Real-time algorithms for JET hard X-ray and gamma-ray profile monitor

The steady state operation with high energy content foreseen for future generation of fusion devices will necessarily demand dedicated real-time tools and mechanisms for data handling and machine control. Consequently, the real-time systems for those devices should be carefully selected and their capabilities previously established. The Joint European Torus (JET) is undertaking an enhancement program, which includes tests of relevant real-time tools for the International Thermonuclear Experimental Reactor (ITER), a key experiment for future fusion devices. In these enhancements a new Data AcQuisition (DAQ) system is included, with real-time processing capabilities, for the JET hard X-ray and gamma-ray profile monitor. The DAQ system is composed of dedicated digitizer modules with embedded Field Programmable Gate Array (FPGA) devices. The interface between the DAQ system, the JET control and data acquisition system and the JET real-time data network is provided by the Multithreaded Application Real-Time executor (MARTe). This paper describes the real-time algorithms, developed for both digitizers’ FPGAs and MARTe application, capable of meeting the DAQ real-time requirements. The new DAQ system, including the embedded real-time features, was commissioned during the 2012 experiments. Results achieved with these real-time algorithms during experiments are presented.     

A digital spectrometer approach to obtaining multiple time-resolved gamma-ray spectra for pulsed spectroscopy

Neutron-induced gamma-ray emission and its detection using a pulsed neutron generator system is an established analytical technique for quantitative multi-element analysis. Traditional gamma-ray spectrometers used for this type of analysis are normally operated either in coincidence mode - for counting prompt gamma-rays following inelastic neutron scattering (INS) events when the neutron generator is ON, or in anti-coincidence mode - for counting prompt gamma-rays from thermal neutron capture (TNC) processes when the neutron generator is OFF. We have developed a digital gamma-ray spectrometer for concurrently measuring both the INS and TNC gamma-rays using a 14 MeV pulsed neutron generator. The spectrometer separates the gamma-ray counts into two independent spectra together with two separate sets of counting statistics based on the external gate level. Because the TNC gamma-ray yields are time dependent, additional accuracy in analyzing the data can be obtained by acquiring multiple time-resolved gamma-ray spectra at finer time intervals than simply ON or OFF. For that purpose we are developing a multi-gating system that will allow gamma-ray spectra to be acquired concurrently in real time with up to 16 time slots. The conceptual system design is presented, especially focusing on considerations for tracking counting statistics in multiple time slots and on the placement of pulse heights into multiple spectra in real time.     

Study of time-domain digital pulse shaping algorithms for nuclear signals

With the development on high-speed integrated circuit,fast high resolution sampling ADC and digital signal processors are replacing analog shaping amplifier circuit.This paper firstly presents the numerical analysis and simulation on R-C shaping circuit model and C-R shaping circuit model.Mathematic models are established based on 1st order digital differential method and Kirchhoff Current Law in time domain,and a simulation and error evaluation experiment on an ideal digital signal are carried out with Excel VBA.A digital shaping test for a semiconductor X-ray detector in real time is also presented.Then a numerical analysis for Sallen-Key(S-K) low-pass filter circuit model is implemented based on the analysis of digital R-C and digital C-R shaping methods.By applying the 2nd order non-homogeneous differential equation,the authors implement a digital Gaussian filter model for a standard exponential-decaying signal and a nuclear pulse signal.Finally,computer simulations and experimental tests are carried out and the results show the possibility of the digital pulse processing algorithms.     

用背散射X射线穆斯堡尔谱研究涂层下钢铁的腐蚀

用背散射X射线穆斯堡尔谱分析了涂有掺不同颜料的醇酸调合漆的低碳钢在含氯化氢的气氛中的腐蚀产物,以及不同颜料对腐蚀的影响。通过这一实例,表明了背散射X射线穆斯堡尔谱可以成为研究涂层下金属腐蚀的一种有效方法。     

Anti-noise performance of the pulse coupled neural network applied in discrimination of neutron and gamma-ray

In this study, the anti-noise performance of a pulse-coupled neural network(PCNN) was investigated in the neutron and gamma-ray(n-γ) discrimination field. The experiments were conducted in two groups. In the first group,radiation pulse signals were pre-processed using a Fourier filter to reduce the original noise in the signals, whereas in the second group, the original noise was left untouched to simulate an extremely high-noise scenario. For each part, artificial Gaussian noise with different ...     

Semiconductor drift detectors for X- and gamma-ray spectroscopy and imaging

The semiconductor drift detectors (SDDs) show basic advantages, in terms of spectroscopic resolution and detection rate, with respect to other semiconductor detectors. These advantages are strictly related to the very low values of the output capacitance of these devices. In this paper the working principles and the performance of the SDDs are presented and the most recent devices (“droplet type” SDDs and monolithic arrays of SDDs) are introduced. The requirements of front-end electronics for the readout of the SDDs signals are then discussed and the most recent implementations (pulsed-reset preamplifiers, multi-channel ASIC readout circuits) are introduced. Some relevant applications of SDDs in the field of X-ray spectroscopy for material analysis and for nuclear physics experiments, and in the field of gamma-ray imaging, are presented as a conclusion.     

