ʻAlepa (α) Palaho
ʻO ka palaho Alpha (α) kekahi o nā ʻano nui ʻekolu o ka palaho radioactive, nona pū kekahi palaho beta (β) a me ka palaho gamma (γ). He mea nui loa kēia hanana i ka physics nukelea a me ka ʻepekema mea, a he mau hopena kūpono hoʻi i nā kahua o ka lāʻau lapaʻau nukelea, ka mana nukelea, a me ke kaiapuni.
Ke Hoʻomaopopo nei i ka Alpha Decay
ʻO ka palaho Alpha ke kaʻina hana e hoʻokuʻu ai kahi nucleus atomic paʻa ʻole i kahi ʻāpana alpha e hoʻokō ai i kahi hoʻonohonoho paʻa. Loaʻa i nā ʻāpana Alpha ʻelua protons a me ʻelua neutrons, like me ka nucleus o kahi atom helium-4 (He-4). Ke hele ka palaho alpha i kahi nucleus atomic, nalowale ia i ʻelua protons a me ʻelua neutrons, e hopena ana i kahi nucleus atomic hou me ka helu atomic haʻahaʻa a me ka nui atomic haʻahaʻa.
Hiki ke kākau ʻia ke ʻano hana kumu no ka palaho alpha penei:
\[ _Z^AX \rightarrow _{Z-2}^{A-4} Y + \alpha \]
Ma hea:
– ʻO \( _Z^AX \) ka nucleus atomika ma mua o ka palaho me ka helu nuipa \( A \) a me ka helu atomika \( Z \),
– ʻO \( _{Z-2}^{A-4} Y \) ka nucleus i loaʻa mai ka palaho,
– He ʻāpana alpha ʻo \( \alpha \).
Eia kekahi laʻana, ʻo Uranium-238 (\( _{92}^{238} U \)) ke hele nei i ka palaho alpha i Thorium-234 (\( _{90}^{234} Th \)):
\[ _{92}^{238} U \rightarrow _{90}^{234} Th + \alpha \]
ʻAno Hoʻopōʻino Alpha
Hana ʻia ka palaho Alpha ma muli o ka ikaika nukelea e hana ana i loko o ka nukelea. Aia i loko o ka nukelea atomika nā proton a me nā neutron i hoʻopaʻa ʻia e ka ikaika ikaika. ʻOiai ʻo ka ikaika electrostatic ma waena o nā proton i hoʻopiʻi maikaʻi ʻia e hoʻokaʻawale iā lākou, ua lawa ka ikaika o ka ikaika e hoʻopaʻa iā lākou i ka hapa nui o nā hihia. Eia nō naʻe, i loko o nā nukelea kaumaha me nā proton he nui, lilo ka repulsion electromagnetic i mea koʻikoʻi a lilo ka nukelea i mea paʻa ʻole.
No nā nuclei kaumaha, he mea maikaʻi loa ka hoʻokuʻu ʻana o nā ʻāpana alpha i ka hoʻohaʻahaʻa ʻana i ka ikehu o ka ʻōnaehana. He mau ʻāpana paʻa nā ʻāpana Alpha me ka ikehu hoʻopaʻa kiʻekiʻe no kēlā me kēia nucleon, no laila e kōkua kā lākou hoʻokuʻu ʻana i ka nucleus e hoʻokō i ka paʻa nui aʻe.
Nā Waiwai o nā ʻĀpana Alpha
He nui nā ʻano koʻikoʻi o nā ʻāpana Alpha e hōʻike ana i ko lākou mau ʻano kino a me nā pilina me nā mea:
1. Nuipaʻa a me ka Uhi: Loaʻa i kēlā me kēia ʻāpana alpha kahi nuipaʻa ma kahi o 4 mau anakahi nuipaʻa atomika (u) a me kahi ukupaʻa o +2 e, no ka mea, aia i loko o ia mea ʻelua mau proton a me ʻelua mau neutron.
2. Ikehu a me ka Māmā: Loaʻa i nā ʻāpana Alpha ka ikehu kinetic kiʻekiʻe loa (ʻo ka maʻamau he mau MeV) akā haʻahaʻa ko lākou wikiwiki i ka hoʻohālikelike ʻia me nā ʻāpana beta a i ʻole nā kukui gamma.
3. Ke komo ʻana a me ka laulā: No ka mea, he nui ka hoʻouka ʻana o nā ʻāpana alpha a he nui ka nui, he pōkole loa ko lākou laulā i ka mea. Hiki ke hoʻōki maʻalahi ʻia lākou e kekahi mau kenimika o ka ea a i ʻole kekahi mau micrometer o nā mea paʻa e like me ka pepa a i ʻole ka ʻili kanaka.
4. Ionization: He kiʻekiʻe ka ionization o nā ʻāpana Alpha, ʻo ia hoʻi hiki iā lākou ke hana i ka nui o ka ionization i loko o nā mea a lākou e hele ai. ʻO kēia ka mea e lilo ai lākou i mea kūpono loa i ka hōʻike ʻana i ke kiʻiʻoniʻoni kiʻi a i ʻole ke hoʻopaʻa ʻana i nā scintillation i loko o nā mea ʻike.
