2-D mapping of the response of SDD cells of different shape in monolithic arrays for XRF spectroscopy

In the frame of the INFN experiment REDSOX/REDSOX2 and in collaboration with Fondazione Bruno Kessler (FBK), Trento, we are developing trapezoidal-shaped monolithic arrays of Silicon Drift Detector (SDD) cells for low energy X-ray fluorescence (XRF) experiments. The shape of the individual SDD cell must be carefully selected in order to find the optimal compromise between spectroscopic performance and the number of SDD cells. We conducted an experimental campaign with a pulsed IR laser in order to map in detail the transport properties inside square SDD cells (3.1 mm side) and inside triangular SDD cells (3.1 mm side). The main parameters investigated are i) collected amplitude, ii) drift time and iii) the rise time at the charge-sensing preamplifier output. The collected experimental data are a precious guide for the optimization of the final detector prototype.