The Hybrid detector: A phonon-mediated iZip style detector for low mass Dark Matter search

There are numerous evidences that support the existence of dark matter but there is no terrestial experiment which has yet been able to detect it. The nature of dark matter is still unknown and multiple candidates are proposed which can be a dark matter particle and can account for the cosmological evidences found till date. There are multiple earth-based detection experiments like SuperCDMS, LUX etc. which look at the direct interaction of the dark matter particles with some standard model particle. Two big challenges faced by these type of experiments are the low energy threshold of the detectors to reach an energy range where they might be able to detect the dark matter signal and the ability to discriminate signal-like events from the plethora of background events in the detectors due to a variety of other sources. SuperCDMS interleaved Z-sensitive Ionization and Phonon(iZIP) detectors have shown great success in discriminating electron recoils (the major background) and nuclear recoils (the signal-like events), while the High Voltage (HV) detectors have reached very low (a few eV) energy thresholds by sacrificing that discrimination. This thesis focuses on a novel phonon-mediated two-stage silicon detector that retains both an excellent threshold performance of the HV detector and maintain the iZIP-style background discrimination. Over multiple runs in the Nader's Test Facility and the MINER experiment at NSC, the detector characterization and testing was done with the first prototype Si detector which gave an encouraging result of clear discrimination between signal and background events. This new detector technology has the potential to significantly enhance the sensitivity to dark matter and coherent neutrino scattering experiments beyond the capabilities of current technologies that have limited discrimination at low energies

A Search for Low-mass Dark Matter via Bremsstrahlung Radiation and the Migdal Effect in SuperCDMS

In this paper, we present a re-analysis of SuperCDMS data using a profile likelihood approach to search for sub-GeV dark matter particles (DM) through two inelastic scattering channels: bremsstrahlung radiation and the Migdal effect. By considering possible inelastic scattering channels, experimental sensitivity can be extended to DM masses that would otherwise be undetectable through the DM-nucleon elastic scattering channel, given the energy threshold of current experiments. We exclude DM masses down to $220~\textrm{MeV}/c^2$ at $2.7 \times 10^{-30}~\textrm{cm}^2$ via the bremsstrahlung channel. The Migdal channel search excludes DM masses down to $30~\textrm{MeV}/c^2$ at $5.0 \times 10^{-30}~\textrm{cm}^2$.Comment: This paper is being withdrawn due to an error in data selection during the analysis. Although incorrect, the limits are roughly representative of the sensitivity. The new corrected version of the result will be uploaded once read

EXCESS workshop: Descriptions of rising low-energy spectra

International audienceMany low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was initiated. In its first iteration in June 2021, ten rare event search collaborations contributed to this initiative via talks and discussions. The contributing collaborations were CONNIE, CRESST, DAMIC, EDELWEISS, MINER, NEWS-G, NUCLEUS, RICOCHET, SENSEI and SuperCDMS. They presented data about their observed energy spectra and known backgrounds together with details about the respective measurements. In this paper, we summarize the presented information and give a comprehensive overview of the similarities and differences between the distinct measurements. The provided data is furthermore publicly available on the workshop’s data repository together with a plotting tool for visualization