Silicon Drift Detectors for Readout of Scintillators in Gamma-Ray Spectroscopy

Abstract

In this work, we report on a new development of Silicon Drift Detectors (SDDs) for gamma-ray spectroscopy with space science applications. The research is supported by the European Space Agency through the Technology Research Programme (TRP). The final goal of the development is the realization of monolithic arrays of SDDs which will be assembled to readout large (2” and 3”) (Ce) scintillators. We present here the results of the development of a single SDD prototype, with active area, produced at Fondazione Bruno Kessler (FBK) semiconductor laboratories. We discuss the design issues related to the specific use of this device as a photo-detector for scintillators. Then, we focus on the read-out electronics. Since this SDD does not include a front-end transistor on the silicon chip, we have adopted a CMOS charge preamplifier (CUBE) recently developed at Politecnico di Milano. This preamplifier has allowed the achievement of state-of-the-art noise performance using a SDD technology process without the integration of the FET (Field Effect Transistor) on the detector chip. A quantum efficiency of about 80% has been measured for the SDD at the emission wavelength band of (360–380 nm). First experimental measurements consisting of direct irradiation of the SDD without scintillator, have demonstrated energy resolution of 140 eV and 129 eV at and respectively. By coupling the SDD with a (Ce) scintillator (9 mm diameter), we have measured energy resolution of 5.6% FWHM and 2.6% FWHM at 122 keV and 662 keV respectively

A flexible scintillation light apparatus for rare event searches

“…Since a desirable order of magnitude for the detector surface -to collect the light from a scintillating crystal devoted to ββ0ν search -is of tens of square centimeters, this would result in a leakage current of several nA that would spoil the ENC. On the other hand, measurements on SDDs [27] show a marked decrease in the leakage current with decreasing temperature. In principle this decrease should have an exponential trend: therefore the leakage current could become negligible by reducing the operating temperature, although carrier freeze-out sets a lower limit around 77 K [32].…”

“…The basic idea of the proposed new technique is to optically couple suitable scintillating crystals to Silicon Drift Detectors (SDD) at a working temperature around 120 K. Indeed, many scintillating crystals have been used at low temperatures showing improved light emission [26] with respect to room temperature. On the other hand, in the recent years there have been many advances in the light detection using solid state devices [27]. The innovative idea is to combine these features to provide the winning technology for future experiments.…”

“…Moreover it is very difficult to obtain commercial photubes with a low intrinsic radioactivity of the glass envelope. The use of SDDs as photodetectors represents therefore an appealing possibility, since these devices are characterized by a Q larger than 80% in a wide range of wavelenghts [27]. In addition, silicon is one of the cleanest materials from the radioactivity point of view.…”

A flexible scintillation light apparatus for rare events searches

“…Silicon drift detectors (SDDs) are solid state devices very appealing since they are characterized by quantum efficiencies Q larger than 80% in a wide range of wavelengths [3]. As demonstrated in [4], an SDD of 1 cm 2 operated at a temperature of about 120 K and coupled to a JFET closely placed are a viable solution for reading out the light emitted by a scintillating crystal with high resolution.…”

European Space Agency detector development for space science: present and future activities

“…Based on this, the Agency has pursued the development of custom SDD arrays, optimized for use at the peak light output wavelength of LaBr3 (Ce) scintillators, through an Italian consortium. Led by Politecnico di Milano, the consortium have successfully designed and manufactured arrays of 8 mm square format SDD detectors 36 . Arranged as a group of 3 x 3 SDDs, a single array directly supports the read-out of a 1" LaBr3 crystal.…”