Search Prospects for Axion-like Particles at Rare Nuclear Isotope Accelerator Facilities

TL;DR

This paper proposes DAMSA, a novel experimental scheme at rare nuclear isotope facilities to search for axion-like particles and dark photons, leveraging high-flux proton beams and prompt decay detection close to the source.

Contribution

Introduction of DAMSA, a new experimental setup utilizing rare isotope accelerators for dark-sector particle searches with enhanced background suppression techniques.

Findings

DAMSA can probe high-mass ALP parameter space beyond current experiments.

The detector's proximity to the dump enables detection of prompt decay signals.

BRN background can be effectively suppressed with correlated visible final states.

Abstract

We propose a novel experimental scheme, called DAMSA (Dump-produced Aboriginal Matter Searches at an Accelerator), for searching for dark-sector particles, using rare nuclear isotope accelerator facilities that provide high-flux proton beams to produce a large number of rare nuclear isotopes. The high-intensity nature of their beams enables the investigation of dark-sector particles, including axion-like particles (ALPs) and dark photons. By contrast, their typical beam energies are not large enough to produce the backgrounds such as neutrinos resulting from secondary charged particles. The detector of DAMSA is then placed immediate downstream of the proton beam dump to maximize the prompt decay signals of dark-sector particles, which are often challenging to probe in other beam-dump-type experiments featuring a longer baseline, at the expense of an enormous amount of the beam-related neutron (BRN) background. We demonstrate that BRN can be significantly suppressed if the signal accompanies multiple, correlated visible particles in the final state. As an example physics case, we consider ALPs interacting with the Standard Model photon and their diphoton decay signal at DAMSA implemented at a rare nuclear isotope facility similar to the Rare isotope Accelerator complex for ON-line experiment under construction in South Korea. We show that the close proximity of the detector to the ALP production dump makes it possible to probe a high-mass region of ALP parameter space that the existing experiments have never explored.