arXiv subjects

Cornelia Arcaro

Publications and source records attributed to Cornelia Arcaro.

6 recordsLinked to original sources

arXiv2025

Toward the End-To-End Optimization of the SWGO Array Layout

In this document we consider the problem of finding the optimal layout for the array of water Cherenkov detectors proposed by the SWGO collaboration to study very-high-energy gamma rays in the southern hemisphere. We develop a continuous model of the secondary particles produced by atmospheric showers initiated by high-energy gamma rays and protons, and build an optimization pipeline capable of identifying the most promising configuration of the detector elements. The pipeline employs stochastic gradient descent to maximize a utility function aligned with the scientific goals of the experiment. We demonstrate how the software is capable of finding the global maximum in the high-dimensional parameter space, and discuss its performance and limitations.

astro-ph.IM↗

arXiv2024

Chasing Gravitational Waves with the Cherenkov Telescope Array

The detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this gravitational wave event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100GeV) photons which have yet to be detected in coincidence with a gravitational wave signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. New observing modes and follow-up strategies are being developed for CTA to rapidly cover localization areas of gravitational wave events that are typically larger than the CTA field of view. This work will evaluate and provide estimations on the expected number of of gravitational wave events that will be observable with CTA, considering both on- and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA.

astro-ph.HE↗

arXiv2023

A study on Performance Boost of a 17~m class Cherenkov telescope with a SiPM-based camera

The current generation of Imaging Atmospheric Cherenkov Telescopes (IACTs), comprised of major installations such as the MAGIC telescopes, H.E.S.S. and VERITAS, is classified as the 3$^{\mathrm{rd}}$ generation of suchs instruments. These telescopes use multipixel cameras composed of thousands of photomultiplier tubes (PMTs). The total light throughput of such instruments depends, besides the PMT photon detection efficiency (PDE), on the mirror dish reflectivity, and the light absorption by the camera window. The supremacy of PMTs is currently being challenged by photon sensors rapidly spreading in popularity, the silicon photomultipliers (SiPMs), that are becoming a valid alternative thanks to their high PDE, low operating voltage and flexibility in installation. In this report, we investigate the performance of an existing 3$^{\mathrm{rd}}$-generation IACT array (taking as an example MAGIC) in which PMTs would be replaced with SiPMs, with minimal further hardware intervention. This would mean that other systems of the telescope responsible for the light collection, in particular the optics, would remain the same, and only the electronic to steer the different photodetectors would be modified. We find an increase of sensitivity up to a factor of 2 for energies below 200~GeV. Interestingly, we also find that the stronger sensitivity of SiPMs in the red part of the spectrum, a source of background for IACTs, does not affect this conclusion.

astro-ph.IM↗

arXiv2023

A prototype tank for the SWGO detector

The Southern Wide-field Gamma-ray Observatory (SWGO) is an international collaboration working on realizing a next-generation observatory located in the Southern hemisphere, which offers a privileged view of our galactic center. We are working on the construction of a prototype water Cherenkov detector at Politecnico di Milano using a flexible testing facility for several candidate light sensors and configurations. A structure able to hold different types of detectors in multiple configurations has been designed, built and tested in Politecnico's labs. Furthermore, an analytical study of muons and electrons showers has been carried out using the SWGO observatory simulation software to examine the correlation between the detection capabilities of the prototype tank and its water level.

astro-ph.IM↗

arXiv2019

MAGIC eyes to the extreme: testing the blazar emission models on EHBLs

Extreme high-energy peaked BL Lac objects (EHBLs) are blazars whose synchrotron emission peaks at exceptionally high energies, above few keV, in the hard X-ray regime. So far, only a handful of those objects has been detected at very high energy (VHE, E > 100 GeV) gamma rays by Imaging Atmospheric Cherenkov Telescopes. Very remarkably, VHE observations of some of these blazars (like 1ES 0229+200) have provided evidence of a VHE gamma-ray emission extending to several TeV, which is difficult to explain with standard, one-zone synchrotron self-Compton models usually applied to BL Lac objects. The MAGIC collaboration coordinated a multi-year, multi-wavelength observational campaign on ten targets. The MAGIC telescopes detected VHE gamma rays from four EHBLs. In this paper we focus on the source 1ES 1426+426 and its X-ray and VHE gamma-ray properties. The results of different models (synchrotron self-Compton, spine-layer, hadronic) reproducing the broadband spectral energy distribution are also presented.

astro-ph.HE↗

arXiv2018

Absolute reflectance of a concave mirror used for astro-particle physics experiments

The absolute reflectance of a reflector and its point spread function are the key parameters of a telescope for measuring light flux. Typically, one is using low-cost technologies for producing mirrors for the needs of astro-particle physics experiments. As a rule, these are operating telescopes in open air conditions at desert or mountainous locations, for cost reasons without protecting domes. The mirrors on such telescopes are exposed to sand in strong winds, precipitation and large temperature variations. Due to weathering, their reflectance is declining within few years. In this report we describe in a great detail the application of an in-situ method to the MAGIC imaging air Cherenkov telescopes for regularly monitoring their absolute reflectance and the point spread function. Compared to similar work that was previously performed, in this report we focus on important details of light losses due to scattering. These allowed us to further refine the method and significantly improve its precision. Also, we report on an in-situ comparison of two mirror types produced with different technologies.

astro-ph.IM↗