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Background: FLASH Radiotherapy (RT) is an emergent cancer RT modality where an entire therapeutic dose is delivered at more than 1000 times higher dose rate than conventional RT. For clinical trials to be conducted safely, a precise and fast beam monitor that can generate out‐of‐tolerance beam interrupts is required. This paper describes the overall concept and provides results from a prototype ultra‐fast, scintillator‐based beam monitor for both proton and electron beam FLASH applications. Purpose: A FLASH Beam Scintillator Monitor (FBSM) is being developed that employs a novel proprietary scintillator material. The FBSM has capabilities that conventional RT detector technologies are unable to simultaneously provide: (1) large area coverage; (2) a low mass profile; (3) a linear response over a broad dynamic range; (4) radiation hardness; (5) real‐time analysis to provide an IEC‐compliant fast beam‐interrupt signal based on true two‐dimensional beam imaging, radiation dosimetry and excellent spatial resolution. Methods: The FBSM uses a proprietary low mass, less than 0.5 mm water equivalent, non‐hygroscopic, radiation tolerant scintillator material (designated HM: hybrid material) that is viewed by high frame rate CMOS cameras. Folded optics using mirrors enable a thin monitor profile of ∼10 cm. A field programmable gate array (FPGA) data acquisition system generates real‐time analysis on a time scale appropriate to the FLASH RT beam modality: 100–1000 Hz for pulsed electrons and 10–20 kHz for quasi‐continuous scanning proton pencil beams. An ion beam monitor served as the initial development platform for this work and was tested in low energy heavy‐ion beams (86Kr+26 and protons). A prototype FBSM was fabricated and then tested in various radiation beams that included FLASH level dose per pulse electron beams, and a hospital RT clinic with electron beams. Results: Results presented in this report include image quality, response linearity, radiation hardness, spatial resolution, and real‐time data processing. The HM scintillator was found to be highly radiation damage resistant. It exhibited a small 0.025%/kGy signal decrease from a 216 kGy cumulative dose resulting from continuous exposure for 15 min at a FLASH compatible dose rate of 237 Gy/s. Measurements of the signal amplitude versus beam fluence demonstrate linear response of the FBSM at FLASH compatible dose rates of >40 Gy/s. Comparison with commercial Gafchromic film indicates that the FBSM produces a high resolution 2D beam image and can reproduce a nearly identical beam profile, including primary beam tails. The spatial resolution was measured at 35–40 µm. Tests of the firmware beta version show successful operation at 20 000 Hz frame rate or 50 µs/frame, where the real‐time analysis of the beam parameters is achieved in less than 1 µs. Conclusions: The FBSM is designed to provide real‐time beam profile monitoring over a large active area without significantly degrading the beam quality. A prototype device has been staged in particle beams at currents of single particles up to FLASH level dose rates, using both continuous ion beams and pulsed electron beams. Using a novel scintillator, beam profiling has been demonstrated for currents extending from single particles to 10 nA currents. Radiation damage is minimal and even under FLASH conditions would require ≥50 kGy of accumulated exposure in a single spot to result in a 1% decrease in signal output. Beam imaging is comparable to radiochromic films, and provides immediate images without hours of processing. Real‐time data processing, taking less than 50 µs (combined data transfer and analysis times), has been implemented in firmware for 20 kHz frame rates for continuous proton beams. [ABSTRACT FROM AUTHOR]

In positron emission tomography (PET), parallax errors degrade spatial resolution. The depth of interaction (DOI) information provides the position in the depth of the scintillator interacting with the γ-rays, thus reducing parallax errors. A previous study developed a Peak-to-Charge discrimination (PQD), which can separate spontaneous alpha decay in LaBr3:Ce. Since decay constant of GSO:Ce depends on Ce concentration, the PQD is expected to discriminate GSO:Ce scintillators with different Ce concentration. In this study, the PQD-based DOI detector system was developed, which can be processed online and implemented in PET. A detector was composed of four layers of GSO:Ce crystals and a PS-PMT. The four crystals were obtained from both the top and bottom of ingots with a nominal Ce concentration of 0.5 mol% and 1.5 mol%. The PQD was implemented on the Xilinx Zynq-7000 SoC board with 8ch Flash ADC to gain real-time processing, flexibility, and expandability. The results showed that the mean Figure of Merits in 1D between four scintillators are 1.5, 0.99, 0.91 for layers between 1st–2nd, 2nd–3rd, and 3rd–4th respectively, and the mean Error Rate in 1D between four scintillators are 3.50%, 2.96%, 13.3%, and 1.88% for layers 1, 2, 3, and 4, respectively. In addition, the introduction of the 2D PQDs resulted in the mean Figure of Merits in 2D greater than 0.9 and the mean Error Rate in 2D less than 3% in all layers. [ABSTRACT FROM AUTHOR]

