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

Evolutionary Algorithms for Tracking Algorithm Parameter Optimization

“…It is able to achieve this independence through the development of an event data model and geometry description that does not depend on any specific details of a particular detector and by implementing algorithms which are general mathematical formulations with no assumptions on detector geometry. Thus far it has been used with the ATLAS experiment geometry, the ATLAS HL-LHC upgraded detector geometry, the Open Detector [5], the Belle-II detector [6] and the LDMX detector [7].…”

Characterizing Dark Matter Signals with Missing Momentum Experiments

“…Over the past decade the experimental dark matter (DM) search effort has greatly expanded in scope to explore the sub-GeV mass range. This push towards lower masses has been driven by several complementary strategies, including new direct-detection techniques (e.g., electron ionization) [1][2][3][4][5][6][7][8][9] and low-energy accelerator searches [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] -see Refs. [30][31][32][33] for reviews.…”

“…• Experimental Control: Unlike direct detection searches, whose sensitivity is subject to to astrophysical uncertainties and environmental backgrounds, the MM signal strength is fully calculable and irreducible background events occur at a rate of ∼ 10 −15 per incident beam particle [14].…”

“…The electron beam MM strategy is currently being developed by the LDMX collaboration [14,34] and additional studies are underway to explore a future muon beam MM experiment (M 3 ) at Fermilab [16]. Collectively, these efforts have the potential to test nearly every model of sub-GeV freeze-out for which the MM signal strength is parametrically related to the DM annihilation rate in the early universe [12,17,23].…”

“…The existing MM literature has largely focused on the kinematics of signals arising from the radiative production of massive spin-1 bosons with vector current interactions (e.g. kinetically mixed dark photons) [14,18,34]. In this paper we generalize these studies to explore the kinematics of recoiling beam leptons in fixed target interactions…”