Research of nuclide identification method based on background comparison method.

Radioactive material inspection in public is important to nuclear safety, and it is also the key security for holding large-scale events, while fast and efficient means of detecting radioactive materials are an important technical guarantee for nuclear safety. In this paper, energy and time distribution characteristics information of the natural background and target nuclide gamma particles are used to improve the sequential background comparison method. By using those energy and time distribution characteristics information, with the half-life and characteristic gamma-ray energy and branching ratio information of the nuclide, the response time and the identification accuracy of extremely low radioactive nuclides detected under natural-radiation background can be improved.

Accurate-parametric SAR-TL dating protocols for older sediments using quartz.

Thermoluminescence (TL) dating is one of the most significant chronological tools used in Quaternary research. However, for changes in the characteristics of quartz, the larger deviation is still a problem in TL dating, especially with the single-aliquot regeneration-does (SAR) procedure. In the SAR-TL protocol, changes in the characteristics of quartz inevitably cause a shift in the TL peak position and a reduction in the sensitivity of the TL peak during repetitive thermal treatment.

Study of a full-digital multi-waveform nuclear pulse signal generator.

The traditional nuclear pulse signal generator outputs the nuclear pulse signal of specific waveform according to the input pulse amplitude probability distribution and counting rate, following the signal output laws of radiation detector in both pulse amplitude and time interval. However, the output waveform is generally regulated by an analog circuit, with the single waveform and difficult parameter adjustment. In this study, the digital C-R and R-C filters were explored, a cascading digital C-R or R-C filter algorithm was proposed, realizing multiple pragmatic nuclear pulse signal outputs through the serial or parallel connection of multiple digital filters.

IMPACT OF THE THREE GORGES WATER CONSERVANCY PROJECT ON RADIOACTIVITY CONCENTRATION LEVELS IN SURROUNDING WATERS.

Large-scale water conservancy projects bear much economic and social significance. However, there is a lack of systematic research on how such projects affect radioactivity levels in regional water bodies. For the first time, the present paper uses data for nearly 10 y at different impoundment levels during construction of the dam to analyze changes in water radioactivity concentration levels in China's Three Gorges region, in order to provide a valuable reference for evaluating the impact of large-scale water conservancy projects on radioactivity concentration levels.

A hybrid method on sourceless sensitivity calculation for airborne gamma-ray spectrometer.

The sensitivity calculation of airborne gamma-ray spectrometer (AGS) is usually performed by on-ground or in-flight calibration. However, both methods are cost-ineffective or not permissive, especially for artificial radioisotopes with short half-lives. Alternative to these methods is the Monte Carlo simulation, which has been widely applied over the last few decades.

The Study of the Rescale Method of the Spectrum Shifting in X-Ray Fluorescence Well Logging.

The X-ray fluorescence well logging technology is a significant method that can make quantitative analysis orsemi-quantitative analysis on the wellface. This method is very important to mineral exploration. The spectrum shifting is often observed in the X-rayfluorescence well logging because the temperature in the well changes acutely.

The Research on Matrix Effect and Correction Technology of Rock Sample in In-Situ Energy Dispersive X-Ray Fluorescence Analysis.

The mineral constituents of the rock sample can be analyzed with in-situ energy dispersive X-ray fluorescence analysis technology (In-situ EDXRF), the matrix effect of rock sample will effects on measurement results. The Monte Carlo simulation method is used to conduct fluorescence analysis spectrum with ideal measurement conditions, which provides analytical data for matrix effect research. The measured spectrum of seventeen kinds rock samples are being simulated, which has the same Cu content.

[X-Ray Fluorescence Intensity Calculation for Micro-Particles via MCNPX and WDXRF Experiment].

In order to research the effect of X-ray fluorescence (XRF) analysis on the results in the sample’s micro particles, MCNPX models had been established for an X-ray fluorescence analyzer in this paper. It had studied the characteristics of the samples with different particle sizes, the fluorescence peak counts, the peak to total ratios and the peak to source ratios. A micro particle analysis experiment had been designed for its verification.

Research and development of a high-performance differential-hybrid charge sensitive preamplifier.