• A new high-speed digital pulse signal acquisition and processing (SAQP) system based on micro telecommunications computing architecture (MTCA) is developed, and realizes the first application of MTCA on EAST. • The new SAQP system is capable to process and transfer data in real time. • Analyzed the characteristics of two trigger detection methods and applied them to baseline restoration, pulse processing and pile-up detection. • The real-time algorithm possesses the capability for real-time baseline restoration, n- γ discrimination, pulse amplitude analysis, pile-up event detection and dynamic pulse recording window for recording entire pulse waveform. Neutron emission spectroscopy (NES) diagnosis is an important technique in high-power thermonuclear fusion experiments for studying fast ions. In the fusion NES measurement on the Experimental Advanced Superconducting Tokamak (EAST), the liquid scintillator detector was employed. This selection was based on the detector's high sensitivity, fast time-response and superior n- γ discrimination properties. In order to meet the demands of high-parameter experiments and fully leverage the diagnostic capabilities, a new signal acquisition and processing (SAQP) system based on Micro-telecommunications computing architecture (MTCA) was developed equipped with real-time processing capabilities. The new SAQP system aims to perform real-time acquisition, processing and storage of neutron and gamma flux data from the NES system, allowing the possibility of maximum count rates of 2 Mcps during the EAST experiment. This paper presents the real-time algorithm implemented on field programmable gate array (FPGA). It possesses the capability for real-time baseline restoration, n- γ discrimination, pulse amplitude analysis, pile-up event detection and dynamic pulse recording window for recording entire pulse waveforms. The new SAQP system, including the integrated real-time algorithm, underwent detailed testing with both a signal generator and a neutron generator. The experimental results indicate that the real-time algorithm successfully achieve all expected functions, enhancing performance in n- γ discrimination and dynamically recording entire pulse waveforms at high count rates without data loss. [ABSTRACT FROM AUTHOR]

These days, research on the classification of neutron/gamma waveforms in scintillators using pulse shape discrimination (PSD) techniques is a highly studied topic. Numerous methods have been explored to optimize this classification, with some of the most recent research being focused on machine learning techniques with excellent results. These approaches are mainly based on the use of 1-D convolutional neural networks (CNNs). In this field, field-programmable gate arrays (FPGAs) with high-sampling rate analog to digital converters (ADCs) have been used to perform this classification in real-time. In this work, we select a potential architecture and implement it with the help of the IntelFPGA OpenCL SDK environment. A shorter and C-like development of OpenCL enables a more straightforward modification and optimization of the network architecture. The main goal of this work is the evaluation of the needed resources and the obtained performance to prototype a complete solution in the FPGA. The FPGA design is generated as if it was connected to an ADC module streaming the data samples with the help of a Board Support Package developed for an IntelFPGA ARRIA10 available in an Advanced Mezzanine Card (AMC) module in an Micro Telecommunications Computing Architecture (MTCA.4) platform. The prototyped solution has been integrated into Experimental Physics and Industrial Control System (EPICS) using the nominal device support (NDS) model currently being developed by ITER. [ABSTRACT FROM AUTHOR]

A 6LiF:ZnS(Ag)-based cold neutron detector with wavelength shifting (WLS) fibers and Silicon photomultiplier (SiPM) photodetector was developed at the NIST Center for Neutron Research. For neutron scattering applications at the NCNR, detector false positives severely diminish the quality of very faint neutron scatter patterns. Thermal noise generated by the SiPM significantly increases the likelihood of false positives by the detector/discriminator. This article describes and evaluates a digital real-time algorithm implemented on a field programmable gate array (FPGA) which quickly differentiates SiPM thermal noise and noise pulse pile-up from neutron signals. The algorithm reduces deadtime spent on examining noise pulses as well as reduces the number of false positives. [ABSTRACT FROM AUTHOR]

• The performance of a Multi Pixel Photon Counting (MPPC) module device was explored using a Light Emitting Diode (LED) Programmable Logic Device (PLD) controller based light source to fully simulate the irradiation delivered from a clinical linear accelerator via an Optical Fibre Sensor resulting in considerable cost savings for the hospital. • The experimental data has verified that the MPPC module is an excellent choice of photodetector due to its linearity, stability and ultra-high sensitivity, being able to capture the single photon incident events, whilst not suffering from "burn in" if entering the saturated state. • This study has confirmed that it is essential that the analogue output signal is monitored in order to accurately profile the captured light signal. Hence, combining the information from the oscilloscope (analogue output) and software means that this detection system is ideally suited for monitoring the output of an optical fibre based sensor to measure dose during treatment in the case of therapeutic X-Ray Linacs in real-time. A novel robust compact light emitting diode (LED) based laboratory simulator system for mimicking the output from an optical fibre sensor used to detect therapeutic X-ray pulses from a clinical linear accelerator (linac) is described and performance characterised with reference to real clinical data. The purpose of configuring the LED system is to facilitate accurate assessment of the operating characteristics of the optical fibre based measurement system without having to deploy it in the clinic, thus minimising the need for expensive repeated clinical testing. The output signal from the scintillation material based optical fibre sensor is known to be pulsatile in response to the pulsed X-ray output of the linac. An in-depth knowledge of the characteristics of the X-ray pulsed waveform arising from a series of previous clinical based measurements has facilitated the design and construction of the dedicated LED source described in this article. Results are presented using a field programmable gate array (FPGA) LED simulator source system that replicates a wide range of the linac's pulsed output waveforms including being able to vary the amplitude, pulse width and frequency (repetition rate) of the source. These results are compared to recent results captured using a multi-pixel photon counting (MPPC) detector in the clinic for proving efficacy. [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]

