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Zatserklyaniy, A.

Publications and source records attributed to Zatserklyaniy, A..

10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Properties of HPK UFSD after neutron irradiation up to 6e15 n/cm 2

In this article we report results from a neutron irradiation campaign of Ultra-Fast Silicon Detectors (UFSD) with fluences of 1e14, 3e14, 6e14, 1e15, 3e15 and 6e15 neq/cm 2 . The UFSD used in this study are circular 50 μm thick Low-Gain Avalanche Detectors (LGAD), with a 1.0 mm diameter active area. Hamamatsu Photonics (HPK), Japan, produced the UFSD with pre-irradiation internal gain in the range 5–70 depending on the bias voltage. The sensors were tested pre-irradiation and post-irradiation with minimum ionizing particles (MIPs) from a 90 Sr β-source. The leakage current, internal gain and the timing resolution were measured as a function of bias voltage at -20 °C and -30 °C. The timing resolution of each device under test was extracted from the time difference with a second calibrated UFSD in coincidence, using the constant fraction discriminator (CFD) method for both. The dependence of the gain upon the irradiation fluence is consistent with the acceptor removal mechanism; at -20 °C the highest gain decreases from 70 before radiation to 2 after a fluence of 6e15 n/cm 2 . Consequently, the timing resolution was found to deteriorate from 20 ps to 50 ps. The results indicate that the most accurate time resolution is obtained varying with fluence the CFD value used to determine the time of arrival, from 0.1 for pre-irradiated sensors to 0.6 at the highest fluence. Key changes to the pulse shape induced by irradiation, i.e. (i) the contribution of charge multiplication not limited to the gain layer zone, (ii) the shortening of the rise time and (iii) the reduced pulse height, were compared with the WF2 simulation program and were found to be in agreement.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Beam test measurements of Low Gain Avalanche Detector single pads and arrays for the ATLAS High Granularity Timing Detector

For the high luminosity upgrade of the LHC at CERN, ATLAS is considering the addition of a High Granularity Timing Detector (HGTD) in front of the end cap and forward calorimeters at (z) = 3.5 m and covering the region 2.4 < (Eta) < 4 to help reducing the effect of pile-up. The chosen sensors are arrays of 50 Mu-m thin Low Gain Avalanche Detectors (LGAD). This paper presents results on single LGAD sensors with a surface area of 1.3x1.3 mm2 and arrays with 2x2 pads with a surface area of 2x2 mm2 or 3x3 mm2 each and different implant doses of the p+ multiplication layer. They are obtained from data collected during a beam test campaign in autumn 2016 with a pion beam of 120 GeV energy at the CERN SPS. In addition to several quantities measured inclusively for each pad, the gain, efficiency and time resolution have been estimated as a function of the position of the incident particle inside the pad by using a beam telescope with a position resolution of few Mu-m. Different methods to measure the time resolution are compared, yielding consistent results. The sensors with a surface area of 1.3x1.3 mm 2 have a time resolution of about 40 ps for a gain of 20 and of about 27 ps for a gain of 50 and fulfill the HGTD requirements. Larger sensors have, as expected, a degraded time resolution. All sensors show very good efficiency and time resolution uniformity.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2016

SU-F-I-54: Spatial Resolution Studies in Proton CT Using a Phase-II Prototype Head Scanner

Purpose: To characterize the modulation transfer function (MTF) of the pre-clinical (phase II) head scanner developed for proton computed tomography (pCT) by the pCT collaboration. To evaluate the spatial resolution achievable by this system. Methods: Our phase II proton CT scanner prototype consists of two silicon telescopes that track individual protons upstream and downstream from a phantom, and a 5-stage scintillation detector that measures a combination of the residual energy and range of the proton. Residual energy is converted to water equivalent path length (WEPL) of the protons in the scanned object. The set of WEPL values and associated paths of protons passing through the object over a 360° angular scan is processed by an iterative parallelizable reconstruction algorithm that runs on GP-GPU hardware. A custom edge phantom composed of water-equivalent polymer and tissue-equivalent material inserts was constructed. The phantom was first simulated in Geant4 and then built to perform experimental beam tests with 200 MeV protons at the Northwestern Medicine Chicago Proton Center. The oversampling method was used to construct radial and azimuthal edge spread functions and modulation transfer functions. The spatial resolution was defined by the 10% point of the modulation transfer function in units of lp/cm. Results: The spatial resolution of the image was found to be strongly correlated with the radial position of the insert but independent of the relative stopping power of the insert. The spatial resolution varies between roughly 4 and 6 lp/cm in both the the radial and azimuthal directions depending on the radial displacement of the edge. Conclusion: The amount of image degradation due to our detector system is small compared with the effects of multiple Coulomb scattering, pixelation of the image and the reconstruction algorithm. Improvements in reconstruction will be made in order to achieve the theoretical limits of spatial resolution.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Development of a New Fast Shower Maximum Detector Based on Microchannel Plates Photomultipliers (MCP-PMT) as an Active Element

One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photodetectors based on microchannel plates (MCPs) as the secondary emitter. We performed the measurements at the Fermilab Test Beam Facility with 120GeV proton beam and 12GeV and 32GeV secondary beams. The goal of the measurement with 120GeV protons was to determine time resolution for minimum ionizing particles (MIPs). The SM time resolution we obtained for this new type of detector is at the level of 20-30ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP. This work can be considered as the first step in building a new type of calorimeter based on this principle.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