Alfa-zarrachalar spektroskopiyasi sahifasining manbasini koʻrish

'''Alfa-spektrometriya''' (shuningdek ''', alfa (-zarracha) spektroskopiyasi''' sifatida ham tanilgan) [[Alfa-parchalanish|alfa-emitter]] boʻlgan radioaktiv nuklid tomonidan chiqarilgan [[Alfa-zarralar|alfa zarrachalarining]] energiyasini miqdoriy oʻrganishdir.

Chiqarilgan alfa zarralari mono-energetik (yaʼni [[Beta-yemirilish|beta-parchalanish]] kabi energiya spektri bilan chiqarilmagan) boʻlgani uchun energiyalari koʻpincha parchalanishdan farq qiladi, ular qaysi radionukliddan kelib chiqqanligini aniqlash uchun ishlatilishi mumkin.

Chiqarilgan alfa zarralari mono-energetik (ya'ni [[Beta-yemirilish|beta-parchalanish]] kabi energiya spektri bilan chiqarilmagan) bo'lgani uchun energiyalari ko'pincha parchalanishdan farq qiladi, ular qaysi radionukliddan kelib chiqqanligini aniqlash uchun ishlatilishi mumkin.<ref>{{Veb manbasi |muallif=Siegel |ism=Peter |sana=29 March 2021 |sarlavha=Nuclear decays |url=https://www.cpp.edu/~pbsiegel/phy432/labman/decays.pdf |ish=Physics Department at Cal Poly Pomona |arxivurl=https://web.archive.org/web/20180413202018/http://www.cpp.edu:80/~pbsiegel/phy432/labman/decays.pdf |arxivsana=2018-04-13}}</ref>

'''Alfa-spektrometrlar''' — radioaktiv yadrolar chiqarayotgan alfa (a)-zarralar energiyasini oʻlchaydigan asbob. Ishlash tarzi a-zarralarning magnitik tahliliga (magnit A.-s.) yoki ularning ionlovchi taʼsirlarini tadqiq qilishga (ionlash kamerasi) asoslangan. a-zarralarning energetik spektri (na-fis strukturasi)ni oʻrganish yadro fi-zikasida katta ahamiyatga ega. Spektrlar yadroning energetik sathlari toʻgʻrisida maʼlumot beradi. Odatda, mahsul yadroning energetik sathlari bir-biriga yaqin boʻladi. Masalan, Ra226 yadrosining ik-kinchi va uchinchi uygʻongan holati ener-giyalari farqi 20-43 keV. Shuning uchun a-spektrometrlarning energetik sathlar bir-biriga yaqin boʻlgan guruhlarini aj-rata olish qobiliyati katta boʻlishi ke-rak. Hozirgi zamon magnit a-spektrometri energetik sathlar farqi 0,07% boʻlgan chiziqlarni ajrata oladi.

== Eksperimental usullar ==
[[Fayl:Si_Detector_energy_broadening.svg|alt=Graphic showing how mono-energetic emissions will not show as a single sharp peak due to energy losses depending on emission path. Longer paths (lines not perpendicular to source and detector) will lose energy to the air they pass through. Paths originating within the source material will additionally lose energy passing through the source material.|thumb|300x300px| Chiqarilgan mono-energetik alfa zarralarining turli yo'llari energiyani yo'qotishi va shuning uchun chiziq spektrida signalning kengayishiga olib kelishiga misol. Barcha yo'llar havo va detektor oynasiga energiya yo'qotadi. Uzunroq yo'llar ko'proq energiya yo'qotadi. iii va iv yo'llari manba materialining o'zidan o'tadigan energiya yo'qolishini ham ko'rsatadi. Qizil o'qlar zarracha aniqlangan energiya kattaligini ko'rsatadi.]]
[[Metallar|Metall]] diskka bir tomchi sinov eritmasini qo'yish odatiy holdir, keyin diskda bir xil qoplama hosil qilish uchun quritiladi. Keyinchalik bu sinov namunasi sifatida ishlatiladi. Agar diskda hosil bo'lgan qatlamning qalinligi juda qalin bo'lsa, [[spektr]]ning chiziqlari pastroq energiyaga qadar kengaytiriladi. Buning sababi shundaki [[Alfa-zarralar|, alfa zarralari]] [[energiya]]sining bir qismi faol material qatlami orqali harakatlanayotganda yo'qoladi.<ref>{{Citation |last=Vajda |first=Nora |title=Alpha Spectrometry |date=2012 |url=https://linkinghub.elsevier.com/retrieve/pii/B9780123848734000062 |work=Handbook of Radioactivity Analysis |pages=380–381 |access-date=2021-03-29 |publisher=Elsevier |language=en |doi=10.1016/b978-0-12-384873-4.00006-2 |isbn=978-0-12-384873-4 |last2=Martin |first2=Paul |last3=Kim |first3=Chang-Kyu}}</ref>