A real-time $n/\gamma $ discrimination prototype system based on high-speed waveform sampling and high-performance field-programmable gate array (FPGA) is presented in this paper. In order to accurately record detector signals, a high-speed sampling board with a 14-bit analog-to-digital converter (AD9680) is designed. The BC501A liquid scintillator is employed as the neutron detector, and a discrimination algorithm is implemented in the FPGA of the sampling board. The system is calibrated by 22Na, 137Cs, and 60Co $\gamma $ -sources. A PuC neutron source is used to evaluate the discrimination ability. The figure-of-merit of PuC neutron source is determined to be about 1.005 over an energy range of 0–4000 keVee, which is consistent with the test results of the commercial digitizer, and the false alarm rate of 60Co is 0.19%. This system has been successfully applied for the environmental neutron monitoring experiment during the first commissioning of white neutron source tunnel of China spallation neutron source. [ABSTRACT FROM AUTHOR]

This paper describes the high-priority testing activities supporting the ITER radial neutron camera (RNC) design, performed by a consortium of European institutes within a framework contract placed by fusion for energy, the ITER European Domestic Agency. The main role of the RNC is to measure the uncollided 14- and 2.5-MeV neutrons from deuterium–tritium and deuterium–deuterium fusion reactions through an array of flux monitors/spectrometers located in collimated lines of sight viewing the plasma through the ITER equatorial port plug #1. The line-integrated neutron fluxes will be used to evaluate, through reconstruction techniques, the radial profile of the neutrons emitted per unit time and volume (neutron emissivity) and, therefore, the neutron yield and the alpha particles’ birth profile. The activity of high-priority testing is dedicated to the preparation and the design of experimental test environment, the conduction of appropriate tests and reporting of test results for the high-priority prototypes, clarifying or verifying the expected key function and system behavior, and enhancing learning on specific issues (potential showstoppers). [ABSTRACT FROM AUTHOR]

The electrical pattern recognition can be useful in several applications; generally it is used to detect particular events or anomalies in the signal under analysis or to identify precursors, especially in electrophysiology. Each application requires customized algorithms and appropriate signal processing capabilities. In this article we present the pattern recognition applied to neutron and gamma scintillator analysis; the algorithm can be used considering that the incident particles on the detector produce pulses having different shape. The discrimination of particles is performed starting from a reference patterns set. The algorithm has been designed to be efficiently implemented in programmable logic gate array; anyway, considering the broadband of the signals under analysis, the real time implementation needs simply reference set based on a limited number of patterns due to technological constrains. The algorithm can also be applied off line by using a more complex reference pattern sets in order to detect and to classify the pile-up event, or to compress the scintillator data. The proposed pattern recognition algorithm is based on the cross-correlation operator and on the Euclidean distance between the reference pattern and the shape of the signal under analysis. The automatic pattern recognition algorithm and its simulations are reported in the article. In order to verify the performances in the case of scintillator signals, the algorithm has been applied on data acquired by two scintillator systems irradiated by a neutron-γ source at the Frascati Tokamak Upgrade laboratories. The results confirm the suitability of the method and its future usability. With minor changes the systems can be used in different diagnostic fields. [ABSTRACT FROM AUTHOR]

This paper introduces a novel and extremely simple—and therefore, easily implemented in a field-programmable gate array—method of neutron/gamma pulse discrimination called the histogram-difference method (HDM). Crucially, this method relies on the use of a “reference set” of \gamma -only pulses from 22Na, 137Cs, and 60Co sources and on features extracted from the pulses. The pulses from this reference set are compared to a set of an identical number of n+\gamma pulses from a 252Cf source. Not only can HDM determine the presence of neutrons in the 252Cf source, but it can also estimate the approximate percentage of neutron pulses from that source. The results reported in this paper are based on data from different radioactive sources and a standard scintillator for this type of research, namely, BC-501A. These results were confirmed using three other scintillators, one made in-house and two others that are commercially available, EJ-299–33 and EJ-200. Pulses were encoded using Q values, which are features extracted from the pulses, that is, ( , Q_{\mathrm{ tail}} ) pairs in \text{S}\mathbb {R}^{2}$ . As control, we also encoded pulses as the root-mean-square (RMS) distances from the average pulse of all known $\gamma $ -only pulses and ran HDM using these pulse representations. The results are very similar to those obtained using a $Q$ -value encoding of the pulses. [ABSTRACT FROM PUBLISHER]