Utilizing PUNITA experiments to evaluate fundamental delayed gamma-ray spectroscopy interrogation requirements for nuclear safeguards

ABSTRACT

Present safeguards verification methods for small samples of high-radioactivity nuclear material (e.g. spent nuclear fuel solution) in reprocessing facilities use destructive analysis techniques since passive non-destructive techniques are incapable of directly determining the nuclear material content. To supplement these methods, the Japan Atomic Energy Agency and European Commission Joint Research Centre (JRC) are collaborating to develop delayed gamma-ray spectroscopy non-destructive assay technology for composition analysis of the fission nuclides. Multiple experiments were performed in the JRC-Ispra site using the Pulsed Neutron Interrogation Test Assembly (PUNITA) to study the signature from short-lived fission products from low-radioactivity U and Pu standard samples. From these spectra, we identify many gamma rays useful to determine the composition of a mixed nuclear material sample. Here we present the results of these experiments along with correlations to the interrogation, mass, volume, and sample homogeneity.     

Microprobe analysis of neutron irradiated and autoclaved zirconium niobium claddings using synchrotron-based hard X-ray imaging and spectroscopy

Two zirconium alloys (Zr-2.5%Nb) - one oxidized in a pressurized water reactor, the other oxidized in autoclave and used as reference - are analyzed by combining synchrotron-based scanning transmission and fluorescence X-ray microscopy and micro-X-ray absorption spectroscopy (micro-XAS). Two-dimensional zirconium distribution maps recorded on the neutron irradiated and the non-irradiated autoclaved Zr-2.5%Nb alloys clearly allow the localization of the oxide and the metal parts of the interface with a micrometer spatial resolution. Micro-XAS investigations make possible the determination of the speciation of zirconium and niobium both in the oxide and the metal parts of the interface for the irradiated and non-irradiated samples. The coordination environment and/or the valency of zirconium and niobium in the metal and the oxide parts of the interface have been determined for both materials, and interpreted on the basis of comparison with metal and oxide reference compounds.     

Toward real-time digital pulse process algorithms for CsI(Tl) detector array at external target facility in HIRFL-CSR

A fully digital data acquisition system based on a field-programmable gate array(FPGA) was developed for a CsI(Tl) array at the external target facility(ETF) in the Heavy Ion Research Facility in Lanzhou(HIRFL). To process the CsI(Tl) signals generated by γ-rays and light-charged ions, a scheme for digital pulse processing algorithms is proposed. Every step in the algorithms was benchmarked using standard γ and α sources. The scheme, which included a moving average filter, baseline restoration, ...     

Tables for reaction gamma-ray spectroscopy part II. A = 21 to A = 32

Observed γ-ray transitions from bound and nearly bound levels of all known nuclides in the mass range A = 21 to A = 32 are tabulated for use in reaction (on-line, in-beam) γ-ray spectroscopy. The tables present energies, spins, and parities of the nuclear levels, the transition (photopeak) energy corrected for recoil, the corresponding Compton edge and escape peaks, as well as competing decays, mean lives, and branching ratios when known. The information is arranged in order of both increasing γ-ray energy and nuclide mass number. The literature cutoff date is Aug. 15, 1974.     

Tables for reaction gamma-ray spectroscopy part III. A = 33 to A = 44

Observed γ-ray transitions from bound and nearly bound levels of all known nuclides in the mass range A = 33 to A = 44 are tabulated for use in reaction (on-line, in-beam) γ-ray spectroscopy. The tables present energies, spins, and parities of the nuclear levels, the transition (photopeak) energy corrected for recoil, the corresponding Compton edge and escape peaks as well as competing decays, mean lives, and branching ratios when known. The information is arranged in order of both increasing γ-ray energy and nuclide mass number. The literature cutoff date is Oct. 15, 1975.     

Tables for reaction gamma-ray spectroscopy part I. A = 6 to A = 20

Observed and possible γ-ray transitions from bound and nearly bound levels of all known nuclides up to A = 20 are tabulated for use in reaction (on-line, in-beam) γ-ray spectroscopy. The tables present energies, spins and parities of the nuclear levels, the transition (photopeak) energy corrected for recoil, the corresponding Compton edge and escape peaks, as well as competing decays, mean life and branching ratios when known. The information is arranged in order of both increasing γ-ray energy and nuclide mass number.     

