IEEE Transactions on Nuclear Science
ISSN / EISSN : 0018-9499 / 1558-1578
Published by: IEEE (10.1109)
Total articles ≅ 28,676
Latest articles in this journal
Published: 28 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3100863
Gamma spectrometry is a passive non-destructive assay method used to quantify radionuclides present in nuclear objects. Basic methods using empirical calibration with a standard to quantify the activity of nuclear materials by determining the calibration coefficient are ineffective on non-reproducible nuclear objects such as waste packages. Package specifications such as composition or geometry change from one package to another and exhibit large variability of objects. The current standard quantification process uses numerical modelling of the measured scene with few available data such as geometry or composition, in particular density, material, screen, geometric shape, matrix composition, matrix and source distribution. Some of them are strongly dependent on package data knowledge and operator backgrounds. The French Atomic Energy Commission (CEA) is developing a methodology to quantify nuclear materials in waste packages and waste drums without operator adjustment and internal package configuration knowledge. This method suggests combining a stochastic approach which uses, among others, surrogate models available to simulate the gamma attenuation behaviour, a Bayesian approach considering conditional probability densities and prior information of problem inputs, and Markov Chain Monte Carlo algorithms (MCMC) which solve inverse problems, with gamma ray emission radionuclide spectra, and the outside dimensions of the objects of interest. The methodology has been tested to quantify actinide activity with a low bulk density matrix, weakly attenuating compositions, without information on the distribution of the source in terms of actinide masses and materials composing the drums. Activity uncertainties are taken into account.
Published: 26 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3099202
This paper presents an analysis of the multiple events (and more specifically, Multiple Cell Upsets or MCUs) that may occur at successive generations of bulk CMOS SRAMs operating under harsh conditions, such as in avionics or space. Such MCU distribution is greatly impacted by the bitcell topology, which, in the International Technology Roadmap for Semiconductors (ITRS) / International Roadmap for Devices and Systems (IRDS) history, experienced a drastic change in the transition between the 90-nm and the 65-nm nodes. Experimental results obtained from proton and neutron accelerators, along with predictions issued from the MUSCA-SEP3 modeling tool, are provided. Various COTS Static Random Access Memories (SRAMs) manufactured by Infineon in bulk CMOS 130-nm nodes down to the 65-nm one were used as targets for the experimental results. Finally, MUSCA-SEP3 was also used to analyze and discuss scaling trends on more modern nodes (45-nm down to 14-nm).
Published: 26 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3096146
We present the first results of a custom low-noise silicon photodiode detector designed for use with X-ray capillary optics. This system is intended to perform as a smaller, lighter, and low-powered alternative to currently existing X-ray telescope technologies. The detector has an active area with a diameter of 100 μm, and its small size leads to a low capacitance of well under 1 pF and a leakage current of 1 pA or less at the depletion voltage. We tested the detector with both a discrete preamp and an ultra-low noise front-end application specific integrated circuit (ASIC). The front-end ASIC, developed at Brookhaven National Laboratory, was designed for low capacitance detectors but had not been previously tested with a detector. Here we discuss the detector design, the experimental setup, and the resulting detector performance. Using radioactive lab sources, we measure a FWHM of 211±8 eV at 5.9 keV with the ASIC and are able to set the threshold as low as 0.6 keV.
Published: 26 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3099296
We present an FPGA-based technique for the online identification of highly ionizing particles in a Liquid Xenon detector. The method was developed and successfully exploited to select α particles emitted by 241Am sources submerged in the liquid xenon in an overwhelming, mostly beam-related, γ-ray background. After revising the main features of xenon and other liquid noble gases as UV scintillating media, we describe the algorithm idea and its firmware implementation. We then present the results in terms of efficiency and background suppression for the real time α-particle tagging and the limits of the MEG trigger configuration. Finally we show that in MEG II we are going to overcome the main issues and further improve the performances.
Published: 26 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3099685
A 128-channel positron detection system will be constructed at Experimental Muon Source (EMuS) of China Spallation Neutron Source (CSNS) to conduct muon spin rotation/relaxation/resonance (μSR) measurements. Each detector channel consists of a scintillator, a light guide and a photo-multiplier tube (PMT). The long light guide is bent to an “L" shape to propagate optical photons from the scintillator to the PMT. A series of Geant4 simulations and experiments have been done to optimize the light collection performance of the L-bent detector. Geometry deformation induced by the bending process has been well modelled. Simulation results agree with the experimental tests. Accordingly, a novel hybrid wrapping method (scintillator with polytetrafluoroethylene (PTFE), light guide with aluminum tape) has been developed to improve the amplitude of detector signals greatly. Compared to wrapping the detector with merely PTFE tapes or aluminum tapes, this method leads to an enhancement in light collection efficiency of 73% or 14%, respectively. Two optimally manufactured prototype detectors using the novel wrapping method have been tested at the ISIS Muon Facility. The beam tests demonstrated that the L-bent detectors can precisely measure the behavior of muon spins inside samples. Therefore, the L-bent detector design is competent for μSR applications at CSNS/EMuS.
