Nuclear-tech-stub sahifasining manbasini koʻrish

{{Short description|Lazer bilan sovutilgan atomlarning uchishi}}
'''Atom favvorasi''' — neytral atomlar tutqichi bo‘lib, unda [[hyperfine transition|gipernozik o‘tish]]ni o‘lchash uchun [[laser-cooled|lazer bilan sovutilgan]] atomlar buluti vertikal ravishda yuqoriga yo‘naltiriladi va gravitatsiya ta’sirida o‘zaro ta’sir hududidan pastga tushishiga imkon beriladi. Atomlar buluti [[optical molasses|optik molassa]] konfiguratsiyasida qarama-qarshi yo‘nalgan lazerlar yordamida sovutiladi va yuqoriga itariladi.
Atomlar o‘zaro ta’sir hududidan o‘tayotganda atom o‘tishi kogerent mikroto‘lqinlar yordamida aniq o‘lchanadi. O‘lchangan o‘tish [[atomic clock|atom soati]] o‘lchovida yuqori aniqlik bilan ishlatilishi mumkin<ref name="nist-f1">[[https://www.nist.gov/public_affairs/releases/n99-22.cfm](https://www.nist.gov/public_affairs/releases/n99-22.cfm) How the NIST-F1 Caesium Fountain Clock Works]</ref>.

Atom favvorasida gipernozik o‘tishni o‘lchashda [[Ramsey interferometry#The Ramsey method|Ramsey usuli]]dan foydalaniladi.<ref name="foot">{{Cite book |last=C. J. Foot |url=[https://archive.org/details/atomicphysics0000foot/page/132|title=Atomic](https://archive.org/details/atomicphysics0000foot/page/132|title=Atomic) Physics |year=2005 |page=212}}</ref> Umuman olganda, Ramsey usuli atomlar bulutini o‘zaro ta’sir hududida ikki marta qisqa [[radiofrequency|radiochastotali]] (rf) elektromagnit maydonga ta’sir ettirishni o‘z ichiga oladi. Atomlar o‘zaro ta’sir hududidan vertikal ravishda yuqoriga itarilgach, ular erkin tushish vaqti ''T'' davomida yana pastga tushadi, bu vaqt bir necha soniya bo‘lishi mumkin. Atomlar buluti pastga tushib, o‘zaro ta’sir hududidan yana o‘tadi va ikkinchi rf impulsiga ta’sir ettiriladi. Rezonans chastotasini aniqlash uchun mikroto‘lqin chastotasi ko‘plab takroriy o‘lchovlar davomida atom o‘tishi bo‘ylab o‘zgartiriladi<ref>{{YouTube| z-jE7DXy1x0 | "NIST Launches a New U.S. Time Standard: NIST-F2 Atomic Clock" }}</ref>. Bulutdagi boshlang‘ich holatdan yakuniy holatga o‘tkazilgan atomlarning ulushi aniqlash sxemasi yordamida aniqlanadi<ref name="foot" />.

[[File:F1clock.jpg|thumb|NIST-F1 seziy atom favvorasi soati]]

[[laser cooling|Sovutilgan]] atomlar buluti bilan atom favvorasidan foydalanish taxminan bir soniyalik kutish vaqtlariga imkon beradi, bu esa o‘nlab mikrosekundlar tartibida o‘zaro ta’sir vaqtiga ega bo‘lishi mumkin bo‘lgan issiq [[atomic beam|atomlar dastasi]]ga nisbatan ancha yuqori chastota aniqligini ta’minlaydi<ref name="foot" /> Bu [[NIST-F1]], seziy favvora soati,<ref>{{cite journal |last1=Jefferts |first1=SR |last2=Heavner |first2=TP |last3=Parker |first3=TE |last4=Shirley |first4=JH |editor-first1=R. Jason |editor-last1=Jones |title=NIST cesium fountains: current status and future prospects |journal=Time and Frequency Metrology |date=2007 |volume=6673 |doi=10.1117/12.734965 |bibcode=2007SPIE.6673E..09J |url=[https://doi.org/10.1117/12.734965|url-access=subscription](https://doi.org/10.1117/12.734965|url-access=subscription) }}</ref> kasrli beqarorligi <math>2 \times 10^{-16} </math> bo‘lgani sababli, yiliga bir nanosekunddan kam vaqt yo‘qotishining sabablaridan biridir. [[NIST-7]] seziy dastasi soati esa <math>1 \times 10^{-14}</math> kasrli beqarorlik bilan yiliga 30 nanosekund yo‘qotadi.<ref>{{cite journal |last1=Lee |first1=W D |last2=Shirley |first2=J H |last3=Lowe |first3=J P |title=The accuracy evaluation of NIST-7 |journal=IEEE Transactions on Instrumentation and Measurement |date=1995 |volume=44 |issue=2 |pages=120–123 |doi=10.1109/19.377788 |bibcode=1995ITIM...44..120L | url=[https://doi.org/10.1109/19.377788|url-access=subscription](https://doi.org/10.1109/19.377788|url-access=subscription) }}</ref>

==Tarixi==

Atom favvorasi g‘oyasi ilk bor 1950-yillarda [[Jerrold Zacharias]] tomonidan ilgari surilgan.<ref name="Kasevich">{{cite journal|author=M. A. Kasevich|title=Atomic fountains and clocks|journal=Optics News|volume=15|issue=12|year=1989|pages=31–32|doi=10.1364/ON.15.12.000031 |display-authors=etal}}</ref><ref>{{cite journal |last1=Forman |first1=P |title=Atomichron®: The atomic clock from concept to commercial product |journal=Proceedings of the IEEE |date=1985 |volume=73 |issue=7 |pages=1181–1204 |doi=10.1109/PROC.1985.13266 |bibcode=1985IEEEP..73.1181F }}</ref> Zacharias atomlarning [[Maxwell–Boltzmann distribution|Maksvell–Boltsman taqsimoti]]dagi past tezlikli qismida joylashgan atomlar yetarlicha past energiyaga ega bo‘lib, maqbul kattalikdagi parabolik trayektoriyani amalga oshiradi, degan taxmin asosida issiqlik atomlar dastasidan foydalanib atom favvorasini yaratishga urindi.<ref name="chu">{{cite journal|author=S. Chu|title=The manipulation of neutral particles|url=[https://www.nobelprize.org/nobel_prizes/physics/laureates/1997/chu-lecture.pdf|journal=Rev](https://www.nobelprize.org/nobel_prizes/physics/laureates/1997/chu-lecture.pdf|journal=Rev). Mod. Phys.|volume=70|pages=685–706|year=1998|issue=3 |bibcode = 1998RvMP...70..685C |doi = 10.1103/RevModPhys.70.685 |doi-access=free}}</ref> Biroq, bu urinish muvaffaqiyatsiz tugadi, chunki issiqlik dastasidagi tez atomlar past tezlikli atomlarga urilib, ularni sochib yubordi.<ref name="chu" />

==Manbalar==
{{reflist}}

[[Category:Atoms]]
[[Category:Atomic physics]]
[[Category:Atomic clocks]]
[[Category:Nuclear technology]]

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