Scintillation detectors offer a single-step detection method for fast neutrons and necessitate real-time acquisition, whereas this is redundant in two-stage thermal detection systems using helium-3 and lithium-6, where the fast neutrons need to be thermalized prior to detection. The relative affordability of scintillation detectors and the associated fast digital acquisition systems have enabled entirely new measurement setups that can consist of sizeable detector arrays. These detectors in most cases rely on photomultiplier tubes, which have significant tolerances and result in variations in detector response functions. The detector tolerances and other environmental instabilities must be accounted for in measurements that depend on matched detector performance. This paper presents recent advances made to a high-speed FPGA-based digitizer. The technology described offers a complete solution for fast-neutron scintillation detectors by integrating multichannel high-speed data acquisition technology with dedicated detector high-voltage supplies. This configuration has significant advantages for large detector arrays that require uniform detector responses. We report on bespoke control software and firmware techniques that exploit real-time functionality to reduce setup and acquisition time, increase repeatability, and reduce statistical uncertainties. [ABSTRACT FROM AUTHOR]

Continuous scintillator-based detectors have been considered as a competitive and cheaper approach than highly pixelated discrete crystal positron emission tomography (PET) detectors, despite the need for algorithms to estimate 3D gamma interaction position. In this work, we report on the implementation of a positioning algorithm to estimate the 3D interaction position in a continuous crystal PET detector using a Field Programmable Gate Array (FPGA). The evaluated method is the Statistics-Based Processing (SBP) technique that requires light response function and event position characterization. An algorithm has been implemented using the Verilog language and evaluated using a data acquisition board that contains an Altera Stratix III FPGA. The 3D SBP algorithm was previously successfully implemented on a Stratix II FPGA using simulated data and a different module design. In this work, improvements were made to the FPGA coding of the 3D positioning algorithm, reducing the total memory usage to around 34%. Further the algorithm was evaluated using experimental data from a continuous miniature crystal element (cMiCE) detector module. Using our new implementation, average FWHM (Full Width at Half Maximum) for the whole block is 1.71±0.01 mm, 1.70±0.01 mm and 1.632±0.005 mm for x, y and z directions, respectively. Using a pipelined architecture, the FPGA is able to process 245,000 events per second for interactions inside of the central area of the detector that represents 64% of the total block area. The weighted average of the event rate by regional area (corner, border and central regions) is about 198,000 events per second. This event rate is greater than the maximum expected coincidence rate for any given detector module in future PET systems using the cMiCE detector design. [ABSTRACT FROM AUTHOR]

Basic concepts and the development of a high counting rate digital spectrometry system based on efficient ADCs and latest available FPGA are presented with the aim of using such a system, coupled to fast scintillators, in plasma experiments. The prototype system is a 1 channel 12-bit 1 GSPS digitizer with 2~\mathrm V\mathrm {pp} input voltage. Preliminary results tested with different radioactive sources are shown for low (0.03 Mcps) and high (2.2 Mcps) counting rates. A comparison of energy spectra and energy resolution with what obtained by a commercial device is also shown. [ABSTRACT FROM PUBLISHER]

Pulse shape discrimination applied to certain fast scintillators is usually performed offline. In sufficiently high-event rate environments data transfer and storage become problematic, which suggests a different analysis approach. In response, we have implemented a general purpose pulse shape analysis algorithm in the XIA Pixie-500 and Pixie-500 Express digital spectrometers. In this implementation waveforms are processed in real time, reducing the pulse characteristics to a few pulse shape analysis parameters and eliminating time-consuming waveform transfer and storage. We discuss implementation of these features, their advantages, necessary trade-offs and performance. Measurements from bench top and experimental setups using fast scintillators and XIA processors are presented. [ABSTRACT FROM AUTHOR]

The SeaQuest experiment (Fermilab E906) detects pairs of energetic μ + and μ − produced in 120 GeV/c proton–nucleon interactions in a high rate environment. The trigger system consists of several arrays of scintillator hodoscopes and a set of field-programmable gate array (FPGA) based VMEbus modules. Signals from up to 96 channels of hodoscope are digitized by each FPGA with a 1-ns resolution using the time-to-digital convertor (TDC) firmware. The delay of the TDC output can be adjusted channel-by-channel in 1-ns step and then re-aligned with the beam RF clock. The hit pattern on the hodoscope planes is then examined against pre-determined trigger matrices to identify candidate muon tracks. Information on the candidate tracks is sent to the 2nd-level FPGA-based track correlator to find candidate di-muon events. The design and implementation of the FPGA-based trigger system for SeaQuest experiment are presented. [ABSTRACT FROM AUTHOR]

