 convertido em pr\u00f3ton, el\u00e9tron e\u00a0<\/span><a title=\"Antineutrino\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/antineutrino\/\"><span>antineutrino<\/span><\/a><span>\u00a0.<\/span><\/p>\n<figure id=\"attachment_11688\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11688\"><a href=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Beta_Minus_Decay.png\"><img loading=\"lazy\" class=\"size-full wp-image-11688 lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Beta_Minus_Decay.png\" alt=\"decaimento beta\" width=\"668\" height=\"178\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Beta_Minus_Decay.png\" \/><\/a><figcaption id=\"caption-attachment-11688\" class=\"wp-caption-text\"><span>Decaimento beta do n\u00facleo C-14.<\/span><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-60 lgc-tablet-grid-60 lgc-mobile-grid-100 lgc-equal-heights  lgc-first\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spacer\"><\/div>\n<h2><span>Caracter\u00edsticas da radia\u00e7\u00e3o beta<\/span><\/h2>\n<p><span>As principais caracter\u00edsticas da radia\u00e7\u00e3o beta est\u00e3o resumidas nos seguintes pontos:<\/span><\/p>\n<ul>\n<li><b><a title=\"Part\u00edcula Beta\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\"><span>As part\u00edculas beta<\/span><\/a>\u00a0<\/b><span>\u00a0s\u00e3o el\u00e9trons energ\u00e9ticos, s\u00e3o relativamente leves e carregam uma<\/span><strong><span>\u00a0\u00fanica carga negativa<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><span>Sua massa \u00e9 igual \u00e0 massa dos el\u00e9trons orbitais com os quais eles est\u00e3o interagindo e, diferentemente da part\u00edcula alfa, uma fra\u00e7\u00e3o muito maior de sua energia cin\u00e9tica pode ser perdida em uma \u00fanica intera\u00e7\u00e3o.<\/span><\/li>\n<li><span>O caminho deles n\u00e3o \u00e9 t\u00e3o direto.\u00a0As part\u00edculas beta seguem um\u00a0<\/span><strong><span>caminho<\/span><\/strong><span>\u00a0muito em\u00a0<strong>zigue-zague<\/strong>\u00a0atrav\u00e9s do material absorvente.\u00a0Esse caminho resultante da part\u00edcula \u00e9 maior que a penetra\u00e7\u00e3o linear (faixa) no material.<\/span><\/li>\n<li><span>Como possuem massa muito baixa, as part\u00edculas beta atingem\u00a0<\/span><strong><span>principalmente as energias relativ\u00edsticas.<\/span><\/strong><\/li>\n<li><span>As part\u00edculas beta tamb\u00e9m diferem de outras part\u00edculas carregadas pesadas na fra\u00e7\u00e3o de energia perdida pelo processo radiativo conhecido como\u00a0<\/span><a title=\"Bremsstrahlung\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/bremsstrahlung-2\/\"><strong><span>bremsstrahlung<\/span><\/strong><\/a><span>\u00a0.\u00a0Portanto, para prote\u00e7\u00e3o contra radia\u00e7\u00e3o beta de alta energia, materiais densos s\u00e3o inapropriados.<\/span><\/li>\n<li><span>Quando a part\u00edcula beta se move mais r\u00e1pido que a velocidade da luz (velocidade de fase) no material, gera uma onda de choque de radia\u00e7\u00e3o eletromagn\u00e9tica conhecida como\u00a0<\/span><a title=\"Radia\u00e7\u00e3o Cherenkov\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/cherenkov-radiation\/\"><strong><span>radia\u00e7\u00e3o de Cherenkov<\/span><\/strong><\/a><span>\u00a0.<\/span><\/li>\n<li><span>A emiss\u00e3o beta tem o espectro cont\u00ednuo.<\/span><\/li>\n<li><span>Uma part\u00edcula beta de 1 MeV pode viajar aproximadamente 3,5 metros no ar.<\/span><\/li>\n<li><span>Devido \u00e0 presen\u00e7a do material de\u00a0<\/span><strong><span>baixo n\u00famero at\u00f4mico (Z)<\/span><\/strong><span>\u00a0da bremsstrahlung\u00a0\u00a0\u00a0, s\u00e3o apropriados como blindagens de part\u00edculas beta.