Title: Energy calibration of bulk events in the BULLKID detector Show Chinese title

Title: 大块事件在BULLKID探测器中的能量标定

Abstract: BULLKID is a cryogenic, solid-state detector designed for direct searches of particle Dark Matter candidates, with mass $\lesssim 1$ GeV/c$^2$, and coherent neutrino-nucleus scattering. It is based on an array of dice carved in 5 mm thick silicon crystal, sensed by phonon-mediated Kinetic Inductance Detectors. In previous works, the array was calibrated with bursts of optical photons, which are absorbed in the first hundreds nanometers of the dice and give rise to surface events. In this work, we present the reconstruction of bulk events through the 59.5 keV $\gamma$-ray generated by an $^{241}$Am source, which emulates more closely the interaction of Dark Matter and neutrinos. The peak resolution is $5\%~(\sigma)$ and its position is shifted by less than $10\%$ with respect to the optical calibration. We observe that the resolution is further improved by a factor $2$ combining the signal from neighboring dice. These results confirm the performance of the detector in view of the physics goals of the BULLKID-DM experiment for dark matter search. Show Chinese abstract

Abstract: BULLKID是一种低温固态探测器，专门用于直接搜索粒子暗物质候选者，其质量为$\lesssim 1$ GeV/c$^2$，并涉及相干中微子-核散射。 它基于在5毫米厚的硅晶体上雕刻的骰子阵列，由声子介导的动能电感探测器进行感应。 在以前的研究中，该阵列通过光学光子脉冲进行校准，这些光子被骰子前几百纳米吸收，并产生表面事件。 在本研究中，我们通过由$^{241}$钚源产生的59.5 keV$\gamma$射线重建体事件，这更接近暗物质和中微子的相互作用。 峰值分辨率是$5\%~(\sigma)$，其位置相对于光学校准的偏移小于$10\%$。 我们观察到，通过结合相邻骰子的信号，分辨率进一步提高了因子$2$。 这些结果证实了探测器的性能，以满足BULLKID-DM实验在暗物质搜索方面的物理目标。