{"id":5849,"date":"2025-05-14T11:50:56","date_gmt":"2025-05-14T09:50:56","guid":{"rendered":"https:\/\/www.zsvltava.cz\/fyzika\/?p=5849"},"modified":"2025-05-15T15:53:10","modified_gmt":"2025-05-15T13:53:10","slug":"zareni-a-rozpady-alfa-beta-gama","status":"publish","type":"post","link":"https:\/\/www.zsvltava.cz\/fyzika\/?p=5849","title":{"rendered":"Z\u00e1\u0159en\u00ed a rozpady alfa, beta, gama"},"content":{"rendered":"

Na prvn\u00ed pohled se m\u016f\u017ee zd\u00e1t, \u017ee v\u0161e kolem n\u00e1s je klidn\u00e9 a pevn\u00e9 \u2013 stoly, kameny, lidsk\u00e9 t\u011blo. Ale pod povrchem, hluboko uvnit\u0159 atom\u016f, se odehr\u00e1v\u00e1 neust\u00e1l\u00fd pohyb, nap\u011bt\u00ed a n\u011bkdy i v\u00fdbuchy neuv\u011b\u0159iteln\u00e9 energie.<\/strong><\/p>\n

Atomy nejsou nedotknuteln\u00e9 koule. Jsou slo\u017een\u00e9 z mal\u00fdch \u010d\u00e1stic, kter\u00e9 dr\u017e\u00ed pohromad\u011b silami siln\u011bj\u0161\u00edmi ne\u017e cokoliv, co za\u017e\u00edv\u00e1me v b\u011b\u017en\u00e9m \u017eivot\u011b. A n\u011bkdy \u2013 kdy\u017e je rovnov\u00e1ha poru\u0161ena \u2013 za\u010dnou tyto \u010d\u00e1stice tan\u010dit ne\u010dekan\u00fd tanec z\u00e1niku a zrozen\u00ed. Tento tanec zn\u00e1me jako radioaktivitu.<\/p>\n

\"\"<\/p>\n

Radioaktivn\u00ed prvky jsou atomy, kter\u00e9 nejsou spokojeny se sv\u00fdm vnit\u0159n\u00edm uspo\u0159\u00e1d\u00e1n\u00edm. Maj\u00ed p\u0159\u00edli\u0161 mnoho proton\u016f, neutron\u016f, nebo energie. Aby se zklidnily, vys\u00edlaj\u00ed ze sv\u00e9ho nitra \u010d\u00e1stice \u2013 mal\u00e9 v\u00fdbuchy informace o jejich zm\u011bn\u011b. Tyto \u010d\u00e1stice a z\u00e1\u0159en\u00ed nejsou jen p\u0159\u00edznakem nestability. Jsou kl\u00ed\u010dem k pochopen\u00ed fungov\u00e1n\u00ed vesm\u00edru.<\/p>\n

A pr\u00e1v\u011b zde vstupuj\u00ed na sc\u00e9nu t\u0159i slavn\u00ed \u201eposlov\u00e9\u201c radioaktivity:<\/p>\n

Alfa z\u00e1\u0159en\u00ed<\/strong> \u2013 t\u011b\u017ek\u00e9, pomal\u00e9, ale siln\u00e9.
\nBeta z\u00e1\u0159en\u00ed<\/strong> \u2013 lehk\u00e9, hbit\u00e9 a z\u00e1ludn\u011b pronikav\u00e9.
\nGama z\u00e1\u0159en\u00ed<\/strong> \u2013 \u010dist\u00e1 energie, bez hmoty, ale s ni\u010divou silou.<\/p>\n

Ka\u017ed\u00fd typ z\u00e1\u0159en\u00ed vypr\u00e1v\u00ed jin\u00fd p\u0159\u00edb\u011bh o tom, co se v j\u00e1d\u0159e atomu stalo. Nen\u00ed to jen v\u011bda \u2013 je to dramatick\u00fd p\u0159\u00edb\u011bh p\u0159\u00edrodn\u00edch z\u00e1kon\u016f.<\/p>\n

\n

Alfa rozpad a z\u00e1\u0159en\u00ed (\u03b1)<\/h2>\n

Alfa rozpad<\/h3>\n

P\u0159i alfa rozpadu nestabiln\u00ed j\u00e1dro vypust\u00ed \u010d\u00e1stici alfa, kter\u00e1 se skl\u00e1d\u00e1 ze dvou proton\u016f a dvou neutron\u016f (tedy j\u00e1dro H\u00e9lia). Tento proces sn\u00ed\u017e\u00ed hmotnostn\u00ed \u010d\u00edslo j\u00e1dra o 4 a protonov\u00e9 \u010d\u00edslo o 2.<\/p>\n