A differential-hybrid charge sensitive preamplifier (CSP) was designed by taking a monolithic dual N-Channel Junction Field-effect Transistor (JFET) and a high-speed, low-noise, operational amplifier as the core parts. Input-stage of the circuit employs low-noise differential dual JFET, which ensures high input impedance and low noise. The differential dual transistor makes the quiescent point of the first-stage differential output stable, which is convenient for connecting with the post stage high-speed operational amplifier.

[Analyzer Design of Atmospheric Particulate Matter's Concentration and Elemental Composition Based on β and X-Ray's Analysis Techniques].

Monitoring atmospheric particulate matter requires real-time analysis, such as particulate matter's concentrations, their element types and contents. An analyzer which is based on β and X rays analysis techniques is designed to meet those demands. Applying β-ray attenuation law and energy dispersive X-ray fluorescence analysis principle, the paper introduces the analyzer's overall design scheme, structure, FPGA circuit hardware and software for the analyzer.

[Influence of the Experiment Energy Dispersive X-Ray Fluorescence Measurement of Uranium by Different Excitation Source].

Aiming at the self-excitation effect on the interference of measurements which exist in the process of Energy dispersive X-ray fluorescence method for uranium measurement. To solve the problem of radioactive isotopes only used as excitation source in determination of uranium. Utilizing the micro X-ray tube to test Self-excitation effect to get a comparison of the results obtained by three different uranium ore samples--109 Cd, 241 Am and Mirco X-ray tube.

[Rapid Determination of Cu and Zn in PM2.5 with Wavelength Dispersive X-Ray Fluorescence Spectrometry].

This paper proposes the analyzing method of adopting wavelength dispersive X-ray fluorescence spectrometry to measure the content of Cu and Zn in PM2.5. PTFE membrane is used to prepare standard samples and atmospheric particulate samples; a research into sample cup’s structure，using polypropylene film of 6.

[Analyse Output Specurum in Miniature Transmission X-Ray Tube of Aluminum Window and Silver Target by MC Simulation].

The miniature transmission X-ray tube is widely used in energy dispersive X-ray Fluorescence Analysis (EDXRFA). The miniature transmission X-ray tube with a small, low power consumption, X-ray emission efficiency that can be made the excitation source of handheld X-ray energy dispersive fluorescence analyzer. Beryllium (Be) is the most commonly used X-ray window material.

[Determination of 22 Elements in Herb Tea by X-Ray Fluorescence Spectrometry].

N, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Ba and Pb in herb tea were determined by X-ray fluorescence spectrometry with pressed powder pellets. The measuring conditions of target elements were investigated, including how to select its analytical line. In addition to Ba and Pb using L line, Kalpha line was selected for the rest.

[The Study of Advanced Fundamental Parameter Method in EDXRFA].

The X-ray Fluorescence Analysis(XRFA) is an important and efficient method on the element anylsis and is used in geology, industry and environment protection. But XRFA has a backdraw that the determination limit and accuracy are effected by the matrix of the sample. Now the fundamental parameter is usually used to calculate the content of elements in XRFA, and it is an efficient method if the matrix and net area of characteristic X-ray peak are obtained.

Reset charge sensitive amplifier for NaI(Tl) gamma-ray spectrometer.

The time constant of the output signal of the front-end readout circuit of a traditional gamma-ray spectrometer with a NaI(Tl)+PMT structure is affected by temperature, measurement environment and the signal transmission cable, so it is difficult to get a good resolution spectrum, especially at higher counting rates. In this paper, a reset charge sensitive amplifier (RCSA) is designed for the gamma-ray spectrometer with a NaI(Tl)+PMT structure. The designed RCSA outputs a step signal, thus enabling the acquisition of double-exponential signals with a stable time constant by using the next stage of a CR differentiating circuit.

[Application of the racial algorithm in energy dispersive X-ray fluorescence overlapped spectrum analysis].