A compact, low-cost, wireless gamma-ray spectrometer is a tool sought by a number of different organizations in the field of radiation detection. Such a device has applications in emergency response, battlefield assessment, and personal dosimetry. A prototype device fitting this description has been constructed in the Advanced Radiation Instrumentation Laboratory at Oregon State University. The prototype uses a CsI(Tl) scintillator coupled to a solid-state photomultiplier and a 40MHz, 12-bit, FPGA-based digital pulse processor to measure gamma radiation, and is able to be accessed wirelessly by mobile phone. The prototype device consumes roughly 420mW, weighs about 28g (not including battery), and measures 2.54x3.81cm². The prototype device is able to achieve 5.9% FWHM energy resolution at 662keV. [ABSTRACT FROM AUTHOR]

A new pulse-processing electronics architecture for photomultipliers coupled to fast scintillators used in nuclear physics experiments is described. The system comprises a field programmable gate array (FPGA) based time-to-digital converter (TDC), as well as custom analog electronics for amplification and efficient analog signal processing. These electronics include separate fast and slow discrete amplifiers to extract the timing and energy information of the incident radiation on cerium doped lanthanum bromide scintillators. With the slow amplifier, a novel circuit that is able to convert energy information directly into pulse width with a linear dependence is introduced. Advanced and highly demanded features such as low-processing time, high data rate handling capabilities and long collection windows have been tested with radioactive ion-beams. These characteristics of pulse-processing modules will further push the boundaries of experimental freedom. [ABSTRACT FROM AUTHOR]

A novel digital PET scanner based on Time over Threshold method is developed. The positron emission tomography (PET) is composed of 144channel Ce:Gd3Al2Ga3O12 (GAGG)-Avaranche photodiode (APD) detector arrays individually coupled with custom designed Time over Threshold (ToT) application-specific integrated circuit (ASIC) to realize the high count rate and good spatial resolution. Such an imaging system provides a simple front-end circuit and flexible digital signal processing like multiplexing such as a pulse train method. The measured energy resolution of the detector system was 6.7% for the 511 keV peak, and 4.25 ns time resolution was measured with a single detector module. The measured spatial resolution for a point source was 1.37 mm FWHM for our initial data with a columnar ^22Na source. [ABSTRACT FROM PUBLISHER]

A DAQ architecture for a PET system is presented that focuses on modularity, scalability and reusability. The system defines two basic building blocks: data acquisitors and concentrators, which can be replicated in order to build a complete DAQ of variable size. Acquisition modules contain a scintillating crystal and either a position-sensitive photomultiplier (PSPMT) or an array of silicon photomultipliers (SiPM). The detector signals are processed by AMIC, an integrated analog front-end that generates programmable analog outputs which contain the first few statistical moments of the light distribution in the scintillator. These signals are digitized at 156.25 Msamples/s with free-running ADCs and sent to an FPGA which detects single gamma events, extracts position and time information online using digital algorithms, and submits these data to a concentrator module. Concentrator modules collect single events from acquisition modules and perform coincidence detection and data aggregation. A synchronization scheme over data links is implemented that calibrates each link’s latency independently, ensuring that there are no limitations on module mobility, and that the architecture is arbitrarily scalable. Prototype boards with both acquisition and concentration functionality have been built for evaluation purposes. The performance of a small PET system with two detectors based on continuous scintillators is presented. A synchronization error below 50 ps rms is measured, and energy resolutions of 19% and 24% and timing resolutions of 2.0 ns and 4.7 ns FWHM are obtained for PMT and SiPM photodetectors, respectively. [ABSTRACT FROM PUBLISHER]

Small solid-state photomultipliers (SSPMs) are an alternative scintillator light-detection technology to traditional photomultiplier tubes that offer advantages such as lower bias voltages and insensitivity to magnetic fields. A digital spectrometer using a commercially available SSPM was constructed and characterized at Oregon State University as a prototype for small, highly-mobile, low-power, robust spectroscopy devices. The SSPM has over 19,000 microcells in a photo-sensitive area of 6.32\,\times\,6.32 mm and was coupled to 6\,\times\,6\,\times\,10 mm reflectively-coated CsI(Tl) crystals. The rest of the spectrometer consists of a fast preamplifier and 200 MHz, 12-bit digital pulse processor based around a field-programmable gate array (FPGA). The efficiency, resolution, linearity, and peak-to-Compton ratio of the system were characterized. [ABSTRACT FROM PUBLISHER]

