arXiv subjects

G. R. C Rischbieter

Publications and source records attributed to G. R. C Rischbieter.

3 recordsLinked to original sources

arXiv2026

Design Studies Of A Pulsed Quasimonoenergetic 2-keV Neutron Source For Calibration Of Low Threshold Dark Matter Detectors

We describe design studies for a pulsed quasi-monoenergetic 2-keV neutron source for calibration of sub-keV nuclear recoils. Such a calibration is required for detectors sensitive to sub- GeV dark matter and also the coherent elastic scattering of reactor neutrinos. In our design, neutrons from a commercial deuterium-tritium generator are moderated to the keV scale and subsequently filtered to achieve a monoenergetic spectrum utilizing the antiresonance feature, characterized by a drop in neutron transmission spectra at 2-keV for scandium. The analyses and conclusions presented are primarily based on simulations, as this study represents a critical first step toward the final goal. We address challenges such as unmoderated high-energy neutrons and gamma backgrounds from neutron capture in the moderator materials. Through optimization of the moderator+filter and shielding geometry, we identify a configuration that achieves the target neutron flux at 2 keV while maintaining subdominant rates of background interactions in simulation. Lastly, we outline a future pathway to lower-energy (few eV scale) calibrations using time-of-flight and sub-keV neutrons

physics.ins-det↗

arXiv2025

First Limits on Light Dark Matter Interactions in a Low Threshold Two Channel Athermal Phonon Detector from the TESSERACT Collaboration

We present results of a search for spin-independent dark matter-nucleon interactions in a 1 cm$^2$ by 1 mm thick (0.233 gram) high-resolution silicon athermal phonon detector operated above ground. For interactions in the substrate, this detector achieves a r.m.s. baseline energy resolution of 361.5 $\pm$ 0.4 MeV/$c^2$, the best for any athermal phonon detector to date. With an exposure of 0.233g $\times$ 12 hours, we place the most stringent constraints on dark matter masses between 44 and 87 MeV/$c^2$, with the lowest unexplored cross section of 4 $\times 10^{-32}$ cm$^2$ at 87 MeV/$c^2$. We employ a conservative salting technique to reach the lowest dark matter mass ever probed via direct detection experiment. This constraint is enabled by two-channel rejection of low-energy backgrounds that are coupled to individual sensors.

hep-ex↗

arXiv2024

First Demonstration of the HeRALD Superfluid Helium Detector Concept

The SPICE/HeRALD collaboration is performing R&D to enable studies of sub-GeV dark matter models using a variety of target materials. Here we report our recent progress on instrumenting a superfluid $^4$He target mass with a transition-edge sensor based calorimeter to detect both atomic signals (scintillation) and $^4$He quasiparticle (phonon and roton) excitations. The sensitivity of HeRALD to the critical "quantum evaporation" signal from $^4$He quasiparticles requires us to block the superfluid film flow to the calorimeter. We have developed a heat-free film-blocking method employing an unoxidized Cs film, which we implemented in a prototype "HeRALD v0.1" detector of ~10 g target mass. This article reports initial studies of the atomic and quasiparticle signal channels. A key result of this work is the measurement of the quantum evaporation channel's gain of 0.15 $\pm$ 0.01, which will enable $^4$He-based dark matter experiments in the near term. With this gain the HeRALD detector reported here has an energy threshold of 145 eV at 5 sigma, which would be sensitive to dark matter masses down to 220 MeV/c$^2$.

physics.ins-det↗