NA'URAR GANO NEUTRINO A ƘARƘASHIN ƘANƘARA NA IYA AUNA ZAFIN STRATOSPHERE

Stratosphere da ke saman Antarctica yana sauyawa a ma’aunin shekaru gommai, yayin da layin ozone ke farfaɗowa kuma zagayawar iska da ke kewaye da ƙarshen duniyar (pole) ke sauyawa. Amma tsakiyar nahiyar na ɗaya daga cikin wuraren da ke da mafi ƙarancin kayan aunawa a cikin sararin sama (atmosphere). Sake gina yanayi (weather reconstructions) — “reanalyses” da ke haɗa abubuwan da aka lura da su a warwatse da samfurin yanayi — suna cike giɓin, kuma ingancinsu bai wuce na abubuwan da aka lura da su da ke ciyar da su ba. Wani ma’auni mai zaman kansa zai yi amfani ƙwarai.

Wataƙila ɗaya ya riga ya wanzu, kwatsam. IceCube cibiyar kallon neutrino ce mai girman kilomita mai siffar kubi (cubic kilometre) ɗaya, mai na’urorin jin haske (light sensors) fiye da 5,000 da aka binne tsakanin zurfin mita 1,450 da 2,450 a cikin ƙanƙarar South Pole. Ban da neutrinos ɗinta da ba kasafai ake samu ba, tana rubuta wata kwarara ta muons mafi girma nesa ba kusa ba — ƙwayoyin (particles) da ke samuwa idan hasken sararin samaniya (cosmic rays) ya bugi saman sararin sama — a kusan 2,150 a kowace daƙiƙa. Ga masu farautar neutrino, su hayaniyar baya (background noise) ne. Amma adadinsu ya dogara da zafin iskar da ke sama.

Dalilin da ya sa muons ke jin zafi

Hasken sararin samaniya da ke bugun sararin sama suna samar da ƙwayoyi masu gajeren rai da ake kira pions da kaons. Kowanne ko dai ya ruɓe (decays) zuwa muon ko ya fara karo da ƙwayar iska (air molecule). Idan stratosphere ya yi zafi, yana yin siriri a wani tsayi, don haka ƙarin daga cikinsu suna ruɓewa zuwa muons kafin su yi karo. Saboda haka adadin IceCube yana bin yanayin shekara (seasons): kusan 8% a kewayen matsakaicinsa, kuma sauyin 1% a “zafi mai tasiri” (effective temperature) — matsakaici mai nauyi (weighted average) na ginshiƙin iska — yana sauya adadin muons da kusan 0.75%.

Yadda aka rarraba nauyin (weighting) yana da muhimmanci. Kusan 94% nasa yana fitowa daga iskar da ke sama da kusan kilomita 8, yana kai ƙololuwa kusa da kilomita 14: muons na IceCube galibi suna ba da labarin stratosphere, a matsayin matsakaici guda na ginshiƙin.

Gwajin yiwuwa

Tanvi Krishnan da Carlos Argüelles, a Harvard University, da Gabriela Barenboim, a University of Valencia, sun tambayi ko sigina ɗaya za ta iya bin yanayin sauyi (trends) masu tafiyar hawainiya, na shekaru gommai. Ba su yi amfani da ainihin adadin IceCube ba: sun gina ƙidayar muons ta kwaikwayo daga sake gina zafi na jama’a a South Pole, daga bayanan hasken sararin samaniya da na Rana, da kuma daga hankalin (sensitivity) IceCube da adadinta da aka wallafa.

Lissafinsu yana sake samar da jujjuyawar yanayin shekara (seasonal swing) da IceCube ta auna. Yanayin sauyi na dogon lokaci yana da siffa dabam a tsaye — stratosphere yana yin sanyi yayin da ƙananan iska ke yin zafi — kuma martanin (response) da ake samu gare shi ya fito kusan 3% mafi ƙarfi fiye da na yanayin shekara, ƙaramin gyara. Rana da ƙyar take tsoma baki: hasken sararin samaniya da ke bayan muons na IceCube suna da ƙarfi ƙwarai, a tiriliyoyin electronvolts, har aikin Rana (solar activity) yana sauya kwararar su da 0.01 zuwa 0.13% kawai.

