Dosimetry Methods of Fast Neutron Using the Semiconductor Diodes

Semiconductor detectors based on a silicon pin diode are frequently used in the detection of different nuclear radiations. For the detection and dosimetry of fast neutrons, these silicon detectors are coupled with a fast neutron converter. Incident neutrons interact with the converter and produce charged particles that can deposit their energy in the detectors and produce a signal. In this study, three methods are introduced for fast neutron dosimetry by using the silicon detectors, which are： recoil proton spectroscopy, similarity of detector response function with conversion function, and a discriminator layer. Monte Carlo simulation is used to calculate the response of dosimetry systems based on these methods. In the different doses of an 241Am-Be neutron source, dosimetry responses are evaluated. The error values of measured data for dosimetry by these methods are in the range of 15-25%. We find fairly good agreement in the 241Am-Be neutron sources.     

Comparative analysis of phase extraction methods based on phase-stepping and shifting curve in grating interferometry

Two phase extraction methods which are based separately on phase-stepping and shifting curve are mainly used in phase-sensitive imaging in gating interferometry to determine the x-ray phase shift induced by an object in the beam. In this paper, the authors perform a full comparative analysis and present the main virtues and limitations of these two methods according to the theoretical analysis of the grating interferometry.     

Application of wavelet transform in-ray spectra analysis

The frequency distribution of different ingredients in-ray spectra,e.g.,photo-peak,fluctuations of counts and Compton region,is separately analyzed.After wavelet transform of-ray spectra,the wavelet coefficients of a photo-peak increase with transforming scales and these coefficients show direct proportion with intensity of peak at determinate scale.A novel algorithm based on wavelet transform is proposed and studied.The results indicate that most of the photo-peaks in multi-spectra can be determined accurately,the-rays energy and intensity of the peak can also be determined.This method has the prospect of being applied in on-line multi-spectra analysis in such fields as radioprotection and nuclear safety monitoring.     

Three-dimensional display technologies in wave and ray optics: a review (Invited Paper)

Multiple three-dimensional （3D） display technologies are reviewed. The display mechanisms discussed in this paper are classified into two categories： holographic display in wave optics and light field display in ray optics, which present the 3D optical wave field in two different ways. Key technical characteristics of the optical systems and the depth cues of human visual system are analyzed. It is to be expected that these 3D display technologies will achieve practical applications with the increase of the optical system bandwidth.     

Relations Between Helicity Coupling Amplitude and L—S Coupling Amplitude

Relations between helicity coupling amplitude and L-S coupling amplitude are discussed.The equivalence condition for these two kinematic analysis methods and the limitations of the L-S coupling amplitude are also studied in this paper.     

Multi-goal Control of Chaotic Connected Complex Networks

Beam transport network （BTN） with small world （SW） （so-called BTN-SW） and Lorenz chaotic connected network with scale-free （SF） are taken as two typical examples, we proposed a global linear coupling and combined with local error feedback methods in sub-networks to realize multi-goal control method of halo and chaos in two networks above. The simulation results show that the methods above is effective for any chaotic connected networks and has a potential of applications in based-halo-chaos secure communication.     

Structure study of light unbound nuclei near drip line

Some experimental techniques and theoretical analysis on unbound nuclei structure study are briefly introduced in this article. The unbound nuclei structure investigation can inspect the reliability of theoretical calculation, and is also important to extend the modern nuclear structure model to exotic nuclear regions. With the recent development of radioactive Ion Beam (RIB) facility and some new experimental methods, the structure of unbound nuclei near drip line can be studied in experiment.     

Attractive target wave patterns in complex networks consisting of excitable nodes

This review describes the investigations of oscillatory complex networks consisting of excitable nodes,focusing on the target wave patterns or say the target wave attractors.A method of dominant phase advanced driving(DPAD) is introduced to reveal the dynamic structures in the networks supporting oscillations,such as the oscillation sources and the main excitation propagation paths from the sources to the whole networks.The target center nodes and their drivers are regarded as the key nodes which can completely determine the corresponding target wave patterns.Therefore,the center(say node A) and its driver(say node B) of a target wave can be used as a label,(A,B),of the given target pattern.The label can give a clue to conveniently retrieve,suppress,and control the target waves.Statistical investigations,both theoretically from the label analysis and numerically from direct simulations of network dynamics,show that there exist huge numbers of target wave attractors in excitable complex networks if the system size is large,and all these attractors can be labeled and easily controlled based on the information given by the labels.The possible applications of the physical ideas and the mathematical methods about multiplicity and labelability of attractors to memory problems of neural networks are briefly discussed.     

A high sensitivity spectrometer with tunable diode laser for ambient methane monitoring

Tunable diode laser absorption spectroscopy (TDLAS) has been widely employed in atmospheric trace gases detection. In the measurement of these trace gases, harmonic detection combined with a multi-pass white cell could remarkably enhance the detection sensitivity. In this paper, a portable TDLAS system built specifically for long time monitoring methane in the atmosphere is introduced. The detection limit is below 100 ppb that is enough for the monitoring of ambient methane, and the long time monitoring results obtained in Beijing are given, which is well coincident with that of the Fourier transform infrared (FTIR) spectroscopy.     

