Charge calibration of MALTA2, a radiation hard depleted monolithic active pixel sensor
Lucian Fasselt, Ignacio Asensi Tortajada, Prafulla Behera, Dumitru Vlad Berlea, Daniela Bortoletto, Craig Buttar, Valerio Dao, Ganapati Dash, Leyre Flores Sanz de Acedo, Martin Gazi, Laura Gonella, Vicente González, Sebastian Haberl, Tomohiro Inada, Pranati Jana, Long Li, Heinz Pernegger, Petra Riedler, Walter Snoeys, Carlos Solans Sánchez, Milou van Rijnbach, Marcos Vázquez Núñez, Anusree Vijay, Julian Weick, Steven Worm
公開日: 2025/1/23
Abstract
MALTA2 is a depleted monolithic active pixel sensor (DMAPS) designed for tracking at high rates and typically low detection threshold of $\sim150\,\mathrm{e^-}$. A precise knowledge of the threshold is crucial to understanding the charge collection in the pixel and specifying the environment for sensor application. A simple procedure is developed to calibrate the threshold to unit electrons making use of a dedicated charge injection circuit and an Fe-55 source with dominant charge deposition of $1600\, \mathrm{e^-}$. The injection voltage is determined which corresponds to the injection under Fe-55 exposure and is the basis for charge calibration. The charge injection circuit incorporates a capacitance with design value of $\mathrm{C_{inj}}=$ 230 aF. Experimentally, the average capacitance value for non-irradiated samples is found to be $\mathrm{C_{inj,exp}}=$ 257 aF. The 12 % divergence motivates the need for the presented precise calibration procedure, which is proposed to be performed for each MALTA2 sensor.