A high efficiency photon veto for the Light Dark Matter eXperiment

• DOI: 10.1007/jhep04(2020)003
• Publication Date: 2020-04-02T10:03:44Z
• Authors: 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
• Keywords: Physics - Instrumentation and Detectors; FOS: Physical sciences; QC770-798; Instrumentation and Detectors (physics.ins-det); 530; 7. Clean energy; 01 natural sciences; High Energy Physics - Experiment; High Energy Physics - Phenomenology; High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); Fixed target experiments; Nuclear and particle physics. Atomic energy. Radioactivity; Beyond Standard Model; 0103 physical sciences; Dark matter

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.