{"id":22084,"date":"2020-07-24T10:15:42","date_gmt":"2020-07-24T10:15:42","guid":{"rendered":"https:\/\/www.radiation-dosimetry.org\/o-que-e-blindagem-de-radiacao-gama-definicao\/"},"modified":"2020-07-24T10:20:07","modified_gmt":"2020-07-24T10:20:07","slug":"o-que-e-blindagem-de-radiacao-gama-definicao","status":"publish","type":"post","link":"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-blindagem-de-radiacao-gama-definicao\/","title":{"rendered":"O que \u00e9 blindagem de radia\u00e7\u00e3o gama &#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 blindagem eficaz da radia\u00e7\u00e3o gama \u00e9 baseada no uso de materiais de alta densidade e alto Z.\u00a0Tamb\u00e9m \u00e1gua e ur\u00e2nio empobrecido podem ser usados \u200b\u200bcomo prote\u00e7\u00e3o contra raios gama.\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<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>Princ\u00edpios b\u00e1sicos de prote\u00e7\u00e3o contra radia\u00e7\u00e3o<\/span><\/h2>\n<p><span>Na prote\u00e7\u00e3o contra radia\u00e7\u00e3o, existem tr\u00eas maneiras de proteger as pessoas das fontes de radia\u00e7\u00e3o identificadas:<\/span><\/p>\n<ul>\n<li><strong><span>Limitando o tempo.\u00a0<\/span><\/strong><span>A quantidade de exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o depende diretamente (linearmente)\u00a0<\/span><strong><span>do tempo que as<\/span><\/strong><span>\u00a0pessoas passam perto da fonte de radia\u00e7\u00e3o.\u00a0A dose pode ser\u00a0<\/span><strong><span>reduzida limitando o tempo de exposi\u00e7\u00e3o<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><strong><span>Dist\u00e2ncia.\u00a0<\/span><\/strong><span>A quantidade de exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o depende da dist\u00e2ncia da fonte de radia\u00e7\u00e3o.\u00a0Da mesma forma que o calor do fogo, se voc\u00ea estiver muito pr\u00f3ximo, a intensidade da radia\u00e7\u00e3o t\u00e9rmica \u00e9 alta e voc\u00ea pode se queimar.\u00a0Se voc\u00ea estiver na dist\u00e2ncia certa, voc\u00ea pode suportar sem problemas e, al\u00e9m disso, \u00e9 confort\u00e1vel.\u00a0Se voc\u00ea estiver muito longe da fonte de calor, a insufici\u00eancia de calor tamb\u00e9m poder\u00e1 prejudic\u00e1-lo.\u00a0Essa analogia, em certo sentido, pode ser aplicada \u00e0 radia\u00e7\u00e3o tamb\u00e9m de fontes de radia\u00e7\u00e3o.<\/span><\/li>\n<li><strong><span>Blindagem.\u00a0<\/span><\/strong><span>Finalmente, se a fonte for muito intensa e o tempo ou a dist\u00e2ncia n\u00e3o fornecerem prote\u00e7\u00e3o suficiente contra radia\u00e7\u00e3o, a blindagem deve ser usada.\u00a0A prote\u00e7\u00e3o contra radia\u00e7\u00e3o geralmente consiste em barreiras de chumbo, concreto ou \u00e1gua.\u00a0Existem muitos materiais que podem ser usados \u200b\u200bpara prote\u00e7\u00e3o contra radia\u00e7\u00e3o, mas existem muitas situa\u00e7\u00f5es na prote\u00e7\u00e3o contra radia\u00e7\u00e3o.\u00a0Depende muito do tipo de radia\u00e7\u00e3o a ser protegida, de sua energia e de muitos outros par\u00e2metros.\u00a0Por exemplo, at\u00e9 o ur\u00e2nio empobrecido pode ser usado como uma boa prote\u00e7\u00e3o contra a radia\u00e7\u00e3o gama, mas, por outro lado, o ur\u00e2nio \u00e9 uma\u00a0<\/span><a title=\"Blindagem da radia\u00e7\u00e3o de n\u00eautrons\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/shielding-neutron-radiation\/\"><span>blindagem<\/span><\/a><span>\u00a0absolutamente inadequada\u00a0<a title=\"Shielding of Neutron Radiation\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/shielding-neutron-radiation\/\">da radia\u00e7\u00e3o de n\u00eautrons<\/a>\u00a0.<\/span><\/li>\n<\/ul>\n<figure id=\"attachment_12696\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-12696\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/radiation_protection_principles.gif\"><img loading=\"lazy\" class=\"size-full wp-image-12695 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/radiation_protection_principles.gif\" alt=\"pronciples de prote\u00e7\u00e3o contra radia\u00e7\u00e3o - tempo, dist\u00e2ncia, blindagem\" width=\"900\" height=\"700\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/radiation_protection_principles.gif\" \/><\/a><figcaption id=\"caption-attachment-12696\" class=\"wp-caption-text\"><span>Princ\u00edpios de prote\u00e7\u00e3o contra radia\u00e7\u00e3o &#8211; tempo, dist\u00e2ncia e blindagem<\/span><\/figcaption><\/figure>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\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\"><\/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<h2><span>Caracter\u00edsticas