  <\/span>   <\/span>\"\[<\/p>\n

Alfa z\u00e1\u0159en\u00ed<\/h3>\n

– Alfa z\u00e1\u0159en\u00ed je tvo\u0159eno t\u011b\u017ek\u00fdmi, kladn\u011b nabit\u00fdmi \u010d\u00e1sticemi.
\n– M\u00e1 mal\u00fd dosah (zastav\u00ed ho pap\u00edr nebo lidsk\u00e1 k\u016f\u017ee), ale vysokou ioniza\u010dn\u00ed schopnost.
\n– Nebezpe\u010dn\u00e9 hlavn\u011b p\u0159i vdechnut\u00ed nebo po\u017eit\u00ed.<\/p>\n

\n

Beta rozpad a z\u00e1\u0159en\u00ed (\u03b2)<\/h2>\n

K beta rozpadu doch\u00e1z\u00ed, kdy\u017e je v atomov\u00e9m j\u00e1d\u0159e nerovnov\u00e1ha mezi po\u010dtem proton\u016f a neutron\u016f, a j\u00e1dro se sna\u017e\u00ed dos\u00e1hnout stabiln\u011bj\u0161\u00edho stavu. Atomov\u00e1 j\u00e1dra maj\u00ed optim\u00e1ln\u00ed pom\u011br mezi protony a neutrony. Pokud tento pom\u011br nen\u00ed \u201espr\u00e1vn\u00fd\u201c, j\u00e1dro je nestabiln\u00ed a sna\u017e\u00ed se upravit sv\u016fj vnit\u0159n\u00ed stav. Jedn\u00edm zp\u016fsobem je pr\u00e1v\u011b beta rozpad.<\/p>\n

Nerovnov\u00e1ha mezi po\u010dtem neutron\u016f (N) a proton\u016f (P) v j\u00e1d\u0159e m\u016f\u017ee nastat z p\u0159irozen\u00fdch d\u016fvod\u016f souvisej\u00edc\u00edch s jadernou fyzikou \u2013 hlavn\u011b p\u0159i tvorb\u011b atomov\u00fdch jader a jejich energetick\u00fdch stavech.<\/p>\n

Existuj\u00ed 2 druhy beta rozpadu.<\/p>\n

Beta–<\/sup> rozpad<\/h3>\n

Neutron se zm\u011bn\u00ed na proton, vznik\u00e1 elektron a antineutrino<\/strong>.<\/p>\n

  <\/span>   <\/span>\"\[<\/p>\n

(neutron \u2192 proton + elektron + antineutrino)<\/p>\n

  <\/span>   <\/span>\"\[<\/p>\n

Beta+<\/sup> rozpad<\/h3>\n

Proton se zm\u011bn\u00ed na neutron, vznik\u00e1 pozitron a neutrino<\/strong>.<\/p>\n

  <\/span>   <\/span>\"\[<\/p>\n

(proton \u2192 neutron + pozitron + neutrino)<\/p>\n

  <\/span>   <\/span>\"\[<\/p>\n

Beta z\u00e1\u0159en\u00ed<\/h3>\n

– Beta z\u00e1\u0159en\u00ed tvo\u0159\u00ed elektrony nebo pozitrony.
\n– M\u00e1 v\u011bt\u0161\u00ed dosah ne\u017e alfa, ale men\u0161\u00ed ioniza\u010dn\u00ed schopnost.
\n– Zastav\u00ed ho nap\u0159. hlin\u00edkov\u00e1 f\u00f3lie nebo p\u00e1r mm plastu.<\/p>\n

\n

Gama z\u00e1\u0159en\u00ed (\u03b3)<\/h2>\n

Gama nen\u00ed samostatn\u00fd rozpad, ale \u010dasto doprov\u00e1z\u00ed alfa nebo beta rozpad. J\u00e1dro po rozpadu z\u016fst\u00e1v\u00e1 ve vzbuzen\u00e9m stavu a uvoln\u00ed p\u0159ebyte\u010dnou energii ve form\u011b gama fotonu.<\/p>\n

– Gama z\u00e1\u0159en\u00ed je elektromagnetick\u00e9 vln\u011bn\u00ed (podobn\u00e9 rentgenov\u00e9mu).
\n– Nem\u00e1 \u017e\u00e1dnou hmotnost ani n\u00e1boj.
\n– M\u00e1 velk\u00fd dosah a malou ioniza\u010dn\u00ed schopnost, ale pronik\u00e1 hluboko do materi\u00e1l\u016f \u2013 zastav\u00ed ho olovo nebo siln\u00fd beton.<\/p>\n