=== Suyuqlik sintilatsiyasi ===
Muqobil usul - suyuqlik sintilatsiyasini hisoblash (LSC) dan foydalanish, bu yerda namuna to'g'ridan-to'g'ri sintillash kokteyli bilan aralashtiriladi. Shaxsiy [[Yorugʻlik|yorug'lik]] emissiya hodisalari hisoblanganda, LSC asbobi [[radioaktiv parchalanish]] hodisasi uchun yorug'lik energiyasi miqdorini qayd qiladi. Suyuqlik sintilatsiyasini hisoblash yo'li bilan olingan alfa spektrlari LSC usulining ikkita asosiy ichki cheklovlari tufayli kengayadi: (1) tasodifiy söndürme radioaktiv parchalanishda chiqariladigan [[foton]]lar sonini kamaytiradi va (2) chiqarilgan [[foton]]lar so'rilishi mumkinligi sababli. bulutli yoki rangli namunalar bo'yicha ( [[Buger - Lambert - Ber qonuni|Lambert-Beer qonuni]] ). Suyuq ssintilatsiya spektrlari diskda yotqizilgan faol moddaning qatlami juda qalin bo'lganda, namuna tomonidan alfa-zarrachalarning yutilishi natijasida yuzaga keladigan buzilishdan ko'ra, Gauss kengayishiga duchor bo'ladi.

== Alfa spektrlari ==
[[Fayl:Alpha1spec.png|thumb|300x300px| To'rt [[Izotoplar|izotop]] uchun alfa energiyasiga qarshi intensivlik, chiziq kengligi tor va nozik tafsilotlarni ko'rish mumkinligiga e'tibor bering.]]
[[Fayl:Alpha5spec.png|thumb|300x300px| To'rtta izotop uchun alfa energiyasiga qarshi intensivlik, chiziq kengligi keng va ba'zi nozik tafsilotlarni ko'rish mumkin emasligiga e'tibor bering. Bu tasodifiy ta'sirlar alfa parchalanishida hosil bo'ladigan ko'rinadigan fotonlar sonining o'zgarishiga olib keladigan suyuqlik sintilatsiyasini hisoblash uchundir.]]
Chapdan o'ngga cho'qqilar <sup>209</sup> Po, <sup>239</sup> Pu, <sup>210</sup> Po va <sup>241</sup> Am bilan bog'liq. [[Plutoniy|<sup>239</sup> Pu]] va [[Ameritsiy|<sup>241</sup> Am]] kabi [[izotoplar]]ning bir nechta alfa chizig'iga ega bo'lishi (qizi) [[Atom yadrosi|yadro]] turli xil diskret energiya darajalarida bo'lishi mumkinligini ko'rsatadi.

Kalibrlash: MCA energiyada ishlamaydi, kuchlanishda ishlaydi. Energiyani kuchlanish bilan bog'lash uchun aniqlash tizimini kalibrlash kerak. Bu yerda detektor ostiga ma'lum energiyaning turli xil alfa chiqaradigan manbalari joylashtirilgan va to'liq energiya cho'qqisi qayd etilgan.

Yupqa plyonkalar qalinligini o'lchash: radioaktiv manbalardan alfa zarrachalarining energiyalari yupqa plyonkalardan o'tishdan oldin va keyin o'lchanadi. Farqni o'lchash va SRIM yordamida biz yupqa plyonkalarning qalinligini o'lchashimiz mumkin.

== Alfa yemirilish kinematikasi ==
Parchalanish energiyasi Q ( ''reaksiyaning Q-qiymati'' deb ham ataladi) massaning yo'qolishiga to'g'ri keladi.