<\/span><\/li>\n<\/ul>\n<div class=\"su-spacer\"><\/div>\n<div class=\"su-spacer\"><\/div>\n<h2><span>Blindagem de radia\u00e7\u00e3o beta &#8211; el\u00e9trons<\/span><\/h2>\n<p><span>A radia\u00e7\u00e3o beta ioniza a mat\u00e9ria mais fraca que\u00a0<\/span><a title=\"Alpha Particle\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/alpha-particle\/\"><span>a radia\u00e7\u00e3o alfa<\/span><\/a><span>\u00a0.\u00a0Por outro lado, os\u00a0<\/span><strong><span>intervalos de part\u00edculas beta s\u00e3o mais longos<\/span><\/strong><span>\u00a0e dependem fortemente da energia cin\u00e9tica inicial da part\u00edcula.\u00a0Alguns t\u00eam energia suficiente para se preocupar com a exposi\u00e7\u00e3o externa.\u00a0Uma part\u00edcula beta de 1 MeV pode viajar aproximadamente 3,5 metros no ar.\u00a0Tais part\u00edculas beta podem penetrar no corpo e depositar a dose nas estruturas internas pr\u00f3ximas \u00e0 superf\u00edcie.\u00a0Portanto, \u00e9 necess\u00e1ria uma blindagem maior do que no caso de radia\u00e7\u00e3o alfa.<\/span><\/p>\n<p><span>Materiais com\u00a0<\/span><strong><span>baixo n\u00famero at\u00f4mico Z<\/span><\/strong><span>\u00a0s\u00e3o apropriados como blindagens de part\u00edculas beta.\u00a0<\/span><a title=\"Bremsstrahlung\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/bremsstrahlung-2\/\"><span>Nos<\/span><\/a><span>\u00a0materiais com alto teor de Z,\u00a0<a title=\"Bremsstrahlung\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/bremsstrahlung-2\/\">a bremsstrahlung<\/a>\u00a0(radia\u00e7\u00e3o secund\u00e1ria &#8211; raios X) est\u00e1 associada.\u00a0Essa radia\u00e7\u00e3o \u00e9 criada durante a desacelera\u00e7\u00e3o das part\u00edculas beta, enquanto elas viajam em um meio muito denso.\u00a0Roupas pesadas, papel\u00e3o grosso ou chapa fina de alum\u00ednio fornecer\u00e3o prote\u00e7\u00e3o contra radia\u00e7\u00e3o beta e impedir\u00e3o a produ\u00e7\u00e3o do bremsstrahlung.<\/span><\/p>\n<p><span>Veja tamb\u00e9m mais teoria:\u00a0<\/span><a title=\"Intera\u00e7\u00e3o da radia\u00e7\u00e3o beta com a mat\u00e9ria\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-beta-radiation\/\"><span>Intera\u00e7\u00e3o da radia\u00e7\u00e3o beta com a mat\u00e9ria<\/span><\/a><\/p>\n<p><span>Veja tamb\u00e9m calculadora:\u00a0<\/span><a title=\"Rad Pro Calculator\" href=\"http:\/\/www.radprocalculator.com\/Beta.aspx\"><span>atividade beta para dose\u00a0<\/span><\/a><\/p>\n<div class=\"su-spacer\"><\/div>\n<h2><span>Blindagem de radia\u00e7\u00e3o beta &#8211; Positrons<\/span><\/h2>\n<p><strong><span>As for\u00e7as de coulombe<\/span><\/strong><span>\u00a0que constituem o principal mecanismo de perda de energia para os el\u00e9trons est\u00e3o presentes tanto para a carga positiva quanto negativa na part\u00edcula e constituem o principal mecanismo de perda de energia tamb\u00e9m para os positrons.\u00a0Qualquer que seja a intera\u00e7\u00e3o, envolva uma for\u00e7a repulsiva ou atraente entre a part\u00edcula incidente e o el\u00e9tron orbital (ou n\u00facleo at\u00f4mico), o impulso e a transfer\u00eancia de energia para part\u00edculas de igual massa\u00a0\u00a0<\/span><strong><span>s\u00e3o praticamente os mesmos<\/span><\/strong><span>\u00a0.\u00a0Portanto, os\u00a0<\/span><strong><span>p\u00f3sitrons interagem de maneira semelhante<\/span><\/strong><span>\u00a0com a mat\u00e9ria\u00a0\u00a0<\/span><strong><span>quando s\u00e3o energ\u00e9ticos<\/span><\/strong><span>\u00a0.\u00a0A trilha de p\u00f3sitrons no material \u00e9 semelhante \u00e0 trilha de el\u00e9trons.\u00a0<\/span><strong><span>At\u00e9 a perda de energia<\/span><\/strong><span>\u00a0e o alcance espec\u00edficos\u00a0<\/span><strong><span>s\u00e3o os mesmos<\/span><\/strong><span>\u00a0para as energias iniciais iguais.<\/span><\/p>\n<p><strong><span>No final de seu caminho<\/span><\/strong><span>\u00a0, os\u00a0<\/span><strong><span>p\u00f3sitrons diferem significativamente<\/span><\/strong><span>\u00a0dos el\u00e9trons.