The 71Ga(3He, t) reaction and the low-energy neutrino response

Abstract

A 71 Ga(3 He, t) 71 Ge charge-exchange experiment was performed to extract with high precision the Gamow-Teller (GT) transition strengths to the three lowest-lying states in 71 Ge, i.e., the ground state (1/2 −), the 175 keV (5/2 −) and the 500 keV (3/2 −) excited states. These are the relevant states, which are populated via a charged-current reaction induced by neutrinos from reactor-produced 51 Cr and 37 Ar sources. A precise measurement of the GT transition strengths is an important input into the calibration of the SAGE and GALLEX solar neutrino detectors and addresses a long-standing discrepancy between the measured and evaluated capture rates from the 51 Cr and 37 Ar neutrino calibration sources, which has recently spawned new ideas about unconventional neutrino properties.

Light sterile neutrinos

“…[155]) and, more precisely, in 2011 in the ( 3 He, 3 H) experiment of Frekers et al [159]. The results are listed in Tab.…”

“…Reference Method BGT 175 BGT 500 Krofcheck et al [157,158] 71 Ga(p, n) 71 Ge < 0.005 0.011 ± 0.002 Frekers et al [159] 71 Ga( 3 He, 3 H) 71 Ge 0.0034 ± 0.0026 0.0176 ± 0.0014 71 Ge at about 175 keV and 500 keV (see Fig. 3(a)).…”

Gamow-Teller strength in deformed nuclei within the self-consistent charge-exchange quasiparticle random-phase approximation with the Gogny force

“…Second, in astrophysics where they govern β decay, electron and neutrino capture processes, hence stellar evolution and nucleosynthesis [3,4]. Finally, in particle physics in connection with the evaluation of the V ud element and the unitarity of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix [5], on the one hand, and with neutrino physics beyond the standard model (neutrinoless double beta decay [6][7][8] and neutrino oscillation [9,10]), on the other hand.…”

Neutrino phenomenology in a3+1+1framework

“…The deficit based on four measurements of the average ν e scattering cross section from the process ν e + 71 Ga → 71 Ge + e − is, with correlated errors taken to be those in [17], R GA = 0.86 ± 0.06. Independent measurements of the strength of the relevant Gamow-Teller transitions [27] supports the conclusion that this deficit might be due to averaged oscillations of a heavy neutrino. Finally, measurements of the energy dependence of the scattering cross section in the process ν e + 12 C → 12 N g.s.…”