{"id":17593,"date":"2020-06-16T00:08:12","date_gmt":"2020-06-16T00:08:12","guid":{"rendered":"https:\/\/www.radiation-dosimetry.org\/o-que-e-o-principio-de-operacao-dos-detectores-hpge-definicao\/"},"modified":"2020-07-21T11:49:54","modified_gmt":"2020-07-21T11:49:54","slug":"o-que-e-o-principio-de-operacao-dos-detectores-hpge-definicao","status":"publish","type":"post","link":"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-o-principio-de-operacao-dos-detectores-hpge-definicao\/","title":{"rendered":"O que \u00e9 o princ\u00edpio de opera\u00e7\u00e3o dos detectores HPGe &#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\">Detector HPGe &#8211; Princ\u00edpio de opera\u00e7\u00e3o.\u00a0A opera\u00e7\u00e3o dos detectores de semicondutores \u00e9 resumida nos seguintes pontos: A radia\u00e7\u00e3o ionizante entra no volume sens\u00edvel\u2026 Dosimetria 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<figure id=\"attachment_26112\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-26112\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/HPGe-Detector-Germanium.png\"><img loading=\"lazy\" class=\"size-medium wp-image-26112 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/HPGe-Detector-Germanium-300x204.png\" alt=\"Detector HPGe - Germ\u00e2nio\" width=\"300\" height=\"204\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/HPGe-Detector-Germanium-300x204.png\" \/><\/a><figcaption id=\"caption-attachment-26112\" class=\"wp-caption-text\">Detector HPGe com criostato LN2 Fonte: canberra.com<\/figcaption><\/figure>\n<p><strong>Detectores de germ\u00e2nio de alta pureza<\/strong>\u00a0(\u00a0<strong>detectores\u00a0<\/strong><strong>HPGe<\/strong>\u00a0) s\u00e3o a melhor solu\u00e7\u00e3o para\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/gamma-spectroscopy\/\">espectroscopia<\/a>\u00a0precisa de\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/gamma-spectroscopy\/\">raios gama e raios-x<\/a>\u00a0.\u00a0Em compara\u00e7\u00e3o com os\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/semiconductor-detectors\/silicon-based-semiconductor-detectors\/\">detectores de sil\u00edcio<\/a>\u00a0, o\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/semiconductor-detectors\/types-of-semiconductors\/germanium-as-semiconductor-properties\/\">germ\u00e2nio<\/a>\u00a0\u00e9 muito mais eficiente do que o\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/semiconductor-detectors\/types-of-semiconductors\/silicon-as-semiconductor-properties\/\">sil\u00edcio<\/a>\u00a0para a detec\u00e7\u00e3o de radia\u00e7\u00e3o devido ao seu n\u00famero at\u00f4mico ser muito maior que o sil\u00edcio e \u00e0 menor energia m\u00e9dia necess\u00e1ria para criar um\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/semiconductor-detectors\/what-are-semiconductors-properties-of-semiconductors\/electron-hole-pair\/\">par de el\u00e9trons-orif\u00edcios<\/a>\u00a0, que \u00e9 3,6 eV para sil\u00edcio e 2,9 eV para germ\u00e2nio.\u00a0Devido ao seu n\u00famero at\u00f4mico mais alto, o\u00a0<strong>Ge<\/strong>\u00a0possui um coeficiente de atenua\u00e7\u00e3o linear muito maior, o que leva a um caminho livre m\u00e9dio mais curto.\u00a0Al\u00e9m disso, os detectores de sil\u00edcio n\u00e3o podem ser mais grossos do que alguns mil\u00edmetros, enquanto o germ\u00e2nio pode ter um esgotamento,<strong>espessura sens\u00edvel de cent\u00edmetros<\/strong>\u00a0e, portanto, pode ser usado como um detector de absor\u00e7\u00e3o total para raios gama de at\u00e9 poucos MeV.