A 300 μm thick thin p-on-n silicon sensor was connected to an energy sensitive pixel readout ASIC and exposed to a beam of highly energetic charged particles. By exploiting the spectral information ...and the fine segmentation of the detector, we were able to measure the evolution of the transverse profile of the charge carriers cloud in the sensor as a function of the drift distance from the point of generation. The result does not rely on model assumptions or electric field calculations. The data are also used to validate numerical simulations and to predict the detector spectral response to an X-ray fluorescence spectrum for applications in X-ray imaging.
•A Multiple Coulomb scattering of a proton causing image blurring is studied.•A phantom with several tissue surrogates is irradiated.•A proton scattering angle is calculated using direction and ...position information.•Clinically relevant proton beam energies were studied.•Using proton direction gives factor 2 less statistics than proton position.
Proton radiography is a novel imaging modality that allows direct measurement of the proton energy loss in various tissues. Currently, due to the conversion of so-called Hounsfield units from X-ray Computed Tomography (CT) into relative proton stopping powers (RPSP), the uncertainties of RPSP are 3–5% or higher, which need to be minimized down to 1% to make the proton treatment plans more accurate.
In this work, we simulated a proton radiography system, with position-sensitive detectors (PSDs) and a residual energy detector (RED). The simulations were built using Geant4, a Monte Carlo simulation toolkit. A phantom, consisting of several materials was placed between the PSDs of various Water Equivalent Thicknesses (WET), corresponding to an ideal detector, a gaseous detector, silicon and plastic scintillator detectors. The energy loss radiograph and the scattering angle distributions of the protons were studied for proton beam energies of 150MeV, 190MeV and 230MeV. To improve the image quality deteriorated by the multiple Coulomb scattering (MCS), protons with small angles were selected. Two ways of calculating a scattering angle were considered using the proton’s direction and position.
A scattering angle cut of 8.7mrad was applied giving an optimal balance between quality and efficiency of the radiographic image. For the three proton beam energies, the number of protons used in image reconstruction with the direction method was half the number of protons kept using the position method.
Probing active-edge silicon sensors using a high precision telescope Akiba, K.; Artuso, M.; van Beveren, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2015, Letnik:
777
Journal Article
Recenzirano
Odprti dostop
The performance of prototype active-edge VTT sensors bump-bonded to the Timepix ASIC is presented. Non-irradiated sensors of thicknesses 100–200μm and pixel-to-edge distances of 50μm and 100μm were ...probed with a beam of charged hadrons with sub-pixel precision using the Timepix telescope assembled at the SPS at CERN. The sensors are shown to be highly efficient up to a few micrometers from the physical edge of the sensor. The distortion of the electric field lines at the edge of the sensors is studied by reconstructing the streamlines of the electric field using two-pixel clusters. These results are supported by TCAD simulations. The reconstructed streamlines are used to study the field distortion as a function of the bias voltage and to apply corrections to the cluster positions at the edge.
We study the influence of active edges on the response of edge pixels by comparing simulations of the electrostatic-potential distribution to position-defined measurements on the energy deposition. A ...laser setup was used to measure the edge-pixel response function and shows the sensitive edge is only about 2 mu m from the physical edge. 3D reconstruction of tracks from highenergy pions and muons, produced at the SPS H6 test beam facility at CERN, enabled to relate the energy deposition at edge pixels to the particle's interaction depth. A clear correlation is observed between the simulated electric-field distortion and the reconstructed interaction-depth dependent effective size.
Some X-ray imaging applications demand sensitive areas exceeding the active area of a single sensor. This requires a seamless tessellation of multiple detector modules with edgeless sensors. Our ...research is aimed at minimising the insensitive periphery that isolates the active area from the edge. Reduction of the edge-defect induced charge injection, caused by the deleterious effects of dicing, is an important step. We report on the electrical characterisation of 300 mu m thick edgeless silicon p super(1)-v-n super(1) diodes, diced using deep reactive ion etching. Sensors with both n-type and p-type stop rings were fabricated in various edge topologies. Leakage currents in the active area are compared with those of sensors with a conventional design. As expected, we observe an inverse correlation between leakage-current density and both the edge distance and stop-ring width. From this correlation we determine a minimum acceptable edge distance of 50 mu m. We also conclude that structures with a p-type stop ring show lower leakage currents and higher breakdown voltages than the ones with an n-type stop ring.
The ATLAS experiment is preparing for the planned luminosity upgrade of the LHC (the super-luminous LHC or sLHC) with a programme of development for tracking able to withstand an order of greater ...magnitude radiation fluence and much greater hit occupancy rates than the current detector. This has led to the concept of an all-silicon tracker with an enhanced performance pixel-based inner region and short-strips for much of the higher radii. Both sub-systems employ many common technologies, including the proposed “stave” concept for integrated cooling and support. For the short-strip region, use of this integrated stave concept requires single-sided modules mounted on either side of a thin central lightweight support.
Each sensor is divided into four rows of 23.82
mm length strips; within each row, there are 1280 strips of 74.5μm pitch. Well over a hundred prototype sensors are being delivered by Hamamatsu Photonics (HPK) to Japan, Europe and the US.
We present results of the first 20 chip ABCN25 ASIC hybrids for these sensors, results of the first prototype 5120 strip module built with 40 ABCN25 read-out ASICs, and the status of the hybrids and modules being developed for the ATLAS tracker upgrade stave programme.
The construction of the ZEUS micro vertex detector Koffeman, E.N.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2001, Letnik:
473, Številka:
1
Journal Article
Recenzirano
After an 8 month shutdown the HERA collider at DESY (Hamburg, Germany) will resume operation in the summer of 2001. To enhance the tagging capabilities of long lived particles after the expected ...fivefold luminosity increase the ZEUS experiment will install a silicon vertex detector. The barrel part of the detector is a
60
cm
long cylinder with silicon sensors arranged around the beam pipe. The forward part consists of four circular shaped disks. In total just over
200
K
channels are read out using
2.9
m
2
of silicon. In this report the production process is reviewed in detail.
The Timepix readout chip with its 65k pixels on a sensitive area of 14mm×14mm provides a fine spatial resolution for particle tracking or medical imaging. We explore the operation of Timepix in a ...dual-phase xenon environment (around −110°C). Used in dual-phase xenon time projection chambers, e.g. for dark matter search experiments, the readout must have a sufficiently low detection limit for small energy deposits. We measured the electronic pixel noise of three bare Timepix chips. For the first time Timepix readout chips were cooled to temperatures as low as −125°C. In this work, we present the results of analysing noise transition curves recorded while applying a well-defined charge to the pixel׳s input. The electronic noise reduces to an average of 99e−, a reduction of 23% compared to operation at room temperature.
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