Digital signal processing and algorithms for γ-ray tracking

Gamma-ray tracking is a new concept to improve efficiency and sensitivity of the next generation, high resolution γ-ray spectrometers. Tracing multiple scattered γ-rays inside an array of large volume composite, segmented Ge-detectors, the photo energies of the individual γ-rays and their incident directions can be precisely reconstructed. This results in an improved efficiency and peak-to-total ratio, and a reduced Doppler-broadening. The reconstruction efficiency depends on how accurate the positions, where the γ-rays interact with the Ge-crystals, can be localized. Novel digital signal processing hardware modules and related software algorithms are described, which allow an online determination of the energies, times, and interaction positions of the γ-rays by analyzing the shapes of the charge signals induced on the segments     

Deuteron induced gamma-ray emission method applied at a nuclear microprobe for carbon and oxygen content measurements

The deuteron induced gamma-ray emission (DIGE) method is not usually used for analytical purposes at nuclear microprobes; therefore we show here its capabilities at the microprobe facility of the Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI). In this paper the compositional analysis of magnetic spherules carried out earlier [Nucl. Instr. and Meth B 181 (2001) 557] is combined with the determination of their carbon and oxygen contents, elements which (beside nitrogen and hydrogen) play a relevant role in the study of planetary evolution and in the elucidation of the composition of cosmic parent bodies.     

多路穆斯堡尔谱数据获取与处理系统

本文叙述了一个以BC3-80微型计算机为基础,通过一个以Z80-CPU为中心的控制机与8个带有存贮器的数据获取通道组成的多路数据获取与处理系统。这个系统除能对8个通道的数据进行数据获取外,同时可以对其进行显示、保存和数据处理。它与穆斯堡尔谱仪部件相接,构成一个恒加速穆斯堡尔谱仪系统。 这个系统配上高计数率多丝正比室,可以使穆斯堡尔谱的探测效率大大提高。多丝室中的每根丝的信号分别通过各自的放大器、单道分析器,由相应的数据通道记录下来,然后由微机进行相加和处理。另一方面,这个系统还可以利用不同的通道同时测出样品的透射谱和散射谱,同时得到样品的内部和表面信息。     

Fuzzy methodology applied to Probabilistic Safety Assessment for digital system in nuclear power plants

A fuzzy inference system (FIS) modeling technique to treat a nuclear reliability engineering problem is presented. Recently, many nuclear power plants (NPPs) have performed a shift in technology to digital systems due to analog obsolescence and digital advantages. The fuzzy inference engine uses these fuzzy IF-THEN rules to determine a mapping of the input universe of discourse over the output universe of discourse based on fuzzy logic principles. The risk priority number (RPN) (typical of a traditional failure mode and effects analysis - FMEA) is calculated and compared to fuzzy risk priority number (FRPN), obtained by the use of the scores from expert opinions. It was adopted the digital feedwater control system as a practical example in the case study. The results demonstrated the potential of the inference system to this class of problem.     

Real time application of simultaneous estimation theory for parameters and state to one-dimensional heat conduction

This paper applies filtering theory of the parameters and states of a distributed system to one-dimensional heat conduction in order to obtain information on the real time application of nonlinear estimation theory. This involves a trial to study a simple and fast algorithm for the state estimation of power reactors limited to a small number of sensors by noisy observations. The authors estimated the heat transfer coefficients and the transient temperature profile in a copper rod simultaneously in real time by using a small computer, NOVA 3/12, where the parameter and state of the heat conduction-type P.D.E. could serve as a simplified alternative to the nuclear constant and power profile. The authors also examined the feasibility of a nonlinear filter provided for simultaneous estimation, considering unknown parameters as alternative state variables. The filter tested converged during the sampling period and generated reasonable estimates of the parameter and state from noisy observations with a small number of sensors and at a discrete number of times.     

硬X射线亚微米聚焦高稳定柔性铰链压弯机构的模拟分析

空间分辨率和聚焦效率是X射线微纳探针最关键的技术指标。压弯非球面镜具备聚焦效率高、空间分辨好、加工难度低、色散消除等优点。基于上海光源硬X射线微聚焦及应用线站的现有条件,在精确压弯理论的基础上设计了高精度柔性铰链压弯机构并进行了有限元分析,并且进一步对压弯镜体宽度进行了优化。通过长程面形仪(Long Trace Profiler,LTP)对压弯机构的测试,得到压弯非球面镜的斜率误差为430 nrad,理论上可实现230 nm的硬X射线聚焦光斑。     

基于DSP的核信号波形数字化获取与处理系统设计

介绍了一种基于DSP的高速核信号波形数据采集与处理系统的软硬件设计及实现,并给出了在不同条件下的采样结果.     

Spatial resolution and image processing for pinhole camera-based X-ray fluorescence imaging: a simulation study

Spatial resolution and image-processing methods for full-field X-ray fluorescence(FF-XRF) imaging using X-ray pinhole cameras were studied using Geant4simulations with different geometries and algorithms for image reconstruction. The main objectives were:(1) calculating the quantum efficiency curves of specific cameras,(2) studying the relationships between the spatial resolution and the pinhole diameter, magnification, and camera binning value, and(3) comparing image-processing methods for pinh...