dos Raios Gama \/ Radia\u00e7\u00e3o<\/span><\/h2>\n<p><strong><span>Os principais recursos dos\u00a0<\/span><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<\/span><\/a><\/strong><span>\u00a0est\u00e3o resumidos nos seguintes pontos:<\/span><\/p>\n<ul>\n<li><span>Os raios gama s\u00e3o\u00a0<\/span><strong><span>f\u00f3tons de alta energia<\/span><\/strong><span>\u00a0(cerca de 10.000 vezes mais energia que os f\u00f3tons vis\u00edveis), os mesmos\u00a0<\/span><a title=\"F\u00f3ton - Part\u00edcula Fundamental\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/\"><span>f\u00f3tons<\/span><\/a><span>\u00a0que os f\u00f3tons que formam a faixa vis\u00edvel do espectro eletromagn\u00e9tico &#8211; a luz.<\/span><\/li>\n<li><span>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.<\/span><\/li>\n<li><span>Os raios gama ionizam a mat\u00e9ria principalmente via\u00a0<\/span><strong><span>ioniza\u00e7\u00e3o indireta<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><span>Embora seja conhecido um grande n\u00famero de poss\u00edveis intera\u00e7\u00f5es, existem tr\u00eas mecanismos principais de intera\u00e7\u00e3o com a mat\u00e9ria.<\/span>\n<ul>\n<li><a title=\"Efeito fotoel\u00e9trico\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/photoelectric-effect\/\"><strong><span>Efeito fotoel\u00e9trico<\/span><\/strong><\/a><\/li>\n<li><a title=\"Efeito Compton\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/compton-scattering\/\"><strong><span>Efeito Compton<\/span><\/strong><\/a><\/li>\n<li><a title=\"Produ\u00e7\u00e3o de Par Positron-El\u00e9tron\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/pair-production\/\"><strong><span>Produ\u00e7\u00e3o de pares<\/span><\/strong><\/a><\/li>\n<\/ul>\n<\/li>\n<li><span>Os raios gama viajam\u00a0<\/span><strong><span>na velocidade da luz<\/span><\/strong><span>\u00a0e podem viajar milhares de metros no ar antes de gastar sua energia.<\/span><\/li>\n<li><span>Como a radia\u00e7\u00e3o gama \u00e9 uma mat\u00e9ria muito penetrante, ela deve ser protegida por materiais muito densos, como chumbo ou ur\u00e2nio.<\/span><\/li>\n<li><span>A distin\u00e7\u00e3o entre raios X e raios gama n\u00e3o \u00e9 t\u00e3o simples e mudou nas \u00faltimas d\u00e9cadas.\u00a0De acordo com a defini\u00e7\u00e3o atualmente v\u00e1lida, os raios X s\u00e3o emitidos por el\u00e9trons fora do n\u00facleo, enquanto\u00a0<\/span><strong><span>os raios gama s\u00e3o emitidos pelo n\u00facleo<\/span><\/strong><span>\u00a0.<\/span><\/li>\n<li><span>Os raios gama frequentemente\u00a0<\/span><strong><span>acompanham a emiss\u00e3o<\/span><\/strong><span>\u00a0de\u00a0<a title=\"Part\u00edcula Beta\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\">radia\u00e7\u00e3o\u00a0<\/a><\/span><a title=\"Alpha Particle\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/alpha-particle\/\"><span>alfa<\/span><\/a><span>\u00a0e\u00a0<\/span><a title=\"Part\u00edcula Beta\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\"><span>beta<\/span><\/a><span>\u00a0.<\/span><\/li>\n<\/ul>\n<div class=\"su-accordion su-u-trim\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\"><\/div>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<figure id=\"attachment_11707\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11707\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/cloud-chamber-2.png\"><img loading=\"lazy\" class=\"size-medium wp-image-11707 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/cloud-chamber-2-300x167.png\" alt=\"Compara\u00e7\u00e3o de part\u00edculas em uma c\u00e2mara de nuvens.  Fonte: wikipedia.org\" width=\"300\" height=\"167\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/cloud-chamber-2-300x167.png\" \/><\/a><figcaption id=\"caption-attachment-11707\" class=\"wp-caption-text\"><span>Compara\u00e7\u00e3o de part\u00edculas em uma c\u00e2mara de nuvens.\u00a0Fonte: wikipedia.org<\/span><\/figcaption><\/figure>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<figure id=\"attachment_11684\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11684\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/total_photon_attenuation.png\"><img loading=\"lazy\" class=\"size-medium wp-image-11684 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/total_photon_attenuation-300x217.png\" alt=\"Coeficientes de atenua\u00e7\u00e3o.\" width=\"300\" height=\"217\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/total_photon_attenuation-300x217.png\" \/><\/a><figcaption id=\"caption-attachment-11684\" class=\"wp-caption-text\"><span>Total de se\u00e7\u00f5es transversais de f\u00f3tons.