Prospects for precision CE$ν$NS measurements with electron-capture neutrinos and lithium-based bolometers

Abstract

We evaluate the feasibility of high-precision coherent elastic neutrino-nucleus scattering measurements exploiting mono-energetic neutrinos produced by electron-capture (EC) decays of intense radioactive sources, such as $^{51}$Cr or $^{37}$Ar. To fully exploit the high neutrino flux achievable with EC sources, and accounting for the low energy of EC neutrinos, we evaluate the sensitivity of a compact array of bolometric detectors with absorbers based on light elements, such as lithium, oxygen and fluorine. With 1 kg of LiF detectors, source activities of $\sim10^{17}$ Bq, and assuming an energy threshold of 20 eV, we expect to achieve a $\sim 3\%$ precision on the determination of the neutrino flux with 90 days of measurement. Such a measurement would represent a test of the gallium neutrino anomaly, and could disentangle nuclear effects on gallium from the misevaluation of the EC source activity or short-baseline neutrino oscillations.

Figures (3)

• Figure 1: Expected event rate for different lithium-based crystals for a 1 kg detector and 90 days exposure using a $^{51}$Cr (upper panel) and $^{37}$Ar (lower panel) source.
• Figure 2: Attainable precision on the neutrino flux as a function of the detector mass for different crystals, assuming 90 days of exposure and with energy thresholds of 20 eV (solid lines) or 100 eV (dashed lines). The upper (lower) panel shows the precision achievable with the $^{51}$Cr ($^{37}$Ar) source.
• Figure 3: Exclusion sensitivity contours at 2$\sigma$ for light sterile neutrino oscillations assuming 90 days of measurement using a 1 kg detector with 20 eV threshold (blue) or a 5 kg detector with 200 eV threshold (red). The solid and dashed lines correspond to the use of a $^{51}$Cr or $^{37}$Ar source, respectively. The green line corresponds to the parameter space allowed to explain the gallium neutrino anomaly with neutrino oscillations.