arXiv subjects

C. Valieri

Publications and source records attributed to C. Valieri.

6 recordsLinked to original sources

arXiv2025

Cryogenic characterization of FBK NUV-HD-Cryo 3T SiPM sensors for the DUNE photon detection system

The Deep Underground Neutrino Experiment (DUNE) is a long-baseline neutrino experiment based in the USA and composed of a Near Detector (ND) complex at Fermi National Laboratory (FNAL), and a Far Detector (FD) complex located at the Sanford Underground Research Facility (SURF) $\sim$1300\,km distant. DUNE will study neutrino oscillations looking for unresolved issues of the Standard Model of particle physics (SM) such as CP violation in the leptonic sector, neutrino mass ordering and others, starting from the early 2030s. The FD, with a mass of $\sim$17\,kt, that will exploit both ionization and scintillation signals to detect neutrino interactions with Argon. Scintillating photons in LAr will be detected by the photon detection system (PDS) based on light collectors coupled to Silicon Photomultipliers (SiPMs). During a test campaign, different laboratories of the collaboration performed an investigation of the best SiPM candidates that fulfill the DUNE FD requirements. We identified two models of SiPM, produced by Hamamatsu Photonics K.K. (HPK) and Fondazione Bruno Kessler (FBK), respectively. In this paper, we focus on the FBK selected model showing its main features. We will describe the characterization protocol, the results at both room and cryogenic temperatures and the photon detection efficiency measurements.

physics.ins-det↗

arXiv2025

Performance of the image persistence model for Euclid infrared detectors

Large-format infrared detectors are at the heart of major ground and space-based astronomical instruments, and the HgCdTe HxRG is the most widely used. The Near Infrared Spectrometer and Photometer (NISP) of the ESA's Euclid mission launched in July 2023 hosts 16 H2RG detectors in the focal plane. Their performance relies heavily on the effect of image persistence, which results in residual images that can remain in the detector for a long time contaminating any subsequent observations. Deriving a precise model of image persistence is challenging due to the sensitivity of this effect to observation history going back hours or even days. Nevertheless, persistence removal is a critical part of image processing because it limits the accuracy of the derived cosmological parameters. We will present the empirical model of image persistence derived from ground characterization data, adapted to the Euclid observation sequence and compared with the data obtained during the in-orbit calibrations of the satellite.

astro-ph.IM↗

arXiv2023

Euclid's Near-Infrared Spectrometer and Photometer ready for flight -- review of final performance

ESA's mission Euclid, while undertaking its final integration stage, is fully qualified. Euclid will perform an extragalactic survey ($0<z<2$) by observing in the visible and near-infrared wavelength range. To detect infrared radiation, it is equipped with the Near Infrared Spectrometer and Photometer (NISP) instrument, operating in the 0.9--2 $\mu$m range. In this paper, after introducing the survey strategy, we focus our attention on the NISP Data Processing Unit's Application Software, highlighting the experimental process to obtain the final parametrization of the on-board processing of data produced by the array of 16 Teledyne HAWAII-2RG (HgCdTe) detectors. We report results from the latest ground test campaigns with the flight configuration hardware - complete optical system (Korsh anastigmat telescope), detectors array (0.56 deg$^2$ field of view), and readout systems (16 Digital Control Units and Sidecar ASICs). The performance of the on-board processing is then presented. We also describe a major issue found during the final test phase. We show how the problem was identified and solved thanks to an intensive coordinated effort of an independent review `Tiger' team, lead by ESA, and a team of NISP experts from the Euclid Consortium. An extended PLM level campaign at ambient temperature in Li\`ege and a dedicated test campaign conducted in Marseille on the NISP EQM model eventually confirmed the resolution of the problem. Finally, we report examples of the outstanding spectrometric (using a Blue and two Red Grisms) and photometric performance of the NISP instrument, as derived from the end-to-end payload module test campaign at FOCAL 5 -- CSL; these results include the photometric Point Spread Function (PSF) determination and the spectroscopic dispersion verification.

astro-ph.IM↗

arXiv2008

Results of the Search for Strange Quark Matter and Q-balls with the SLIM Experiment

The SLIM experiment at the Chacaltaya high altitude laboratory was sensitive to nuclearites and Q-balls, which could be present in the cosmic radiation as possible Dark Matter components. It was sensitive also to strangelets, i.e. small lumps of Strange Quark Matter predicted at such altitudes by various phenomenological models. The analysis of 427 m^2 of Nuclear Track Detectors exposed for 4.22 years showed no candidate event. New upper limits on the flux of downgoing nuclearites and Q-balls at the 90% C.L. were established. The null result also restricts models for strangelets propagation through the Earth atmosphere.

hep-ex↗

arXiv2008

The treatment and rejection of two "strange" candidate events in the SLIM experiment

During the analysis of the CR39 Nuclear Track Detectors (NTDs) of the SLIM experiment exposed at the high altitude lab of Chacaltaya (Bolivia) we observed a sequence of puzzling etch-pits. We made a detailed investigation of all the CR39 and Makrofol detectors in the same stack and in all the stacks around the candidate event. We found a second puzzling sequence of etch-pits (plus some single etch-pits). The analysis of this configuration was important because we were searching for rare particles (Magnetic Monopoles, Nuclearites, Q-balls) in the cosmic radiation. Thus we analyzed in detail the evolution with increasing etching time of the etch-pits. We concluded that the two sequences of the etch-pits (and some other background etch-pits) may have originated from a rare manufacture malfunctioning which involved 1 m^2 of produced CR39.

hep-ex↗

arXiv2006

Bulk Etch Rate Measurements and Calibrations of Plastic Nuclear Track Detectors

New calibrations of CR39 and Makrofol nuclear track detectors have been obtained using 158 A GeV Pb (82+) and In (49+) ions; a new method for the bulk etch rate determination, using both cone height and base diameter measurements was developed. The CR39 charge resolution based on the etch-pit base area measurement is adequate to identify nuclear fragments in the interval 7 <= Z/beta <= 49. For CR39 the detection threshold is at REL~50 MeV cm^2/g, corresponding to a nuclear fragment with Z/beta~7. Base cone area distributions for Makrofol foils exposed to Pb (82+) ions have shown for the first time all peaks due to nuclear fragments with Z > 50; the distribution of the etched cone heights shows well separated individual peaks for Z/beta = 78 - 83 (charge pickup). The Makrofol detection threshold is at REL 2700 MeV cm^2/g, corresponding to a nuclear fragment with Z/beta~50.

physics.ins-det↗