Abstract: Astro-H is the sixth Japanese X-ray space observatory which will be launched in 2014. Two of onboard instruments of Astro-H, Hard X-ray Imager and Soft Gamma-ray Detector are surrounded by many number of large Bismuth Germanate (Bi4Ge3O12; BGO) scintillators. Optimum readout system of scintillation lights from these BGOs are essential to reduce the background signals and achieve high performance for main detectors because most of gamma-rays from out of field-of-view of main detectors or radio-isotopes produced inside them due to activation can be eliminated by anti-coincidence technique using BGO signals. We apply Avalanche Photo Diode (APD) for light sensor of these BGO detectors since their compactness and high quantum efficiency make it easy to design such large number of BGO detector system. For signal processing from APDs, digital filter and other trigger logics on the Field-Programmable Gate Array (FPGA) is used instead of discrete analog circuits due to limitation of circuit implementation area on spacecraft. For efficient observations, we have to achieve as low threshold of anti-coincidence signal as possible by utilizing the digital filtering. In addition, such anti-coincident signals should be sent to the main detector within to make it in time to veto the A–D conversion. Considering this requirement and constraint from logic size of FPGA, we adopt two types of filter, 8 delay taps filter with only 2 bit precision coefficient and 16 delay taps filter with 8 bit precision coefficient. The data after former simple filter provides anti-coincidence signal quickly in orbit, and the latter filter is used for detail analysis after the data is down-linked. [Copyright &y& Elsevier]

Monte Carlo simulations of a time-of-flight Positron Emission Tomography front end readout system (TOF-PET) are performed to investigate obtainable timing resolution at different ADC sample times using LYSO scintillators. Results from simulations with different combinations of ADC sample times and analog filter time constants are presented. To determine the coincidence resolving time (CRT), a trigger system based on a digital constant fraction zero crossing discriminator (CFD) is investigated. Such a trigger system would be suitable for running real time in a field-programmable gate array (FPGA). It is seen that below a certain sample time, the time resolution is limited by the scintillator and MPPC combination, and not the readout system. [ABSTRACT FROM PUBLISHER]

Abstract: In a recent development of a fully digital spectrometer for time differential perturbed angular correlations a true constant fraction trigger (CFT) algorithm was implemented that, however, allowed for integer delays, i.e. integer multiples of the sampling interval, only. With a sampling rate of 1GS/s and BaF2 scintillators this turned out to be insufficient. Here, we present an extension of the algorithm to fractional delays implemented in field programmable gate arrays (FPGAs). Furthermore, we derive a criterion for the delay for optimum timing based on the steepest slope of the CFT signal. Experimental data are given for LaBr3(Ce) scintillators and 511keV–511keV prompt coincidences that corroborate the theoretical result. [Copyright &y& Elsevier]

Abstract: We present a single pixel prototype of a pixelated Bragg edge detector for neutron transmission measurements. The optical signal coming from a scintillator is collected by an optical fiber and is detected by an avalanche photodiode. A fast, Field Programmable Gate Array based, readout allows to obtain transmission spectra within reasonable acquisition times. The performances of the instrument have been tested by measuring the transmission spectra of iron powder samples with two different scintillators. The instrument accuracy in detecting the Bragg edges positions is comparable with the state of the art for similar devices. [Copyright &y& Elsevier]

A user-friendly fully digital time differential perturbed angular correlation (TDPAC)-spectrometer with six detectors and fast digitizers using field programmable gate arrays (FPGA) is described and performance data are given. The new spectrometer has an online data analysis feature, a compact size, and a time resolution such as conventional analog spectrometers. Its calculation intensive part was implemented inside the digitizer. This gives the possibility to change parameters (energy windows, constant fraction trigger delay) and see their influence immediately in the γ-γ correlation diagrams. Tests were performed which showed that the time resolution using a 60Co source with energy window set at 1.17 MeV and 1.33 MeV is 265 ps with LaBr3(Ce) scintillators and 254 ps with BaF2 scintillators. A true constant fraction algorithm turned out to be slightly better than the constant fraction of amplitude method. The spectrometer performance was tested with a TDPAC measurement using a 44Ti in rutile source and a positron lifetime measurement using 22Na. The maximum possible data rate of the spectrometer is 1.1 × 106 γ quanta per detector and second. [ABSTRACT FROM AUTHOR]

Abstract: The ATLAS Tile Calorimeter is a sampling detector composed by cells made of iron-scintillator tiles. The calorimeter cell signals are digitized in the front-end electronics and transmitted to the Read-Out Drivers (RODs) at the first level trigger rate. The ROD receives triggered data from up to 9856 channels and provides the energy, phase and quality factor of the signals to the second level trigger. The back-end electronics is divided into four partitions containing eight RODs each. Therefore, a total of 32 RODs are used to process and transmit the data of the TileCal detector. In order to emulate the detector signals in the production and commissioning of ROD modules a board called ROD Injector and Multiplexer Board (RIMBO) was designed. In this paper, the RIMBO main functional blocks, PCB design and the different operation modes are described. It is described the crucial role of the board within the TileCal ROD test-bench in order to emulate the front-end electronics during the validation of ROD boards as well as during the evaluation of the ROD signal reconstruction algorithms. Finally, qualification and performance results for the injection operation mode obtained during the Tile Calorimeter ROD production tests are presented. [ABSTRACT FROM AUTHOR]

