Silicon drift detectors (SDDs), due to their collection electrode geometry, have excellent noise performance and are well suited for low-energy X-ray spectroscopy applications. On the other hand ...these detectors, when dedicated to low energy X-ray spectroscopy, have a small sensitive area (from few square millimeters up to one square centimeter) to reduce the leakage current and its impact on the energy resolution. Because of this limitation they are rarely used in applications where large sensitive surfaces are required. We present the characterization of the spectroscopic performance of a very large sensitive area SDD (about 53 cm 2 ) that has been realized in the frame of the LHC-ALICE experiment. We studied the energy resolution of the detector analyzing its dependence on both biasing conditions and temperature to evaluate the contribution of the different noise sources exploiting their relation with the shaping time. The experimental results obtained with 241 Am and 55 Fe sources show that the goal of a high energy resolution combined with large sensitive areas can be achieved.
Silicon drift detectors (SDD) of small dimensions (up to 1
cm
2) have been successfully employed in X-ray spectroscopy due to their small anode geometry, which allows to minimize the electronic noise ...due to the readout device. Many applications, however, require large sensitive areas to be covered (e.g. X-ray astronomy), so that these detectors are effectively impractical. We present the spectroscopic performance of a 53
cm
2 sensitive area, multi-anode SDD, measured at room temperature using an eight-channel readout setup. The measurements, taken using
55Fe and
241Am sources, and X-ray tubes generating energies down to 2
keV, show energy resolutions in the range 290–570
eV FWHM, at 20
°C, depending on the number of anodes collecting the signal. Further developments we are carrying out could improve the detector characteristics and allow to approach the performance of small area SDDs.
Large-area multi-anode Silicon Drift Detectors (SDDs) have X-ray imaging and spectroscopic characteristics that make them extremely attractive in the perspective of their applications to the field of ...space astrophysics. We describe here the imaging performance of such a detector, originally developed for particle tracking in the ALICE experiment at LHC, as derived by laboratory measurements and Monte Carlo simulations. Despite an anode pitch of
294
μ
m
, we measured a position resolution as high as
∼
20
μ
m
by charge weighting in the anode direction, for photon energies in the range 2–10
keV. These results are comparable to those obtained with the same detectors in particle tracking. Notwithstanding the 1-D nature of the devices, as far as their read-out is concerned, we envisaged an algorithm that exploits the charge diffusion to reconstruct the position of the photon absorption point also along the drift direction (that is, the one formally not position-sensitive). With the current set-up, the position resolution was measured as
∼
3
–
5
mm
in the same energy range as above. Such 2-D imaging capability in a 1-D detector, although asymmetric, is highly useful in space applications, where the power and the complexity requested by a 2-D read-out system is sometimes unaffordable.
Phase contrast x-ray imaging is a powerful technique for the detection of low-contrast details in weakly absorbing objects. This method is of possible relevance in the field of diagnostic radiology. ...In fact, imaging low-contrast details within soft tissue does not give satisfactory results in conventional x-ray absorption radiology, mammography being a typical example. Nevertheless, up to now all applications of the phase contrast technique, carried out on thin samples, have required radiation doses substantially higher than those delivered in conventional radiological examinations. To demonstrate the applicability of the method to mammography we produced phase contrast images of objects a few centimetres thick while delivering radiation doses lower than or comparable to doses needed in standard mammographic examinations (typically approximately 1 mGy mean glandular dose (MGD)). We show images of a custom mammographic phantom and of two specimens of human breast tissue obtained at the SYRMEP bending magnet beamline at Elettra, the Trieste synchrotron radiation facility. The introduction of an intensifier screen enabled us to obtain phase contrast images of these thick samples with radiation doses comparable to those used in mammography. Low absorbing details such as 50 microm thick nylon wires or thin calcium deposits (approximately 50 microm) within breast tissue, invisible with conventional techniques, are detected by means of the proposed method. We also find that the use of a bending magnet radiation source relaxes the previously reported requirements on source size for phase contrast imaging. Finally, the consistency of the results has been checked by theoretical simulations carried out for the purposes of this experiment.