<\/span><br \/>\n<span>Fonte: Wikimedia Commons<\/span><\/figcaption><\/figure>\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<h2><span>Blindagem de radia\u00e7\u00e3o gama<\/span><\/h2>\n<p><span>Em resumo, a blindagem eficaz da radia\u00e7\u00e3o gama baseia-se na maioria dos casos no uso de materiais com duas propriedades de materiais a seguir:<\/span><\/p>\n<ul>\n<li>alta densidade de material.<\/li>\n<li>alto n\u00famero at\u00f4mico de material (materiais com alto Z)<\/li>\n<\/ul>\n<p>No entanto, materiais de baixa densidade e materiais de baixo Z podem ser compensados \u200b\u200bcom espessura aumentada, o que \u00e9 t\u00e3o significativo quanto a densidade e o n\u00famero at\u00f4mico em aplica\u00e7\u00f5es de blindagem.<\/p>\n<p>Um chumbo \u00e9 amplamente utilizado como um escudo gama.\u00a0A principal vantagem da blindagem de chumbo est\u00e1 na sua compacidade devido \u00e0 sua maior densidade.\u00a0Por outro lado, o\u00a0\u00a0<a title=\"Ur\u00e2nio empobrecido\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-fuel\/uranium\/depleted-uranium\/\">ur\u00e2nio empobrecido<\/a>\u00a0\u00e9 muito mais eficaz devido ao seu maior Z. O ur\u00e2nio empobrecido \u00e9 usado para blindagem em fontes port\u00e1teis de raios gama.<\/p>\n<p><span>Em\u00a0<\/span><a title=\"Usina nuclear\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/\"><span>usinas nucleares, a<\/span><\/a><span>\u00a0\u00a0blindagem de um\u00a0<\/span><a title=\"N\u00facleo do reator\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor-core\/\"><span>n\u00facleo de reator<\/span><\/a><span>\u00a0pode ser fornecida por materiais do vaso de press\u00e3o do reator, internos do reator (\u00a0<\/span><a title=\"Refletor de n\u00eautrons\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor\/neutron-reflector\/\"><span>refletor de n\u00eautrons<\/span><\/a><span>\u00a0).\u00a0Tamb\u00e9m o concreto pesado \u00e9 geralmente usado para proteger os\u00a0<\/span><a title=\"Blindagem da radia\u00e7\u00e3o de n\u00eautrons\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/shielding-neutron-radiation\/\"><span>n\u00eautrons<\/span><\/a><span>\u00a0e a radia\u00e7\u00e3o gama.<\/span><\/p>\n<p><span>Embora a \u00e1gua n\u00e3o seja de alta densidade nem de material com alto teor de Z, \u00e9 comumente usada como escudos gama.\u00a0A \u00e1gua fornece uma prote\u00e7\u00e3o contra radia\u00e7\u00e3o dos conjuntos de combust\u00edvel em um pool de combust\u00edvel irradiado durante o armazenamento ou durante o transporte de e para o\u00a0<\/span><a title=\"N\u00facleo do reator\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor-core\/\"><span>n\u00facleo<\/span><\/a><span>\u00a0do\u00a0<a title=\"N\u00facleo do reator\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power-plant\/nuclear-reactor-core\/\">reator<\/a>\u00a0.<\/span><\/p>\n<p><span>Em geral, a prote\u00e7\u00e3o contra radia\u00e7\u00e3o gama \u00e9 mais complexa e dif\u00edcil do que a\u00a0<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\/\">prote\u00e7\u00e3o contra radia\u00e7\u00e3o\u00a0<\/a><\/span><a title=\"Blindagem da radia\u00e7\u00e3o alfa\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/shielding-of-ionizing-radiation\/shielding-of-alpha-radiation\/\"><span>alfa<\/span><\/a><span>\u00a0ou\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>beta<\/span><\/a><span>\u00a0.\u00a0Para entender de maneira abrangente como um raio gama perde sua energia inicial, como pode ser atenuado e como pode ser protegido, precisamos ter um conhecimento detalhado dos mecanismos de intera\u00e7\u00e3o.<\/span><\/p>\n<p><span>Veja tamb\u00e9m mais teoria:\u00a0<\/span><a title=\"Intera\u00e7\u00e3o da radia\u00e7\u00e3o gama com a mat\u00e9ria\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/\"><span>Intera\u00e7\u00e3o da radia\u00e7\u00e3o gama 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\/Gamma.aspx\"><span>Atividade gama para taxa de dose (com \/ sem prote\u00e7\u00e3o)<\/span><\/a><\/p>\n<p><span>Consulte tamb\u00e9m XCOM &#8211; se\u00e7\u00e3o transversal do f\u00f3ton DB:\u00a0<\/span><a title=\"Banco de dados XCOM\" href=\"http:\/\/www.nist.gov\/pml\/data\/xcom\/\"><span>XCOM: banco de dados de se\u00e7\u00f5es transversais do f\u00f3ton<\/span><\/a><\/p>\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<h2><span>Atenua\u00e7\u00e3o de raios gama<\/span><\/h2>\n<p><span>A se\u00e7\u00e3o transversal total da\u00a0<\/span><a title=\"Intera\u00e7\u00e3o da radia\u00e7\u00e3o gama