BULLKID: Monolithic array of particle absorbers sensed by Kinetic Inductance Detectors

TL;DR

BULLKID is a monolithic particle detector array using carved silicon dices sensed by multiplexed Kinetic Inductance Detectors, achieving a baseline energy resolution suitable for low-energy physics experiments.

Contribution

It introduces a novel monolithic array of particle absorbers integrated with KID sensors, simplifying construction and potentially improving performance for low-energy detection.

Findings

Achieved an average baseline energy resolution of 26±7 eV.

Demonstrated operation of 8 detector units with similar response.

Proved the array's suitability for detecting low-energy interactions.

Abstract

We introduce BULLKID, an innovative phonon detector consisting of an array of dices acting as particle absorbers sensed by multiplexed Kinetic Inductance Detectors (KIDs). The dices are carved in a thick crystalline wafer and form a monolithic structure. The carvings leave a thin common disk intact in the wafer, acting both as holder for the dices and as substrate for the KID lithography. The prototype presented consists of an array of 64 dices of 5.4x5.4x5 mm$^3$ carved in a 3" diameter, 5 mm thick silicon wafer, with a common disk 0.5 mm thick hosting a 60 nm patterned aluminum layer. The resulting array is highly segmented but avoids the use of dedicated holding structures for each unit. Despite the fact that the uniformity of the KID electrical response across the array needs optimization, the operation of 8 units with similar features shows, on average, a baseline energy resolution of $26\pm7$ eV. This makes it a suitable detector for low-energy processes such as direct interactions of dark matter and coherent elastic neutrino-nucleus scattering.