We investigate the improvement from the use of high-Z CdTe sensors for pre-clinical K-edge imaging with the hybrid pixel detectors XPAD3. We compare XPAD3 chips bump bonded to Si or CdTe sensors in ...identical experimental conditions. Image performance for narrow energy bin acquisitions and contrast-to-noise ratios of K-edge images are presented and compared. CdTe sensors achieve signal-to-noise ratios at least three times higher than Si sensors within narrow energy bins, thanks to their much higher detection efficiency. Nevertheless Si sensors provide better contrast-to-noise ratios in K-edge imaging when working at equivalent counting statistics, due to their better estimation of the attenuation coefficient of the contrast agent. Results are compared to simulated data in the case of the XPAD3/Si detector. Good agreement is observed when including charge sharing between pixels, which have a strong impact on contrast-to-noise ratios in K-edge images.
The CHiPSpeCT consortium aims at building a large multi-modules CdTe based photon counting detector for hard X-ray applications. For this purpose, we tested nine XPAD3.2 single chip hybrids in ...various configurations (i.e. Ohmic vs. Schottky contacts or electrons vs. holes collection mode) in order to select the most performing and best suited configuration for our experimental requirements. Measurements have been done using both X-ray synchrotron beams and 241Am source. Preliminary results on the image quality, calibration, stability, homogeneity and linearity of the different types of detectors are presented.
We present a design study of PIXSIC, a new β + radiosensitive microprobe implantable in rodent brain dedicated to in vivo and autonomous measurements of local time activity curves of beta ...radiotracers in a small (a few mm 3 ) volume of brain tissue. This project follows the initial β microprobe previously developed at IMNC, which has been validated in several neurobiological experiments. This first prototype has been extensively used on anesthetized animals, but presents some critical limits for utilization on awake and freely moving animals. Consequently, we propose to develop a wireless setup that can be worn by an animal without constraints upon its movements. To that aim, we have chosen a Silicon-based detector, highly β sensitive, which allows for the development of a compact pixellated probe (typically 600 × 200 × 1000 μm 3 ), read out with miniaturized wireless electronics. Using Monte-Carlo simulations, we show that high resistive Silicon pixels are appropriate for this purpose, assuming that the pixel dimensions are adapted to our specific signals. More precisely, a tradeoff has to be found between the sensitivity to β + particles and to the 511 keV j background resulting from annihilations of β + with electrons. We demonstrate that pixels with maximized surface and minimized thickness can lead to an optimization of their β + sensitivity with a relative transparency to the annihilation background.
The ATLAS silicon pixel sensors Alam, M.S; Ciocio, A; Einsweiler, K ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2001, Letnik:
456, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Prototype sensors for the ATLAS silicon pixel detector have been developed. The design of the sensors is guided by the need to operate them in the severe LHC radiation environment at up to several ...hundred volts while maintaining a good signal-to-noise ratio, small cell size, and minimal multiple scattering. The ability to be operated under full bias for electrical characterization prior to attachment of the readout integrated circuit electronics is also desired.
The development of diamond tracking detectors for the LHC Adam, W.; Berdermann, E.; Bergonzo, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2003, Letnik:
514, Številka:
1-3
Journal Article
Recenzirano
Chemical vapor deposition diamond has been discussed extensively as an alternate sensor material for use very close to the interaction region of the LHC where extreme radiation conditions exist. ...During the last few years diamond devices have been manufactured and tested with LHC electronics with the goal of creating a detector usable by all LHC experiment. Extensive progress on diamond quality, on the development of diamond trackers and on radiation hardness studies has been made. Transforming the technology to the LHC specific requirements is now underway. In this paper we present the recent progress achieved.
X-ray pixel detector for crystallography Delpierre, P.; Berar, J.F.; Blanquart, L. ...
IEEE transactions on nuclear science,
08/2001, Letnik:
48, Številka:
4
Journal Article
Recenzirano
Odprti dostop
For X-ray diffraction experiments, the required dynamic range is a challenge. The signal ranges usually over more than six orders of magnitude. To meet this requirement and to reduce the readout time ...with respect to the commonly used charge-coupled device camera, a dedicated hybrid pixel detector is under development. We have designed a new counting chip with pixel size of 330 /spl mu/m. The expected counting rate per pixel is 10/sup 7/ ph/s, and a continuous readout with time stamping will allow a dynamic range for up to 4/spl times/10/sup 9/ (16-bit counter in each pixel and 16-bit counter per pixel in the readout boards). This chip has been submitted for fabrication and is under test. First results of this chip will be presented. As a first step, a small detector (4/spl times/1.6 cm/sup 2/) is being built, using a DELPHI(LEP/CERN) silicon array of diodes, which have good efficiency for collecting X-rays between 5 and 25 keV. After the electrical tests, the performance of this X-ray detector will be measured in the ESRF-D2AM beam line (Grenoble, France), scheduled for December 2000. If this prototype performs as expected, a large array (25/spl times/25 cm/sup 2/) of such detectors could be built.
Results obtained using a hybrid pixel photon‐counting detector in powder diffraction experiments are presented. The detector works at room temperature and its dynamic response ranges from 0.01 ...photons pixel−1 s−1 up to 106 photons pixel−1 s−1. The pixel sizes are 0.33 mm × 0.33 mm for a total area of 68 mm × 68 mm. On recording high‐resolution diffraction patterns of powders, a reduction of the experimental time by more than a factor of 20 is obtained without loss of data quality. The example of an X‐zeolite shows that such detectors can be used for very demanding anomalous experiments. In situ experiments of quenching liquid oxides show that frames of 0.01 s can be achieved for studying such processes.
XPAD: pixel detector for material sciences Basolo, S.; Berar, J.-F.; Boudet, N. ...
IEEE transactions on nuclear science,
10/2005, Letnik:
52, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Currently available 2D detectors do not make full use of the high flux and high brilliance of third generation synchrotron sources. The XPAD prototype, using active pixels, has been developed to ...fulfil the needs of materials science scattering experiments. At the time, its prototype is build of eight modules of eight chips. The threshold calibration of /spl ap/4 10/sup 4/ pixels is discussed. Applications to powder diffraction or SAXS experiments prove that it allows to record high quality data.
Silicon pixel sensors developed by the ATLAS collaboration to meet LHC requirements and to withstand hadronic irradiation to fluences of up to
10
15
n
eq
/
cm
2
have been evaluated using a test beam ...facility at CERN providing a magnetic field. The Lorentz angle was measured and found to alter from 9.0° before irradiation, when the detectors operated at
150
V
bias at
B=1.48
T
, to 3.1° after irradiation and operating at
600
V
bias at
1.01
T
. In addition to the effect due to magnetic field variation, this change is explained by the variation of the electric field inside the detectors arising from the different bias conditions.
The depletion depths of irradiated sensors at various bias voltages were also measured. At
600
V
bias
280
μm
thick sensors depleted to
≈200
μm
after irradiation at the design fluence of
1×10
15
1
MeV
n
eq
/
cm
2
and were almost fully depleted at a fluence of
0.5×10
15
1
MeV
n
eq
/
cm
2
.
The spatial resolution was measured for angles of incidence between 0° and 30°. The optimal value was found to be better than
5.3
μm
before irradiation and
7.4
μm
after irradiation.
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