Gama z\u00e1\u0159en\u00ed – p\u0159\u00edklady:<\/p>\n

  <\/span>   <\/span>\"\[<\/p>\n

\u0160t\u011bpen\u00ed j\u00e1dra Uranu:<\/p>\n

  <\/span>   <\/span>\"\[<\/p>\n

\n

Shrnut\u00ed<\/h2>\n\n\n\n\n\n\n\n\n
Typ z\u00e1\u0159en\u00ed<\/th>\nSymbol \u010d\u00e1stice<\/th>\nSlo\u017een\u00ed<\/th>\nN\u00e1boj<\/th>\nSt\u00edn\u00edc\u00ed materi\u00e1l<\/th>\n<\/tr>\n<\/thead>\n
Alfa (\u03b1)<\/td>\n4<\/sup>2<\/sub>He<\/td>\n2 protony + 2 neutrony<\/td>\n+2<\/td>\nPap\u00edr, poko\u017eka<\/td>\n<\/tr>\n
Beta (\u03b2\u207b)<\/td>\ne–<\/sup><\/td>\nElektron<\/td>\n-1<\/td>\nHlin\u00edk, tenk\u00fd plech<\/td>\n<\/tr>\n
Beta (\u03b2\u207a)<\/td>\ne+<\/sup><\/td>\nPozitron<\/td>\n+1<\/td>\nHlin\u00edk, tenk\u00fd plech<\/td>\n<\/tr>\n
Gama (\u03b3)<\/td>\n\u03b3<\/td>\nFoton (elektromagnetick\u00e9 z\u00e1\u0159en\u00ed)<\/td>\n0<\/td>\nOlovo, siln\u00fd beton<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

O nestabilit\u011b atomov\u00fdch jader<\/h1>\n

\"\"<\/p>\n

Pro\u010d nen\u00ed pom\u011br neutron\u016f a proton\u016f v\u017edy 1:1?<\/h2>\n

U lehk\u00fdch prvk\u016f, jako je uhl\u00edk nebo kysl\u00edk, b\u00fdv\u00e1 stabiln\u00ed pom\u011br mezi po\u010dtem neutron\u016f (N) a proton\u016f (P) p\u0159ibli\u017en\u011b 1:1. Nap\u0159\u00edklad uhl\u00edk-12 obsahuje 6 proton\u016f a 6 neutron\u016f, co\u017e zaji\u0161\u0165uje jeho stabilitu.<\/p>\n

U t\u011b\u017e\u0161\u00edch jader je v\u0161ak pot\u0159eba v\u011bt\u0161\u00ed po\u010det neutron\u016f. Ty toti\u017e pom\u00e1haj\u00ed neutralizovat elektrostatick\u00e9 odpuzov\u00e1n\u00ed mezi kladn\u011b nabit\u00fdmi protony, kter\u00e9 by jinak j\u00e1dro roztrhlo. Neutrony tedy p\u016fsob\u00ed jako \u201epojivo\u201c, kter\u00e9 dr\u017e\u00ed j\u00e1dro pohromad\u011b.<\/p>\n

P\u0159i vzniku jadern\u00fdch izotop\u016f ve hv\u011bzd\u00e1ch nebo p\u0159i v\u00fdbu\u0161\u00edch supernovy m\u016f\u017ee doch\u00e1zet k nerovnov\u00e1ze mezi po\u010dtem neutron\u016f a proton\u016f. Tato nevyv\u00e1\u017eenost \u010dasto vede k nestabilit\u011b j\u00e1dra.<\/p>\n

Radioaktivn\u00ed p\u0159em\u011bny, jako je nap\u0159\u00edklad alfa rozpad, mohou tak\u00e9 zanechat j\u00e1dro ve stavu s p\u0159\u00edli\u0161 velk\u00fdm mno\u017estv\u00edm neutron\u016f nebo proton\u016f. Takov\u00e1 j\u00e1dra pak obvykle podl\u00e9haj\u00ed dal\u0161\u00edm p\u0159em\u011bn\u00e1m, dokud nedos\u00e1hnou stabiln\u00edho stavu.<\/p>\n

Pokud je v j\u00e1d\u0159e neutron\u016f p\u0159\u00edli\u0161 mnoho, j\u00e1dro se zbav\u00ed neutronu pomoc\u00ed \u03b2\u207b rozpadu (neutron \u2192 proton).<\/strong>
\nPokud je p\u0159\u00edli\u0161 mnoho proton\u016f, nast\u00e1v\u00e1 \u03b2\u207a rozpad (proton \u2192 neutron) nebo z\u00e1chyt elektronu.<\/strong><\/p>\n

Zaj\u00edmav\u00e1 role neutron\u016f<\/h2>\n

A\u010dkoliv neutron nem\u00e1 elektrick\u00fd n\u00e1boj, hraje kl\u00ed\u010dovou roli ve stabilit\u011b j\u00e1dra. Pom\u00e1h\u00e1 udr\u017eet protony pohromad\u011b, i kdy\u017e se ty navz\u00e1jem elektrostaticky odpuzuj\u00ed (proto\u017ee maj\u00ed kladn\u00fd n\u00e1boj).<\/p>\n

