Yadro fizikasi — fizikaning yadro materiyasining boshqa shakllarini o‘rganish bilan bir qatorda atom yadrolari va ularning tarkibiy qismlari va o‘zaro ta'sirini o‘rganadigan bo‘limi hisoblanadi.

Yadro fizikasi

Yadro fizikasini atom fizikasi bilan chalkashtirib yubormaslik kerak. Yadro fizikasi atomni, shu jumladan uning elektronlarini ham o‘rganadi.

Yadro fizikasidagi kashfiyotlar juda ko‘plab sohalarda qo‘llaniladi: yadro energetikasi, yadro tibbiyoti, yadroviy qurollar, magnit-rezonans tamografiyasi shular jumlasiga kiradi.

Yadro fizikasidan ajralib chiqqan tarmoq — elementar zarralar fizikasi bo‘lib, aksar hollarda bu ikkala sohada birgalikda o‘qitiladi. Elementar zarralar fizikasi — yadro astrofizikasi va kimyo sohasida muhim o‘ringa ega.

Tarixi

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Yadro fizikasi tarixi 1896-yilda[1] fransuz fizigi Henri Becquerelning uran tuzlaridagi fosforessensiyani tadqiq qilishi vaqtida radioaktivlikning kashf qilishi bilan boshlandi [2]. Bir yildan so‘ng, ya'ni 1897-yilda Joseph John Thomson tomonidan elektronning kashf etilishi — atomning ichki tuzilishga ega ekanligidan dalolat berdi [3]. XX-asr boshida atomning ilk qabul qilingan modeli — Thomsonning "olxo‘rili keks" modeli bo‘lib, u atom musbat zaryadlangan shar, uning ichida manfiy zaryadga ega elektronlar suzib yuradi, degan farazga asoslangan edi.

 
Henri Becquerel

Keyingi yillarda radioaktivlik, xususan, Sklodkowska nomi bilan mashhur polyak fizigi Marie Curie, uning turmush o‘rtog‘i Pierre Curie shuningdek, ingliz fizigi Ernest Rutherford tomonidan juda keng miqyosda o‘rganilib, ko‘plab tajribalar o‘tkazildi. Asrning birinchi yarmiga kelib, uch xil turdagi radioaktiv nurlanishlar ma'lum bo‘ldi:  -yemirilish,  -yemirilish va  -nurlanish. 1911-yilda nemis fizigi Otto Han va 1914-yilda ingliz fizigi James Chadwick o‘tkazilgan tajribalar  -yemirilish spektri diskret emas, balki uzluksiz ekanligini aniqladi. Ya'ni  -yemirilishda   va  -parchalanishlarda kuzatilgan diskret energiya miqdori emas, balki doimiy energiya diapazoni kuzatildi. Bu o‘sha paytda yadro fizikasi uchun muammo edi, chunki bu parchalanishlarda energiya saqlanmaganligini ko‘rsatar edi.

1903-yilgi fizika bo‘yicha Nobel mukofoti birgalikda Becquerelga kashfiyoti uchun va Marie va Pierre Curielarga radioaktivlik bo‘yicha keyingi tadqiqotlari uchun berildi. Rutherford 1908-yilda "elementlarning parchalanishi va radioaktiv moddalar kimyosi bo‘yicha tadqiqotlari" uchun kimyo bo‘yicha Nobel mukofotiga sazovor bo‘ldi.

1905-yilda Albert Einstein massa-energiya ekvivalentligi g‘oyasini ishlab chiqdi. Becquerel va Marie Curie tomonidan radioaktivlik bo‘yicha ishlar bundan oldin bo‘lgan bo‘lsa-da, radioaktivlik energiyasining manbasini tushuntirish yadroning o‘zi yanada kichikroq tarkibiy qismlardan — nuklonlardan iborat ekanligi kashf etilishini kutib turaradi.