Alfa-parchalanish yadro reaktsiyasi uchun:&lt;math xmlns="http://www.w3.org/1998/Math/MathML"&gt;<semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mrow class="MJX-TeXAtom-ORD"><mmultiscripts><mtext> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mtext><mtext> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mtext><mtext> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mtext></mmultiscripts><mo stretchy="false"> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mo><mmultiscripts><mtext> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mtext><mrow class="MJX-TeXAtom-ORD"><mo stretchy="false"> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mo><mtext> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mtext><mrow class="MJX-TeXAtom-ORD"><mo> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mo></mrow><mn> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mn><mo stretchy="false"> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mo></mrow><mrow class="MJX-TeXAtom-ORD"><mo stretchy="false"> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mo><mtext> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mtext><mrow class="MJX-TeXAtom-ORD"><mo> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mo></mrow><mn> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mn><mo stretchy="false"> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mo></mrow></mmultiscripts><mo> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mo><mi> <chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></mi></mrow></mstyle></mrow><annotation encoding="application/x-tex"> </annotation></semantics>&lt;/math&gt;<chem>^{A}_{Z}P -> ^{(A-4)}_{(Z-2)}D + \alpha
</chem></img> , (bu yerda P - asosiy nuklid va D - qizi).

<math>Q{_\alpha} = (m_P - m_D - m_\alpha) \ c^2</math>, yoki ko'proq ishlatiladigan birliklarni qo'yish uchun: ''Q'' (M [[Elektronvolt|eV]] ) = -931,5 D ''M'' ( [[Massaning atom birligi|Da]] ), (bu yerda D ''M = SM <sub>mahsulotlar</sub> - SM <sub>reaktivlari</sub>'' ).<ref>{{Kitob manbasi |last=Choppin |first=Gregory R. |url=https://www.worldcat.org/oclc/182729523 |title=Radiochemistry and nuclear chemistry |date=2002 |publisher=Butterworth-Heinemann |others=Gregory R. Choppin, Jan-Olov Liljenzin, Jan Rydberg |isbn=978-0-08-051566-3 |edition=3rd |location=Woburn, MA |pages=62 |oclc=182729523}}</ref>

Hosil bo'lgan qiz nuklid va alfa zarrachalari o'zlarining asosiy holatida bo'lganda (alfa-parchalanish uchun umumiy), umumiy parchalanish energiyasi kinetik energiya (T) bo'yicha ikkalasiga bo'linadi:

<math>Q_\alpha = T_\alpha + T_D</math>

T ning o'lchami mahsulotlar massalarining nisbatiga bog'liq va impulsning saqlanishi tufayli (parchalanish momenti = 0) buni hisoblash mumkin:

<math>p_\alpha + p_D = 0</math>

<math>T = 0.5mv^2</math> va <math>p = mv</math>, <math>\therefore p = \sqrt{2mT}</math>

<math display="inline">\begin{align}
\sqrt{2m_\alpha T_\alpha} &= -\sqrt{2m_D T_D} \\[4pt]
2m_\alpha T_\alpha &= 2m_D T_D \\[4pt]
\frac{m_\alpha}{m_D}T_\alpha &= T_D
\end{align}</math>

<math>\begin{align} 
Q_\alpha &= T_\alpha + \frac{m_\alpha}{m_D}T_\alpha \\[4pt]
&= T_\alpha\bigg(1 + \frac{m_\alpha}{m_D}\bigg) \\[4pt]
&= T_\alpha\bigg(\frac{m_D}{m_D}+\frac{m_\alpha}{m_D}\bigg) \\[4pt]
&= T_\alpha\bigg(\frac{m_D+m_\alpha}{m_D}\bigg) \\[4pt]
\end{align}</math>

<math>\therefore T_\alpha = \frac{m_D}{m_P}Q_\alpha</math>

Alfa zarrasi yoki <sup>4</sup> He yadrosi ayniqsa kuchli bog'langan zarradir. Bu nuklonga bog'lanish energiyasi A=56 ga yaqin maksimal qiymatga ega bo'lishi va og'irroq yadrolar uchun muntazam ravishda kamayib borishi bilan birgalikda A>150 bo'lgan yadrolar alfa zarrachalarini chiqarish uchun ijobiy Q <sub>a</sub> -qiymatlariga ega bo'lgan vaziyatni yaratadi.