com a mat\u00e9ria\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/\"><span>intera\u00e7\u00e3o de raios gama<\/span><\/a><span>\u00a0com um \u00e1tomo \u00e9 igual \u00e0 soma das tr\u00eas se\u00e7\u00f5es parciais mencionadas:\u00a0<\/span><strong><span>\u03c3 = \u03c3\u00a0<\/span><sub><span>f<\/span><\/sub><span>\u00a0+ \u03c3\u00a0<\/span><sub><span>C<\/span><\/sub><span>\u00a0+ \u03c3\u00a0<\/span><sub><span>p\u00a0<\/span><\/sub><\/strong><\/p>\n<ul>\n<li><strong><span>\u03c3\u00a0<\/span><sub><span>f<\/span><\/sub><span>\u00a0&#8211; Efeito fotoel\u00e9trico<\/span><\/strong><\/li>\n<\/ul>\n<ul>\n<li><strong><span>\u03c3\u00a0<\/span><sub><span>C<\/span><\/sub><span>\u00a0&#8211; espalhamento de Compton<\/span><\/strong><\/li>\n<\/ul>\n<ul>\n<li><strong><span>\u03c3\u00a0<\/span><sub><span>p<\/span><\/sub><span>\u00a0&#8211; Produ\u00e7\u00e3o em pares<\/span><\/strong><\/li>\n<\/ul>\n<p><span>Dependendo da energia dos raios gama e do material absorvedor, uma das tr\u00eas se\u00e7\u00f5es parciais pode se tornar muito maior que as outras duas.\u00a0Em pequenos valores de energia de raios gama, o\u00a0<\/span><a title=\"Efeito fotoel\u00e9trico\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/photoelectric-effect\/\"><strong><span>efeito fotoel\u00e9trico<\/span><\/strong><\/a><span>\u00a0domina.\u00a0<\/span><a title=\"Efeito Compton\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/compton-scattering\/\"><strong><span>A dispers\u00e3o de Compton<\/span><\/strong><\/a><span>\u00a0domina em energias intermedi\u00e1rias.\u00a0A dispers\u00e3o de comptons tamb\u00e9m aumenta com a diminui\u00e7\u00e3o do n\u00famero at\u00f4mico de mat\u00e9ria; portanto, o intervalo de domina\u00e7\u00e3o \u00e9 maior para os n\u00facleos leves.\u00a0Finalmente,\u00a0<\/span><a title=\"Produ\u00e7\u00e3o de Par Positron-El\u00e9tron\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/pair-production\/\"><strong><span>a produ\u00e7\u00e3o de pares el\u00e9tron-p\u00f3sitron<\/span><\/strong><\/a><span>\u00a0domina com altas energias.<\/span><\/p>\n<p><span>Com base na defini\u00e7\u00e3o de se\u00e7\u00e3o transversal de intera\u00e7\u00e3o, pode-se derivar a depend\u00eancia da intensidade dos raios gama na espessura do material absorvente.\u00a0Se\u00a0<\/span><strong><span>os raios gama monoenerg\u00e9ticos<\/span><\/strong><span>\u00a0forem colimados em um\u00a0<\/span><strong><span>feixe estreito<\/span><\/strong><span>\u00a0e se o detector atr\u00e1s do material detectar apenas os raios gama que passaram por esse material sem nenhum tipo de intera\u00e7\u00e3o com esse material, a depend\u00eancia dever\u00e1 ser uma\u00a0<\/span><strong><span>atenua\u00e7\u00e3o exponencial<\/span><\/strong><span>\u00a0simples\u00a0<strong>dos raios gama<\/strong>\u00a0.\u00a0Cada uma dessas intera\u00e7\u00f5es remove o f\u00f3ton do feixe por absor\u00e7\u00e3o ou dispers\u00e3o na dire\u00e7\u00e3o do detector.\u00a0Portanto, as intera\u00e7\u00f5es podem ser caracterizadas por uma probabilidade fixa de ocorr\u00eancia por unidade de comprimento do caminho no absorvedor.\u00a0A soma dessas probabilidades \u00e9 chamada de<\/span><strong><span>coeficiente de atenua\u00e7\u00e3o linear<\/span><\/strong><span>\u00a0:<\/span><\/p>\n<p><strong><span>\u03bc = \u03c4\u00a0<\/span><sub><span>(fotoel\u00e9trico)<\/span><\/sub><span>\u00a0+ \u03c3\u00a0<\/span><sub><span>(Compton)<\/span><\/sub><span>\u00a0+ \u03ba\u00a0<\/span><sub><span>(par)<\/span><\/sub><\/strong><\/p>\n<figure id=\"attachment_11791\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11791\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/attenuation.png\"><img loading=\"lazy\" class=\"size-full wp-image-11796 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/attenuation.png\" alt=\"Atenua\u00e7\u00e3o de raios gama\" width=\"570\" height=\"357\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/attenuation.png\" \/><\/a><figcaption id=\"caption-attachment-11791\" class=\"wp-caption-text\"><span>A import\u00e2ncia relativa de v\u00e1rios processos de intera\u00e7\u00e3o da radia\u00e7\u00e3o gama com a mat\u00e9ria.<\/span><\/figcaption><\/figure>\n<h2><span>Coeficiente de atenua\u00e7\u00e3o linear<\/span><\/h2>\n<p><span>A atenua\u00e7\u00e3o da radia\u00e7\u00e3o gama pode ser descrita pela seguinte equa\u00e7\u00e3o.