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arXiv · 2609.30004

Impact of the position effects in the energy calibration of the BULLKID detector

Matteo Folcarelli·Matteo Cappelli·Giorgio Del Castello·Camilla Bonomo·Angelo Cruciani·Daniele Delicato·Leonardo Pesce·Davide Quaranta·Marco Vignati
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Abstract

BULLKID is a cryogenic solid-state detector based on an array of silicon dice equipped with Kinetic Inductance Detectors (KIDs) for low-mass dark matter searches and coherent elastic neutrino-nucleus scattering. Energy calibration can be performed using optical LED photon bursts, which are absorbed within the first few hundred nanometers of the substrate. An energy calibration using a $^{241}$Am gamma-ray source revealed a $<10\%$ discrepancy with the LED calibration. A recent study by Matava and Williams suggested that phonon statistics and phonon collection varying with the interaction position could explain such a discrepancy. This work evaluates the impact of these effects on the calibration of the BULLKID detector, demonstrating they both have a negligible effect. We clarify the results obtained during the $^{241}$Am calibration regarding the origin of the observed discrepancy.

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Matteo Folcarelli, Matteo Cappelli, Giorgio Del Castello, Camilla Bonomo, Angelo Cruciani, Daniele Delicato, Leonardo Pesce, Davide Quaranta, Marco Vignati. 2026-09-24. Impact of the position effects in the energy calibration of the BULLKID detector. https://arxiv.org/abs/2609.30004

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