<\/p>\n<p>Para obter a m\u00e1xima efici\u00eancia, os\u00a0<strong>detectores de HPGe<\/strong>\u00a0devem operar a temperaturas muito baixas de nitrog\u00eanio l\u00edquido (-196 \u00b0 C), porque, \u00e0 temperatura ambiente, o ru\u00eddo causado pela excita\u00e7\u00e3o t\u00e9rmica \u00e9 muito alto.<\/p>\n<h2>Detector HPGe &#8211; Princ\u00edpio de opera\u00e7\u00e3o<\/h2>\n<p>A opera\u00e7\u00e3o dos detectores de semicondutores \u00e9 resumida nos seguintes pontos:<\/p>\n<ul>\n<li><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/ionizing-radiation\/\">A radia\u00e7\u00e3o ionizante<\/a>\u00a0entra no volume sens\u00edvel (\u00a0<strong>cristal de germ\u00e2nio<\/strong>\u00a0) do detector e interage com o material semicondutor.<\/li>\n<li>O f\u00f3ton de alta energia que passa pelo detector ioniza os \u00e1tomos do semicondutor, produzindo os\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/semiconductor-detectors\/what-are-semiconductors-properties-of-semiconductors\/electron-hole-pair\/\">pares el\u00e9tron-buraco<\/a>\u00a0.\u00a0O n\u00famero de pares el\u00e9tron-buraco \u00e9 proporcional \u00e0 energia da radia\u00e7\u00e3o para o semicondutor.\u00a0Como resultado, um n\u00famero de el\u00e9trons \u00e9 transferido da banda de val\u00eancia para a banda de condu\u00e7\u00e3o e um n\u00famero igual de orif\u00edcios \u00e9 criado na banda de val\u00eancia.<\/li>\n<li>Como o germ\u00e2nio pode ter uma espessura sens\u00edvel e esgotada de cent\u00edmetros, eles s\u00e3o capazes de\u00a0<strong>absorver totalmente os f\u00f3tons de alta energia<\/strong>\u00a0\u00a0(at\u00e9 alguns MeV).<\/li>\n<li>Sob a influ\u00eancia de um campo el\u00e9trico, el\u00e9trons e buracos viajam para os eletrodos, onde resultam em um pulso que pode ser medido em um circuito externo.<\/li>\n<li>Esse pulso carrega informa\u00e7\u00f5es sobre a energia da radia\u00e7\u00e3o incidente original.\u00a0O n\u00famero desses pulsos por unidade de tempo tamb\u00e9m fornece informa\u00e7\u00f5es sobre a intensidade da radia\u00e7\u00e3o.<\/li>\n<\/ul>\n<p>Em todos os casos, um f\u00f3ton deposita uma parte de sua energia ao longo do caminho e pode ser absorvido totalmente.\u00a0A absor\u00e7\u00e3o total de um f\u00f3ton de 1 MeV produz cerca de 3 x 10\u00a0<sup>5<\/sup>\u00a0pares de furos de el\u00e9trons.\u00a0Este valor \u00e9 menor em compara\u00e7\u00e3o com o n\u00famero total de portadores livres em de 1 cm\u00a0<sup>3\u00a0<\/sup><a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/semiconductor-detectors\/types-of-semiconductors\/intrinsic-semiconductor-pure-semiconductor\/\">semicondutor intr\u00ednseco<\/a>\u00a0.\u00a0As part\u00edculas que passam pelo detector ionizam os \u00e1tomos do semicondutor, produzindo os pares el\u00e9tron-buraco.\u00a0Mas em detectores \u00e0 base de germ\u00e2nio \u00e0 temperatura ambiente,\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/semiconductor-detectors\/what-are-semiconductors-properties-of-semiconductors\/optical-and-thermal-excitation\/\"><strong>a excita\u00e7\u00e3o t\u00e9rmica<\/strong><\/a>\u00a0\u00e9 dominante.\u00a0\u00c9 causada por impurezas, irregularidades na estrutura ou\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-detection\/semiconductor-detectors\/types-of-semiconductors\/what-is-dopant-in-semiconductors\/\">dopante<\/a>\u00a0.