\u00a0Quando um p\u00f3sitron (part\u00edcula de antimat\u00e9ria) p\u00e1ra, ele interage com um el\u00e9tron (part\u00edcula de mat\u00e9ria), resultando na\u00a0<\/span><a title=\"Aniquila\u00e7\u00e3o de Positrons\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/positron-annihilation-2\/\"><strong><span>aniquila\u00e7\u00e3o<\/span><\/strong><\/a><span>\u00a0de ambas as part\u00edculas e na convers\u00e3o completa de sua massa de repouso\u00a0<\/span><strong><span>em energia pura<\/span><\/strong><span>\u00a0(de acordo com a\u00a0f\u00f3rmula\u00a0E = mc\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0) na forma de dois\u00a0<\/span><strong><a title=\"Raios gama \/ radia\u00e7\u00e3o gama\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\"><span>raios gama de<\/span><\/a>\u00a0<\/strong><span>\u00a00,511 MeV direcionados de maneira oposta\u00a0(f\u00f3tons).<\/span><\/p>\n<p><span>Portanto, qualquer blindagem de p\u00f3sitron deve incluir tamb\u00e9m uma blindagem de raios gama.\u00a0A fim de minimizar o rompimento da barreira, \u00e9 apropriado um escudo contra radia\u00e7\u00e3o de v\u00e1rias camadas.\u00a0O material da primeira camada deve atender aos requisitos para\u00a0<\/span><a title=\"Blindagem de radia\u00e7\u00e3o beta - el\u00e9trons\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/shielding-of-ionizing-radiation\/shielding-beta-radiation\/\"><span>blindagem negativa da radia\u00e7\u00e3o beta<\/span><\/a><span>\u00a0.\u00a0A primeira camada desse escudo pode ser, por exemplo, uma fina placa de alum\u00ednio (para proteger p\u00f3sitrons), enquanto a segunda camada desse escudo pode ser um material denso, como chumbo ou ur\u00e2nio empobrecido.<\/span><\/p>\n<p><span>Veja tamb\u00e9m:\u00a0<\/span><a title=\"Blindagem de radia\u00e7\u00e3o gama\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/shielding-of-ionizing-radiation\/shielding-gamma-radiation\/\"><span>Blindagem de radia\u00e7\u00e3o gama<\/span><\/a><\/p>\n<div class=\"su-spacer\"><\/div>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-40 lgc-tablet-grid-40 lgc-mobile-grid-100 lgc-equal-heights  lgc-last\">\n<div class=\"inside-grid-column\">\n<figure id=\"attachment_11672\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11672\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Alpha_particle_cloud_chamber.jpg\"><img loading=\"lazy\" class=\"size-medium wp-image-11672 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Alpha_particle_cloud_chamber-300x156.jpg\" alt=\"Alpha Particle - Cloud Chamber\" width=\"300\" height=\"156\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Alpha_particle_cloud_chamber-300x156.jpg\" \/><\/a><figcaption id=\"caption-attachment-11672\" class=\"wp-caption-text\"><span>Part\u00edculas alfa e el\u00e9trons (desviados por um campo magn\u00e9tico) de uma haste de t\u00f3rio em uma c\u00e2mara de nuvens.<\/span><br \/>\n<span>Fonte: wikipedia.org<\/span><\/figcaption><\/figure>\n<div class=\"su-spacer\"><\/div>\n<figure id=\"attachment_11704\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11704\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Bremsstrahlung-vs.-Ionization.png\"><img loading=\"lazy\" class=\"size-medium wp-image-11704 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Bremsstrahlung-vs.-Ionization-300x207.png\" alt=\"Bremsstrahlung vs. Ioniza\u00e7\u00e3o\" width=\"300\" height=\"207\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Bremsstrahlung-vs.-Ionization-300x207.png\" \/><\/a><figcaption id=\"caption-attachment-11704\" class=\"wp-caption-text\"><span>Perda de energia fracion\u00e1ria por comprimento de radia\u00e7\u00e3o no chumbo em<\/span><br \/>\n<span>fun\u00e7\u00e3o da energia do el\u00e9tron ou do p\u00f3sitron.