Speaker
Description
Phonon-sensitive Microwave Kinetic Inductance Detectors (MKIDs) are scalable superconducting sensors enabling the next-generation low-mass dark matter direct search and neutrinoless double beta decay search. We have identified Hafnium (Hf) as a promising material to fabricate high-sensitivity MKID and developed the microfabrication process for low-Tc (140mK~200mK) resonators. Furthermore, since the Tc is lower than aluminum (Al) Tc, we designed Al phonon absorbers to collect phonons efficiently and couple them with Hf MKID via quasiparticle trapping to enhance sensitivity. Quasiparticle trapping solves the dilemma between the large inductor volume required by phonon collection efficiency and the small volume required by high kinetic inductance. This presentation will cover Hf MKID design and fabrication details, the measures to improve phonon collection efficiency, and results with x-ray calibration sources.
