{"id":18268,"date":"2020-06-27T21:57:32","date_gmt":"2020-06-27T21:57:32","guid":{"rendered":"https:\/\/www.radiation-dosimetry.org\/o-que-e-neutrino-definicao\/"},"modified":"2020-07-24T10:54:05","modified_gmt":"2020-07-24T10:54:05","slug":"o-que-e-neutrino-definicao","status":"publish","type":"post","link":"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-neutrino-definicao\/","title":{"rendered":"O que \u00e9 Neutrino – Defini\u00e7\u00e3o"},"content":{"rendered":"
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Um neutrino \u00e9 uma part\u00edcula subat\u00f4mica elementar com massa infinitesimal e sem carga el\u00e9trica. Os neutrinos s\u00e3o part\u00edculas subat\u00f4micas que interagem fracamente com \u00bd unidade de rota\u00e7\u00e3o. Dosimetria de Radia\u00e7\u00e3o<\/div>\n<\/div>\n
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Um neutrino<\/span><\/strong>\u00a0\u00e9 uma part\u00edcula subat\u00f4mica elementar com\u00a0<\/span>massa infinitesimal<\/span><\/strong>\u00a0(menor que 0,3 eV ..?) E\u00a0<\/span>sem carga el\u00e9trica<\/span><\/strong>\u00a0.\u00a0Os neutrinos pertencem \u00e0 fam\u00edlia dos lept\u00f5es, o que significa que eles\u00a0<\/span>n\u00e3o interagem via for\u00e7a nuclear forte<\/span><\/strong>\u00a0.\u00a0Os neutrinos s\u00e3o\u00a0part\u00edculas subat\u00f4micas que\u00a0<\/span>interagem fracamente<\/span><\/strong>\u00a0com \u00bd unidade de rota\u00e7\u00e3o.\u00a0O termo neutrino vem do italiano que significa “pouco neutro” e os neutrinos s\u00e3o denotados pela letra grega\u00a0<\/span>\u03bd (nu)<\/span><\/strong>\u00a0.\u00a0Existem tr\u00eas tipos de lept\u00f5es carregados, cada um associado ao neutrino, formando\u00a0<\/span>tr\u00eas gera\u00e7\u00f5es<\/span><\/strong>\u00a0(entre gera\u00e7\u00f5es, as part\u00edculas diferem pelo seu n\u00famero qu\u00e2ntico e massa).\u00a0A primeira gera\u00e7\u00e3o consiste no el\u00e9tron (e\u00a0<\/span>–<\/span><\/sup>) e neutrino-el\u00e9tron (\u03bd\u00a0<\/span>e<\/span><\/sub>\u00a0).\u00a0A segunda gera\u00e7\u00e3o consiste no m\u00faon (\u03bc\u00a0<\/span>–<\/span><\/sup>\u00a0) e no neutrino do mu\u00e3o (\u03bd\u00a0<\/span>\u03bc<\/span><\/sub>\u00a0). A terceira gera\u00e7\u00e3o consiste no tau (\u03c4\u00a0<\/span>–<\/span><\/sup>\u00a0) e no tau neutrino (\u03bd\u00a0<\/span>\u03c4<\/span><\/sub>\u00a0).\u00a0Cada tipo de neutrino est\u00e1 associado a uma part\u00edcula de antimat\u00e9ria, chamada\u00a0<\/span>antineutrino<\/span><\/strong>\u00a0, que tamb\u00e9m possui carga el\u00e9trica neutra e meia rota\u00e7\u00e3o.\u00a0Atualmente (2015), n\u00e3o est\u00e1 resolvido se o neutrino e sua antipart\u00edcula n\u00e3o s\u00e3o part\u00edculas id\u00eanticas.<\/span>Sem carga el\u00e9trica,\u00a0<\/span>eles n\u00e3o s\u00e3o afetados por for\u00e7as eletromagn\u00e9ticas<\/span><\/strong>\u00a0que atuam em outros l\u00e9ptons carregados, como el\u00e9trons.\u00a0Como os neutrinos pertencem \u00e0 fam\u00edlia dos lept\u00f5es, eles n\u00e3o est\u00e3o sujeitos \u00e0 for\u00e7a forte.\u00a0Os neutrinos est\u00e3o sujeitos \u00e0\u00a0<\/span>for\u00e7a fraca<\/span><\/strong>\u00a0, que \u00e9 de\u00a0<\/span>alcance muito menor<\/span><\/strong>\u00a0que a for\u00e7a eletromagn\u00e9tica e a for\u00e7a da gravidade.\u00a0Portanto, os neutrinos s\u00e3o as\u00a0<\/span>part\u00edculas subat\u00f4micas mais penetrantes<\/span><\/strong>\u00a0, capazes de passar pela Terra sem nenhuma intera\u00e7\u00e3o.\u00a0Estima-se que os neutrinos tenham se\u00e7\u00f5es transversais de intera\u00e7\u00e3o cerca de 20 ordens de magnitude inferiores \u00e0s se\u00e7\u00f5es transversais t\u00edpicas de espalhamento de dois n\u00facleons (~\u00a0<\/span>10-47<\/span><\/sup>\u00a0m2 = 10\u00a0<\/span>-19<\/span><\/sup>celeiro).\u00a0Estima-se que a se\u00e7\u00e3o transversal de neutrinos para a intera\u00e7\u00e3o aumente linearmente com a energia do neutrino incidente.<\/span><\/p>\n

