Reducing the MIPs Charge-Sharing Background in X-Ray Spectroscopic SDD Arrays

The current work describes a method for dealing with an anomalous background observed in parallel to the signal of interest (X-rays or gammas) on spectroscopic silicon drift detector (SDD) arrays exposed to large fluxes of ionizing radiation. The increment could not be explained by the Monte Carlo simulation reproducing well the single SDD cell response and containing realistic multicell array structure, neither by measurements on single devices. After rejecting the crosstalk hypothesis, an asymmetry in the drift-time distribution brought attention to the primary signal structure, eventually reaching the conclusion that the effect comes from the minimum ionizing particle (MIP)-induced charge, shared between the SDD cells. Successively, an analysis of three signal parameters (amplitude, drift time, and rise time) brought up a solution and two practical implementations, at different cost and performance levels.