Cov Lus Nug Piv Txwv Sib Tham Txog Alpha (α) Decay
Pendahuluuan
Kev puas tsuaj ntawm cov khoom siv hluav taws xob yog cov txheej txheem uas cov nuclei atomic tsis ruaj khov poob zog los ntawm kev tso tawm cov khoom me me. Ib hom kev puas tsuaj ntawm cov khoom siv hluav taws xob feem ntau tham txog hauv physics yog kev puas tsuaj ntawm alpha (α). Hauv kev puas tsuaj ntawm alpha, lub nucleus tso tawm cov khoom me me alpha, uas muaj ob lub protons thiab ob lub neutrons, sib npaug rau lub nucleus helium-4. Kev nkag siab txog kev puas tsuaj ntawm alpha yog qhov tseem ceeb hauv nuclear physics, chemistry, thiab lwm yam teb uas cuam tshuam nrog radioactivity. Hauv tsab xov xwm no, peb yuav tham txog ib qho piv txwv ntawm kev puas tsuaj ntawm alpha, ua raws li kev sib tham los txhawb peb txoj kev nkag siab ntawm lub tswv yim no.
Kev Taw Qhia rau Alpha Decay
Kev lwj ntawm Alpha ua rau muaj kev hloov pauv hauv lub nucleus ntawm lub atom uas lwj. Thaum lub nucleus tso tawm ib qho alpha particle, nws tus lej atomic txo qis los ntawm ob thiab nws tus lej pawg txo qis los ntawm plaub. Qhov no tuaj yeem qhia los ntawm cov qauv dav dav hauv qab no:
\( _{Z}^{A}X \rightarrow _{Z-2}^{A-4}Y + _{2}^{4}\alpha \)
Qhov twg:
– \( _{Z}^{A}X \) yog lub nucleus pib (ua ntej lwj).
– \( _{Z-2}^{A-4}Y \) yog lub nucleus tshiab (tom qab lwj).
- \( _{2}^{4}\alpha \) yog cov khoom me me alpha uas tawm los.
Piv txwv teeb meem Alpha Decay
Lo lus nug thib 1:
Uranium-238 (\( _{92}^{238}U \)) lwj los ntawm kev tso tawm alpha. Txheeb xyuas cov khoom tshiab tsim tawm tom qab ib qho alpha lwj!
Kev Sib Tham:
Yuav kom daws tau qhov teeb meem no, peb yuav siv cov ntsiab cai yooj yim ntawm alpha decay.
1. Sau qhov kev hloov pauv ntawm alpha decay:
\( _{92}^{238}U \rightarrow _{Z}^{A}Y + _{2}^{4}\alpha \)
2. Txheeb xyuas cov nqi Z thiab A rau cov khoom tshiab:
Vim tias cov khoom alpha muaj tus lej atomic 2 thiab tus lej loj 4, peb tuaj yeem xam:
– Tus lej atomic ntawm cov khoom tshiab, \( Z = 92 – 2 = 90 \)
– Tus lej loj ntawm cov khoom tshiab, \( A = 238 – 4 = 234 \)
3. Nrhiav lub ntsiab lus uas muaj tus lej atomic 90:
Raws li lub rooj sib tham, lub caij nrog atomic number 90 yog Thorium (Th).
Yog li, cov khoom tshiab uas tsim yog Thorium-234 (\( _{90}^{234}Th \)). Qhov kev ua tiav tag nrho yog:
\( _{92}^{238}U \rightarrow _{90}^{234}Th + _{2}^{4}\alpha \)
Lo lus nug thib 2:
Radium-226 (\( _{88}^{226}Ra \)) lwj mus rau Radon-222 tom qab tso tawm ib lub alpha particle. Muaj zog npaum li cas raug tso tawm hauv cov txheej txheem no? (Xav tias qhov hnyav ntawm cov khoom me me tsis tseem ceeb thiab siv cov qauv atomic masses: \( ^{226}Ra = 226.025402 \), \( ^{222}Rn = 222.017570 \), thiab \( ^{4}He = 4.002602 \); 1 atomic mass unit \( \approx \) 931 MeV/c²)
Kev Sib Tham:
Lub zog tso tawm thaum lub sijhawm alpha lwj tuaj yeem suav los ntawm qhov sib txawv ntawm qhov hnyav ntawm lub nucleus pib thiab cov khoom kawg thiab cov khoom alpha, hloov mus ua lub zog siv cov qauv E = mc².
