Development of arrays of Silicon Drift Detectors and readout ASIC for the SIDDHARTA experiment

This work deals with the development of new Silicon Drift Detectors (SDDs) and readout electronics for the upgrade of the SIDDHARTA experiment. The detector is based on a SDDs array organized in a 4×2 format with each SDD square shaped with 64 mm2 (8×8) active area. The total active area of the array is therefore 32×16 mm2 while the total area of the detector (including 1 mm border dead area) is 34×18mm2. The SIDDHARTA apparatus requires 48 of these modules that are designed and manufactured by Fondazione Bruno Kessler (FBK). The readout electronics is composed by CMOS preamplifiers (CUBEs) and by the new SFERA (SDDs Front-End Readout ASIC) circuit. SFERA is a 16-channels readout ASIC designed in a 0.35μm CMOS technology, which features in each single readout channel a high order shaping amplifier (9th order Semi-Gaussian complex-conjugate poles) and a high efficiency pile-up rejection logic. The outputs of the channels are connected to an analog multiplexer for the external analog to digital conversion. An on-chip 12-bit SAR ADC is also included. Preliminary measurements of the detectors in the single SDD format are reported. Also measurements of low X-ray energies are reported in order to prove the possible extension to the soft X-ray range.