Commissioning of the camera of the first Large Size Telescope of the Cherenkov Telescope Array

TL;DR

This paper reports on the successful commissioning and performance evaluation of the camera system of the first Large Size Telescope of the Cherenkov Telescope Array, highlighting calibration, noise, trigger optimization, and data acquisition performance.

Contribution

It presents the first detailed commissioning results and performance metrics of the LST-1 camera, including calibration, noise levels, trigger optimization, and data acquisition efficiency.

Findings

Readout noise level of 0.2 p.e.

PMT gain variation within 2%

Trigger system synchronized within 1 ns

Abstract

The first Large Size Telescope (LST-1) of the Cherenkov Telescope Array has been operational since October 2018 at La Palma, Spain. We report on the results obtained during the camera commissioning. The noise level of the readout is determined as a 0.2 p.e. level. The gain of PMTs are well equalized within 2\% variation, using the calibration flash system. The effect of the night sky background on the signal readout noise as well as the PMT gain estimation are also well evaluated. Trigger thresholds are optimized for the lowest possible gamma-ray energy threshold and the trigger distribution synchronization has been achieved within 1~ns precision. Automatic rate control realizes the stable observation with 1.5\% rate variation over 3 hours. The performance of the novel DAQ system demonstrates a less than 10\% dead time for 15 kHz trigger rate even with sophisticated online data correction.