Refer\u00eancia: Griffiths, David, Introdu\u00e7\u00e3o \u00e0s Part\u00edculas Elementares, Wiley, 1987.<\/span><\/p>\n

Veja tamb\u00e9m:\u00a0<\/span>Antineutrino<\/span><\/a><\/p>\n

Veja tamb\u00e9m:\u00a0<\/span>Reator nuclear como fonte de antineutrinos<\/span><\/a><\/p>\n<\/div>\n<\/div>\n

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\"Evento<\/a>Fonte: wikipedia.org<\/span><\/p>\n
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\"Detector<\/a>O interior de um detector de antineutrino cil\u00edndrico antes de ser preenchido com um cintilador l\u00edquido claro, que revela intera\u00e7\u00f5es antineutrino pelos muito fracos lampejos de luz que emitem.\u00a0Tubos fotomultiplicadores sens\u00edveis revestem as paredes do detector, prontos para amplificar e registrar os flashes indicadores.<\/span>
\nFoto: Roy Kaltschmidt, LBNL<\/span>
\nFonte: Experi\u00eancia de neutrinos do reator Daya Bay<\/span><\/div>\n<\/div>\n

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Produ\u00e7\u00e3o de neutrinos<\/span><\/h2>\n

Neutrinos<\/span><\/strong>\u00a0podem ser produzidos de v\u00e1rias maneiras.\u00a0A fonte mais poderosa de neutrinos no sistema solar \u00e9 sem d\u00favida o pr\u00f3prio Sol.\u00a0Bilh\u00f5es de\u00a0<\/span>neutrinos solares<\/span><\/strong>\u00a0por segundo passam (principalmente sem intera\u00e7\u00e3o) por cada cent\u00edmetro quadrado (~ 6 x 10\u00a0<\/span>10<\/span><\/sup>\u00a0cm\u00a0<\/span>-2<\/span><\/sup>\u00a0s\u00a0<\/span>-1<\/span><\/sup>\u00a0) na superf\u00edcie da Terra.\u00a0No Sol, os neutrinos s\u00e3o produzidos ap\u00f3s a rea\u00e7\u00e3o de fus\u00e3o de dois pr\u00f3tons durante o decaimento beta positivo do n\u00facleo de h\u00e9lio-2.<\/span><\/p>\n

\"_<\/p>\n

Cada\u00a0<\/span>reator nuclear<\/span><\/a>\u00a0tamb\u00e9m \u00e9 uma fonte muito poderosa de neutrinos.\u00a0De fato,\u00a0<\/span>antineutrinos<\/span><\/a>\u00a0.\u00a0Em um reator nuclear ocorre especialmente o \u03b2\u00a0<\/span>–<\/span><\/sup>\u00a0decad\u00eancia, porque a caracter\u00edstica comum dos\u00a0<\/span>produtos de fiss\u00e3o<\/span><\/a>\u00a0\u00e9 um excesso de\u00a0<\/span>n\u00eautrons<\/span><\/a>\u00a0(veja\u00a0<\/span>Estabilidade Nuclear<\/span><\/a>\u00a0).\u00a0Um fragmento de fiss\u00e3o inst\u00e1vel com excesso de n\u00eautrons sofre \u03b2\u00a0<\/span>–<\/span><\/sup>\u00a0decaimento, onde o n\u00eautron \u00e9 convertido em pr\u00f3ton, el\u00e9tron e antineutrino.<\/span><\/p>\n

Refer\u00eancia: Griffiths, David, Introdu\u00e7\u00e3o \u00e0s Part\u00edculas Elementares, Wiley, 1987.<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n

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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":"

Um neutrino \u00e9 uma part\u00edcula subat\u00f4mica elementar com massa infinitesimal e sem carga el\u00e9trica. Os neutrinos s\u00e3o part\u00edculas subat\u00f4micas que interagem fracamente com \u00bd unidade de rota\u00e7\u00e3o. Dosimetria de Radia\u00e7\u00e3o Um neutrino\u00a0\u00e9 uma part\u00edcula subat\u00f4mica elementar com\u00a0massa infinitesimal\u00a0(menor que 0,3 eV ..?) E\u00a0sem carga el\u00e9trica\u00a0.\u00a0Os neutrinos pertencem \u00e0 fam\u00edlia dos lept\u00f5es, o que significa que … 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":"\nO que \u00e9 Neutrino - Defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"Um neutrino \u00e9 uma part\u00edcula subat\u00f4mica elementar com massa infinitesimal e sem carga el\u00e9trica. 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