FLARES (a Flexible scintillation Light Apparatus for Rare Event Searches) is a project for an innovative detector technology to be applied to rare event searches, and in particular to neutrinoless ...double beta decay experiments. Its novelty is the enhancement and optimization of the collection of the scintillation light emitted by ultra-pure crystals through the use of arrays of high performance silicon photodetectors cooled to 120 K. This would provide scintillation detectors with ~1% level energy resolution, with the advantages of a technology offering relatively simple low cost mass scalability and powerful background reduction handles, as requested by future neutrinoless double beta decay experimental programs.
Large area silicon drift detector for the ALICE experiment Rashevsky, A.; Bonvicini, V.; Burger, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2002, Letnik:
485, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Two hundred and sixty Silicon Drift Detectors (SDDs), each with an active area of
7.0×7.5
cm
2
, will equip two of the six cylindrical layers of high precision position sensitive detectors that ...constitute the Inner Tracking System (ITS) of the ALICE experiment at LHC. In developing the ALICE SDD, one of the objectives was to work out a robust and redundant design. Unlike the case of silicon microstrip or pixel detectors, a single defect in a SDD may be propagated throughout the whole detector. One of the features of the detector is the original design of the integrated voltage divider that allows to attenuate effectively such a propagation in the most practical cases. Device simulations and laboratory measurements are presented.
The bio-distribution and targeting capability of pharmaceuticals may be assessed in small animals by imaging gamma-rays emitted from radio-isotope markers. Detectors that exploit the Compton concept ...allow higher gamma-ray efficiency compared to conventional Anger cameras employing collimators, and feature sub-millimeter spatial resolution and compact geometry.
We are developing a Compton Camera that has to address several requirements: the high rates typical of the Compton concept; detection of gamma-rays of different energies that may range from 140
keV (
99
m
Tc) to 511
keV (
β
+
emitters); presence of gamma and beta radiation with energies up to 2
MeV in case of
188Re. The camera consists of a thin position-sensitive Tracker that scatters the gamma ray, and a second position-sensitive detection system to totally absorb the energy of the scattered photons (Calorimeter).
In this paper we present the design and discuss the realization of the calorimetric tract, including the choice of scintillator crystal, pixel size, and detector geometry. Simulations of the gamma-ray trajectories from source to detectors have helped to assess the accuracy of the system and decide on camera design. Crystals of different materials, such as LaBr
3 GSO and YAP, and of different size, in continuous or segmented geometry, have been optically coupled to a multi-anode
Hamamatsu H8500 detector, allowing measurements of spatial resolution and efficiency.
Beam test results of the irradiated silicon drift detector for ALICE Kushpil, S.; Crescio, E.; Giubellino, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2006, Letnik:
566, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Inner Tracking System (ITS) of the ALICE experiment at LHC will use high precision Silicon Drift Detectors (SDD) in two of the six cylindrical layers. In this paper we report on the results of ...beam test of a SDD irradiated with 1
GeV electrons. The aim of this test was to verify the radiation tolerance of the device under an electron fluence equivalent to twice the particle fluence expected during 10 years of ALICE operation.
The front-end system of the silicon drift detectors of ALICE Rivetti, A.; Idzik, M.; Martinez, M.I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2005, Letnik:
541, Številka:
1
Journal Article
Recenzirano
The ALICE experiment at CERN will have an inner tracker made of six barrels of semiconductor detectors. The two intermediate layers of the system will employ Silicon Drift Detectors (SDD) technology. ...The front-end electronics of the SDDs, which required the development of two full-custom integrated circuits, is reviewed in this paper. The design of the front-end hybrid is discussed and results obtained with full-size prototypes are presented.
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