Kate Hildebrandt | Searcharxiv

arXiv2024

Detecting Boosted Dark Photons with Gaseous Detectors

We search for indirect signals of $\mathscr{O}$(keV) dark matter annihilating or decaying into $\mathscr{O}$(eV) dark photons. These dark photons will be highly boosted and have decay lengths larger than the Milky Way, and can be absorbed by neutrino or dark matter experiments at a rate dependent on the photon-dark photon kinetic mixing parameter and the optical properties of the experiment. We show that current experiments can not probe new parameter space, but future large-scale gaseous detectors with low backgrounds (i.e. CYGNUS, NEXT, PANDAX-III) may be sensitive to this signal when the annihilation cross section is especially large.

hep-ph↗

arXiv2022

Geant4 Modeling of a Cerium Bromide Scintillator Detector for the IMPRESS CubeSat Mission

Solar flares are some of the most energetic events in the solar system and can be studied to investigate the physics of plasmas and stellar processes. One interesting aspect of solar flares is the presence of accelerated (nonthermal) particles, whose signatures appear in solar flare hard X-ray emissions. Debate has been ongoing since the early days of the space age as to how these particles are accelerated, and one way to probe relevant acceleration mechanisms is by investigating short-timescale (tens of milliseconds) variations in solar flare hard X-ray flux. The Impulsive Phase Rapid Energetic Solar Spectrometer (IMPRESS) CubeSat mission aims to measure these fast hard X-ray variations. In order to produce the best possible science data from this mission, we characterize the IMPRESS scintillator detectors using Geant4 Monte Carlo models. We show that the Geant4 Monte Carlo detector model is consistent with an analytical model. We find that Geant4 simulations of X-ray and optical interactions explain observed features in experimental data, but do not completely account for our measured energy resolution. We further show that nonuniform light collection leads to double-peak behavior at the 662 keV $^{137}$Cs photopeak and can be corrected in Geant4 models and likely in the lab.

astro-ph.SR↗