Published: 13 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3096837
Recent advances in acquisition equipment are providing experiments with growing amounts of precise yet affordable sensors. At the same time, an improved computational power, coming from new hardware resources (GPU, FPGA, ACAP), has been made available at relatively low costs. This led us to explore the possibility of completely renewing the chain of acquisition for a fusion experiment, where many high-rate sources of data, coming from different diagnostics, can be combined in a wide framework of algorithms. If on one hand adding new data sources with different diagnostics enriches our knowledge about physical aspects, on the other hand the dimensions of the overall model grow, making relations among variables more and more opaque. A new approach for integrating such heterogeneous diagnostics, based on the composition of deep variational autoencoders, could ease this problem, acting as a structural sparse regularizer. This has been applied to RFX-mod experiment data, integrating the soft X-ray linear images of plasma temperature with the magnetic state. However, to ensure a real-time signal analysis, those algorithmic techniques must be adapted to run in well suited hardware. In particular, it is shown that, attempting a quantization of neurons transfer functions, such models can be adapted to run in an embedded programmable logic device. The resulting firmware, approximating the deep inference model to a set of simple operations, fits well with the simple logic units that are largely abundant in FPGAs. This is the key factor that permits the use of affordable hardware with complex deep neural topology and operates them in real-time.
Published: 13 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3096926
High performance radiation detection materials are an integral part of national security, medical imaging, and nuclear physics applications. Those that offer compositional and manufacturing versatility are of particular interest. Here, we report a new family of radiological particle-discriminating scintillators containing bis(9,9-dimethyl-9H-fluoren-2-yl)diphenylsilane (compound “P2”) and in-situ polymerized vinyltoluene (PVT) that is phase stable and mechanically robust at any blend ratio. The gamma-ray light yield increases nearly linearly across the composition range, to ~16,400 photons/MeV at 75 % wt. P2. These materials are also capable of γ/n pulse shape discrimination (PSD) and between 20-50 % P2 loading are competitive with the PSD quality of commercially-available plastic scintillators. The 137Cs scintillation rise and decay times are sensitive to P2 loading and approach the values for “pure” P2. Additionally, the radiation detection performance of P2-PVT blends can be made stable in 60°C air for at least 1.5 months with the application of a thin film of poly(vinylalcohol) to the scintillator surfaces.
Published: 12 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3096757
At the ELBE Center for High-Power Radiation Sources, electrons are accelerated to an energy of up to 40 in a superconducting linear accelerator that is operated in continuous wave mode. The acceleration is achieved using superconducting RF cavities, which are driven by an analogue low level RF system and solid-state based RF amplifiers. The analogue low level RF system was transformed to a digital system based on the MicroTCA standard. It is in user operation since 2020. Here the new digital system and its integration in the ELBE control system is described. Furthermore, the system is characterised by noise measurements and shows RMS field stability of the digital low level RF system of 0.01° in phase and 0.005% in amplitude. In addition, an algorithm for compensating long term drifts is presented and characterised.
Published: 12 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3096162
This paper presents a low-power highly-linear multi-channel data acquisition (DAQ) system for silicon photomultiplier (SiPM) readout. A low-input impedance current-mode front-end with a programmable current gain is developed to achieve high-precision charge readout over a large dynamic range. An integrated 10-bit successive-approximation-register (SAR) analog-to-digital data converter (ADC) shared by 16 readout channels in a time-multiplexed manner is designed to reduce the overall chip area and power consumption of the SiPM readout. Implementation challenges of field-programmable gate array (FPGA)-based time-to-digital converters (TDCs) including bubble error, zero length bins, inter-clock region nonlinearity, and chain overflow, are addressed for high accuracy timing measurement. Multi-chain averaging is developed to improve the TDC linearity. Fabricated in a 180 nm CMOS process, the current-mode 16-channel readout application-specific integrated circuit (ASIC) achieves 3.6% maximum gain nonlinearity over an input dynamic range of 800 pC with dissipating 3.89 mW of power per readout channel, and the ADC achieves an SFDR of 58.34 dB and an SNDR of 51.37 dB at 16 MS/s. Implemented in a Xilinx 28 nm Kintex-7 FPGA, the 32-channel TDC achieves a 15 ps root mean square (RMS) resolution, a differential nonlinearity (DNL) of less than 4 ps, and an integral nonlinearity (INL) of less than 10 ps.
Published: 9 July 2021
IEEE Transactions on Nuclear Science, pp 1-1; doi:10.1109/tns.2021.3095845
The paper presents the design and evaluation of the first cryogenic switched capacitor array (SCA) based waveform digitizer (CryoSCA) for HPGe detectors for low-background physics experiments. The chip has integrated 16 channels, and was fabricated using a 0.18 μm CMOS process with modified BSIM3v3 model parameters at 77 K. Each channel employs two 32-cell sample blocks working in the ping-pong mode, a 256-cell storage array, 32 parallel Wilkinson type ADCs with 12 bits dynamic range, and registers. The chip was fully evaluated and showed promising performance at 300 K and 77 K. The measured power consumption of each channel increased from 3.3 mW at 300 K to 3.6 mW at 77 K. The averaging integral non-linearity (INL) over 1 V dynamic range was measured to be 0.3% and 0.2% at 300 K and 77 K respectively. The static noise decreased from 0.8 mV at 300 K to 0.6 mV at 77 K. The leakage current decreased from 18.2 fA at 300 K to 2.2 fA at 77 K.