Search

A 256-channel time-of-flight electronics system has been developed for a facility called “Back-n white neutron source (WNS)” in China Spallation Neutron Source (CSNS). This paper presents the structure and performance of the electronics system and test results at CSNS-WNS. A piece of lithium glass scintillator, coupled with a 256-channel multi-anode photomultiplier tube, is placed at the center of the neutron beam line as the detector. A 256-channel readout electronics system, including one front-end board (FEB), four time-to-digital converter (TDC) cards and one clock distribution module (CDM), measures the arrival time of each signal from the detector. Signals are sent to FEB from the detector through 15-cm cables and discriminated on FEB. FEB drives differential signals over 2-m cables to the TDC cards. Each TDC card has 64 channels, using a field-programmable gate array (FPGA) to measure the arrival time of each signal. The CDM supplies clock signals to the TDC cards to make them work synchronously. The TDC cards and CDM are housed in one peripheral component interconnect (PCI) eXtensions for Instrumentation chassis. The TDC cards achieve a timing precision of 3.5 ns. The electronics system meets the requirement of the experiment and is currently being used in CSNS. [ABSTRACT FROM AUTHOR]

The Circular Electron Positron Collider (CEPC) is a proposing electron–positron collider in China, which aims for generating high center-of-mass energy colliding above 250 GeV. The high-granularity electromagnetic calorimeter (ECAL) is included in a calorimeter system, which is mainly responsible for the measurement of photon. A particle flow algorithm (PFA)-based ECAL solution will utilize about 400k channels/m3. Here, we present the design and development status of readout electronics based on SPIROC2b for the CEPC ECAL with high-granularity scintillants and silicon photomultipliers (SiPMs). The readout electronics consists of front-end electronics (FEE), data interface (DIF) board, and data acquisition (DAQ) board. The front-end board (FEB) carries SiPMs (S12571-010P), scintillants (PSD), and FEB application-specific integrated circuit (ASIC) (SPIROC2b). Two electronics were designed in this paper, one is for ASIC functionality and performance only, and the other is used as a single layer of a further prototype of ECAL. Electronic test and cosmic ray test have been done to electronics. The results indicate that a charge dynamic from 62 fC to 300 pC at S/N = 2 is successfully achieved, and the minimum ionizing particles (MIPs) are separated from the pedestal. [ABSTRACT FROM AUTHOR]

While the original Compton coincidence technique provided accurate measurements of electron response in scintillators, the data rate was low and measurements took weeks. We present the conceptual design for a high throughput version that is predicted to collect data at 65 cps, reducing measurement times from weeks to hours. In this design, a collimated 1 mCi 137Cs source will illuminate the scintillator sample from a distance of 18 cm and 5 high-purity germanium (HPGe) detectors placed 10 cm from the scintillator will measure the energy of the scattered gamma ray. The source can be placed in either of two positions spaced 15deg apart, allowing relatively uniform scattering angle coverage from 0deg to 146deg, corresponding to electron energies in the scintillator from 0 to 466 keV. The scintillator will be coupled to a hybrid photodetector (HPD), which has extremely linear response, and the HPD's ability to resolve single photoelectrons provides a built-in calibration mechanism. The output of each HPGe detector and the HPD will be digitized with a free-running 12-bit, 200 MHz ADC, providing accurate measurement of the signal amplitudes and the ability to measure the electron response for different temporal components of the scintillator signals. The facility will be located at Lawrence Livermore National Laboratory (LLNL) and is intended to be made available to the community at large. The goals are to facilitate scintillator development and to understand the nature of the light-yield non-proportionality and its effect on the energy resolution. [ABSTRACT FROM PUBLISHER]

This paper investigates the potential of 6LiI(Eu)/photodiode (PD) detector systems for application as neutron counters in radioisotope identification devices (RIID). Those are exposed to mixed neutron-gamma fields. An effective suppression of signals due to gamma interactions with the scintillator or the PD bulk material is of major importance since neutron alarms in RIID are triggered by a few single neutron counts; any gamma signal not rejected may generate a false neutron alarm. Measurements demonstrated that digital signal processing combined with simultaneous pulse height and pulse shape analysis can provide efficient neutron-gamma discrimination. The results were obtained with a compact, basic detector configuration and sampling rates of only 10 MS/s. Such systems can be realized with state-of-the-art miniaturized electronics. [ABSTRACT FROM AUTHOR]

