This work deals with the development of a new gamma detector based on Silicon Drift Detectors (SDDs) to read out large (3"×3") LaBr 3 :Ce scintillators for gamma-ray spectroscopy for astronomy ...applications, an activity supported by European Space Agency (ESA). SDDs, characterized by high quantum efficiency and low electronic noise, are good candidates in applications with a wide energy range of gamma rays to be detected from 150keV to 15MeV. A first prototype is under development with the aim to achieve an energy resolution of 3% FWHM at 662 keY. The SDDs are designed as monolithic arrays of 3×3 units, each one of an active area of 8 mm × 8 mm (total array area of 26 mm × 26 mm).To cover the large surface of the 3"×3" LaBr3:Ce scintillator the modules are expected to be arranged in a 3×3 matrix, for a total of 81 SDDs read out by a custom developed electronics. In this work we will report on the design issues of this detector and on the first experimental results obtained in gamma-ray spectroscopy with a 1"×1" LaBr 3 :Ce scintillator.
The
system at rest plays a key role for the understanding of strong interaction of hadrons with strangeness involved. The experiment SIDDHARTA used X-ray spectroscopy of kaonic atoms to measure the ...strong interaction induced shift and width of the ground state. It was the first experiment on kaonic He3 and deuterium ever, kaonic hydrogen was measured with improved precision resulting in
eV and
eV. Additionally a scheme for an improved future experiment on kaonic deuterium is introduced in this contribution.
In nuclear physics basic research and, particularly, in gamma spectroscopy, the use of an imaging detector can be extremely useful to reduce the Doppler Broadening effect in experiments where the ...gamma-ray source moves with high/relativistic velocity. In this work, we propose to use a recently developed gamma camera, based on CsI:Tl scintillator coupled to an array of Silicon Drift Detectors, for such type of experiments. The camera, suitably modified to cope with high-energy detection, has shown, in preliminary measurements with a 1cm thick scintillator, a spatial resolution of 2mm with a collimated source of 137 Cs (662keV).
LaBr3 crystals are well known to provide the brightest light pulses between commercially available 3" scintillators. Recent development of high density SiPMs has made high dynamic range electronics ...readout a necessity in different applications. GAMMA-8 was the first prototype of a new chip designed to cope with large DR requirements while maintaining low noise and high tolerance to disturbances. GAMMA-16 is the upgraded version of the aforementioned chip with improved DR and Full Scale Range. This work will focus first on the first release of this ASIC (GAMMA-8) to assess its performance. This ASIC has been implemented in a first prototype of the GAMMA Instrument, performing the readout of a 12x12 SiPM matrix with only 8 analog channels. The ASIC input stage properties have also been addressed in the case of large input capacitance. The first experimental results obtained with upgraded version of the chip, exploiting 16 channels and engineered structure are also presented in the paper.
The SIDDHARTA experiment measured the kaonic
3
He and
4
He 3
d
→2
p
X-ray transitions using gaseous targets for the first time. The strong-interaction shift both of the kaonic
3
He and
4
He 2
p
...states was determined with a precision of a few eV. The shift of kaonic
4
He is much smaller than the values obtained in the experiments performed in 70’s and 80’s, while it is consistent with the recent result of the KEK E570 experiment, as well as the theoretical calculated values. Therefore, the problem on kaonic helium (the “kaonic helium puzzle”) was definitely solved. The first observation of the kaonic
3
He X-rays was also achieved in the SIDDHARTA experiment. The shift both of kaonic
3
He and
4
He was found to be as small as a few eV.
The estimation of the Depth-of-Interaction (DOI) of detected gamma photons is especially challenging for thick scintillators, yet relevant for moderately thin ones (8 mm CsI(Tl) in our case) employed ...in nuclear imaging. In SPECT, in particular using pinhole or slit-slat collimation, the parallax error produced by photons passing through the collimator holes, with trajectories non orthogonal to the crystal surface, can be reduced by including the DOI information into the tomographic reconstruction. We present an algorithm based on maximum likelihood that classifies into 4 layers the events absorbed in the scintillator. A novel initialization signal (a ring footprint surrounding the channel detecting the highest intensity) is proposed, only requiring a flood field irradiation as training. The algorithm is experimentally validated by means of a tilted collimated beam on a single camera. The DOI information will be applied in a stationary clinical MRI-compatible SPECT insert which is composed of 20 identical modules mounted in a partial ring.
In this paper we present the results of an experimental characterization of ROTOR, a new VLSI shaping amplifier conceived for multi-anode Silicon Drift Detectors, or other multi-element solid-state ...X-ray detection systems. The readout scheme is suitable for the demanding requirements of new X-ray spectroscopy experiments with synchrotron light, like X-ray Holography, where both high count-rates and good energy resolutions are required. The circuit, which is of time-variant nature, features a trapezoidal weighting function obtained by means of a switched-current technique. A first prototype of the circuit, integrated with the 1 /spl mu/m/5 V JFET/CMOS technology of the Fraunhofer-Institut, Duisburg (Germany), has been characterized in spectroscopy measurements with a Silicon Drift Detector. The experimental results are presented and discussed in the work.
The aim of the HICAM project is to build a compact, high-resolution γ-ray imager for human patients, designed according to the Anger Camera principle. The imager is based on an array of 10 × 10 ...Silicon Drift Detectors, coupled to a single CsI:Tl scintillator. The array of photo detectors is read out by four 25-channel ASICs, which are the subject of this paper. Each channel of the ASIC features a low-noise preamplifier, compatible with the pulsed reset mode of the SDD, a gain stage, a high order semi-Gaussian shaping amplifier with selectable peaking times, a baseline holder and a peak stretcher. The ASIC also contains a 25:1 analog multiplexer, a digital section and a differential ADC driver. The pulsed reset mode of the preamplifier, which reduces the parallel noise of the system, is particularly well suited for the use with long shaping times, which are required by the CsI:Tl scintillator, due to its long primary decay time constant. The ASIC, however, features peaking times ranging from 1.1 μs up to 11 μs, optimized for both X-ray direct conversion measurements and for γ-ray measurements with LaBr3:Ce and CsI:Tl. In the paper we describe the design and the first experimental characterization of the ASIC, together with a test SDD. With an ultra-low noise test SDD we have measured an energy resolution of 130 eV FWHM at the Mn Kα line, showing that the ASIC has a good potential for high resolution γ-spectroscopy.
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