VCI2025 - The 17th Vienna Conference on Instrumentation

Charge reconstruction from binary hit data on irradiated MALTA2 Czochralski sensors

18 Feb 2025, 15:40

50m

Vienna University of Technology

Board: 79

Poster Semiconductor Detectors Coffee & Posters A

Speaker

Lucian Fasselt (DESY)

Description

MALTA2 is a depleted monolithic active pixel sensor (DMAPS) designed for tracking at high rates and is produced in the modified Tower 180 nm CMOS technology. The sensing layer of the 36.4×36.4 $\mu {\mathrm{m}}^2$ pixels consists of either high resistivity epitaxial or Czochralski silicon. A small collection electrode features a small pixel capacitance and offers low noise. Typically, the detection threshold is around 200 e-. A simple procedure is developed to calibrate the threshold to unit electrons making use of a dedicated charge injection circuit on chip and an Fe-55 source with dominant charge deposition of 1600 e-.
In this contribution, MALTA2 sensors are characterised in terms of hit detection efficiency inside the pixel and cluster size at fine threshold steps, for samples produced with different doping concentration of the internal n- layer, substrate voltage and irradiation dose. Data was taken at CERN SPS test beam campaigns in 2023 and 2024, using a MALTA beam telescope consisting of multiple sensor planes with 4 μm spatial and 2 ns timing resolution. A reconstruction of the signal amplitude from binary hit data is performed. Through the charge calibration a two-dimensional map of the collected charge is obtained with sub-pixel resolution. The presented method provides an in-beam alternative to grazing angle studies or Edge-TCT for determining a charge collection profile.

Presentation materials

VCI_MALTA2_Poster_Fasselt.pdf