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The performance of a silicon drift detector (SDD) with an integrated FET, delivered by the company PNSensor, Munich, Germany, was studied in gamma spectrometry at room temper- ature (23-25°C) with a LaBr3 :Ce crystal of 6 mm diameter and 6 mm height. The SDD characteristics were compared with those measured with a Photonis XP5212 photomultiplier, a Large Area Avalanche Photodiode (LAAPD) of Advanced Photonix, Inc., and a Hamamatsu S3590-18 Photodiode (PD). Energy resolution versus gamma ray energies and its components related to the photoelectron/electron-hole pair statistics and dark noise were measured and compared. At low energies, below 100 keV, the light readout by the photomultiplier gives the best results, while for high energies, above 300 keV, the light readout by the SDD delivers superior energy resolution. In particular, the best energy resolution of 2.7% was determined for 662 keV gamma rays from a 137Cs source. [ABSTRACT FROM AUTHOR]

In this paper, the authors propose a gamma-ray spectrometer based on a LaBr3 :Ce scintillator coupled to a silicon drift detector (SDD). The SDD is a photodetector characterized by a very low noise thanks to the low value of output capacitance independent from the active area. With respect to a PMT, the SDD offers a higher quantum efficiency which reduces the spread associated to the statistic of photoelectrons generation. Also with respect to an APD, the SDD offers a lower photoelectrons statistic contribution, which, in the APD, is worsened by the excess noise factor with respect to pure Poisson statistics. Moreover, the SDD has a stable behavior, less sensitive to temperature and bias drift. In the past years, good energy resolutions were measured using a SDD coupled to a CsI:Tl crystal. However, the long shaping time, to be used with this scintillator to prevent ballistic deficit, was too far to exploit the best noise performances achievable with a SDD obtained at shaping times in the order of 1 μs. On the contrary, this optimum shaping time is fully compatible with the short decay time of the LaBr3 :Ce crystal (about 25 ns). The results of the experimental characterization of the LaBr3 :Ce-SDD gamma-ray spectrometer are presented in this work and are compared with the performances achieved with the same crystal coupled to a PMT and to a CsI(Tl) crystal coupled to the same SDD. The SDD has an active area of 30 mm². Antireflective coatings have been implemented. Good energy resolutions were measured at room temperature, thanks to the low leakage current of the detector: 2.7% at the 137Cs 661.7 KeV line and 6.1% at the 57Co 122 KeV line. A resolution of 5.7% at 122 KeV line was measured at 0 °C. [ABSTRACT FROM AUTHOR]

A monolithic X- and gamma-ray detector based on a silicon drift detector coupled to a CsI(TI) scintillator is presented. The detector is operated both as a direct X-ray detector for photons interacting in silicon and as an indirect detector for photons interacting in the scintillator. As interactions in silicon and in CsI yield different amount of charge per unit energy deposited, discrimination of the place of interaction is necessary to obtain the correct energy. Discrimination of the interaction type is carried out by means of pulse shape discrimination performed with two parallel processing chains with different shaping times. In this paper an extensive characterization of the detector with temperature is presented. It is shown that cooling the detector at 10 ° allows to obtain a nearly 100% efficiency between 8 and 200 keV. Further cooling below 0 °C allows pulse shape discrimination with 100% accuracy throughout the detector's energy range. The detector has also been tested with X-rays at various energies by means of a tun- able X-ray facility. These tests allowed an investigation of the light yield nonproportionality in CsI(Tl) at low energies, necessary for a proper energy calibration of the detector. [ABSTRACT FROM AUTHOR]

Monolithic arrays of Silicon Drift Detectors (SDDs) have been employed successfully in X-ray spectroscopy and γ-ray imaging applications. Thanks to the low electronics noise achieved at short shaping lime, the SDD is an ideal device for high-resolution and high-rate X-ray spectroscopy experiments at synchrotron sources. Moreover, small monolithic arrays of SDDS have also been used as photodetector of the scintillation light in a first prototype of Anger Camera for γ-ray imaging characterized by an intrinsic resolution better than 0.3 mm. En this work we present a new large- area monolithic array of Silicon Drift Detectors. It consists of a single chip composed by 77 single hexagonal units, each one with a front-end JFET integrated in its center, arranged in a honeycomb configuration. Each SDD unit has an active area of 8.7 mm², for a total active area of the device of 6.7 cm². The linear dimensions of the active area are approximately 29 × 26 mm². It represents the largest monolithic array of SDDs with on-chip JFETs produced up to now for X-ray and γ-ray detection. The results achieved in the experimental characterization of a first prototype of the detector array are presented. They include also the preliminary X-ray spectroscopy characterization of the SDD's units. The energy resolution measured at 6 keV with the single unit of the array is of 142 eV at -10 °C. [ABSTRACT FROM AUTHOR]

Abstract: Silicon drift detectors (SDDs) have shown to be a competitive device for the readout of scintillators with respect to conventional photodetectors, thanks to their high quantum efficiency and low electronics noise. Recently, they have been successfully employed in first small prototypes of Anger cameras to achieve sub-millimeter spatial resolution in gamma-ray imaging. To cover larger formats of Anger cameras, in particular in the framework of the HICAM project, specially focused on human imaging, we have developed new SDD arrays of larger active areas. To assemble photodetector planes of several cm2, we have designed a basic unit composed by a linear array of 5 SDDs of 1cm2 active area each. In this work, we present the results of the experimental characterization of these photodetector arrays in direct X-ray detection to evaluate the electronics noise, as well as gamma-ray detection with a scintillator. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we present the results achieved in the experimental characterization of a Silicon Drift Detector (SDD) in X-ray spectroscopy measurements at high counting rates. The main goal of the work is to verify that high peak stability can be achieved when using an SDD with the input JFET and when the feedback capacitor directly integrated on the detector and a charge preamplifier configuration. In the proposed circuit, the SDD anode voltage is stabilized by means of a low-frequency feedback loop which operates according to the ‘drain feedback’ technique. The stabilization of the anode voltage is necessary to guarantee the stabilization of the feedback capacitor; moreover, the implemented design allows to obtain a sufficiently fixed decay time constant of the preamplifier with respect to rate variations. In the characterization of the preamplifier with an SDD, a Mn-Kalpha peak shift within ±0.05% (i.e. below 6eV) has been achieved changing the rate from few kcounts/s up to several hundred kcounts/s. The same circuit has been modified and then employed to be used with an SDD without feedback capacitor, exploiting a parasitic capacitor between anode and a neighbour ring as feedback capacitor. The results achieved with this configuration are also presented in this work. [Copyright &y& Elsevier]

In this work, we present a monolithic array of 19 silicon drift detectors (SDDs) used as photodetectors of the scintillation light in position sensitive γ-ray detectors. In this array, having a total sensitive area of about 1 cm2, each SDD has a front-end JFET directly integrated on the detector chip, close to the collecting anode. The low electronic noise offered by each single unit allows to reach a sub-millimeter position resolution by coupling the SDD array to a single CsI(Tl) scintillator crystal in a “mini”-Anger camera scheme. In the paper, a detection module based on the SDD array is described and the noise performances are reported. Moreover, the results in terms of position resolution obtained with the mini Anger Camera realized with the SDD module are presented. [Copyright &y& Elsevier]