The absence of conclusive signals in weakly interacting massive particle (WIMP) searches has motivated increased interest in alternative dark matter candidates such as axions and axion-like particles (ALPs), which also provide a solution to the strong CP problem. In this work, we employ a ∼100kg scale CsI(Tl)-based detector operated in proximity to a nuclear reactor to achieve a sub-100 DRU (differential rate unit, expressed in counts/keV/kg/day) background level in the MeV energy range through a combination of active veto and passive shielding techniques. Such a low-background environment enables sensitivity to ALPs with axion--photon coupling gaγγ≳10−6 and axion--electron coupling in the range 10−8<gaee<10−4 for ALP masses between 1~keV and 10~MeV. These results demonstrate that the experiment has the potential to probe previously unexplored regions of parameter space, including the so-called cosmological triangle in the ALP--photon coupling for MeV-scale ALPs.
@article{arxiv.2407.14704,
title = {Reactor-based Search for Axion-Like Particles using CsI(Tl) Detector},
author = {S. Sahoo and S. Verma and M. Mirzakhani and N. Mishra and A. Thompson and S. Maludze and R. Mahapatra and M. Platt},
journal= {arXiv preprint arXiv:2407.14704},
year = {2026}
}