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arXiv · 1912.05535

A High Efficiency Photon Veto for the Light Dark Matter eXperiment

Abstract

Fixed-target experiments using primary electron beams can be powerful discovery tools for light dark matter in the sub-GeV mass range. The Light Dark Matter eXperiment (LDMX) is designed to measure missing momentum in high-rate electron fixed-target reactions with beam energies of 4 GeV to 16 GeV. A prerequisite for achieving several important sensitivity milestones is the capability to efficiently reject backgrounds associated with few-GeV bremsstrahlung, by twelve orders of magnitude, while maintaining high efficiency for signal. The primary challenge arises from events with photo-nuclear reactions faking the missing-momentum property of a dark matter signal. We present a methodology developed for the LDMX detector concept that is capable of the required rejection. By employing a detailed GEANT4-based model of the detector response, we demonstrate that the sampling calorimetry proposed for LDMX can achieve better than $10^{-13}$ rejection of few-GeV photons. This suggests that the luminosity-limited sensitivity of LDMX can be realized at 4 GeV and higher beam energies.

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Torsten Åkesson, Nikita Blinov, Lene Bryngemark, Owen Colegrove, Giulia Collura, Craig Dukes. Valentina Dutta, Bertrand Echenard, Thomas Eichlersmith, Craig Group, Joshua Hiltbrand, David G. Hitlin, Joseph Incandela, Gordan Krnjaic, Juan Lazaro, Amina Li, Jeremiah Mans, Phillip Masterson, Jeremy McCormick, Omar Moreno, Geoffrey Mullier, Akshay Nagar, Timothy Nelson, Gavin Niendorf, James Oyang, Reese Petersen, Ruth Pöttgen, Philip Schuster, Harrison Siegel, Natalia Toro, Nhan Tran, Andrew Whitbeck. 2019-12-11. A High Efficiency Photon Veto for the Light Dark Matter eXperiment. https://arxiv.org/abs/1912.05535

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