材料化学分析的物理方法(Ⅰ)

材料的化学信息是理解科学、工程与技术领域各种过程、机制和材料行为的最基本要素，材料研究的第一步是要确定材料的化学，包括构成材料的原子的种类、分布以及具体的化学态等内容，任何具有元素特征的物理信息，包括原子量、电子的能级、原子核自旋，甚至局域的电子态密度等都可以用来做材料的化学分析，化学信息由来自材料本身的或用作探针的电子、光子、离子或中性原子携带，相应的分析技术包括X射线光电子能谱、俄歇电子谱、核磁共振、特征X射线分析、二次离子质谱、能量损失谱、溅射中性粒子质谱，各类离子散射谱以及扫描隧道显微学方法等等，文章对上述各种分析方法的物理原理、仪器以及应用等逐一做扼要的介绍。     

基于紫外-可见光光谱的水质分析方法研究进展与应用

相对于传统水质分析方法,紫外-可见光(ultraviolet-visible,UV-Vis)光谱法具有检测速度快、维护成本低、无二次污染等优点,目前已被广泛应用于水质在线监测各个领域。介绍了UV-Vis光谱法的检测原理,论述了基于UV-Vis光谱的常规水质分析方法研究现状,以及UV-Vis光谱法与其他水质检测方法相融合以提高水质检测性能方面的研究进展,探讨了UV-Vis光谱分析在水质多参数在线监测、水质分类、水质报警等方面的应用现状及其发展趋势。     

核弹头惰层厚度的反解方法

高分辨γ探测技术是一种可靠的核弹头核查技术.通过模拟计算和实验标定的方法，研究特定核弹头模型出壳γ射线强度与吸收材料厚度的关系，提出了一种简便的反解核弹头惰层厚度的方法，并讨论了该方法的应用条件.     

Compton Back-Scattering γ-Ray Source Based on Synchrotron Radiation Facility (Ⅰ) Numerical Calculation of the Produced MeV γ-Ray

We propose a build to low-energy γ-ray beam line (SLEGS-Ⅰ) at the Shanghai Synchrotron Radiation Facility (SSRF). By Compton back scattering (BCS) of infrared or far-infrared laser lights from 3.5 GeV electrons circulating in the storage ring of SSRF, high intense quasi-monochromatic BCS γ-rays with high linear or circular polarization ranging 1-25MeV will be produced. It can be widely applied to fundamental researching fields of nuclear physics, nuclear astrophysics and related applications. In this paper, we briefly present the outline of BCS theory and the properties of BCS γ-ray with numerical compution based on the major parameters of SSRF storage ring.     

Suppression of inhomogeneous line broadening of Mössbauer resonance by a spinning magnetic field

A spinning magnetic field, satisfying the so-called “magic-angle” condition, is widely used for the suppression of inhomogeneous line broadening of spin transitions in nuclear magnetic resonance (NMR) spectroscopy. We show that the redefined “magic-angle” condition can also be used for the narrowing of γ-ray nuclear transitions in the Mössbauer spectroscopy.     

核物理与核探测、核分析技术的应用

文章概要介绍了随着核物理研究发展起来的辐射和粒子探测的原理、方法和主要技术,举例介绍了相关核物理与核探测、核分析的典型技术及其在高精度测量和医学中的广泛应用,如活化分析技术、穆斯堡尔谱学、核磁共振技术、加速器质谱技术、核医学成像、同步辐射技术、中子散射分析、放射性示踪技术等等.     

Study of 113Cd by the 110Pd(α,nγ) reaction

The nuclear structure of ¹¹³Cd was studied using in-beam γ-ray spectroscopy. A level scheme, consisting of 65 levels and more than 100 transitions, was constructed on the basis of γγ coincidences using five compton-suppressed Ge detectors. Spins were assigned by means of excitation function slopes and angular distribution analysis. The resulting level scheme was interpreted in the framework of the interacting boson-fermion model.     

基于微通道板的中子探测器γ射线灵敏度

研制了一种基于微通道板的超快脉冲中子探测器,对其γ射线灵敏度进行了理论和实验研究。建立了探测器的γ射线灵敏度理论计算模型,利用蒙特卡罗方法模拟计算了不同能量γ射线在不同厚度聚乙烯靶中产生的出射电子能谱和出射角度分布,并结合经验公式计算了单个电子在微通道板(MCP)孔道中产生的二次电子产额,最后得到了探测器的γ射线灵敏度,结果表明当聚乙烯靶厚度大于某一值时,γ射线灵敏度基本相同。利用西北核技术研究所的标准γ射线放射源对探测器的γ射线灵敏度进行了实验标定,实验结果与理论计算结果一致。     

A WAVELET TRANSFORM AND ITS APPLICATION TO SPECTROSCOPIC ANALYSIS

ABSTRACT

An introduction to the wavelet transform and its applications in spectroscopy analysis are presented. Owing to the property of the dual localization both in time and in frequency domains, the wavelet transform exhibits several useful characteristics. With the wavelet transform a signal can be decomposed into series of contributions according to the frequency difference, these contributions are respectively called discrete approximations and discrete details. By applying certain treatment to the discrete approximations (the low frequency part) or the discrete details (the high frequency part), a part of the original signal within a certain frequency range can be obtained. The wavelet transform has been applied in various fields of the analytical chemistry, including removal of high frequency noise, information extraction, resolution of overlapping signals, and data compression etc. Research concerning application in analytical chemistry are introduced in respect of photoacoustic spectroscopy, EXAFS spectrum, NMR analysis, and Raman spectrum.