Masalan, eng og'ir tabiiy izotoplardan biri,&lt;math xmlns="http://www.w3.org/1998/Math/MathML"&gt;<semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mrow class="MJX-TeXAtom-ORD"><mmultiscripts><mtext> <chem>^238U -> ^234Th + ^4He
</chem></mtext><mn> <chem>^238U -> ^234Th + ^4He
</chem></mn></mmultiscripts><mo stretchy="false"> <chem>^238U -> ^234Th + ^4He
</chem></mo><mmultiscripts><mtext> <chem>^238U -> ^234Th + ^4He
</chem></mtext><mn> <chem>^238U -> ^234Th + ^4He
</chem></mn></mmultiscripts><mo> <chem>^238U -> ^234Th + ^4He
</chem></mo><mmultiscripts><mtext> <chem>^238U -> ^234Th + ^4He
</chem></mtext><mn> <chem>^238U -> ^234Th + ^4He
</chem></mn></mmultiscripts></mrow></mstyle></mrow><annotation encoding="application/x-tex"> </annotation></semantics>&lt;/math&gt;<chem>^238U -> ^234Th + ^4He
</chem></img> (to'lovlarni hisobga olmaganda):

: Q <sub>a</sub> = -931,5 (234,043 601 + 4,002 603 254 13 - 238,050 788 2) = 4,2699 MeV <ref>{{Veb manbasi |sarlavha=Livechart – Table of Nuclides – Nuclear structure and decay data |url=https://nds.iaea.org/relnsd/vcharthtml/VChartHTML.html |qaralgan sana=2021-03-31 |ish=nds.iaea.org}}</ref>

E'tibor bering, parchalanish energiyasi alfa-zarracha va og'ir ortga qaytuvchi qiz o'rtasida taqsimlanadi, shunda alfa zarrasining kinetik energiyasi (T <sub>a</sub> ) biroz kamroq bo'ladi:

T <sub>a</sub> = (234,043 601 / 238,050 788 2) 4,2699 = 4,198 MeV, (esda tuting, bu <sup>238 g</sup> U dan <sup>238 g</sup> gacha bo'lgan Th reaktsiyasi uchun, bu holda 79% dallanma nisbati mavjud). Orqaga qaytuvchi <sup>234</sup> Th qiz yadrosining kinetik energiyasi T <sub>D</sub> = (m <sub>a</sub> / m <sub>P</sub> ) Q <sub>a</sub> = (4,002 603 254 13 / 238,050 788 2) 4,2699 = 0,0718 MeV yoki 71,8 keV dan kichikroq, qaysi biri undan kattaroqdir. kimyoviy bog'lanishlarga qaraganda (<10 eV), ya'ni qiz nuklid ota-onasi bo'lgan har qanday kimyoviy muhitdan ajralib chiqadi.
[[Fayl:Change_of_alpha_E_with_air_pressure.png|thumb|Aniqlangan alfa zarracha energiyasi havo bosimi ortishi bilan qanday kamayishiga misol (o'ngdan chapga).]]
Qaytish energiyasi, shuningdek, alfa-spektrometrlarning past bosim ostida ishlagan holda, juda past bosimda ishlamasligining sababidir, shunda havo orqaga qaytgan qizning asl alfa-manbadan butunlay chiqib ketishini to'xtatishga yordam beradi va agar bo'lsa, jiddiy ifloslanish muammolarini keltirib chiqaradi. qizlarning o'zlari radioaktivdir.<ref>{{Jurnal manbasi|last=Sill|first1=Claude W.|last2=Olson|first2=Dale G.|date=1970-11-01|title=Sources and prevention of recoil contamination of solid-state alpha detectors|url=https://pubs.acs.org/doi/abs/10.1021/ac60295a016|journal=Analytical Chemistry|language=en|volume=42|issue=13|pages=1596–1607|doi=10.1021/ac60295a016|issn=0003-2700}}</ref>

Qa-qiymatlari odatda atom sonining ortishi bilan ortadi, ammo qobiq effektlari tufayli massa yuzasining o'zgarishi tizimli o'sishni bartaraf qilishi mumkin. A = 214 yaqinidagi o'tkir cho'qqilar N = 126 qobiqning ta'siridan kelib chiqadi.
<references />

* '''''Ushbu maqola Mirzo Ulug'bek nomidagi [[Oʻzbekiston Milliy universiteti|O'zbekiston Milliy universitieti]] Fizika fakulteti talabasi Aminov Islom tomonidan Wikita'lim loyihasi doirasida ingliz tilidan tarjima qilindi.'''''

 {{Turkumsiz|date=Aprel 2024}}