Absence of a day-night asymmetry in the Be-7 solar neutrino rate in Borexino

作者：Bellini G; Benziger J; Bick D; Bonetti S; Bonfini G; Avanzini M Buizza; Caccianiga B; Cadonati L; Calaprice F; Carraro C; Cavalcante P; Chavarria A; D' Angelo D; Davini S; Derbin A; Etenko A; von Feilitzsch F; Fomenko K; Franco D; Galbiati C; Gazzana S; Ghiano C; Giammarchi M; Goeger Neff M; Goretti A; Grandi L; Guardincerri E; Hardy S; Ianni Aldo; Ianni Andrea; Kobychev V; Korablev D; Korga G; Koshio Y; Kryn D

来源：Physics Letters B, 2012, 707(1): 22-26.

DOI：10.1016/j.physletb.2011.11.025

• Solar neutrinos
• Day-night effect
• CPT violation
• Neutrino oscillations

We report the result of a search for a day-night asymmetry in the Be-7 solar neutrino interaction rate in the Borexino detector at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The measured asymmetry is A(dn) = 0.001 +/- 0.012 (stat) +/- 0.007 (syst), in agreement with the prediction of MSW-LMA solution for neutrino oscillations. This result disfavors MSW oscillations with mixing parameters in the LOW region at more than 8.5 sigma. This region is, for the first time, strongly disfavored without the use of reactor anti-neutrino data and therefore the assumption of CPT symmetry. The result can also be used to constrain some neutrino oscillation scenarios involving new physics.

• 出版日期2012-1-16