<\/span><\/p>\n<p><strong><span>I = I\u00a0<\/span><sub><span>0<\/span><\/sub><span>\u00a0.e\u00a0<\/span><sup><span>-\u03bcx<\/span><\/sup><\/strong><\/p>\n<p><span>, onde I \u00e9 a intensidade ap\u00f3s a atenua\u00e7\u00e3o, I\u00a0<\/span><sub><span>o<\/span><\/sub><span>\u00a0\u00e9 a intensidade do incidente, \u03bc \u00e9 o coeficiente de atenua\u00e7\u00e3o linear (cm\u00a0<\/span><sup><span>-1<\/span><\/sup><span>\u00a0) e a espessura f\u00edsica do absorvedor (cm).<\/span><\/p>\n<figure id=\"attachment_11792\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11792\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/exponential-attenuation.png\"><img loading=\"lazy\" class=\"size-medium wp-image-11796 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/exponential-attenuation-300x217.png\" alt=\"Atenua\u00e7\u00e3o\" width=\"300\" height=\"217\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/exponential-attenuation-300x217.png\" \/><\/a><figcaption id=\"caption-attachment-11792\" class=\"wp-caption-text\"><span>Depend\u00eancia da intensidade da radia\u00e7\u00e3o gama na espessura do absorvedor<\/span><\/figcaption><\/figure>\n<p><span>Os materiais listados na tabela ao lado s\u00e3o ar, \u00e1gua e elementos diferentes do carbono (\u00a0<\/span><i><span>Z<\/span><\/i><span>\u00a0= 6) ao chumbo (\u00a0<\/span><i><span>Z<\/span><\/i><span>\u00a0= 82) e seus coeficientes de atenua\u00e7\u00e3o linear s\u00e3o dados para tr\u00eas energias de raios gama.\u00a0Existem duas caracter\u00edsticas principais do coeficiente de atenua\u00e7\u00e3o linear:<\/span><\/p>\n<ul>\n<li><span>O coeficiente de atenua\u00e7\u00e3o linear aumenta \u00e0 medida que o n\u00famero at\u00f4mico do absorvedor aumenta.<\/span><\/li>\n<li><span>O coeficiente de atenua\u00e7\u00e3o linear para todos os materiais diminui com a energia dos raios gama.<\/span><\/li>\n<\/ul>\n<h2><span>Camada de metade do valor<\/span><\/h2>\n<p><span>A camada de meio valor expressa a espessura do material absorvente necess\u00e1rio para reduzir a intensidade da radia\u00e7\u00e3o incidente por um\u00a0<\/span><strong><span>fator de dois<\/span><\/strong><span>\u00a0.\u00a0Existem duas caracter\u00edsticas principais da camada de meio valor:<\/span><\/p>\n<ul>\n<li><span>A\u00a0<\/span><b><span>camada de metade do valor<\/span><\/b><span>\u00a0diminui \u00e0 medida que o n\u00famero at\u00f4mico do absorvedor aumenta.\u00a0Por exemplo, s\u00e3o necess\u00e1rios 35 m de ar para reduzir a intensidade de um feixe de raios gama de 100 keV por um fator de dois, enquanto apenas 0,12 mm de chumbo podem fazer a mesma coisa.<\/span><\/li>\n<li><span>A\u00a0<\/span><b><span>camada de metade do valor<\/span><\/b><span>\u00a0para todos os materiais aumenta com a energia dos raios gama.\u00a0Por exemplo, de 0,26 cm para ferro a 100 keV a cerca de 1,06 cm a 500 keV.<\/span><\/li>\n<\/ul>\n<h2><span>Exemplo:<\/span><\/h2>\n<p><span>De quanto \u00e1gua voc\u00ea precisa, se voc\u00ea deseja reduzir a intensidade de um\u00a0feixe de raios gama\u00a0<\/span><strong><span>monoenerg\u00e9tico de<\/span><\/strong><span>\u00a0500 keV\u00a0(\u00a0<\/span><strong><span>feixe estreito<\/span><\/strong><span>\u00a0) para\u00a0<\/span><strong><span>1%<\/span><\/strong><span>\u00a0de sua intensidade incidente?\u00a0A camada de meio valor para raios gama de 500 keV na \u00e1gua \u00e9 de 7,15 cm e o coeficiente de atenua\u00e7\u00e3o linear para raios gama de 500 keV na \u00e1gua \u00e9 de 0,097 cm\u00a0<\/span><sup><span>-1<\/span><\/sup><span>\u00a0.\u00a0<\/span><span>A quest\u00e3o \u00e9 bastante simples e pode ser descrita pela seguinte equa\u00e7\u00e3o:<\/span><img class=\"mathtex-equation-editor aligncenter lazy-loaded\" src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=I(x)%3D%5Cfrac%7BI_%7B0%7D%7D%7B100%7D%2C%5C%3B%5C%3B%20when%5C%3B%20x%20%3D%3F%20\" alt=\"I (x) = frac {I_ {0}} {100}, ;;  quando;  x =?\" align=\"absmiddle\" data-lazy-type=\"image\" data-src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=I(x)%3D%5Cfrac%7BI_%7B0%7D%7D%7B100%7D%2C%5C%3B%5C%3B%20when%5C%3B%20x%20%3D%3F%20\" \/><span>Se a camada de meio valor para a \u00e1gua for 7,15 cm, o coeficiente de atenua\u00e7\u00e3o linear \u00e9:<\/span><img class=\"mathtex-equation-editor aligncenter lazy-loaded\" src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Cmu%3D%5Cfrac%7Bln2%7D%7B7.15%7D%3D0.097cm%5E%7B-1%7D\" alt=\"mu = frac {ln2} {7,15} = 0,097cm ^ {- 1}\" align=\"absmiddle\" data-lazy-type=\"image\" data-src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Cmu%3D%5Cfrac%7Bln2%7D%7B7.15%7D%3D0.097cm%5E%7B-1%7D\" \/><span>Agora podemos usar a equa\u00e7\u00e3o de atenua\u00e7\u00e3o exponencial:<\/span><img class=\"mathtex-equation-editor aligncenter lazy-loaded\" src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=I(x)%3DI_0%5C%3Bexp%5C%3B(-%5Cmu%20x)\" alt=\"I (x) = I_0; exp; (- mu x)\" align=\"absmiddle\" data-lazy-type=\"image\" data-src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=I(x)%3DI_0%5C%3Bexp%5C%3B(-%5Cmu%20x)\" \/><img class=\"mathtex-equation-editor aligncenter lazy-loaded\" src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Cfrac%7BI_0%7D%7B100%7D%3DI_0%5C%3Bexp%5C%3B(-0.097%20x)\" alt=\"frac {I_0} {100} = I_0; exp; (- 0,097 x)\" align=\"absmiddle\" data-lazy-type=\"image\" data-src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Cfrac%7BI_0%7D%7B100%7D%3DI_0%5C%3Bexp%5C%3B(-0.097%20x)\" \/><span>Portanto<\/span><img class=\"mathtex-equation-editor aligncenter lazy-loaded\" src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Cfrac%7B1%7D%7B100%7D%3D%5C%3Bexp%5C%3B(-0.097%20x)\" alt=\"frac {1} {100} =; exp; (- 0,097 x)\" align=\"absmiddle\" data-lazy-type=\"image\" data-src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Cfrac%7B1%7D%7B100%7D%3D%5C%3Bexp%5C%3B(-0.097%20x)\" \/><img class=\"mathtex-equation-editor aligncenter lazy-loaded\" src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=ln%5Cfrac%7B1%7D%7B100%7D%3D-ln%5C%3B100%3D-0.097%20x\" alt=\"lnfrac {1} {100} = - ln; 100 = -0,097 x\" align=\"absmiddle\" data-lazy-type=\"image\" data-src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=ln%5Cfrac%7B1%7D%7B100%7D%3D-ln%5C%3B100%3D-0.097%20x\" \/><img class=\"mathtex-equation-editor aligncenter lazy-loaded\" src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=x%3D%5Cfrac%7Bln100%7D%7B%7B0.097%7D%7D%3D47.47%5C%3Bcm\" alt=\"x = frac {ln100} {{0,097}} = 47,47; cm\" align=\"absmiddle\" data-lazy-type=\"image\" data-src=\"http:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=x%3D%5Cfrac%7Bln100%7D%7B%7B0.097%7D%7D%3D47.47%5C%3Bcm\" \/><span>Portanto, a espessura necess\u00e1ria da \u00e1gua \u00e9 de cerca de\u00a0<\/span><strong><span>47,5 cm<\/span><\/strong><span>\u00a0.\u00a0Essa espessura \u00e9 relativamente grande e \u00e9 causada por um pequeno n\u00famero at\u00f4mico de hidrog\u00eanio e oxig\u00eanio.\u00a0Se calcularmos o mesmo problema para o\u00a0<\/span><strong><span>chumbo (Pb)<\/span><\/strong><span>\u00a0, obteremos a espessura\u00a0<\/span><strong><span>x = 2,8 cm<\/span><\/strong><span>\u00a0.<\/span><\/p>\n<p><span>Coeficientes de atenua\u00e7\u00e3o linear<\/span><\/p>\n<p><strong><span>Tabela de coeficientes de atenua\u00e7\u00e3o linear<\/span><\/strong><span>\u00a0(em cm-1) para diferentes materiais com energias de raios gama de 100, 200 e 500 keV.<\/span><\/p>\n<table rules=\"rows\">\n<tbody>\n<tr>\n<td><span>Absorvedor<\/span><\/td>\n<td><span>100 keV<\/span><\/td>\n<td><span>200 keV<\/span><\/td>\n<td><span>500 keV<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Ar<\/span><\/td>\n<td><span>\u00a0 0.000195 \/ cm<\/span><\/td>\n<td><span>\u00a0 0.000159 \/ cm<\/span><\/td>\n<td><span>\u00a0 0.000112 \/ cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>\u00c1gua<\/span><\/td>\n<td><span>0,167 \/ cm<\/span><\/td>\n<td><span>0,136 \/ cm<\/span><\/td>\n<td><span>0,097 \/ cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Carbono<\/span><\/td>\n<td><span>0,335 \/ cm<\/span><\/td>\n<td><span>0,274 \/ cm<\/span><\/td>\n<td><span>0.196 \/ cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Alum\u00ednio<\/span><\/td>\n<td><span>0.435 \/ cm<\/span><\/td>\n<td><span>0,324 \/ cm<\/span><\/td>\n<td><span>0,227 \/ cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Ferro<\/span><\/td>\n<td><span>2,72 \/ cm<\/span><\/td>\n<td><span>1.09 \/ cm<\/span><\/td>\n<td><span>0.655 \/ cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Cobre<\/span><\/td>\n<td><span>3.8 \/ cm<\/span><\/td>\n<td><span>1,309 \/ cm<\/span><\/td>\n<td><span>0,73 \/ cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Conduzir<\/span><\/td>\n<td><span>59,7 \/ cm<\/span><\/td>\n<td><span>10,15 \/ cm<\/span><\/td>\n<td><span>1,64 \/ cm<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><span id=\"more-52\"><\/span><span>Camadas de metade do valor<\/span><\/p>\n<p><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/half-value-layers.png\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-12759 lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/extrinsic-doped-semiconductor-p-type-acceptor-300x206.png\" alt=\"meia camada de valor\" width=\"291\" height=\"300\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/extrinsic-doped-semiconductor-p-type-acceptor-300x206.png\" \/><\/a><\/p>\n<div class=\"su-spacer\"><\/div>\n<p><span>A camada de meio valor expressa a espessura do material absorvente necess\u00e1rio para reduzir a intensidade da radia\u00e7\u00e3o incidente por um fator de dois.