In the energy dispersive X-ray fluorescence spectrum analysis, scintillation detector such as NaI (Tl) detector usually has a low energy resolution at around 8%. The low energy resolution causes problems in spectral data analysis especially in the high background and low counts condition, it is very limited to strip the overlapped spectrum, and the more overlapping the peaks are, the more difficult to peel the peaks, and the qualitative and quantitative analysis can't be carried out because we can't recognize the peak address and peak area. Based on genetic algorithm and immune algorithm, we build a new racial algorithm which uses the Euclidean distance as the judgment of evolution, the maximum relative error as the iterative criterion to be put into overlapped spectrum analysis, then we use the Gaussian function to simulate different overlapping degrees of the spectrum, and the racial algorithm is used in overlapped peak separation and full spectrum simulation, the peak address deviation is in +/- 3 channels, the peak area deviation is no more than 5%, and it is proven that this method has a good effect in energy dispersive X-ray fluorescence overlapped spectrum analysis.

[Research on spectral characteristic of miniature X-ray tube and determination of beryllium window thickness].

Applying Monte Carlo method, the present paper simulates the emitted X-ray spectrum of miniature X-ray tube with thirteen thickness of beryllium window in the range from 50 to 500 microm. By analyzing the characteristic of the spectrums, the reasonable choice of thickness of beryllium window relies on the application and for the beryllium window it is not the thinner the better. Taking in-situ EDXRF as an example, though the emission X-ray intensity is higher as the thickness of the beryllium window becomes thinner, the proportion of useless low-energy X-ray (<5 keV) intensity to all energy X-ray intensity also is higher (>20%).

[Application of in situ micro energy dispersive X-ray fluorescence analysis in mineralogy].

Thirteen rock samples were collected for studying the variation of element content in the mineral during the alteration process from Xinjiang, China. The IED-6000 in situ micro energy dispersive X-ray fluorescence developed by CDUT was applied to get chemical and physical data from minerals. The non-destructive spectrometer is based on a low-power Mo-anode X-ray tube and a Si-PIN peltier cooled X-ray detector.

Frequency spectrum analysis for spectrum stabilization in airborne gamma-ray spectrometer.

Abnormal multi-crystal spectral drifts often can be observed when power on the airborne gamma-ray spectrometer. Currently, these spectral drifts of each crystal are generally eliminated through manual adjustment, which is time-consuming and labor-ineffective. To realize this quick automatic spectrum stabilization of multi-crystal, a frequency spectrum analysis method for natural gamma-ray background spectrum is put forward in this paper to replace traditional spectrum stabilization method used characteristic peak.

[Research on the peak search method based on improved simulated annealing model for x-ray fluorescence spectrum].

In energy dispersive X-ray fluorescence analysis technical analysis, the spectrum information processing has been being the focus of researches, spectrum smooth, peak-search, and peak area processing are the top priority, tA peak search method is based on simulated annealing algorithm principle, and to establish a new search peak model algorithm, this algorithm uses the advantages of the global convergence properties of simulated annealing and the Metropolis criterion is used as a peak valley judgment basis. A new decision criteria on peak valley array is used in this method, too. At the same time, convergence is taken from both ends of the spectrum channel address, it ends up when convergence reaches to the same optimal solution.

[Study on the effect of target thickness on output spectrum in transmission anode micro X-ray tube by MC method].

The transmission anode micro X-ray tube is a key component of energy dispersive X-ray Fluorescence Analysis (EDXRFA) as exciting source. So in EDXRFA we hope to get the primary X-ray spectrum which is simply distributed. In the present paper, the authors used the Monte Carlo (MC) method to study the spectrum character of the transmission anode micro X-ray tube with different thickness of target.

[Research on the application of principal component analysis and improved BP neural network to the determination of Fe and Ti contents in geological samples].

Aiming at forecasting elemental contents in geological samples accurately, a principal component analysis and improved BP (PCA-BP) neural network theory is proposed in the present work. The samples from west Tianshan were measured through X-ray fluorescence measurement method, and the X-Ray fluorescence counts of each element such as Fe, Ti, V, Pb, Zn, etc. were input to the PCA-BP neural network as input variables to forecast Fe and Ti contents in uncertified geological samples quantitatively.

[Theoretical calculation and simulation research on micro X-ray tube target thickness and spectra].

The present paper established a mathematical model, according to the structure of the end-window transmission micro X-ray tube anode. And we discussed the relationship between the average thickness of electron beam targeting and the high voltage. Also we obtained the spectral intensity distribution characteristics of the emitted X-ray on the angle, meanwhile by the use of Monte Carlo, the authors simulated the intensity distribution characteristics of the spectrum in the direction of 2pi.