Camera calibration strategy of the SST-1M prototype of the Cherenokov Telescope Array

TL;DR

This paper presents the calibration strategy for the SST-1M prototype camera of the Cherenkov Telescope Array, focusing on stabilizing SiPM gain and processing signals for Cherenkov imaging.

Contribution

It introduces a comprehensive calibration approach using online feedback and dedicated events to ensure accurate SiPM signal conversion for the SST-1M camera.

Findings

Effective gain stabilization of SiPMs achieved

Calibration method improves Cherenkov image analysis accuracy

Operational calibration procedures established

Abstract

The SST-1M telescope is one of the prototypes under construction proposed to be part of the future Cherenkov Telescope Array. It uses a standard Davis-Cotton design for the optics and telescope structure, with a dish diameter of 4 meters and a large field-of-view of 9 degrees. The innovative camera design is composed of a photo-detection plane with 1296 pixels including entrance window, light concentrators, Silicon Photomultipliers (SiPMs), and pre-amplifier stages together with a fully digital readout and trigger electronics, DigiCam. In this contribution we give a general description of the analysis chain designed for the SST-1M prototype. In particular we focus on the calibration strategy used to convert the SiPM signals registered by DigiCam to the quantities needed for Cherenkov image analysis. The calibration is based on an online feedback system to stabilize the gain of the SiPMs, as well as dedicated events (dark count, pedestal, and light flasher events) to be taken during the normal operation of the prototype.