\u00a0Com meia camada de valor, \u00e9 f\u00e1cil realizar c\u00e1lculos simples.<\/span><br \/>\n<span>Fonte: www.nde-ed.org<\/span><\/p>\n<div class=\"su-spacer\"><\/div>\n<p><strong><span>Tabela de camadas de meio valor<\/span><\/strong><span>\u00a0(em cm) para diferentes materiais com energias de raios gama de 100, 200 e 500 keV.<\/span><\/p>\n<table rules=\"rows\">\n<tbody>\n<tr>\n<td><span>Absorvedor<\/span><\/td>\n<td><span>100 keV<\/span><\/td>\n<td><span>200 keV<\/span><\/td>\n<td><span>500 keV<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Ar<\/span><\/td>\n<td><span>3555 cm<\/span><\/td>\n<td><span>4359 cm<\/span><\/td>\n<td><span>6189 cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>\u00c1gua<\/span><\/td>\n<td><span>4,15 cm<\/span><\/td>\n<td><span>5.1 cm<\/span><\/td>\n<td><span>7.15 cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Carbono<\/span><\/td>\n<td><span>2,07 cm<\/span><\/td>\n<td><span>2,53 cm<\/span><\/td>\n<td><span>3.54 cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Alum\u00ednio<\/span><\/td>\n<td><span>1,59 cm<\/span><\/td>\n<td><span>2,14 cm<\/span><\/td>\n<td><span>3.05 cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Ferro<\/span><\/td>\n<td><span>0,26 cm<\/span><\/td>\n<td><span>0,64 cm<\/span><\/td>\n<td><span>1.06 cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Cobre<\/span><\/td>\n<td><span>0,18 cm<\/span><\/td>\n<td><span>0,53 cm<\/span><\/td>\n<td><span>0,95 cm<\/span><\/td>\n<\/tr>\n<tr>\n<td><span>Conduzir<\/span><\/td>\n<td><span>\u00a00.012 cm<\/span><\/td>\n<td><span>\u00a00.068 cm<\/span><\/td>\n<td><span>\u00a00,42 cm<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\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>\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<h2><span>Coeficiente de atenua\u00e7\u00e3o de massa<\/span><\/h2>\n<p><span>Ao caracterizar um material absorvente, \u00e0s vezes podemos usar o coeficiente de atenua\u00e7\u00e3o da massa. \u00a0<\/span><strong><span>O coeficiente de atenua\u00e7\u00e3o da massa<\/span><\/strong><span>\u00a0\u00e9 definido como a raz\u00e3o entre o coeficiente de atenua\u00e7\u00e3o linear e a densidade do absorvedor\u00a0<\/span><strong><span>(\u03bc \/ \u03c1)<\/span><\/strong><span>\u00a0.\u00a0A atenua\u00e7\u00e3o da radia\u00e7\u00e3o gama pode ser descrita pela seguinte equa\u00e7\u00e3o:<\/span><\/p>\n<p><strong><span>I = I\u00a0<\/span><sub><span>0<\/span><\/sub><span>\u00a0.e\u00a0<\/span><sup><span>&#8211; (\u03bc \/ \u03c1) .\u03c1l<\/span><\/sup><\/strong><\/p>\n<p><span>, onde \u03c1 \u00e9 a densidade do material, (\u03bc \/ \u03c1) \u00e9 o coeficiente de atenua\u00e7\u00e3o da massa e \u03c1.l \u00e9 a espessura da massa.\u00a0A unidade de medida usada para o coeficiente de atenua\u00e7\u00e3o da massa cm\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0g\u00a0<\/span><sup><span>-1<\/span><\/sup><span>\u00a0.<\/span><\/p>\n<p><span>Para energias intermedi\u00e1rias, o espalhamento de Compton domina e diferentes absorvedores t\u00eam coeficientes de atenua\u00e7\u00e3o de massa aproximadamente iguais.\u00a0Isso se deve ao fato de que a se\u00e7\u00e3o transversal da dispers\u00e3o de Compton \u00e9 proporcional ao Z (n\u00famero at\u00f4mico) e, portanto, o coeficiente \u00e9 proporcional \u00e0 densidade do material \u03c1.\u00a0Em pequenos valores de energia de raios gama ou em altos valores de energia de raios gama, em que o coeficiente \u00e9 proporcional a pot\u00eancias mais altas do n\u00famero at\u00f4mico Z (para efeito fotoel\u00e9trico \u03c3\u00a0<\/span><sub><span>f<\/span><\/sub><span>\u00a0~ Z\u00a0<\/span><sup><span>5<\/span><\/sup><span>\u00a0; para produ\u00e7\u00e3o de pares \u03c3\u00a0<\/span><sub><span>p<\/span><\/sub><span>\u00a0~ Z\u00a0<\/span><sup><span>2<\/span><\/sup><span>\u00a0), o o coeficiente de atenua\u00e7\u00e3o \u03bc n\u00e3o \u00e9 uma constante.<\/span><\/p>\n<h2><span>Validade da lei exponencial<\/span><\/h2>\n<p><span>A lei exponencial sempre descrever\u00e1 a atenua\u00e7\u00e3o da radia\u00e7\u00e3o prim\u00e1ria pela mat\u00e9ria.\u00a0Se part\u00edculas secund\u00e1rias forem produzidas ou se a radia\u00e7\u00e3o prim\u00e1ria mudar sua energia ou dire\u00e7\u00e3o, a atenua\u00e7\u00e3o efetiva ser\u00e1 muito menor.\u00a0A radia\u00e7\u00e3o penetrar\u00e1 mais profundamente na mat\u00e9ria do que a prevista pela lei exponencial.