Readout electronics and DAQ system for silicon drift detector arrays in gamma ray spectroscopy applications

In this paper we present the development of an integrated circuit and of a data acquisition system for the readout of silicon drift detector (SDD) arrays to be coupled to scintillators for gamma-ray spectroscopy in the range 150 kev -15 Mev. The final goal is to develop a spectrometer based on an array of 81 silicon drift detectors (SDDs) coupled to a labr3:ce scintillator. The SDD photo-detectors are readout by 3 ASICs (27-channel each) and digitalized by a custom data acquisition (DAQ). Every channel includes a high order semi-Gaussian shaper amplifier with selectable gains and peaking times (from 2 J.1s up to 6 J.1s), a baseline holder and a peak stretcher. The ASIC also includes 27:1 analog multiplexer, custom digital control logic and an output amplifier. The DAQ board converts all the data coming from the three ASICs, with a resolution of 16 bits, and sends them to the host pc via an Ethernet interface. Main features of the electronic digital acquisition system are re-configurability, linearity, low noise and processing data rate through hardware and firmware architecture solutions that also allow the system to operate in presence of disturbances and electromagnetic noise.