New physics searches with an optical dump at LUXE

We propose a novel way to search for feebly interacting massive particles, exploiting two properties of systems involving collisions between high energy electrons and intense laser pulses. The first property is that the electron-intense-laser collision results in large flux hard photons, as behaves effectively thick medium. second emitted photons free-stream inside thus them very thin Combining these features implies an apparatus which can efficiently convert UV hard, co-linear photons. further direct this unique onto physical dump turn capable producing region parameters has never been probed before. denote ``optical dump'' or NPOD (new physics with optical dump). proposed LUXE experiment at Eu.XFEL all required basic ingredients above experimental concept. discuss how concept be realized practice by adding detector after last reconstruct two-photon decay product new spin-0 particle. show even relatively short dump, still background free. Remarkably, 40 TW laser, corresponds initial run, definitely 350 main run one year data taking, LUXE-NPOD will able probe uncharted territory both models pseudo-scalar scalar fields, particular natural theories masses 100 MeV.