Thermal kinetic inductance detectors for charged particle detection in neutron beta decay

Particle detection for nuclear physics still relies heavily on semiconductor or scintillator detectors for charged particle detection at ∼1 MeV and below. Cryogenic detectors such as Thermal Kinetic Inductance Detectors (TKIDs) could potentially provide a significant improvement in sensitivity and scalability. Currently TKIDs are used in X-ray and gamma spectroscopy as well as dark matter searches where they have been shown to have photon resolutions on the order of tens of eV. We report on progress in developing a TKID capable of detecting 1 MeV electrons with an energy resolution <200 eV for neutron beta decay experiments. Our charged particle TKID (CP-TKID) design could consist of a stacked design of a 5 µm thick TKID and a 2 mm thick TKID. The stacked design would allow for the detection of backscattered electrons from the 2 mm thick TKID. To fully understand the potential of TKIDs for future experiments the response must be fully characterized, as a 2 mm thick TKID, necessary to stop 1 MeV electrons, is a significant departure from a typical TKID with µm scale thickness. The increased volume of the detector impacts its energy resolution and potentially the spatial response. We will discuss measurements of the position dependence of single TKIDs as well as the interplay between multiple detectors in stacked geometries.