Applications of an Y-88/Be photo-neutron calibration source to Dark Matter and Neutrino Experiments

TL;DR

This paper demonstrates how an Y-88/Be photo-neutron source can calibrate low-energy nuclear recoils for dark matter and neutrino experiments, revealing smaller quenching factors than previously assumed, impacting experimental interpretations.

Contribution

It introduces a calibration method using Y-88/Be neutron source for low-energy nuclear recoils, providing more accurate quenching factors for dark matter and neutrino detectors.

Findings

Measured <10% quenching factor for sodium recoils below 24 keVnr.

Revealed smaller quenching factors than the commonly assumed 30%.

Implications for interpreting dark matter experiment results.

Abstract

The low-energy monochromatic neutron emission from an Y-88/Be source can be exploited to mimic the few keVnr nuclear recoils expected from low-mass Weakly Interacting Massive Particles (WIMPs) and coherent scattering of neutrinos off nuclei. Using this source, a ~<10% quenching factor is measured for sodium recoils below 24 keVnr in NaI[Tl]. This is considerably smaller than the 30% typically adopted in the interpretation of the DAMA/LIBRA dark matter experiment, resulting in a marked increase of its tension with other searches, under the standard set of phenomenological assumptions. The method is illustrated for other target materials (superheated and noble liquids).