Measurement of the response of a Ga solar neutrino experiment to neutrinos from an ³⁷Ar source

Abstract

An intense source of 37 Ar was produced by the (n, α) reaction on 40 Ca by irradiating 330 kg of calcium oxide in the fast neutron breeder reactor at Zarechny, Russia. The 37 Ar was released from the solid target by dissolution in acid, collected from this solution, purified, sealed into a small source, and brought to the Baksan Neutrino Observatory where it was used to irradiate 13 tonnes of gallium metal in the Russian-American gallium solar neutrino experiment SAGE. Ten exposures of the gallium to the source, whose initial strength was 409 ± 2 kCi, were carried out during the period April to September 2004. The 71 Ge produced by the reaction 71 Ga(ν e , e − ) 71 Ge was extracted, purified, and counted. The measured production rate was 11.0 +1.0 −0.9 (stat) ± 0.6 (syst) atoms of 71 Ge/d, which is 0.79 +0.09 −0.10 of the theoretically calculated production rate. When all neutrino source experiments with gallium are considered together, there is an indication the theoretical cross section has been overestimated.

New limits on neutrino non-unitary mixings based on prescribed singular values

“…Some reported anomalies can be found in Refs. [14][15][16][17][18], though the reason may be different, connected with experimental setups or assumptions, as discussed for instance recently in [19].…”

Predictions for neutrinoless double-beta decay in the 3+1 sterile neutrino scenario

“…However, the standard 3ν mixing paradigm has been challenged by indications in favor of short-baseline oscillations generated by a new larger squared-mass difference ∆m 2 SBL ∼ 1 eV 2 : the reactor antineutrino anomaly [6], which is a deficit of the rate ofν e observed in several short-baseline reactor neutrino experiments in comparison with that expected from the latest calculation of the reactor neutrino fluxes [7,8]; the Gallium neutrino anomaly [9][10][11][12][13], consisting in a short-baseline disappearance of ν e measured in the Gallium radioactive source experiments GALLEX [14] and SAGE [15]; the signal of short-baselinē ν µ →ν e oscillations observed in the LSND experiment [16,17]. The simplest extension of 3ν mixing which can describe these short-baseline oscillations taking into account other constraints is the 3+1 mixing scheme [18,19], in which there is an additional massive neutrino at the eV scale and the masses of the three standard neutrinos are much smaller.…”

Sterile Neutrino Searches in MiniBooNE and MicroBooNE

“…Thus, these sources can be used for electron neutrino disappearance (ve -+ ve) searches. They produce neutrinos with energies of 0.811 and 0.813 MeV for 37 Ar and 0.747, 0.752, 0.427, and 0.432 MeV for 51 Cr [51]. The neutrinos produced by these sources are lower in energy than the neutrinos in LSND or reactor experiments.…”