Nā nīnau hoʻohālike no ke kūkākūkā ʻana i ka ʻepekema nukelea a me ka radioactivity
ʻO ke kinoea nukelea a me ka radioactivity nā lālā o ka physics e pili ana i ke aʻo ʻana i nā nuclei atomika a me nā hanana palaho radioactive e kū nei i loko o kēia mau nuclei. He mea koʻikoʻi ka hoʻomaopopo ʻana i kēia mau manaʻo kumu i nā ʻano like ʻole, me ka lāʻau lapaʻau, ka ikehu nukelea, a me ka ʻepekema mea. Ma kēia ʻatikala, e kūkākūkā mākou i kekahi mau pilikia hoʻohālike e pili ana i ka kinoea nukelea a me ka radioactivity, me kā lākou wehewehe ʻana, e kōkua i kou hoʻomaopopo ʻana.
Hoʻolauna Kumu i ka ʻIke Kino Nuklea a me ka Radioactivity
Ma mua o ko mākou komo ʻana i nā nīnau hoʻohālike, he manaʻo maikaʻi e nānā hou i kekahi mau manaʻo kumu:
– ʻAtomika nuklea: Aia i loko o nā protons a me nā neutrons. Hoʻopiʻi maikaʻi ʻia nā protons, ʻoiai ʻaʻole i hoʻopiʻi ʻia nā neutrons.
– Radioactivity: Ke kaʻina hana o ka palaho ʻana o nā nuclei paʻa ʻole i loko o nā nuclei paʻa me ka hoʻokuʻu ʻana o nā ʻāpana a i ʻole ka radiation.
– Nā ʻAno o ka Palaho Radioactive: Alpha (\(\alpha\)), beta (\(\beta\)), a me ka palaho gamma (\(\gamma\)).
– Ke Kānāwai o ka Palaho Radioactive: Wehewehe pehea e emi ai ka helu o nā nuclei radioactive i ka hala ʻana o ka manawa.
Laʻana Nīnau 1: Nuipa a me ka Ikehu Palaho
Nīnau:
Poho ka nucleus uranium-238 i loko o ka thorium-234 ma o ka hoʻokuʻu ʻia ʻana o kahi ʻāpana alpha. Inā ʻo ke kaumaha o ka uranium-238 he 238.0508 u, ʻo ke kaumaha o ka thorium-234 he 234.0436 u, a ʻo ke kaumaha o ka ʻāpana alpha he 4.0026 u, e helu i ka ikehu i hoʻokuʻu ʻia i loko o kēia pohō.
Kūkākūkā:
Hiki ke helu ʻia ka ikehu i hoʻokuʻu ʻia i ke kaʻina hana palaho me ka hoʻohana ʻana i ka pilina ma waena o ka nuipa a me ka ikehu i hāʻawi ʻia e ka hoohalike a Einstein \(E=mc^2\).
1. E helu i ka nuipa i nalowale:
\( \Delta m = (mass_{U-238}) – (mass_{Th-234} + mass_{\alpha}) \)
\( = 238.0508 – (234.0436 + 4.0026) \)
\( = 238.0508 – 238.0462 \)
\( = 0.0046\, u \)
2. E hoʻololi i ka nuipa i nalowale i ka ikehu me ka hoʻohana ʻana iā \( c^2 \):
\( E = \Delta m \times 931.5\, MeV/u \)
\( = 0.0046 \times 931.5 \)
\( \approx 4.29\, MeV \)
No laila, ʻo ka ikehu i hoʻokuʻu ʻia i kēia palaho ma kahi o 4.29 MeV.
Laʻana Nīnau 2: Hapalua Ola a me ka Hana
Nīnau:
I ka wā mua, he 1000 Bq ka hana o kahi hāpana radioactive. Ma hope o 10 mau hola, e emi ana kāna hana i 125 Bq. E hoʻoholo i ka hapalua ola o ka mea radioactive.