We are currently developing a prototype monolithic scintillator PET detector module based on neural network position estimators. The detector module comprises a 25.5~mm\times 25.5~mm\times 10~mm LYSO crystal coupled to a Hamamatsu 64 channels multi-anode PMT H7546B. The electronics for the detector module reads out all the signal channels, which represents the distribution of the scintillating light for each \gamma event, and calculates the impinging position according to the pre-defined neural network algorithms if the event satisfies the energy and timing selection conditions. Compared with classical pixelated detectors, a monolithic scintillator based detector module features a simpler design, lower cost, and better energy resolution, but has lower signal to noise ratio and a more complicated signal readout scheme and data processing. By Monte-Carlo simulation, the performances of several readout schemes were compared. An optimized readout scheme which combines the 64 channels into 16 digitized signals was adopted in our electronics design. After the high resolution signal waveform digitization, an FPGA takes charge of the remaining digital signal processing, including the on-line hardware execution of the neural network positioning algorithms. [ABSTRACT FROM AUTHOR]

Abstract: Muon telescopes have multiple applications in the area of cosmic ray research. We are currently building such a detector with the objective of comparing the ground penetration of muon vs. electron-gamma signals originated in cosmic ray showers. The detector is composed by a set of three parallel dual-layer scintillator planes, buried at fixed depths ranging from 120 to . Each layer is and is composed by 49 rectangular strips of , oriented at a angle with respect to its companion layer, which gives an pixel of . The scintillators are MINOS extruded polystyrene strips, with an embedded Bicron BC92 wavelength shifting (WLS) fibers, of 1.5mm in diameter. Light is collected by Hamamatsu H7546B multi-anode PMTs of 64 pixels. The front-end (FE) electronics works in counting mode and signals are transmitted to the surface DAQ stage using low-voltage differential signaling (LVDS). Any strip signal above threshold opens a GPS-tagged data collection window. Data, including signal and background, are acquired by a system of FPGA (Spartan 2E) boards and a single-board computer (TS7800). [Copyright &y& Elsevier]

We developed a stand-alone multifunctional pulse processing device based on a 20 MHz and 10 bit flash analog to digital converter. This module has the functions of a peak-sensing ADC, a pulse area-sensing ADC, a time tag by a digital constant fraction discrimination method and a pulse counter. Moreover, it can be used for FADC with 50 μs waveform length for the purpose of monitoring. It has four independent channels. The external trigger and internal trigger functions are implemented and internally triggered signals which can be sent out by the trigger output connector. All of these functions are implemented in the field programmable gate array (FPGA). It operates with a single 5 V DC supply and digitized data can be directly transferred to the host computer by a 100 Mbps Ethernet port. Performance test results will be reported on which include a conventional crystal scintillator as well as liquid scintillator. The module can be used for the signal processing of the various radiation detectors for small nuclear and high energy laboratory experiments, nuclear spectroscopy and particle and radiation detection. [ABSTRACT FROM AUTHOR]

Detectors based on LYSO and LGSO scintillators in a phoswich arrangement coupled to an avalanche photodiode are used in the LabPETtrade, an all-digital positron emission tomography (PET) scanner for small animal imaging developed in Sherbrooke. A Wiener filter based crystal identification (CI) algorithm achieving excellent discrimination accuracy was recently proposed for crystal identification of LYSO-LGSO phoswich detectors . This algorithm was based on estimating parameters describing the scintillation decay time constant and the light yield of events sampled at 45 MSPS. The CI process was performed by applying a threshold on the scintillation decay parameter of events. The light yield was not considered in the CI process even if it should be. We propose a 2-fold faster CI approach which takes both the scintillation decay and light yield coefficients of each crystal into consideration. The new algorithm uses the previous Wiener filter based algorithm as a calibration process in order to evaluate the model of each individual crystal. The DAQ chain model as a priori knowledge is then incorporated into the model of each crystal and the output signal is estimated. The CI is performed by evaluating a single parameter representing the percentage contribution of each crystal characteristics in the event signal. The CI algorithm demonstrated a discrimination rate accuracy for LYSO-LGSO LabPET detectors and for LSO-GSO crystals in phoswich arrangement for 511 keV events. Although a calibration is required, the real-time implementation of the new CI algorithm needs 2 times less direct operations. An FPGA clocked at 400 MHz can process up to 25 M events/sec with such an algorithm. [ABSTRACT FROM PUBLISHER]

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]

We report on the design of a data acquisition (DAQ) module for a small animal PET camera developed at our institutes. During the design an important guideline was to develop a system which is built up from strictly identical DAQ modules, and which has no built-in hardware limitation on the maximum number of modules. The developed DAQ module comprises of an LSO scintillator crystal block, a position sensitive PMT, analog signal conditioning circuits, a digitizer, an field programmable gate array (FPGA) for digital signal processing, and a communication module through which the collected data are sent to a cluster of computers for postprocessing and storage. Instead of implementing hardware coincidence detection between the modules, we attach a precise time stamp to each event in our design, and the coincidence is determined by the data collecting computers during postprocessing. The digital CFD algorithm implemented in the FPGA gives a time resolution of 2 ns FWHM for real detector signals. [ABSTRACT FROM AUTHOR]

