arXiv subjects

Giorgio Del Castello

Publications and source records attributed to Giorgio Del Castello.

5 recordsLinked to original sources

arXiv2026

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

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.

physics.ins-det↗

arXiv2026

Enhanced Athermal Phonon Responsivity in a Kinetic Inductance Detector with Integrated Phonon Collectors

Cryogenic phonon detectors are adopted in light dark matter searches and coherent elastic neutrino-nucleus scattering experiments as they can achieve low energy thresholds. The phonon mediated sensing of silicon particle absorbers has already been proved with Kinetic Inductance Detectors (KIDs), acting both as sensors and athermal phonon absorbers. In this work we present the design and the performance of an improved detector design. In this architecture, the KID acts only as sensor and is coupled to dedicated phonon collectors. When a signal is coming from the substrate, the presence of a separated collector allows to detect an higher increase of quasi-particles density, thereby enhancing its responsivity. The meander of the KID is composed of a 77 nm trilayer wire of Aluminum-Titanium-Aluminum, while the phonon collectors are made of a 100 nm Aluminum layer and act as quasi-particles funnels. Inside the collectors, the absorbed athermal phonons generate quasi-particles which, after diffusion, are trapped in the lower-gap superconducting trilayer. The performance of this setup is compared to that of a standard phonon-mediated KID, showing an increased phonon collection efficiency by a factor of around 7.

physics.ins-det↗

arXiv2026

A Cryogenic Muon Tagging System Based on Kinetic Inductance Detectors for Superconducting Quantum Processors

Ionizing radiation has emerged as a potential limiting factor for superconducting quantum processors, inducing quasiparticle bursts and correlated errors that challenge fault-tolerant operation. Atmospheric muons are particularly problematic due to their high energy and penetration power, making passive shielding ineffective. Therefore, monitoring the real-time muon flux is crucial to guide the development of alternative error-correction or mitigation strategies. We present the design, simulation, and first operation of a cryogenic muon-tagging system based on Kinetic Inductance Detectors (KIDs), developed as a stand-alone cryogenic particle-tagging module for superconducting quantum processors. The system consists of two KIDs arranged in a vertical stack and operated at $\sim$20 mK. Monte Carlo simulations based on Geant4 guided the prototype design and provided reference expectations for muon-tagging efficiency and accidental coincidences due to ambient $γ$-rays. We observed a muon-induced coincidence rate among the top and bottom detectors of (192 $\pm$ 9)$\times10^{-3}$ events/s, in excellent agreement with the Monte Carlo prediction. The prototype achieves a muon-tagging efficiency of about 90% with negligible dead time. These results demonstrate the feasibility of operating a muon-tagging system at millikelvin temperatures and represent a key step toward the integration of cryogenic veto systems with multi-qubit chips to mitigate muon-induced errors.

quant-ph↗

arXiv2026

LANTERN: Characterization technology for low threshold cryogenic detectors

The use of low-temperature detectors, such as cryogenic calorimeters, has pioneered the recent advancements in low-energy rare event searches. These detectors provide a low-noise environment essential for the direct detection of dark matter and neutrinos. Characterizing these detectors within the region of interest (ROI), typically spanning from O(10~eV) to O(1~keV), has proven to be a challenging task. Conventional radioactive sources produce signals above this range, leading to nonlinearities and saturation effects. Moreover, these detectors are usually deployed in low background environments, meaning that having a radioactive source during physics runs can spoil the measurement making the use of this type of solution unfeasible. As a solution to these issues, we introduce LANTERN, an optical calibration system designed for highly segmented cryogenic calorimeters. LANTERN utilizes the photostatistics resulting from the absorption of monochromatic UV-Vis photons emitted by LEDs to analyze the detector response curve, without needing prior knowledge of the total energy deposited. The system employs a fast-switching LED matrix that operates at excitation times faster than the typical response of cryogenic detectors and can currently characterize up to 64 calorimeters independently. In this work, the validation of the final electronics designed for the project is shown. The first test was carried out by calibrating one of the cryogenic detectors of the BULLKID-DM experiment and checking the energy-reconstruction error of the spectral features produced by the surrounding lead casing. An error of $\approx 2\%$ has been observed in the energy reconstruction. The second validation was carried out by cross-calibrating one of the CALDER thin detectors with a commercial LED driver, and compatible results between the two setups were achieved.

physics.ins-det↗

arXiv2023

Development of energy calibration and data analysis systems for the NUCLEUS experiment

Coherent elastic neutrino-nucleus scattering (CEvNS) opens new approaches for the search of new physics beyond the Standard Model. The NUCLEUS experiment aims to use the intense antineutrino flux produced from nuclear reactor cores to perform measurements of the CEvNS cross-section via gram-scale ultra-low threshold cryogenic detectors. A common problem with low threshold detectors is the calibration, since most radioactive sources tend to saturate the dynamical range of the sensors. In this dissertation, a photon-statistic based optical calibration setup has been developed and tested using detectors from the BULLKID R&D project. Both the developed hardware setup and the relative control software allow to automatically perform a full calibration of an array of detectors. During the development of this work, the DIANA analysis framework, developed for the CUORE experiment, has been compatibilized with the NUCLEUS DAQ and a new automatic analysis protocol was developed using the data from the NUCLEUS prototype runs. This protocol proved to be accurate at reproducing the results obtained via a model dependent study performed with an almost event by event inspection that was carried out in the early stages of NUCLEUS. Particular focus was given to the development of an event reconstruction procedure used to measure the energy of events that lie outside the linear response region of the detector. The last activity done for the NUCLEUS experiment was to develop a python based toolkit for the study of the discovery potential of the experiment. This toolkit was originally developed in the early stages of NUCLEUS by J.Rothe and has been intensely upgraded during the work presented in this thesis, in order to deal with different types of statistical checks and procedures.

physics.ins-det↗