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

TL;DR

This study evaluates replacing traditional photomultiplier tubes with silicon photomultipliers in a Cherenkov telescope, demonstrating up to double the sensitivity below 200 GeV without major hardware changes.

Contribution

It shows that SiPMs can significantly enhance Cherenkov telescope performance with minimal hardware modifications, especially in the lower energy range.

Findings

Sensitivity increases up to a factor of 2 below 200 GeV.

SiPM red sensitivity does not negatively impact performance.

Minimal hardware changes suffice for improved detection capabilities.

Abstract

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.