Solid state single photon sensors for the RICH application Korpar, S.; Križan, P.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2020, Volume:
970
Journal Article
Peer reviewed
Silicon photomultipliers, arrays of avalanche photodiodes operated in the Geiger mode, are exciting novel light sensors for RICH detectors. In the present review, we discuss the motivation for ...employing solid-state single-photon sensors, describe their principles of operation and challenges of their use. We review the current state of development and the progress made with semiconductor sensors. We also discuss applications in ongoing and planned future experiments.
We present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e+e−→γa, a→γγ in the ...mass range 0.2<ma<9.7 GeV/c2 using data corresponding to an integrated luminosity of (445±3) pb−1. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength gaγγ of ALPs to photons at the level of 10−3 GeV−1. The limits are the most restrictive to date for 0.2<ma<1 GeV/c2.
Detectors for extreme luminosity: Belle II Adachi, I.; Browder, T.E.; Križan, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2018, Volume:
907
Journal Article
Peer reviewed
We describe the Belle II detector at the SuperKEKB electron–positron accelerator. SuperKEKB operates at the energy of the ϒ(4S) resonance where pairs of B mesons are produced in a coherent quantum ...mechanical state with no additional particles. Belle II, the first Super B factory detector, aims to achieve performance comparable to the original Belle and BaBar B factory experiments, which first measured the large CP violating effects in the B meson system, with much higher luminosity collisions and larger beam-induced backgrounds.
Efficiency of a Cherenkov based PET module with an array of SiPMs Dolenec, R.; Korpar, S.; Križan, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2020, Volume:
952
Journal Article
Peer reviewed
The detectors in positron emission tomography (PET) can be based on detection of Cherenkov light instead of the traditional approach of using scintillation light. This enables excellent time ...resolution that can be used in time-of-flight (TOF) PET, but it proved difficult to achieve efficiency in detection of annihilation gammas comparable to traditional methods. The Cherenkov method however has another advantage — low cost of the most suitable conversion material (lead fluoride) compared to the most commonly used scintillators. Especially when incorporating silicon photomultiplier (SiPM) photodetectors, such PET detectors could be realized at a very competitive price. In this work the performance of such PET module is presented, with an emphasis on the efficiency of detection. A module consisting of 4 × 4 lead fluoride Cherenkov radiator array coupled to a Hamamatsu 4 × 4 SiPM array was assembled and its performance was tested using annihilation gammas from a sodium source.
Theories beyond the standard model often predict the existence of an additional neutral boson, the Z^{'}. Using data collected by the Belle II experiment during 2018 at the SuperKEKB collider, we ...perform the first searches for the invisible decay of a Z^{'} in the process e^{+}e^{-}→μ^{+}μ^{-}Z^{'} and of a lepton-flavor-violating Z^{'} in e^{+}e^{-}→e^{±}μ^{∓}Z^{'}. We do not find any excess of events and set 90% credibility level upper limits on the cross sections of these processes. We translate the former, in the framework of an L_{μ}-L_{τ} theory, into upper limits on the Z^{'} coupling constant at the level of 5×10^{-2}-1 for M_{Z^{'}}≤6 GeV/c^{2}.
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Silicon photomultiplier (SiPM) photodetectors perform well in many particle and medical physics applications, especially where good efficiency, insensitivity to magnetic field and precise timing are ...required. In Cherenkov time-of-flight positron emission tomography the requirements for photodetector performance are especially high. On average only a couple of photons are available for detection and the best possible timing resolution is needed. Using SiPMs as photodetectors enables good detection efficiency, but the large sensitive area devices needed have somewhat limited time resolution for single photons. We have observed an additional degradation of the timing at very low light intensities due to delayed events in distribution of signals resulting from multiple fired micro cells. In this work we present the timing properties of AdvanSiD ASD-NUV3S-P-40 SiPM at single photon level picosecond laser illumination and a simple modification of the time-walk correction algorithm, that resulted in reduced degradation of timing resolution due to the delayed events.
•At single photon level illumination, SiPM timing is degraded by optical crosstalk.•Improvements in timing by modifying the time-walk algorithm were demonstrated.•A time resolution of 173ps FWHM was achived with the investigated SiPM.
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, Volume:
654, Issue:
1
Journal Article
Peer reviewed
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.
Cherenkov TOF PET with silicon photomultipliers Dolenec, R.; Korpar, S.; Križan, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2015, Volume:
804
Journal Article
Peer reviewed
As previously demonstrated, an excellent timing resolution below 100ps FWHM is possible in time-of-flight positron emission tomography (TOF PET) if the detection method is based on the principle of ...detecting photons of Cherenkov light, produced in a suitable material and detected by microchannel plate photomultipliers (MCP PMTs). In this work, the silicon photomultipliers (SiPMs) were tested for the first time as the photodetectors in Cherenkov TOF PET. The high photon detection efficiency (PDE) of SiPMs led to a large improvement in detection efficiency. On the other hand, the time response of currently available SiPMs is not as good as that of MCP PMTs. The SiPM dark counts introduce a new source of random coincidences in Cherenkov method, which would be overwhelming with present SiPM technology at room temperature. When the apparatus was cooled, its performance significantly improved.
Slow control of the Belle II Aerogel Ring Imaging detector Pestotnik, R.; Adachi, I.; Adamczyk, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2023, Volume:
1056
Journal Article
Peer reviewed
Open access
Since 2018, an Proximity Focusing Aerogel Ring Imaging Detector (ARICH) efficiently separates hadrons in the forward end-cap of the Belle II spectrometer. Cherenkov photons emitted in the ...double-layer aerogel radiator are expanded in 16-cm space and detected on the photon detector, which consists of 420 hybrid avalanche photodiodes and rear readout electronics operating in threshold mode. Each of the sensors requires six different high voltages and a supply of four low voltages for the electronics. Because of the power dissipation, the system also includes a cooling system in which cold water circulates through the Al tubes thermally connected to the readout electronics. Reliable control of supply voltages and monitoring of environmental data and sensor status ensure stable operation of the ARICH detector and early response to sudden changes in current, single event disturbances, overheating, and other faults. In this paper, we introduce the ARICH’s slow control system and the data quality monitor used to track performance.
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