The PIENU experiment is going to be carried out at TRIUMF to measure the ratio of pion decay rates, R = Γ (π+ → e+νe)/Γ(π+ → μ+νμ), to an accuracy of 0.1%. In order to achieve this goal, a muon identification with waveform analysis in a target scintillator is necessary. Due to the short lifetime of pions, muon pulses tend to overlap onto the tail of pion pulses. Thus waveform analysis with a high frequency flash-ADC is essential for the identification and separation of muon pulses. We use the 500-MHz flash-ADC of the COmmon Pipelined Platform for Electronics Readout system, which was developed at KEK, to readout waveforms from the target scintillator. Muon pulse identification capability of this flash-ADC system was investigated by artificial pulses simulating photomultiplier signals. [ABSTRACT FROM AUTHOR]

The experimental application of a digital technique for high-resolution estimation of occurrence time of detected events is described. In particular, the method that achieves timing precisions well below the sampling time interval is tested for timing of events from scintillation detectors. The validity of the technique is demonstrated both in terms of achieved performances and of implementation simplicity in an electronic architecture based on a FPGA device. [ABSTRACT FROM AUTHOR]

Readout electronics for the scintillation bar tracking detector (SciBar) in the K2K neutrino oscillation experiment has been developed. SciBar has 14336 scintillator bars in total. The deposited energy and timing of particles from neutrino interactions in the scintillator bars are measured by 64-channel multianode photo-multiplier tubes (MAPMTs). Compact custom-designed electronics to record the MAPMT signals were developed, consisting of front-end circuit boards attached to each MAPMT and back-end electronics modules sitting in a VME crate. The front-end circuit board multiplexes pulse-height information from all 64 anodes and generates a fast triggering signal. Two sets of ASICs (IDEAS VA32HDR11 and TA32CG) are employed for these functions. The bias voltages and relay of control signals are also handled on the board. The back-end electronics module controls the front-end board by providing the control, timing, and low-voltage signals. The board also digitizes the multiplexed signal from the front-end. The electronics achieves low noise of less than 0.3 photoelectrons and and linearity up to 300 (150) photo-electrons for MAPMTs at the gain of 5 × 105 (106). [ABSTRACT FROM AUTHOR]

In this paper, we present a small prototype of Anger camera based on a monolithic array of silicon drift detectors (SDDs) coupled to a single LSO scintillator. The SOD photodetector consists of an array of 19 hexagonal units with on-chip JFET and has about 1 cm2 of total sensitive area. The SOD array was already successfully tested with a CsI(TI) crystal. However, the long scintillation decay time of CsI(TI) requires the use of a long shaping time to reduce the effect of the ballistic deficit. This requirement does not allow to fully exploit the low electronics noise of the SOD, which, on the contrary, reaches its minimum noise at short shaping times. Moreover, the use of a faster scintiliator would improve the overall counting rate capability of the Anger Camera. On the other side, the LSO scintillator is characterized by a lower scintillation conversion efficiency with respect to CsI(TI) and by a natural background. In this work the performances which could be expected from a LSOSSDD Anger Camera are first evaluated. Then, the results achieved in the experimental characterization of a prototype of this detector are presented. A position resolution better than 1 mm FWHM using a 57Co source (122 keV) has been measured. [ABSTRACT FROM AUTHOR]

A compact, low noise, and low cost readout system based on commercially available application-specific integrated circuits (ASICs) is under investigation. These front-end circuits have been used to readout a prototype detector module comprising Lutetium Oxyorthosificate (LSO) scintillation crystals coupled to avalanche photodiode (APD) arrays. A major goal for this work is to build a dedicated high performance breast imaging PET system. Characteristics of signal response, noise, pedestals and gain of the chip have been evaluated. The channels have a linear response to within 2% across a ± 50 fC dynamic range. The circuits allow hardware adjustment of bias levels to allow gain uniformity of less than 5% for all channels within a chip and the gain performance is very stable over all channels. Initial tests of the chip when connected to a prototype APD array also showed good performance. 13% energy resolution was obtained with direct 5.9 keV X-ray interactions in an individual APD pixel. Initial performance evaluation indicates that the ASIC may serve as a foundation for front-end readout electronics for the proposed PET system. [ABSTRACT FROM AUTHOR]