1,519 research outputs found
Construction of a Fast Diode-Laser based Calibration System for Time-of-Flight Systems
No full textFor the calibration and monitoring of scintillator based time-of-flight systems, fast laser pulses, delivered to the individual channels, may be used. Low-cost laser diodes with FWHM time resolution in the range 30-50 ps may be chosen as light source. The problem is their low output power, as compared to traditional solutions as expensive duplicated Nd-Yag lasers. The tests done to assemble a prototype system based on optical switches and fiber fused splitters will be summarized, as well as the ones on the full-scale prototype. The main concern was the tight power budget of the system
A laser diode based system for calibration of fast time-of-flight detectors
No full textA system based on commercially available items, such as a laser diode, emitting in the visible range similar to 400 nm, and multimode fiber patches, fused fiber splitters and optical switches may be assembled, for time calibration of multi-channels time-of-flight (TOF) detectors with photomultipliers' (PMTs') readout. As available laser diode sources have unfortunately limited peak power, the main experimental problem is the tight light power budget of such a system. In addition, while the technology for fused fiber splitters is common in the Telecom wavelength range (lambda similar to 850; 1300-1500 nm), it is not easily available in the visible one. Therefore, extensive laboratory tests had to be done on purpose, to qualify the used optical components, and a full scale timing calibration prototype was built. Obtained results show that with such a system, a calibration resolution (sigma) in the range 20-30 ps may be within reach. Therefore, fast multi-channels TOF detectors, with timing resolutions in the range 50-100 ps, may be easily calibrated in time.
Results on tested optical components may be of interest also for time calibration of different light detection systems based on PMTs, as the ones used for detection of the vacuum ultraviolet scintillation light emitted by ionizing particles in large LAr TPCs
Behaviour in magnetic fields of fast conventional and fine-mesh photomultipliers
No full textThe performance of both conventional and fine-mesh Hamamatsu photomultipliers has been measured inside moderate magnetic fields. This has allowed the test of effective shielding solutions for photomultipliers, to be used in time-of-flight detectors based on scintillation counters. Both signal amplitude reduction and deterioration of the timing properties inside magnetic fields have been investigated
Correlated equilibria for mean field games with progressive strategies
No full textIn a discrete space and time framework, we study the mean field game limit for a class of symmetric N-player games based on the notion of correlated equilibrium. We give a definition of correlated solution that allows to construct approximate N-player correlated equilibria that are robust with respect to progressive deviations. We illustrate our definition by way of an example with explicit solutions
The Refurbishing of MICE TOF0 and TOF1 detectors
No full textThe TOF0 and TOF1 detectors have been refurbished in late 2010 and
beginning 2011. About 50 of the older H6533MOD PMT assemblies
(with R4998 PMTs), dismounted from the two detectors, have been sent
to Hamamatsu, Japan, for refurbishing. TOF1 have been completely re-
built at INFN Milano Bicocca, with improvements to the detector’s me-
chanics. Before mounting, R4998 PMTs have been subject to extensive
tests to assess their reliability
Large area LaBr3:Ce crystals read by SiPM arrays with improved timing and temperature gain drift control
No full textCompact X-rays detectors made of 1/2” or 1”: LaBr3:Ce crystals of cubic shape with SiPM array readout have been developed for the FAMU experiment at RIKEN-RAL. The aim is a precise measurement of the proton Zemach radius with incoming muons. Additional applications may be found in medical physics, such as PET, homeland security and gamma-ray astronomy. Due to the high photon yield of LaBr3:Ce it was possible to use a simple readout scheme based on CAEN V1730 digitizers. Detectors, using Hamamatsu S13361 or S14161 arrays, have good FWHM energy resolutions up to 3% (8%) at the Cs137 (Co57) peak, comparing well with the best results obtained with a photomultiplier's readout. Detailed studies were performed to correct online the drift with temperature of SiPM gain and to reduce the risetime/falltime of detectors’ signals, that increased going from 1/2” to 1” detectors, due to the larger capacity of the used SiPM arrays
Calibration of the ICARUS cryogenic photo-detection system at FNAL
No full textThe calibration of the ICARUS photo-detection system is based on a low power laser diode at 405 nm. Laser pulses arrive to one optical switch and then are sent to 36 UHV flanges, by 20 meters long optical patches. Light is then delivered to the ten PMTs connected to a single flange, by 7 m long injection optical patches. Extensive tests of the used components and care in the design of the optical system have guaranteed to each PMT a sizeable calibration signal with minimal distortion, with respect to the original one. Gain equalization of PMTs has reached a 1% resolution. In this procedure data from background photons were also used. The distribution of the PMTs’ signal arrival time has a distribution with a resolution less than 1 ns, thus allowing a good determination of the absolute event timing. The status of the laser calibration system with its possible upgrades will be reported
Systematic Study of a SiPMT array readout for fast time-of-flight detectors
No full textTime-of-flight detectors, based on scintillation counters, may use conventional photomultipliers
for the readout. Problems arise in presence of external magnetic fields. SiPMT arrays are in-
sensitive to magnetic fields and may be a suitable option to replace photomultipliers. Timing
performances for several types of SiPMT arrays have been studied and results are presented
Performance of SiPMT array readout for fast time-of-flight detectors
No full textScintillator based time-of-flight detectors may use conventional photomultipliers for the readout. Problems arise in presence of stray magnetic fields. SiPMT arrays are insensitive to magnetic fields and are a suitable option to replace photomultipliers. Timing performances for several SiPMT arrays have been studied and results are presented
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