arXiv subjects

Giacomo Gallina

Publications and source records attributed to Giacomo Gallina.

3 recordsLinked to original sources

arXiv2026

The Darkside-20k Data Acquisition System

DarkSide-20k is a WIMP search experiment using liquid argon as a target, designed to perform a background-free search for dark matter with unprecedented sensitivity, and is currently under construction at INFN Laboratori Nazionali del Gran Sasso, Italy. The detector comprises a dual-phase Time Projection Chamber complemented with external veto systems and is equipped with a total of 2720 SiPM-based readout channels. This work presents the DAQ system designed for DarkSide-20k. The system is capable of continuous, triggerless digitisation of the waveforms with high single-photoelectron detection efficiency and online processing, ensuring data reduction for long-term storage. The DarkSide-20k DAQ system employs commercial CAEN VX2745 digitisers with custom FPGA firmware implementation. Timing and synchronisation across all 48 digitisers are provided by custom Global and Crate Data Manager boards distributing a phase-aligned clock derived from a disciplined rubidium standard. Waveform segments are processed in real time by Front End Processor machines. Data are organised into collections containing whole detector information and distributed across a farm of Time Slice Processors for event reconstruction, classification, and further reduction before storage and offline analysis. A full "Quadrant" of the system, corresponding to one quarter of the final DAQ, has been assembled and validated at TRIUMF laboratory in Canada. The Quadrant has been stress-tested with simultaneous pulses and demonstrated sustained digitizer readout exceeding expected physics rates and stable long-term performance.

physics.ins-det↗

arXiv2026

Demonstrating a broadband Photon Detection Efficiency model on VUV sensitive Silicon Photomultipliers

We present a versatile analytic model describing Photon Detection Efficiency (PDE) for P-on-N silicon photomultipliers, with possible applications for device characterization, PDE extrapolation from limited data, simulation and design optimization. Using device specific parameters, SiPM PDE is modeled as a function of wavelength, angle of incidence, voltage, and limited temperature range. By factoring the PDE into transmission and internal efficiency, the performance in liquid nobles and other dense media can be predicted. We present the measurement of the absolute PDE from 350 to 830 nm at 163 K for two VUV sensitive SiPMs: a Hamamatsu VUV4 and Fondazione Bruno Kessler VUV-HD Technology. Additional measurements of relative PDE versus angle are also included. We successfully fit the model to the data, compare with literature and show the model's predictive power by extrapolating PDE to new wavelengths and operation in liquid xenon and argon, which is useful for estimating performance and the impact of external cross-talk in future large-scale experiments. Lastly we use the model to investigate optimizing efficiency for specific applications in astroparticle physics and quantum computing.

physics.ins-det↗

arXiv2024

Stimulated Secondary Emission of Single Photon Avalanche Diodes

Large-area next-generation physics experiments rely on using Silicon Photo-Multiplier (SiPM) devices to detect single photons, which trigger charge avalanches. The noise mechanism of external cross-talk occurs when secondary photons produced during a charge avalanche escape from an SiPM and trigger other devices within a detector system. This work presents measured spectra of the secondary photons emitted from the Hamamatsu VUV4 and Fondazione Bruno Kessler VUV-HD3 SiPMs stimulated by laser light, near operational voltages. The work describes the Microscope for the Injection and Emission of Light (MIEL) setup, which is an experimental apparatus constructed for this purpose. Measurements have been performed at a range of over-voltage values and temperatures from 86~K to 293~K. The number of photons produced per avalanche at the source are calculated from the measured spectra and determined to be 40$\pm$9 and 61$\pm$11 photons produced per avalanche for the VUV4 and VUV-HD3 respectively at 4 volts over-voltage. No significant temperature dependence is observed within the measurement uncertainties. The overall number of photons emitted per avalanche from each SiPM device are also reported.

physics.ins-det↗