Nov, 2012
High precision Be-7 solar neutrinos measurement and day night effect obtained with Borexino
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
- Volume
- 692
- Number
- First page
- 258
- Last page
- 261
- Language
- English
- Publishing type
- Research paper (scientific journal)
- DOI
- 10.1016/j.nima.2012.01.006
- Publisher
- ELSEVIER SCIENCE BV
We report the direct measurement of the Be-7 solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso and the search for a day-night asymmetry of this interaction rate. The interaction rate of the 0.862 MeV Be-7 neutrinos is 46 +/- 1.6(stat)(-1.6)(+1.5)(syst) counts/(day . 100 ton). The hypothesis of no oscillation for this solar neutrinos is inconsistent with our measurement at the 5.8 sigma C.L Our result is the first direct measurement of solar neutrinos with an accuracy better than 5%. We report the survival probability for solar v(e) in the transition region between matter-enhanced and vacuum-driven oscillations. The measured day night asymmetry is A(dn) = 0.001 +/- 0.012 (stat) +/- 0.007 (syst), in agreement with the predicition of MSW-LMA neutrino [13] oscillations. This result discourages MSW oscillations with mixing parameters in the LOW region at more than 8.5 sigma, meaning that this region is, for the first time, strongly rejected without the assumption of CPT symmetry. The result can also be used to constrain some neutrino oscillation scenarios involving new physics. (C) 2012 Elsevier B.V. All rights reserved.
- Link information
- ID information
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- DOI : 10.1016/j.nima.2012.01.006
- ISSN : 0168-9002
- Web of Science ID : WOS:000309786000051