\u00a0Depende fortemente da\u00a0<sub>diferen\u00e7a<\/sub>\u00a0E(uma dist\u00e2ncia entre a val\u00eancia e a banda de condu\u00e7\u00e3o), que \u00e9 muito baixa para o germ\u00e2nio (Egap = 0,67 eV).\u00a0Como a excita\u00e7\u00e3o t\u00e9rmica resulta no ru\u00eddo do detector, \u00e9 necess\u00e1rio um resfriamento ativo para alguns tipos de semicondutores (por exemplo, germ\u00e2nio).<\/p>\n<p><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/germanium-semiconductor-energy-gap.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-26568 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/germanium-semiconductor-energy-gap-300x207.png\" alt=\"Germ\u00e2nio - semicondutor\" width=\"300\" height=\"207\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/germanium-semiconductor-energy-gap-300x207.png\" \/><\/a>Observe que uma\u00a0amostra de\u00a01 cm\u00a0<sup>3<\/sup>\u00a0de germ\u00e2nio puro a 20 \u00b0 C cont\u00e9m cerca de 4,2 \u00d7 10\u00a0<sup>22<\/sup>\u00a0\u00e1tomos, mas tamb\u00e9m cont\u00e9m cerca de 2,5 x 10\u00a0<sup>13<\/sup>\u00a0el\u00e9trons livres e 2,5 x 10\u00a0<sup>13<\/sup>\u00a0orif\u00edcios gerados constantemente a partir da energia t\u00e9rmica.\u00a0Como pode ser visto, a rela\u00e7\u00e3o sinal-ru\u00eddo (S \/ N) seria m\u00ednima (comparar com 3 x 10\u00a0<sup>5<\/sup>\u00a0pares de electr\u00e3o-lacuna).\u00a0A adi\u00e7\u00e3o de 0,001% de ars\u00eanico (uma impureza) doa um extra de 10\u00a0<sup>17<\/sup>el\u00e9trons livres no mesmo volume e a condutividade el\u00e9trica \u00e9 aumentada em um fator de 10.000.\u00a0No material dopado, a rela\u00e7\u00e3o sinal \/ ru\u00eddo (S \/ N) seria ainda menor.\u00a0Como o germ\u00e2nio possui um intervalo de banda relativamente baixo, esses detectores devem ser resfriados para reduzir a gera\u00e7\u00e3o t\u00e9rmica de portadores de carga (portanto, reverter a corrente de fuga) para um n\u00edvel aceit\u00e1vel.\u00a0Caso contr\u00e1rio, o ru\u00eddo induzido pela corrente de fuga destr\u00f3i a resolu\u00e7\u00e3o de energia do detector.<\/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-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 tabindex=\"0\" role=\"button\">\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<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Detector HPGe &#8211; Princ\u00edpio de opera\u00e7\u00e3o.\u00a0A opera\u00e7\u00e3o dos detectores de semicondutores \u00e9 resumida nos seguintes pontos: A radia\u00e7\u00e3o ionizante entra no volume sens\u00edvel\u2026 Dosimetria de radia\u00e7\u00e3o Detector HPGe com criostato LN2 Fonte: canberra.com Detectores de germ\u00e2nio de alta pureza\u00a0(\u00a0detectores\u00a0HPGe\u00a0) s\u00e3o a melhor solu\u00e7\u00e3o para\u00a0espectroscopia\u00a0precisa de\u00a0raios gama e raios-x\u00a0.\u00a0Em compara\u00e7\u00e3o com os\u00a0detectores de sil\u00edcio\u00a0, o\u00a0germ\u00e2nio\u00a0\u00e9 muito &#8230; <a title=\"O que \u00e9 o princ\u00edpio de opera\u00e7\u00e3o dos detectores HPGe &#8211; Defini\u00e7\u00e3o\" class=\"read-more\" href=\"http:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-o-principio-de-operacao-dos-detectores-hpge-definicao\/\" aria-label=\"More on O que \u00e9 o princ\u00edpio de opera\u00e7\u00e3o dos detectores HPGe &#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 o princ\u00edpio de opera\u00e7\u00e3o dos detectores HPGe - Defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"Detector HPGe - Princ\u00edpio de opera\u00e7\u00e3o. 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