Study of TOF PET using Cherenkov light Korpar, S.; Dolenec, R.; Križan, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2011, Letnik:
654, Številka:
1
Journal Article
Recenzirano
This work investigates the possibilities of improving the measurements of arrival time difference of the two 511
keV photons arising from annihilation of a positron in positron emission tomography ...(PET). The new technique of detecting the prompt Cherenkov light, produced by absorption of the annihilation photon in a suitable crystal, could considerably improve the image quality. A simple apparatus with PbF
2 crystals and microchannel plate photomultipliers (MCP PMTs) has been constructed and coincidence resolutions of 71
ps FWHM and 95
ps FWHM have been achieved with 5 and 15
mm thick crystals, respectively. Simulation calculations are in agreement with the experimental findings.
On-detector digital electronics in high-energy physics (HEP) experiments is increasingly being implemented by means of static random access memory (SRAM)-based field programmable gate arrays (FPGAs), ...due to their reconfigurability, fast data processing, and transfer. Radiation-induced single-event upsets (SEUs) in the configuration hinder the correct operation, since they may alter the programmed routing paths and logic functions. In most data acquisition systems, data from clustered front-end modules are aggregated by a single board, which then transmits data to off-detector electronics for acquisition and triggering. In this work, we present a novel scrubber capable of correcting radiation-induced upsets in the configuration of SRAM-based FPGAs by majority voting across clustered modules. We designed it for the Aerogel Ring Imaging CHerenkov (ARICH) counter of the Belle II experiment at the KEK Laboratory, Tsukuba, Japan. We discuss the architecture of the system and its implementation in a Virtex-5 FPGA, in the aggregator board, for correcting the configuration of up to six Spartan-6 LX45 FPGAs, on pertaining front-end modules. We discuss results from neutron irradiation tests at the TRIGA reactor of the Jožef Stefan Institute, Ljubljana, Slovenia, which show that our solution corrects an average of 6.2 k upsets in each target FPGA before the failure of the scrubber. Moreover, with respect to the Xilinx soft error mitigation (SEM) controller, our design improved the mean time before failure of data readout by 30%.
Test of the Hamamatsu MPPC module S11834 as a RICH photon detector Korpar, S.; Tahirović, E.; Križan, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Letnik:
766
Journal Article
Recenzirano
In our previous studies, we have shown that silicon photo-multipliers can be used as single photon detectors in a RICH counter (Korpar et al., 2009, 2010 1 and 2). Their main advantage with respect ...to the classical photo-multiplier tubes is the operation in high magnetic fields, while their disadvantage is a relatively high dark count rate. Recently, Hamamatsu made commercially available sensors with a rather low dark count rate ( approximately 0.1 MHz/mm super(2)) and with a larger active area, offering a possibility for a much better signal-to-noise ratio. We have designed, constructed and tested a module with Hamamatsu 88 channel S11834 MPPCs. To increase the geometric acceptance, light concentrators have been employed. In the present contribution we discuss the results of studies of the light concentrator design optimization and of the detector module response to fast light pulses. Also presented are the results of RICH prototype tests in a test beam.
Silicon photomultipliers (SiPMs) were considered as photodetectors in Cherenkov time-of-flight positron emission tomography (TOF PET) due to their relatively high photon detection efficiency (PDE) ...which resulted in a higher gamma detection efficiency of the Cherenkov PET detector. SiPMs produced by KETEK, AdvanSiD, SensL and Hamamatsu were tested in this application. The coincidence time resolution, gamma detection efficiency and single side event rates were measured in a simple experimental setup, consisting of two detectors placed in a coincidence configuration. The apparatus was cooled to -25° C in order to reduce the SiPM dark count rates. A single side gamma detection efficiency of up to 26% was measured, which is a marked improvement over previous Cherenkov TOF PET measurements. The best measured coincidence time resolution of 297 ps FWHM was limited by the time response of the SiPMs used for this experiments.