(a) Zafi mai tasiri a saman South Pole tun 1979, yana yin sanyi da kelvin 0.58 a kowane shekaru goma a matsakaici. (b) Yanayin sauyin da aka daidaita ya dogara da tsawon tagar lokacin kuma zai iya har ma ya sauya alama (sign), don haka dole kowane ma’auni ya faɗi tagarsa. — Hoto na 3, Krishnan, Barenboim & Argüelles (2026), arXiv:2611.00918.

Tsayawa daram shi ne komai

Hayaniyar ƙirgawa (counting noise) ƙanƙanta ce ƙwarai. Ainihin iyakar ita ce tsayawar na’urar daram (stability). Idan ƙidayar muons ta karkata a hankali saboda kowane dalili na kayan aiki, za a karanta wannan karkacewa a matsayin sauyin zafi:

karkacewar 1% a kowane shekaru goma a cikin adadin tana kwaikwayon yanayin sauyi na kelvin 2.8 a kowane shekaru goma.

Tun 2011, sake gine-ginen suna nuna stratosphere yana yin sanyi da kusan kelvin 0.9 a kowane shekaru goma. Don guje wa nuna yanayin sauyi na ƙarya mai girman haka, dole ne adadin na’urar ya tsaya daram zuwa kusan 0.3% a kowane shekaru goma. Ba kamar hayaniya ta bazuwar (random noise) ba, irin wannan karkacewa ba ta ɓacewa ta hanyar matsakaici idan aka ƙara shekarun bayanai.

Mayar da karkacewar adadin muons da ba a yi la’akari da ita ba zuwa yanayin sauyin zafi na ƙarya: siginar da ake tsammani (layin yanke-yanke) tana daidai da karkacewar kusan 0.3% a kowane shekaru goma. Ratsin shuɗi shi ne karkacewar da aka yi hasashe daga dusar ƙanƙara da ke taruwa a saman na’urar. — Hoto na 4, Krishnan, Barenboim & Argüelles (2026), arXiv:2611.00918.

Har yanayin da ke saman ƙasa yana taka rawa. Dusar ƙanƙara tana taruwa a South Pole a kusan santimita 8 na kwatankwacin ruwa (water equivalent) a shekara, tana ƙara zurfin ƙanƙarar da ke saman IceCube a hankali. Garkuwa mai kauri tana tare ƙarin muons: marubutan suna hasashen raguwar 0.09 zuwa 0.18% a kowane shekaru goma, daidai da kelvin 0.24 zuwa 0.51 a kowane shekaru goma na sanyi na ƙarya — alama ɗaya da ainihin yanayin sauyin, kwata zuwa rabin girmansa. Saboda ana iya hasashensa, ana iya saka shi cikin nazarin.

Tsawon lokacin jira

Stratosphere na yankin ƙarshen duniya (polar) yana da hayaniya: zafin wata-wata yana tsalle sama da ƙasa da kelvin 2.5. Da bayanan shekaru 14, hankalin ƙididdiga (statistical sensitivity) kelvin 1.6 ne a kowane shekaru goma, bai isa ya tabbatar da sanyin kelvin 0.9 ba. Yana kai 0.93 bayan shekaru 20, 0.51 bayan 30 da 0.33 bayan 40. Ana iya tabbatar da sanyin zamanin IceCube bayan kusan shekaru 22 — idan na’urar ta tsaya daram.

Mataki na gaba shi ne a gudanar da hanyar a kan ainihin adadin IceCube, tare da nata baƙin halaye na kayan aiki (instrumental quirks). Marubutan sun lura cewa za ta yi aiki ga kowace na’urar gano mai zurfi da aka san murfin dutse ko ƙanƙararta.