BAƘON AL'AMARIN GALLIUM, AN DUBA SHI DA RANA

Gallium-71 zai iya haɗiye neutrino na electron ya zama germanium-71, yana fitar da electron. Tara ’yan zarrorin germanium da aka samar a cikin gallium, ƙirga su, kuma ka auna kwararar neutrino. Ta haka ne na’urorin gano SAGE da Gallex/GNO suka kalli Rana.

Don duba waɗannan na’urori, masana kimiyyar lissafi kuma sun fallasa su ga tushe-tushen neutrino na wucin gadi — samfurori masu ƙarfin radiation sosai na chromium-51 da argon-37. Ƙirgar germanium ta fito ƙasa. Gwaje-gwajen farko sun nuna alamar hakan ba tare da warware tambayar ba. Sannan gwajin BEST, tare da tushen chromium-51 na megacurie 3.5 a cikin yankuna biyu da ke cikin juna na ƙarfen gallium mai ruwa, ya tabbatar da shi.

Kashi ashirin sun ɓace

An tsara BEST a matsayin gwajin juyawa (oscillation) na gajeren nisa, don gwada ko sterile neutrinos da suka gauraye da neutrino na electron na yau da kullum za su iya bayyana ƙarancin. Ƙimomin kamawa ba su nuna dogaro da nisa ba. Tare, ma’aunai shida na tushe — 0.97, 0.81, 0.97, 0.83, 0.81 da 0.78 na ƙimar da ake tsammani — sun tabbatar da ƙarancin ƙimar a sama da sigma 4, don rabon haɗaka na 0.817. Wannan shi ne baƙon al’amarin gallium.

Ƙimar da ake tsammani ta dogara ne kan cross-section, yiwuwar cewa gallium zai kama neutrino. Ana samun ta daga martanin da ya saɓa, ruɓewar radiation ta germanium-71 ta hanyar kama electron, wanda rabin rayuwarsa (kwanaki 11.465) da makamashinsa an san su daidai. Mataki ɗaya na wannan samarwa yana ɗaukar electron da cibiyar zarra (nucleus) daban-daban — “factorization”. A 2026, Cadeddu da abokan aikinsa sun yi jayayya a cikin Physical Review Letters cewa wannan mataki zai iya gazawa ya sa ainihin cross-section ya ragu da kashi 20%. Steven Elliott, na Dakin Gwaje-gwaje na Ƙasa na Los Alamos, da Hamish Robertson, na Jami’ar Washington, suna da shakka: factorization yana sake samar da ma’aunai a cikin nuclei da yawa zuwa kusan kashi 1%, tare da keɓancewa ɗaya da aka sani, sodium-22, a kusan kashi 10%. “Rushewar factorization a matakin kashi 20% saboda haka zai zama abin mamaki sosai.”

Tushen da babu wanda ya gina

Don haka sun yi amfani da tushen neutrino wanda aka daidaita shi ba tare da dogaro da gallium ba: Rana. Yanzu ana auna fitar neutrino ɗinta a Duniya ta hanyar martanai na asali na Standard Model — neutrino suna buga electron suna billa a cikin na’urar Borexino, kuma suna fasa cibiyoyin deuterium a cikin SNO. Babu ɗaya daga cikin waɗannan da ya dogara da cross-section na gallium.

Marubutan sun haɗa tushe-tushe biyar na Rana: babban sarkar proton-proton (pp), tare da pep, beryllium-7, zagayen CNO da boron-8. Borexino yana samar da kwararar beryllium-7, pep da CNO, SNO kuma kwararar boron-8. Kwararar pp tana fitowa daga hasken Rana: kowace cibiyar helium da aka yi tana sakin neutrino biyu da MeV 26.731, kuma kusan kashi 2% na wannan makamashi yana fita a matsayin neutrino. A kan hanya, neutrino suna canza ɗanɗano (flavour); yiwuwar cewa ɗaya zai iso har yanzu a matsayin neutrino na electron ana lissafa ta da ma’aunan gauraya daga Daya Bay da JUNO, da kuma siffar yawa ta samfurin Rana — dogaro ɗaya tilo da ya rage ga samfuran Rana. Cross-section na gallium sun fito ne daga sabon kimantawa na Haxton da Rule.

Sittin da bakwai cikin sittin da bakwai

Hasashen ga na’urar gano gallium, a cikin ma’aunin neutrino na Rana (kamawa a kowace zarrori 10³⁶ da ake nufa a kowane daƙiƙa):

neutrino na pp: 40.00
beryllium-7: 18.75
boron-8: 4.17
CNO: 3.00
pep: 1.55
jimilla: 67.5 (+1.4 / −1.1)

SAGE da Gallex/GNO, a haɗe, sun auna 66.1 ± 3.1. Rabon shi ne 0.980 (+0.050 / −0.049).

Ɗigo bakwai tare da sandunan kuskure: gwaje-gwajen tushe shida kusa da 0.8 a cikin ɗamara shuɗi, da ɗigon Rana ja kusa da 1.

Ƙimomin kamawa da aka auna idan aka raba da waɗanda ake tsammani: gwaje-gwajen tushe shida (baƙi) da gwajin Rana na wannan aiki (ja). Ɗamarar shuɗi ita ce sakamakon haɗakar tushe-tushe. — Hoto na 3, Elliott da Robertson (2026), arXiv:2610.22219.

Fiye da kashi 90% na wannan ƙimar da aka yi hasashe ya dogara ne kan cross-section da aka ɗauko daga ruɓewar germanium da “daidaiton dalla-dalla” (detailed balance) tsakanin martani da wanda ya saɓa masa — daidai sashen da Cadeddu da abokan aikinsa suka tambaya. Idan Rana ce tushen, babu baƙon al’amari.

A wani wuri daban

An wanke waɗanda ake zargi biyu a lokaci guda. Cross-section na gallium ba ya nuna alamar kuskure, har da factorization. Kuma ingancin fitar da ƙirga zarrorin germanium a cikin SAGE, Gallex da gudanarwar Rana ta BEST sun tabbata; tunda hanyoyin gwaje-gwajen tushe suna kama da juna, wataƙila waɗannan ma suna daidai.

Baƙon al’amarin kansa yana nan daram. Takardar ba ta ba da wani bayani na maye gurbi ba kuma ta ƙare da layi ɗaya: “Tushen baƙon al’amarin gallium a fili yana wani wuri daban.” Wani abu don fahimtar mahallin: duka marubutan biyu kuma suna sa hannu a takardun BEST waɗanda suka tabbatar da baƙon al’amarin tun farko.