Preliminary tests of a phonon-mediated Kinetic Inductance Detector with phonon-funneling volume

Cryogenic phonon detectors are adopted in light dark matter searches or coherent elastic neutrino-nucleus scattering experiments thanks to the low energy threshold they can achieve. The phonon-mediated detection of silicon particle absorbers has been already proved with Kinetic Inductance Detectors (KIDs), acting as phonon collectors and sensors at the same time. We present a first prototype of a KID coupled to a separate structure of phonon absorbers in order to increase the sensitivity. It consists of a thin KID with a trilayer wire of Aluminum/Titanium/Aluminum coupled to larger aluminum phonon collecting volume. Phonons absorbed in the collecting volume create Quasi-Particles which are trapped in the lower-gap trilayer after diffusion. The performance of the device is compared with a standard phonon-mediated KID. We report the results of preliminary tests, which showed that the KID with collection structures had a greater response.