Test of the HAPD light sensor for the Belle II Aerogel RICH Yusa, Y.; Adachi, I.; Dolenec, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2017, Letnik:
876
Journal Article
Recenzirano
The Aerogel Ring-Imaging Cherenkov detector (ARICH) is being installed in the endcap region of Belle II spectrometer to identify particles from B meson decays by detecting the Cherenkov ring image ...from aerogel radiators. To detect single photons, high-sensitive photon detector which has wide effective area (∼70mm × 70mm), a Hybrid Avalanche Photo Detector (HAPD), has been developed in a collaboration with Hamamatsu K.K. The HAPD consists of hybrid structure of a vacuum tube and an avalanche photodiode (APD). It can be operated in 1.5T magnetic field of the spectrometer and withstands the radiation levels expected in the Belle II experiment. There are two steps of electric pulse amplification: acceleration of photo-electron in electric field in the vacuum tube part and electron avalanche in the APD part resulting in total gain of order 105. For the ARICH, we use 420 HAPDs in total. Before installing them, we performed quality assessment studies such as measurements of dark current, noise level, signal-to-noise ratio and two-dimensional scan with laser illumination. We also measured quantum efficiency of the photocathode. During the HAPD performance tests in the magnetic field, we observed very large signal pulses which cause long dead time of the readout electronics in some of the HAPDs. We have carried out a number of studies to understand this phenomenon, and have found a way to mitigate it and suppress the degradation of the ARICH performance. In this report, we will show a summary of the HAPD performance and quality assessment measurements including validation in the magnetic field for all of the HAPDs manufactured for the ARICH in the Belle II.
In the forward end-cap of the Belle II spectrometer, particle identification is provided by a proximity focusing RICH detector with an aerogel radiator (ARICH). The ARICH’s primary function is to ...effectively distinguish between pions and kaons in the momentum range of 0.5GeV/c to about 4GeV/c, as well as to contribute to identification of low-momentum leptons. Since its operation began, Belle II has collected over 420fb−1 of data. Based on this large data sample, studies of several effects that impact the performance of the ARICH detector were carried out. In this paper, we present a comparison of the observed Cherenkov ring image and detector particle identification performance in the measured data and detector simulation. Furthermore, we highlight recent efforts aimed at enhancing the ARICH’s performance by taking into account the effects of particle decay in flight and scattering in materials before the detector, as well as by refining the probability density function used for particle identification likelihood evaluation.
The detection of annihilation photons in PET is based on scintillation light detection, but an interesting alternative is detection based on Cherenkov photons. Dense Cherenkov radiators provide an ...opportunity for high gamma detection efficiency -due to their high stopping power and photofraction -and excellent coincidence time resolution (CTR). However, because only a few tens of Cherenkov photons follow a gamma interaction in the radiator, the detection efficiency and the energy resolution of a pure Cherenkov detector are an issue. This work explores gamma detection efficiency and CTR of PbF2 based detectors with different surface treatments and photo-detectors covering one, two, or all crystal faces. Following the detector simulation analysis, we investigate the potential performance of a full-size Cherenkov PET scanner and quantitatively compare image quality with a commercial clinical PET scanner. We demonstrate that even though pure Cherenkov scanners have basically no energy resolution, the scatter fraction of around 50 is not prohibitively large, and images comparable to the stateof-the-art clinical PET scanner can be achieved due to improved efficiency and CTR attainable with PbF2.
The Belle II experiment is a new generation B factory experiment at the SuperKEKB electron–positron collider. The main purpose of the experiment is to search for new physics with a large sample of B ...meson decays. The proximity-focusing Aerogel Ring-Imaging Cherenkov detector (ARICH) has been designed to identify kaons and pions in the forward end-cap of the Belle II spectrometer. Using aerogel as radiator with specialized photon sensors called HAPD, the K/π separation is expected to reach more than 4 σ in the momentum range from 0.5 GeV/c to 4.0 GeV/c. ARICH detector was constructed in summer 2017 and was installed in the Belle II spectrometer in the beam line of the SuperKEKB collider. The test of the ARICH detector is performed using both cosmic rays and the beam collisions during the accelerator commissioning. We observe Cherenkov rings in the ARICH detector associated with charged tracks detected by the tracking system. The reconstructed Cherenkov angle distribution has a clear and reasonable peak. The ARICH K∕π separation performance is evaluated using Bhabha events in beam runs; the separation power achieve the design value.
Front-end electronics of the Belle II aerogel ring imaging detector Pestotnik, R.; Adachi, I.; Burmistrov, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2020, Letnik:
952
Journal Article
Recenzirano
A proximity focusing RICH detector with an aerogel radiator is used for charged particle identification in the forward end-cap of the Belle II spectrometer. The detector, consisting of a 4 cm aerogel ...radiator, a 16 cm expansion volume and a photon detector with 420 Hybrid Avalanche Photo Detectors, is mounted in a very confined space between Central Drift Chamber and Electromagnetic Calorimeter, allowing only 5 cm of space for the readout electronics. In our solution, low power front-end read-out boards are mounted at the back side of each of the HAPD photosensors. These boards have each been tested individually before their installation onto the photosensors and into the spectrometer. Most important design issues and first experiences with the aforementioned front-end read-out boards are presented in this contribution.
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