Evaluation of silicon photomultipliers for dual-mirror Small-Sized Telescopes of Cherenkov Telescope Array
Abstract
All camera designs for Small-Sized telescopes (SSTs) proposed for the Cherenkov Telescope Array (CTA) utilize silicon photomultipliers (SiPM) as their baseline photon sensor technology. The dual-mirror SST (SST-2M) has a smaller plate scale (i.e. image size) than the single-mirror SST, allowing it to employ 2,000 square SiPMs with pixel sizes of approximately 6 mm, close to the mainstream SiPM sizes.
In CTA, the night sky background level of typically ∼25 Mcounts/s/pixel (>100 Mcounts/s/pixel at maximum) places severe constraints on the trigger capability due to accidental coincidence on neighboring pixels. In order to suppress such events, it is necessary to reduce optical crosstalk, a mechanism whereby a single optical photon can produce multiple avalanches in the SiPM, while keeping good photon detection efficiency. These are, in general, contradicting requirements. In this manuscript, we report on characterization of a variety of SiPM technologies for SST-2M cameras and compare results obtained at different participating institutions. We assess the harmonization of results and discuss the likely performance that will be achieved for the first production cameras.- Publication:
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Nuclear Instruments and Methods in Physics Research A
- Pub Date:
- December 2018
- DOI:
- 10.1016/j.nima.2017.11.017
- Bibcode:
- 2018NIMPA.912..177A
- Keywords:
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- Silicon photomultiplier;
- Photon detector;
- Gamma ray;
- Air shower;
- Cherenkov radiation;
- Astrophysics