\u00a0Fonte: http:\/\/pdg.lbl.gov\/<\/span><\/figcaption><\/figure>\n<div class=\"su-spacer\"><\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<figure id=\"attachment_11708\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11708\"><a href=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/beta-decay-spectrum.gif\"><img loading=\"lazy\" class=\"wp-image-11708 size-full lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/beta-decay-spectrum.gif\" alt=\"Espectro de energia do decaimento beta\" width=\"344\" height=\"274\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/beta-decay-spectrum.gif\" \/><\/a><figcaption id=\"caption-attachment-11708\" class=\"wp-caption-text\"><span>A forma dessa curva de energia depende de qual fra\u00e7\u00e3o da energia da rea\u00e7\u00e3o (valor Q &#8211; a quantidade de energia liberada pela rea\u00e7\u00e3o) \u00e9 transportada pelo el\u00e9tron ou neutrino.<\/span><\/figcaption><\/figure>\n<div class=\"su-spacer\"><\/div>\n<div class=\"su-spacer\"><\/div>\n<p><span>A forma dessa curva de energia depende de qual fra\u00e7\u00e3o da energia da rea\u00e7\u00e3o (valor Q &#8211; a quantidade de energia liberada pela rea\u00e7\u00e3o) \u00e9 transportada pelo el\u00e9tron ou neutrino.<\/span><\/p>\n<div class=\"su-spacer\"><\/div>\n<p><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/shielding_alpha_beta.png\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-12728 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/shielding_alpha_beta-300x250.png\" alt=\"Blindagem da radia\u00e7\u00e3o alfa e beta\" width=\"300\" height=\"250\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/shielding_alpha_beta-300x250.png\" \/><\/a><\/p>\n<div class=\"su-spacer\"><\/div>\n<div class=\"su-spacer\"><\/div>\n<p><span>Materiais b\u00e1sicos para blindagem de part\u00edculas beta.<\/span><\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-accordion su-u-trim\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-arrow\" data-anchor=\"References\">\n<div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"inside-grid-column\"><\/div>\n<div><\/div>\n<div>\n<p>&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;.<\/p>\n<p>Este artigo \u00e9 baseado na tradu\u00e7\u00e3o autom\u00e1tica do artigo original em ingl\u00eas. Para mais informa\u00e7\u00f5es, consulte o artigo em ingl\u00eas. Voc\u00ea pode nos ajudar. Se voc\u00ea deseja corrigir a tradu\u00e7\u00e3o, envie-a para: translations@nuclear-power.com ou preencha o formul\u00e1rio de tradu\u00e7\u00e3o on-line. Agradecemos sua ajuda, atualizaremos a tradu\u00e7\u00e3o o mais r\u00e1pido poss\u00edvel. Obrigado.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>A radia\u00e7\u00e3o beta consiste em el\u00e9trons livres ou p\u00f3sitrons em velocidades relativ\u00edsticas.\u00a0Essas part\u00edculas s\u00e3o conhecidas como part\u00edculas beta.\u00a0Qual \u00e9 a radia\u00e7\u00e3o beta.\u00a0Dosimetria de Radia\u00e7\u00e3o Formas de radia\u00e7\u00e3o ionizante Intera\u00e7\u00e3o da radia\u00e7\u00e3o com a mat\u00e9ria A radia\u00e7\u00e3o ionizante\u00a0\u00e9 categorizada pela natureza das part\u00edculas ou ondas eletromagn\u00e9ticas que criam o efeito ionizante.\u00a0Essas\u00a0part\u00edculas \/ ondas\u00a0t\u00eam diferentes mecanismos de &#8230; <a title=\"O que \u00e9 radia\u00e7\u00e3o beta &#8211; Defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/\" aria-label=\"More on O que \u00e9 radia\u00e7\u00e3o beta &#8211; Defini\u00e7\u00e3o\">Ler mais<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[51],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v15.