arXiv subjects

A. Girardi

Publications and source records attributed to A. Girardi.

3 recordsLinked to original sources

arXiv2025

The optical calibration system for the CTAO North Large Sized Telescope

In 2018, the first prototype of the optical calibration system was installed in the Large Sized Telescopes, LST-1 at the Observatorio del Roque de los Muchachos, ORM, in La Palma, Canary Islands. We have almost completed the construction of the three remaining ones that will be mounted by 2026 on LST-2-3-4. The main feature of this system is to ensure a stable and constant photon flux over time with the characteristics of a signal produced by Cherenkov light when a high-energy gamma ray crosses the atmosphere. Test results that show the performance of the optical calibration system have been recently published. In this article, we present in detail the system used to monitor the photon flux.

astro-ph.IM↗

arXiv2024

Test results of the optical calibration system for the Large Sized Telescope camera

In 2018 the Large Sized Telescope (LST-1) prototype, designed to be the lowest energy detector for the Cherenkov Telescope Array Observatory, was inaugurated at the Observatorio de Roque de Los Muchachos in La Palma, Canary Island and today three more are under construction, LST2-4. The LST camera, with 1855 photomultipliers (PMTs), requires precise and regular calibration. The camera calibration system (hereafter CaliBox), installed at the center of the telescope mirror dish, is equipped with a Q-switching 355 nm UV laser corresponding to the wavelength at which the maximum camera PMT quantum efficiency is achieved, a set of filters to guarantee a large dynamic range of photons on each camera pixel, and a Ulbricht sphere to spread uniformly the laser light over the camera plane 28 m away. The system is managed by an ODROID-C1+ single board computer that communicates through an Open Platform Communication Unified Architecture (OPCUA) protocol to the camera. The CaliBox is designed to fulfill the requirements needed for the calibration of the camera including the monitor of the photon flux to guarantee the quality of the CaliBox system of laser stability, uniform illumination and intensity range. In this paper, we present in detail the optical system, the monitor of the photon flux, the relevant electronic to monitor the device. The performance of the device, the photon flux monitoring, the evaluation of the photon flux sent to the camera obtained during tests performed in Laboratory are shown.

astro-ph.IM↗

arXiv2023

Probing invisible neutrino decay with KM3NeT-ORCA

In the era of precision measurements of the neutrino oscillation parameters, upcoming neutrino experiments will also be sensitive to physics beyond the Standard Model. KM3NeT/ORCA is a neutrino detector optimised for measuring atmospheric neutrinos from a few GeV to around 100 GeV. In this paper, the sensitivity of the KM3NeT/ORCA detector to neutrino decay has been explored. A three-flavour neutrino oscillation scenario, where the third neutrino mass state $ν_3$ decays into an invisible state, e.g. a sterile neutrino, is considered. We find that KM3NeT/ORCA would be sensitive to invisible neutrino decays with $1/α_3=τ_3/m_3 < 180$~$\mathrm{ps/eV}$ at $90\%$ confidence level, assuming true normal ordering. Finally, the impact of neutrino decay on the precision of KM3NeT/ORCA measurements for $θ_{23}$, $Δm^2_{31}$ and mass ordering have been studied. No significant effect of neutrino decay on the sensitivity to these measurements has been found.

hep-ex↗