Pathfinder for a high statistics search for missing energy in gamma cascades

We investigate the feasibility of a high statistics experiment to search for invisible decay modes in nuclear gamma cascades using 200 kg %36 Cs(Tl) scintillators that are presently available at Texas A\&M. The aims missing energy by robustly establishing absence photon well identified cascade. report on experimental demonstration resolution necessary this search. Prior explorations detector concept focused baryonically coupled physics could be emitted $E_2$ transitions. point out protocol can also particles photons searching conversion produced cascade into hidden particle. Examples these processes include oscillation and an axion-like-particle either presence magnetic field or via Primakoff process. This proof-of-concept apparatus appears have ability hitherto unconstrained scalars pseudoscalars $E_0$ $M_0$ If successfully implemented, serves as pathfinder larger with greater containment thoroughly probe existence new mass below 4 MeV lie poorly constrained supernova ``trapping window'' exists between 100 keV 30 MeV.