Rutherfordning yadroni kashf qilishi

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1906-yilda Ernest Rutherford "Radiydan  -zarraning moddadan o‘tishida kechikishi" asarini nashr qialdi.[4] Ernest Rutherfordning assistenti, professor Johannes Hans Geiger[5] va bakalavriat Marsden[6] bilan birgalikda tajriba o‘tkazishadi: oltin folga  -zarralar bilan bombardimon qilinadi.[7] 1911–1912 yillarda Rutherford London qirollik jamiyatida tajribalarni tushuntiradi va atom yadrosining yangi nazariyasini ilgari surdi.

1908-yilda maqola nashr etilgach[8], Rutherford tomonidan 1911-yilning may oyida chop etilgan yakuniy klassik tahlil bilan asosiy hal qiluvchi tajriba 1909-yilda Manchester universitetida o‘tkazildi [9] [10] [11] [12].

 
Rutherford tajribasi

Ernest Ruterford o‘z jamoasiga uni hayratda qoldiradigan narsani izlashni buyurdi: bir nechta zarralar katta burchaklar orqali, hatto ba'zi hollarda butunlay orqaga tarqaladi. U buni qog‘oz varog‘iga o‘q uzilishiga o‘xshatdi. 1911-yilda Ruterford tomonidan ma'lumotlarni tahlil qilish natijasida kashfiyot atomning Rutherford modeliga olib keldi, bunda atom o‘z massasining katta qismini o‘z ichiga olgan juda kichik, juda zich yadroga va og‘ir manfiy zaryadlangan zarralar elektronlardan iborat edi. Misol tariqasida, ushbu modelda   14 ta proton va 7 ta elektron (jami 21 ta zarracha) bo‘lgan yadrodan iborat edi.

Eddington va yadro sintezi

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Taxminan 1920-yilda Arthur Eddington o'zining "Yulduzlarning ichki konstitutsiyasi" nomli maqolasida yulduzlardagi yadroviy sintez jarayonlarining kashfiyoti va mexanizmi haqida faraz yuritadi.[13] [14] O‘sha paytda yulduz energiyasining manbai butunlay noma'lum edi; Eddington bu manba vodorodning geliyga aylanishi va Einsteinning   tenglamasiga ko‘ra juda katta energiya ajralib chiqishi haqida to‘g‘ri taxmin qildi. Bu, o‘sha paytda termoyadroviy energiya va hatto yulduzlar ham asosan vodoroddan tashkil topganligi haqidagi eng yaxshi gipotezalardan biri edi.

Yadro spinining tushuntirilishi

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Uglerod atomining tuzilishi

Rutherford modeli 1929-yilda Franko Rasetti tomonidan Kaliforniya Texnologiya Institutida yadro spinini o‘rganishga qadar juda yaxshi ishladi. 1925-yilga kelib protonlar va elektronlarning har birining spini   ga teng ekanligi ma'lum edi. Azot-14 ning Rezerford modelida jami 21 ta yadro zarralaridan 20 tasi bir-birining spinini kompensatsiya qilishi uchun juftlashgan bo‘lishi va oxirgi toq zarracha yadroni   spin bilan xarakterlashi kerak edi. Rasetti, ammo azot-14 ning spini   ga teng ekanligini aniqladi.

James Chadwickning neytronni kashf qilishi

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1932-yilda Chadwick Walther Bothe, Herbert Becker, Irène va Frédéric Joliot-Curielar tomonidan o‘tkazilgan nurlanish kuzatuvlari proton bilan bir xil massaga ega neytral zarracha tufayli ekanligini tushunib qoladi va u yangi zarrani neytron deb ataydi (Ruterfordning taklifiga binoan) [15]. O‘sha yilda Dmitriy Ivanenko yadroda elektronlar mavjud emas, yadro faqat proton va neytronlardan iborat bo‘lib, ularnign spini   ga tengligini tushuntiradi. Shuning bilan, neytron spini azot-14 spini muammosini darhol hal qildi, chunki bu modeldagi bitta juftlashmagan proton va bitta juftlashmagan neytron bir xil yo‘nalishda   spinni qo‘shilib, to‘la yadro spinni   ga teng bo‘ladi.