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>O que \u00e9 radia\u00e7\u00e3o beta - Defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"A radia\u00e7\u00e3o beta consiste em el\u00e9trons livres ou p\u00f3sitrons em velocidades relativ\u00edsticas. Essas part\u00edculas s\u00e3o conhecidas como part\u00edculas beta. Qual \u00e9 a radia\u00e7\u00e3o beta. Dosimetria de Radia\u00e7\u00e3o\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/\" \/>\n<meta property=\"og:locale\" content=\"pt_BR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"O que \u00e9 radia\u00e7\u00e3o beta - Defini\u00e7\u00e3o\" \/>\n<meta property=\"og:description\" content=\"A radia\u00e7\u00e3o beta consiste em el\u00e9trons livres ou p\u00f3sitrons em velocidades relativ\u00edsticas. Essas part\u00edculas s\u00e3o conhecidas como part\u00edculas beta. Qual \u00e9 a radia\u00e7\u00e3o beta. Dosimetria de Radia\u00e7\u00e3o\" \/>\n<meta property=\"og:url\" content=\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/\" \/>\n<meta property=\"og:site_name\" content=\"Radiation Dosimetry\" \/>\n<meta property=\"article:published_time\" content=\"2020-06-27T11:08:05+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2020-07-24T10:23:28+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Alfa_beta_gamma_neutron_radiation-174x300.png\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\">\n\t<meta name=\"twitter:data1\" content=\"Nick Connor\">\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\">\n\t<meta name=\"twitter:data2\" content=\"7 minutos\">\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.radiation-dosimetry.org\/#website\",\"url\":\"https:\/\/www.radiation-dosimetry.org\/\",\"name\":\"Radiation Dosimetry\",\"description\":\"\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":\"https:\/\/www.radiation-dosimetry.org\/?s={search_term_string}\",\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"pt-BR\"},{\"@type\":\"ImageObject\",\"@id\":\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/#primaryimage\",\"inLanguage\":\"pt-BR\",\"url\":\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Alfa_beta_gamma_neutron_radiation-174x300.png\"},{\"@type\":\"WebPage\",\"@id\":\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/#webpage\",\"url\":\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/\",\"name\":\"O que \\u00e9 radia\\u00e7\\u00e3o beta - Defini\\u00e7\\u00e3o\",\"isPartOf\":{\"@id\":\"https:\/\/www.radiation-dosimetry.org\/#website\"},\"primaryImageOfPage\":{\"@id\":\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/#primaryimage\"},\"datePublished\":\"2020-06-27T11:08:05+00:00\",\"dateModified\":\"2020-07-24T10:23:28+00:00\",\"author\":{\"@id\":\"https:\/\/www.radiation-dosimetry.org\/#\/schema\/person\/e8c544db9afedaec8574d6464f9398bb\"},\"description\":\"A radia\\u00e7\\u00e3o beta consiste em el\\u00e9trons livres ou p\\u00f3sitrons em velocidades relativ\\u00edsticas. Essas part\\u00edculas s\\u00e3o conhecidas como part\\u00edculas beta. Qual \\u00e9 a radia\\u00e7\\u00e3o beta. Dosimetria de Radia\\u00e7\\u00e3o\",\"inLanguage\":\"pt-BR\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/\"]}]},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.radiation-dosimetry.org\/#\/schema\/person\/e8c544db9afedaec8574d6464f9398bb\",\"name\":\"Nick Connor\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","_links":{"self":[{"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/posts\/18218"}],"collection":[{"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/comments?post=18218"}],"version-history":[{"count":0,"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/posts\/18218\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/media?parent=18218"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/categories?post=18218"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.radiation-dosimetry.org\/pt-br\/wp-json\/wp\/v2\/tags?post=18218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}