\u010c\u00edm v\u00edc proton\u016f v j\u00e1d\u0159e je, t\u00edm v\u00edc neutron\u016f je pot\u0159eba, aby p\u0159eva\u017euj\u00edc\u00ed jadern\u00e1 s\u00edla p\u0159etla\u010dila odpuzov\u00e1n\u00ed mezi protony.<\/strong><\/p>\n

Neutron neodpuzuje dal\u0161\u00ed protony, ale pom\u00e1h\u00e1 je dr\u017eet u sebe pomoc\u00ed siln\u00e9 jadern\u00e9 s\u00edly. Kdyby bylo v j\u00e1d\u0159e p\u0159\u00edli\u0161 mnoho proton\u016f bez dostate\u010dn\u00e9ho po\u010dtu neutron\u016f, j\u00e1dro by se rozpadalo kv\u016fli elektrostatick\u00e9mu odpuzov\u00e1n\u00ed.<\/p>\n

P\u016fvod p\u0159ita\u017eliv\u00fdch jadern\u00fdch sil<\/h2>\n

P\u016fvod jadern\u00e9 (siln\u00e9) s\u00edly dnes dob\u0159e ch\u00e1peme d\u00edky kvantov\u00e9 chromodynamice (QCD) \u2013 co\u017e je teorie, kter\u00e1 popisuje interakce mezi kvarky a gluony, tedy z\u00e1kladn\u00edmi stavebn\u00edmi kameny proton\u016f a neutron\u016f. Historicky (p\u0159ed QCD) ji vysv\u011btlil Hideki Yukawa jako v\u00fdm\u011bnu \u010d\u00e1stic zvan\u00fdch mezony (nap\u0159. piony, \u03c0-mesony). Dnes v\u00edme, \u017ee mezony vznikaj\u00ed jako projev siln\u00e9 interakce mezi kvarky\/gluony \u2013 ale Yukawova p\u0159edstava dob\u0159e odpov\u00edd\u00e1 efektu jadern\u00e9 s\u00edly mezi nukleony.<\/p>\n

    \n
  • Jadern\u00e1 s\u00edla je zbytkov\u00e1 siln\u00e1 interakce.<\/li>\n
  • Vznik\u00e1 jako \u201evedlej\u0161\u00ed efekt\u201c siln\u00e9 interakce mezi kvarky uvnit\u0159 nukleon\u016f (proton\u016f a neutron\u016f).<\/li>\n
  • Je p\u0159ita\u017eliv\u00e1 na kr\u00e1tk\u00e9 vzd\u00e1lenosti, proto\u017ee gluony (nosi\u010de siln\u00e9 s\u00edly) v\u00e1\u017eou kvarky tak pevn\u011b, \u017ee jejich vliv prosakuje i mimo jeden nukleon \u2013 na ostatn\u00ed nukleony.<\/li>\n
  • Na del\u0161\u00ed vzd\u00e1lenosti tato s\u00edla rychle sl\u00e1bne \u2192 proto se projevuje jen uvnit\u0159 j\u00e1dra.<\/li>\n<\/ul>\n

    Co jsou kvarky a gluony?<\/h3>\n
      \n
    • Proton a neutron nejsou z\u00e1kladn\u00ed \u010d\u00e1stice \u2013 jsou slo\u017een\u00e9 ze t\u0159\u00ed kvark\u016f (nap\u0159. proton = uud, neutron = udd).<\/li>\n
    • Kvarky jsou dr\u017eeny pohromad\u011b silnou interakc\u00ed, kterou zprost\u0159edkov\u00e1vaj\u00ed gluony.<\/li>\n
    • Gluony nesou tzv. barevn\u00fd n\u00e1boj (analogick\u00fd elektrick\u00e9mu, ale slo\u017eit\u011bj\u0161\u00ed).<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

      Na prvn\u00ed pohled se m\u016f\u017ee zd\u00e1t, \u017ee v\u0161e kolem n\u00e1s je klidn\u00e9 a pevn\u00e9 \u2013 stoly, kameny, lidsk\u00e9 t\u011blo. Ale pod povrchem, hluboko uvnit\u0159 atom\u016f, …. <\/p>\n","protected":false},"author":1,"featured_media":5877,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[76],"tags":[],"class_list":["post-5849","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-atomy-a-zareni"],"_links":{"self":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts\/5849","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5849"}],"version-history":[{"count":34,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts\/5849\/revisions"}],"predecessor-version":[{"id":5897,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/posts\/5849\/revisions\/5897"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=\/wp\/v2\/media\/5877"}],"wp:attachment":[{"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5849"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5849"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.zsvltava.cz\/fyzika\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5849"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}