Noi ʻana o Alpha Decay
1. Lapaʻau Nukelea: Hoʻohana ʻia nā kumu radiation Alpha i kekahi mau ʻano lapaʻau, ʻoi aku hoʻi i ka mālama ʻana i ka maʻi kanesa. No ka laʻana, hoʻohana ʻia ka radium-223 i ka mālama ʻana i nā metastases o ka iwi.
2. Nā Mea ʻIke Uahi: Hoʻohana ka nui o nā mea ʻike uahi o ka hale i ka americium-241, kahi mea hoʻopuka alpha, e ʻike i ka uahi. Hoʻohui nā ʻāpana alpha i hoʻokuʻu ʻia i ka ea i loko o ke keʻena ʻike; ke komo ka uahi i loko o kēia keʻena, loli ka conductivity uila, e hoʻāla ana i kahi alarm.
3. Ka Lāʻau Radiometric: Hoʻohana nā ʻano hana ka lāʻau radiometric e like me ka lāʻau uranium-lead i ka palaho alpha o nā isotopes uranium a me thorium e hoʻoholo ai i ka makahiki o nā pōhaku a me nā minelala.
4. Ka Palekana a me ke Koʻikoʻi o ka Koa: Ma muli o ka haʻahaʻa o ke komo ʻana o nā ʻāpana alpha, ʻaʻole hoʻoweliweli nui nā mea hoʻopuka alpha i ka radiation waho a hiki ke lawelawe ʻia me ka palekana me ka pale maʻalahi; akā naʻe, i ka wā e hanu ʻia ai a ʻai ʻia paha, hiki iā lākou ke lilo i mea weliweli loa.
Nā hopena a me nā pōʻino o ka Alpha Decay
ʻOiai ʻaʻole komo nui nā ʻāpana alpha, hiki iā lākou ke lilo i mea weliweli loa inā hanu ʻia a ʻai ʻia paha nā mea radioactive e hoʻopuka ana i nā ʻāpana alpha. I kēia mau hihia, hiki i ka radiation alpha ke hōʻeha nui i nā ʻiʻo ola ma o ka ionization pololei. No laila, pono e mālama pono i ka wā e lawelawe ai a mālama i nā mea alpha-emitting, e hahai ana i nā kulekele palekana radiation paʻa.
Nā Haʻawina a me ka Noiʻi ʻana o Alpha Decay
Ua hāʻawi ke aʻo ʻana i ka palaho alpha i nā ʻike koʻikoʻi i ke ʻano kumu o nā pilina nuclei a me nā nucleus. Ua wehewehe mua ʻia ke kumumanaʻo o ka palaho alpha e George Gamow i ka makahiki 1928 me ka hoʻohana ʻana i ke ʻano o ka quantum tunneling, kahi hanana e hiki ai i nā ʻāpana ke komo i nā pale hiki ke hiki ʻole ke hana ʻia e like me ka physics kuʻuna.
Wahi a kēia kumumanaʻo, ua manaʻo ʻia nā ʻāpana alpha i loko o ka nucleus he ʻōnaehana e paio ana i kahi pale hiki ke hoʻopuni ana i ka nucleus. ʻOiai ʻaʻole lawa ko lākou ikehu kinetic e hele ai ma waena o ka pale ma ke ʻano maʻamau, ʻo ka hiki ke hiki iā lākou ke 'ʻō' i ka pale ma o ka quantum tunneling e hiki ai ke palaho. Hāʻawi kēia mau helu i nā wānana o ka hapalua ola a me ka ikehu o nā ʻāpana alpha e kūlike me nā nānā hoʻokolohua.
Ka hopena
He hanana koʻikoʻi ka palaho Alpha i ka ʻepekema nukelea, e pili ana i ka hoʻokuʻu ʻia ʻana o nā ʻāpana alpha (ʻelua protons a me ʻelua neutrons) mai nā nuclei atomika paʻa ʻole. ʻAʻole wale kēia kaʻina hana he mea nui no ka hoʻomaopopo pono ʻana i ke ʻano o nā nuclei atomika, akā he mau noi pono koʻikoʻi nō hoʻi i ka ʻenehana lapaʻau, ʻoihana, a me ka ʻepekema.
ʻOiai ʻo ka radiation alpha ponoʻī he haʻahaʻa ka komo ʻana a he maʻalahi hoʻi ke hoʻōki, ʻo ka lawelawe ʻana i nā mea e hoʻopuka ana i ka radiation alpha e pono ai ke akahele loa e pale aku i ka ʻike kūloko e hiki ke hōʻino i nā ʻiʻo olaola. Ke hoʻomau nei nā haʻawina hohonu o ka palaho alpha i ka hāʻawi ʻana i nā ʻike hou i ka physics nukelea a alakaʻi i nā noi ʻenehana palekana a ʻoi aku ka maikaʻi ma nā ʻano kahua like ʻole.