Zamonaviy yadro fizikasi

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Yadro fizikasi muammolari

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Manbalar

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  1. B. R. Martin (2006). Nuclear and Particle Physics. John Wiley & Sons, Ltd. ISBN 978-0-470-01999-3.
  2. Henri Becquerel (1896). "Sur les radiations émises par phosphorescence". Comptes Rendus. 122: 420–421.
  3. Tomson, Jozef Jon (1897). "Katod nurlari" . Buyuk Britaniya Qirollik instituti materiallari . XV : 419–432.
  4. Rutherford, Ernest (1906). "On the retardation of the α particle from radium in passing through matter". Philosophical Magazine. 12 (68): 134–146. doi:10.1080/14786440609463525.
  5. Geiger, Hans (1908). "On the scattering of α-particles by matter". Proceedings of the Royal Society A. 81 (546): 174–177. Bibcode:1908RSPSA..81..174G. doi:10.1098/rspa.1908.0067.
  6. Geiger, Hans; Marsden, Ernest (1909). "On the diffuse reflection of the α-particles". Proceedings of the Royal Society A. 82 (557): 495. Bibcode:1909RSPSA..82..495G. doi:10.1098/rspa.1909.0054.
  7. Geiger, Hans (1910). "The scattering of the α-particles by matter". Proceedings of the Royal Society A. 83 (565): 492–504. Bibcode:1910RSPSA..83..492G. doi:10.1098/rspa.1910.0038.
  8. H. Geiger and E. Marsden, PM, 25, 604 1913, citing, H. Geiger and E. Marsden, Roy. Soc. Proc. vol. LXXXII. p. 495 (1909), in, The Laws of Deflexion of α Particles Through Large Angles \\ H. Geiger and E. Marsden (1913), (published subsequently online by - physics.utah.edu (University of Utah)) Retrieved June 13, 2021 (p.1):"..In an earlier paper, however, we pointed out that α particles are sometimes turned through very large angles..."(p.2):"..Professor Rutherford has recently developed a theory to account for the scattering of α particles through these large angles, the assumption being that the deflexions are the result of an intimate encounter of an α particle with a single atom of the matter traversed. In this theory an atom is supposed to consist of a strong positive or negative central charge concentrated within a sphere of less than about 3 × 10−12 cm. radius, and surrounded by electricity of the opposite sigh distributed throughout the remainder of the atom of about 10−8 cm. radius..."
  9. Radvanyi, Pierre (January–February 2011). "Physics and Radioactivity after the Discovery of Polonium and Radium" (electronic). Chemistry International. online: International Union of Pure and Applied Chemistry. 33 (1). Retrieved 13 June 2021. ..Geiger and an English-New Zealand student, E. Marsden, to study their scattering through thin metallic foils. In 1909, the two physicists observe that some alpha-particles are scattered backwards by thin platinum or gold foils (Geiger 1909)...It takes Rutherford one and a half years to understand this result. In 1911, he concludes that the atom contains a very small 'nucleus'...
  10. Rutherford F.R.S., E. (May 1911). "The Scattering of α and β Particles by Matter and the Structure of the Atom". Philosophical Magazine. 6. 21 May 1911: 669–688. Retrieved 13 June 2021.
  11. Rutherford, E. (May 1911). "LXXIX. The scattering of α and β particles by matter and the structure of the atom". The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science. 21 (125): 669–688.
  12. "1911 John Ratcliffe and Ernest Rutherford (smoking) at the Cavendish Laboratory..." Fermilab. Retrieved 13 June 2021."..that would become a classic technique of particle physics..."
  13. Eddington, A. S. (1920). "The Internal Constitution of the Stars". The Scientific Monthly. 11 (4): 297–303. Bibcode:1920SciMo..11..297E. JSTOR 6491.
  14. Eddington, A. S. (1916). "On the radiative equilibrium of the stars". Monthly Notices of the Royal Astronomical Society. 77: 16–35. Bibcode:1916MNRAS..77...16E.
  15. Chadwick, James (1932). "The existence of a neutron". Proceedings of the Royal Society A. 136 (830): 692–708. Bibcode:1932RSPSA.136..692C.

Adabiyotlar

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Havolalar

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