A data acquisition system for a positron emission tomograph (PET) based on avalanche photodiode (APD) readout of lutetium oxyorthosilicate (LSO) scintillator crystals is presented. The analog data of each APD are read out by fast analog to digital converters (ADCs) and processed within field programmable gate arrays (FPGAs). The ADCs are continuously sampling with a 80 MHz, low jitter clock, which is synchronous for the whole detector. The main tasks of the FPGAs are pulse detection and extraction of signal timing information from the digitized data stream. The detected signal pulse data are therefore compared to a predefined set of pulse shapes with known phase shifts with respect to the sample clock. By searching for the best match within this calibration set, a precise start time information for the signal pulse can be determined. The calculated time values are then transmitted from the ADC cards via fiber optic links to multiplexer modules which combine the different data streams and can also perform further processing like search for coincident events. Finally, the preprocessed detector data are transmitted from the multiplexers to PCI cards in the image reconstruction computers by gigabit optical links. [ABSTRACT FROM AUTHOR]

An overview of the Dø Central Track Trigger (CTT) for the Tevatron Run 2 program is presented. This newly commissioned system uses information from the Dø Central Fiber Tracker and Preshower Detectors to generate trigger information for the first level of the three-tiered Dø Trigger. The system delivers tracking detector trigger decisions every 132 ns, based on input data flowing at a rate of 475 Gbit per second. Initial results indicate excellent performance of the CTT. First studies of efficiency and trigger performance of the CTT are presented. [ABSTRACT FROM AUTHOR]

Inorganic scintillator-based gamma spectrometry is typically carried out under laboratory conditions by using systems that require AC mains supply and dedicated computers for their operation. In this study, an in-house grown CsI(Tl) single crystal scintillator is optically coupled to a bialkali photomultiplier tube (PMT). The output of the PMT is fed to a pulse processing chain consisting of a preamplifier followed by an in-house designed and developed field programmable gate array (FPGA) based multichannel analyzer (MCA). Spectral data from this MCA is sent via serial communication to a microcontroller. A global system for mobile communications (GSM) modem transmits this data in the form of short message service (SMS) packets to a central receiving station, where the spectrum is reconstructed. The requirement of on-site data logging computer to store large spectral data has thereby been eliminated, which, in turn, has eliminated the requirement of AC power supply, reduced the overall power consumption and size of the system, and made it possible to develop a standalone solar-powered unit. For further reduction of overall power consumption, the spectrometer is turned-on only when a Geiger Mueller (GM) counter based gross gamma detection circuit, also included in the system, detects an ambient gamma dose rate beyond a pre-set threshold level. A mathematical methodology has also been implemented for restoration of recorded spectra, shifted due to temperature variations in the environment. All these features have been integrated and a standalone, solar-powered and battery operated field-deployable environmental gamma spectrometry system (EGSS) has been developed and tested for open field deployment. Presence of 41Ar in ambient air was successfully detected by the system. • A CsI(Tl) based standalone, solar-powered, battery operated environmental gamma spectrometry system has been developed. • The CsI(Tl) single crystal has been grown in-house. In-house designed FPGA-based MCA has been used for spectrum building. • Requirement of on-site data logging computer and AC mains supply have been eliminated. • Spectral data is transmitted online through GSM. • Presence of 41Ar in ambient air has been successfully detected by the system deployed under field testing. [ABSTRACT FROM AUTHOR]

Silicon photomultipliers (SiPMs) are considered among the most promising sensors for positron emission tomography (PET) applications. To fully utilize the fast response of SiPMs, a 1-to-1 coupling configuration for scintillators and sensors is applied in SiPM-based detectors, leading to a vast number of channels to process. Previously, we have proposed a multi-voltage threshold (MVT) sampling method that can digitize scintillation pulses by means of simplified circuits. The feasibility of implementing MVT digitizers with only field programmable gate arrays (FPGAs) was proven, and hence, a digital PET detector module based on SiPMs was developed. In this work, we report the performance of our upgraded detector modules based on an evaluation of a fully functional demonstrator system. The system has the form of a 12-sided ring with a 108 mm diameter and a 25 mm axial length composed of 6 detector modules. Our measurements show an energy resolution of 18.9% at 511 keV and a coincidence timing resolution of 354 ps. With an energy window of 450–650 keV, the absolute sensitivity at the center of the scanner is 1.11%. The spatial resolutions are 2.08, 2.19 and 2.24 mm in the radial, tangential and axial directions, respectively. Since inter-crystal scatter (ICS) can cause count loss in the system, a recovery scheme is employed for the same data. As a result, the sensitivity and signal-to-noise ratio in the uniform region for an image quality phantom increase by 83% and 19%, respectively. However, we observe a compromised time resolution of 419 ps and a deterioration of 7–12% in spatial resolution. [ABSTRACT FROM AUTHOR]