The DAMSA Experiment

TL;DR

DAMSA is a novel short-baseline accelerator experiment designed to detect short-lived dark sector particles and rare Standard Model signals, employing a compact detector and beam-dump scheme to overcome sensitivity limitations of longer-baseline experiments.

Contribution

The paper introduces the DAMSA experiment concept and its Path-Finder prototype, demonstrating a new approach to probing short-lived particles in a previously inaccessible regime.

Findings

DAMSA can detect MeV-to-sub-GeV dark-sector messengers with feeble couplings.

The Path-Finder experiment validates the feasibility of DAMSA's detection strategy.

DAMSA's short baseline overcomes the sensitivity ceiling of traditional beam dump experiments.

Abstract

DAMSA (DArk Messenger Searches at an Accelerator) is a novel short-baseline accelerator/beam dump experiment aimed at probing short-lived physics processes, including searches for evidence of a dark sector of particle physics and well-motivated rare Standard Model signals. Motivated by open questions in neutrino physics and the absence of conclusive evidence for conventional weakly interacting massive particles, DAMSA targets MeV-to-sub-GeV dark-sector messengers with feeble couplings that can be produced in abundance at a beam dump/target. By employing an ultra-short baseline, DAMSA is uniquely positioned to overcome the beam-dump "ceiling" that limits sensitivity to fast decaying particles in longer-baseline experiments. The conceptual design emphasizes a beam-dump production scheme combined with a compact detector optimized for rare decays while mitigating intense neutron-induced backgrounds, inherent to high-power proton beams. To validate the experimental strategy and detector technologies, the DAMSA Path-Finder (DPF) proof-of-concept experiment is also proposed, focusing on axion-like particles decaying to two photons, as the benchmark physics case and operating with 8 GeV electron beams at SLAC Linac-to-ESA (LESA) facility. Successful realization of DPF will establish the feasibility of the DAMSA approach, enabling a broad and powerful program to explore short-lived new physics and precision Standard Model processes in a previously inaccessible regime. This paper outlines the technical details of DAMSA's physics goals, key experimental challenges, and how to overcome them.