Abstract
Low-energy electronic recoil caused by solar neutrinos in multi-ton xenon detectors is an important subject not only because it is a source of the irreducible background for direct searches of weakly-interacting massive particles (WIMPs), but also because it provides a viable way to measure the solar pp and 7Be neutrinos at the precision level of current standard solar model predictions. In this work we perform ab initio many-body calculations for the structure, photoionization, and neutrino-ionization of xenon. It is found that the atomic binding effect yields a sizable suppression to the neutrino-electron scattering cross section at low recoil energies. Compared with the previous calculation based on the free electron picture, our calculated event rate of electronic recoil in the same detector configuration is reduced by about 23%. We present in this paper the electronic recoil rate spectrum in the energy window of 100 eV to 30 keV with the standard per ton per year normalization for xenon detectors, and discuss its implication for low energy solar neutrino detection as the signal and WIMP search as a source of background.
Highlights
Direct searches of weakly-interacting massive particles (WIMPs), one of the favored dark matter (DM) candidates, have been actively pursued in experimental nuclear and particle physics
Low-energy electronic recoil caused by solar neutrinos in multi-ton xenon detectors is an important subject because it is a source of the irreducible background for direct searches of weakly-interacting massive particles (WIMPs), and because it provides a viable way to measure the solar pp and 7Be neutrinos at the precision level of current standard solar model predictions
The importance of low-energy electronic recoil induced by solar neutrinos in multi-ton xenon detector is two-fold: On one hand, it is a background that should be properly removed in searches of WIMP-nucleus scattering
Summary
Direct searches of weakly-interacting massive particles (WIMPs), one of the favored dark matter (DM) candidates, have been actively pursued in experimental nuclear and particle physics. Nuclear recoil due to coherent neutrino-nucleus scattering could fake the signal This kind of background is hard to shield and forms an irreducible background called “neutrino floor” which limits the ultimate sensitivity the experiments can achieve [6]. The large flux from pp (end-point energy at 420 keV) and 7Be (two discrete energies at 862 and 384 keV) solar neutrinos makes electronic recoils the limiting background to measure the cross section on a nucleon lower than 4 × 10−49 cm for WIMP mass of 40 GeV/c2. [7] is that this very phenomenon of neutrino electron scattering that limits the WIMP detection can be turned into an opportunity to measure low energy solar neutrino flux to high precision.
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