1. Xam qhov sib txawv ntawm qhov hnyav ua ntej thiab tom qab lwj:
Qhov hnyav ua ntej lwj (Radium-226):
\( m_{\text{ua ntej}} = 226.025402 \)
Qhov hnyav tom qab lwj (Radon-222) thiab cov khoom me me alpha:
\( m_{\text{tom qab}} = 222.017570 + 4.002602 = 226.020172 \)
Qhov sib txawv ntawm pawg:
\( \Delta m = 226.025402 – 226.020172 = 0.005230 \) u
2. Hloov qhov sib txawv ntawm qhov hnyav mus ua lub zog:
Zog tso tawm, E = ∑m3 / 931 MeV
\( E = 0.005230 \times 931 \) MeV
\( E \approx 4.866 \) MeV
Yog li, lub zog tso tawm hauv alpha lwj ntawm Radium-226 rau Radon-222 yog li 4.866 MeV.
Kev cuam tshuam thiab kev siv ntawm Alpha Decay
Kev lwj ntawm Alpha muaj ntau yam cuam tshuam thiab kev siv hauv kev tshawb fawb thiab thev naus laus zis. Qee qhov ntawm cov no suav nrog:
1. Kev Txheeb Xyuas Radiometric: Txoj kev no siv kev puas tsuaj los ntawm cov tshuaj radioactive los txiav txim siab hnub nyoog ntawm ib yam khoom. Kev txheeb xyuas Uranium-Lead yog ib qho piv txwv uas kev puas tsuaj alpha pab txiav txim siab hnub nyoog ntawm cov pob zeb thiab cov zaub mov.
2. Kev Kho Mob Cancer: Qee cov isotopes uas tso tawm cov alpha particles yog siv rau hauv kev kho mob cancer. Cov alpha particles muaj qhov ntev luv thiab muaj zog siab, uas tuaj yeem tua cov cell cancer hauv thaj chaw uas raug tsom yam tsis ua rau cov nqaij ntshiv noj qab haus huv puas tsuaj.
3. Kev Nyab Xeeb ntawm Nuclear: Kev nkag siab txog kev lwj ntawm alpha yog qhov tseem ceeb hauv kev tsim thiab khaws cia cov khoom siv nuclear, vim tias qee cov isotopes uas tso tawm alpha tuaj yeem ua rau muaj kev phom sij heev yog tias nqus tau lossis noj.
4. Cov Khoom Siv Ntsuas Pa Luam Yeeb: Qee cov khoom siv ntsuas pa luam yeeb siv cov isotopes uas tso tawm cov khoom me me alpha los ntsuas pa luam yeeb hauv chav. Cov khoom me me alpha ua rau huab cua hauv lub tshuab ntsuas pa luam yeeb ionize, thiab thaum pa luam yeeb cuam tshuam rau cov txheej txheem no, lub tswb ceeb toom yuav qhib.
Xaus
Kev lwj ntawm Alpha yog ib hom kev lwj ntawm cov khoom siv hluav taws xob uas ua lub luag haujlwm tseem ceeb hauv ntau qhov chaw tshawb fawb thiab kev siv thev naus laus zis. Los ntawm kev nkag siab txog cov piv txwv ntawm kev lwj ntawm alpha, peb tuaj yeem nkag siab zoo dua txog cov txheej txheem nuclear uas ua rau muaj kev lwj no thiab nws cov txiaj ntsig ntawm lub zog. Txawm hais tias kev lwj ntawm alpha cuam tshuam nrog kev hloov pauv yooj yim hauv tus lej loj thiab tus lej atomic, nws qhov cuam tshuam rau peb lub ntiaj teb tuaj yeem tseem ceeb, tshwj xeeb tshaj yog nyob rau hauv cov ntsiab lus ntawm kev khaws sijhawm geological, kev siv kho mob, thiab kev ruaj ntseg. Kev kawm txog kev lwj ntawm alpha txuas ntxiv mus ntxiv, qhib lub qab ntuj tshiab hauv kev tshawb fawb thiab kev siv thev naus laus zis.
