Cosmic Ray Susceptibility of the Terahertz Intensity Mapper Detector Arrays

We report on the effects of cosmic ray interactions with the kinetic inductance detector (KID)-based focal plane array for the terahertz intensity mapper (TIM). TIM is a NASA-funded balloon-borne experiment designed to probe the peak of the star formation in the Universe. It employs two spectroscopic bands, each equipped with a focal plane of four ∼ 900-pixel, KID-based array chips. Measurements of an 864-pixel TIM array show 791 resonators in a 0.5 GHz bandwidth. We discuss challenges with resonator calibration caused by this high multiplexing density. We robustly identify the physical positions of 788 (99.6 events/min/cm^2 in our array. 66 < 5 KIDs per event spread over a 0.66 cm^2 region (2 pixel pitches in radius). We observe a total cosmic ray dead fraction of 0.0011 ∼ 0.124