Optimization of gain calibration in NectarCAM: evaluating the impact of charge extraction methods

The NectarCAM is a camera designed for the Medium Sized Telescopes (MSTs) of the northern site of the Cherenkov Telescope Array Observatory. The NectarCAM camera equipping the MSTs is sensitive to gamma rays in the energy range of approximately 100 GeV to 10 TeV. The camera consists of 1,855 pixels, grouped into modules of 7 pixels each. To accurately reconstruct real data acquisitions, several calibration steps are required. Among them, gain calibration is crucial, as it ensures the conversion of the electronic signal detected by each pixel into a corresponding number of photo-electrons. This calibration can be performed using dedicated systems at the camera integration facility and on site. The full calibration of the camera is carried out with nectarchain, a software framework based on ctapipe. Within this framework, two different methods can be applied to compute the gain. Additionally, multiple charge extraction methods can be used to process the electronic signal in each pixel. In this study, we conduct a quantitative analysis of the impact of different charge extraction methods on gain computation for the entire camera. This allows us to determine the optimal procedure for achieving reliable and accurate gain calibration.