Detection of nuclear recoils in prototype dark matter detectors, made from Al, Sn and Zn Superheated Superconducting Granules

TL;DR

This study investigates the response of superheated superconducting granule detectors made of Al, Sn, and Zn to nuclear recoils induced by neutron irradiation, demonstrating sensitivity down to approximately 1 keV for dark matter and neutrino detection.

Contribution

The paper presents experimental results on the sensitivity of SSG detectors to low-energy nuclear recoils, including comparison with Monte Carlo simulations, for the first time in this context.

Findings

SSG detectors are sensitive to recoil energies down to ~1 keV.

Coincidences between SSG signals and neutron hodoscope confirmed detector response.

Results align with Monte Carlo simulations, validating the detection approach.

Abstract

This work is part of an ongoing project to develop a Superheated Superconducting Granule (SSG) detector for cold dark matter and neutrinos. The response of SSG devices to nuclear recoils has been explored irradiating SSG detectors with a 70MeV neutron beam. The aim of the experiment was to test the sensitivity of Sn, Al and Zn SSG detectors to nuclear recoil energies down to a few keV. The detector consisted of a hollow teflon cylinder (0.1cm$^3$ inner volume) filled with tiny superconducting metastable granules embedded in a dielectric medium. The nuclear recoil energies deposited in the SSG were determined measuring the neutron scattering angles with a neutron hodoscope. Coincidences in time between the SSG and the hodoscope signals have been clearly established. In this paper the results of the neutron irradiation experiments at different SSG intrinsic thresholds are discussed and compared to Monte Carlo simulations. The results show that SSG are sensitive to recoil energies down to $\sim$1keV. The limited angular resolution of the neutron hodoscope prevented us from measuring the SSG sensitivity to even lower recoil energies.