\u00a0O processo deve ser levado em considera\u00e7\u00e3o ao avaliar o efeito da prote\u00e7\u00e3o contra radia\u00e7\u00e3o.<\/span><\/p>\n<figure id=\"attachment_11803\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-11803\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/secondary_length.png\"><img loading=\"lazy\" class=\"size-medium wp-image-11808 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/secondary_length-300x165.png\" alt=\"Exemplo de acumula\u00e7\u00e3o de part\u00edculas secund\u00e1rias.  Depende fortemente do car\u00e1ter e dos par\u00e2metros das part\u00edculas prim\u00e1rias.\" width=\"300\" height=\"165\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/secondary_length-300x165.png\" \/><\/a><figcaption id=\"caption-attachment-11803\" class=\"wp-caption-text\"><span>Exemplo de acumula\u00e7\u00e3o de part\u00edculas secund\u00e1rias.\u00a0Depende fortemente do car\u00e1ter e dos par\u00e2metros das part\u00edculas prim\u00e1rias.<\/span><\/figcaption><\/figure>\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-content su-u-clearfix su-u-trim\">\n<p>&nbsp;<\/p>\n<\/div>\n<\/div>\n<h2><span>Fatores de ac\u00famulo para blindagem de raios gama<\/span><\/h2>\n<p><span>O\u00a0<\/span><strong><span>fator de acumula\u00e7\u00e3o<\/span><\/strong><span>\u00a0\u00e9 um fator de corre\u00e7\u00e3o que considera a influ\u00eancia da radia\u00e7\u00e3o dispersa mais quaisquer\u00a0<\/span><strong><span>part\u00edculas secund\u00e1rias<\/span><\/strong><span>\u00a0no meio durante os c\u00e1lculos de blindagem.\u00a0Se queremos dar conta do ac\u00famulo de radia\u00e7\u00e3o secund\u00e1ria, precisamos incluir o\u00a0<\/span><strong><span>fator de ac\u00famulo<\/span><\/strong><span>\u00a0.\u00a0O fator de acumula\u00e7\u00e3o \u00e9 ent\u00e3o um fator multiplicativo que responde pela resposta aos f\u00f3tons n\u00e3o colididos, de modo a incluir a contribui\u00e7\u00e3o dos f\u00f3tons dispersos.\u00a0Assim, o fator de acumula\u00e7\u00e3o pode ser obtido como uma raz\u00e3o entre a dose total e a resposta para a dose n\u00e3o coletada.<\/span><\/p>\n<p><span>A\u00a0<\/span><strong><span>f\u00f3rmula estendida<\/span><\/strong><span>\u00a0para o c\u00e1lculo da taxa de dose \u00e9:<\/span><\/p>\n<p><a href=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Buildup-Factor-in-Dose-Rate-Calculation.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25983 lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Buildup-Factor-in-Dose-Rate-Calculation.png\" alt=\"Fator de Ac\u00famulo\" width=\"689\" height=\"348\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Buildup-Factor-in-Dose-Rate-Calculation.png\" \/><\/a><\/p>\n<p><span>O padr\u00e3o ANSI \/ ANS-6.4.3-1991 de coeficientes de atenua\u00e7\u00e3o de raios gama e fatores de ac\u00famulo para materiais de engenharia cont\u00e9m coeficientes de atenua\u00e7\u00e3o de raios gama derivados e fatores de ac\u00famulo para materiais e elementos de engenharia selecionados para uso em c\u00e1lculos de blindagem (ANSI \/ ANS-6.1 .1, 1991).<\/span><\/p>\n<\/div>\n<\/div>\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-accordion su-u-trim\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-plus su-spoiler-closed\">\n<div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\">&#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;.<\/div>\n<div class=\"su-spoiler-content su-u-clearfix su-u-trim\">\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<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>A blindagem eficaz da radia\u00e7\u00e3o gama \u00e9 baseada no uso de materiais de alta densidade e alto Z.\u00a0Tamb\u00e9m \u00e1gua e ur\u00e2nio empobrecido podem ser usados \u200b\u200bcomo prote\u00e7\u00e3o contra raios gama.\u00a0Dosimetria de Radia\u00e7\u00e3o Princ\u00edpios b\u00e1sicos de prote\u00e7\u00e3o contra radia\u00e7\u00e3o Na prote\u00e7\u00e3o contra radia\u00e7\u00e3o, existem tr\u00eas maneiras de proteger as pessoas das fontes de radia\u00e7\u00e3o identificadas: Limitando &#8230; <a title=\"O que \u00e9 blindagem de radia\u00e7\u00e3o gama &#8211; Defini\u00e7\u00e3o\" class=\"read-more\" href=\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-blindagem-de-radiacao-gama-definicao\/\" aria-label=\"More on O que \u00e9 blindagem de radia\u00e7\u00e3o gama &#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 blindagem de radia\u00e7\u00e3o gama - Defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"A blindagem eficaz da radia\u00e7\u00e3o gama \u00e9 baseada no uso de materiais de alta densidade e alto Z. 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