Kūkākūkā:
Ua kūlike pololei ka hana (A) o kahi mea radioactive me ka helu o nā nuclei radioactive (N). ʻŌlelo ke kānāwai o ka palaho radioactive:
\[ A(t) = A_0 e^{-\lambda t} \]
Ma kahi o \( \lambda \) ke kūpaʻa palaho:
1. E helu i ke kūpaʻa palaho (\( \lambda \)):
\[ \frac{A(t)}{A_0} = e^{-\lambda t} \]
\[ \frac{125}{1000} = e^{-\lambda \times 10} \]
\[ 0.125 = e^{-\lambda \times 10} \]
\[ \ln(0.125) = -\lambda \times 10 \]
\[ \lambda = -\frac{\ln(0.125)}{10} \]
2. E hoʻoholo i ka hapalua ola (\( T_{1/2} \)):
\[ T_{1/2} = \frac{\ln(2)}{\lambda} \]
\[ \lambda = \frac{\ln(8)}{10} = \frac{2.079}{10} = 0.2079 \, h^{-1} \]
\[ T_{1/2} = \frac{\ln(2)}{0.2079} \approx 3.3 \, hola \]
ʻO ka hapalua ola o ka mea radioactive ma kahi o 3.3 mau hola.
Laʻana 3: Beta Decay a me Antineutrinos
Nīnau:
Hoʻopō ka nucleus Cobalt-60 ma o ka beta-minus decay e hana i kahi nucleus Nickel-60. E kākau i ka hopena nucleus no kēia palaho a kuhikuhi i nā ʻāpana i pili.
Kūkākūkā:
Hana ʻia ka palaho Beta-minus (\(\beta^-\)) ke loli kahi neutron i loko o ka nucleus o kahi ʻātoma i proton, ʻoiai e hoʻopuka ana i kahi electron (\(\beta^-\)) a me kahi antineutrino (\(\bar{\nu}_e\)).
ʻO ka hopena nukelea no kēia palaho:
\[ _{27}^{60}Co \rightarrow _{28}^{60}Ni^ + e^- + \bar{\nu}_e \]
Ma hea:
– ʻO \( _{27}^{60}Co \) ʻo ia ʻo Cobalt-60.
– ʻO \( _{28}^{60}Ni^ \) ʻo Nickel-60 ia i loko o kahi kūlana hoʻonāukiuki.
– He uila (ʻāpana beta-minus) ʻo \( e^- \).
– \( \bar{\nu}_e \) he antineutrino.
ʻO ka nickel-60 i hoʻokumu ʻia he pinepine ia i loko o kahi kūlana hoʻonāukiuki a e hoʻokuʻu pinepine i ka ikehu hou aʻe ma ke ʻano o nā kukuna gamma (\(\gamma\)) e hiki ai i ke kūlana honua. Hiki ke kākau ʻia ka hopena piha penei:
\[ _{27}^{60}Co \rightarrow _{28}^{60}Ni + e^- + \bar{\nu}_e + \gamma \]
Laʻana Nīnau 4: Ka nui o ka radiation
Nīnau:
Inā waiho ʻia kahi kumu o ka radiation gamma me ka hana o 2 Curies ma kahi mamao o 1 mika mai kahi mea a ua omo ʻia ka radiation e ka mea no 5 mau minuke, e helu i ka nui o ka radiation i loaʻa i ka mea ma rems. Manaʻo ʻia ʻo ka nui o ka radiation i uhi ʻia he 0.5 rad no Curie i kēlā me kēia minuke a ʻo ka mea maikaʻi no ka radiation gamma he 1.
Kūkākūkā:
1. E helu i ka mahele lāʻau ma rad:
\[ \text{Dose (rad)} = \text{Ka nui o ka radiation} \times \text{Hana} \times \text{Manawa (minuke)} \]
\[ = 0.5 \, rad/(Ci \cdot min) \times 2 \, Ci \times 5 \, min \]
\[ = 5 \, rad \]
2. E helu i ka nui o nā paleki:
\[ \text{Dose (rem)} = \text{Dose (rad)} \times \text{Quality Factor} \]
\[ = 5 \, rad \times 1 \, (no ka gamma) \]
\[ = 5 \, hoʻomaha \]
ʻO ka nui o ka radiation i loaʻa i ka mea he 5 rem.
Pani
Ma ke aʻo ʻana i nā pilikia hoʻohālike ma luna, ke manaʻolana nei mākou e hoʻoikaika i kou ʻike i nā manaʻo o ka physics nukelea a me ka radioactivity. He mea nui e hoʻomaʻamaʻa pinepine i nā pilikia like e lilo i ʻoi aku ka mākaukau i ka hoʻomaopopo ʻana a me ka hoʻopili ʻana i kēia mau manaʻo physics nukelea. Hauʻoli ke aʻo ʻana!
