Scattering of scalar light wave from a Gaussian—Schell model medium

<正>The scattering of scalar light wave from a random medium with a correlation function of Gaussian-Schell model distribution is studied.It is shown that the properties of the scattered field,i.e.,the spectral density and the spectral degree of coherence of the scattered field,are closely related to the properties of the scattering medium,including the scaled effective radius and the scaled correlation length of the correlation function.     

Stochastic Resonance in a Bistable System Subject to Dichotomous Noise

The stochastic resonance phenomenon in a bistable system subject to Markov dichotomous noise （DN） is investigated. Based on the adiabatic elimination and the two-state theories, the explicit expressions for the signal-tonoise ratio （SNR） and the spectral power amplification （SPA） have been obtained. It is shown that two peaks can occur on the curve of SNR versus the intensity of the DN. Moreover, the SNR is a non-monotonic function of the correlation time of the DN. The SPA varies non-monotonously with the strength of the DN. The dependence of the SNR on the frequency and the amplitude of the external periodic signal are discussed. The effect of the external frequency and the correlation time of the DN on the SPA are analyzed.     

Isospectral and Nonisospectral Lattice Hierarchies Associated with a Discrete Spectral Problem and Their Infinitely Many Conservation Laws

In this paper, based on the discrete zero curvature representation, isospectrai and nonisospectrai lattice hierarchies are proposed. By means of solving corresponding discrete spectral equations, we demonstrate the existence of infinitely many conservation laws for this two hierarchies and obtain the formulae of the corresponding conserved densities and associated fluxes.     

Influence of a phonon bath in a quantum dot cavity QED system:Dependence of the shape

We present a systematic analysis on the role of the quantum dot （QD） shape in the influence of the phonon bath on the dynamics of a QD cavity QED system. The spectral functions of the phonon bath in three representative QD shapes： spherical, ellipsoidal, and disk, are calculated from the carrier wave functions subjected to the confinement potential provided by the corresponding shape. The obtained spectral functions are used to calculate three main effects brought by the phonon bath, i.e., the coupling renormalization, the off-resonance assisted feeding rate and the pure dephasing rate. It is found that the spectral function of a disk QD has the widest distribution, hence the phonon bath in a disk QD can lead to the smallest renormalization factor, the largest dephasing rate in the short time domains（≤2 ps）, and the oft-resonance assisted feeding can support the widest detuning. Except for the pure dephasing rate in the long time domains, all the influences brought by the phonon bath show serious shape dependence.     

Alignment of the photoelectron spectroscopy beamline at NSRL

Tile photoelectron spectroscopy beamline at National Synchrotron Radiation Laboratory （NSRL） is equipped with a spherical grating monochromator with the included angle of 174. Three gratings with line density of 200, 700 and 1200 lines/mm are used to cover the energy region from 60 eV to 1000 eV. After several years＇ operation, the spectral resolution and flux throughput were deteriorated, and realignment was necessary to improve the performance. First, the wavelength scanning mechanism, the optical components position and the exit slit guide direction are aligned according to tile design value. Second, the gratings are checked by Atomic Force Microscopy （AFM） and then the gas absorption spectrum is measured to optimize the focusing condition of the monoehromator. The spectral resolving power E/AE is recovered to the designed value of 1000@244 eV. The flux at the end station for the 200 lines/ram grating is about 1010 photons/sec/200 mA, which is in accordance with the design. The photon flux for the 700 lines/mm grating is about 5 108 photons/sec/200mA, which is lower than expected. This poor flux throughput may be caused by carbon contamination on the optical components. The 1200 lines/ram grating has roughness much higher than expected so the diffraction efficiency is too low to detect any signal. A new grating would be ordered. After the alignment, the beamline has significant performance improvements in both the resolving power aim the flux throughput for 200 and 700 lines/ram gratings and is provided to users.     

The spin dynamics of the random transverse Ising chain with a double-Gaussian disorder

The dynamical properties of one-dimensional random transverse Ising model （RTIM） with a double-Gaussian disorder is investigated by the recursion method. Based on the first twelve recurrences derived analytically, the spin autocorrelation function （SAF） and associated spectral density at high temperature were obtained numerically. Our results indicate that when the standard deviation σg （or OrB） of the exchange couplings Ji （or the random transverse fields Bi） is small, no long-time tail appears in the SAE The spin system undergoes a crossover from a central-peak behavior to a collectivemode behavior, which is the dynamical characteristics of RTIM with the bimodal disorder. However, when σJ （or σB） is large enough, the system exhibits similar dynamics behaviors to those of the RTIM with the Gaussian disorder, i.e., the system exhibits an enhanced central-peak behavior for large σJ or a disordered behavior for large σB. In this instance, SAFs exhibit a similar long-time tail, i.e., C（t） ~ t ^-2 for large t. Similar properties are obtained when Ji （or Bi） satisfy the double-exponential distribution or the double-uniform distribution. Besides, when both the standard deviations and the mean values of the exchange couplings are small, the effects of the Gaussian random bonds may drive the system undergo two crossovers from a triplet state to a doublet state, and then to a collective-mode state.     

Relic Gravity Waves Investigation by Advanced Space-Based Gravitational Waves Detector

This paper focuses on the relic gravity waves produced during the transition from a radiation-dominated inflationary phase to a dust-dominated Friedman-Robertson-Walker-type expansion. We discuss how to investigate the spectral energy density by the latest space-based CWs detectors at f =0.1 Hz （i.e. DECICO）. In the case of power-law and exponential inflation, we apply the cross-correlation method to the latest detector and get the time dependence of the very early Hubble pararneter.     

An Integrable Symplectic Map Related to Discrete Nonlinear SchrSdinger Equation

The method of nonlinearization of spectral problem is developed and applied to the discrete nonlinear Schr6dinger （DNLS） equation which is a reduction of the Ablowitz-Ladik equation with a reality condition. A new integable symplectic map is obtained and its integrable properties such as the Lax representation, r-matrix, and invariants are established.     

An Integrable Decomposition of Defocusing Nonlinear Schrodinger Equation

The method of nonlinearization of spectral problems is developed to the defocusing nonlinear Schrodinger equation. As an application, an integrable decomposition of the defocusing nonlinear Schrodinger equation is presented.     

A novel hierarchy of differential integral equations and their generalized bi-Hamiltonian structures

With the aid of the zero-curvature equation, a novel integrable hierarchy of nonlinear evolution equations associated with a 3 x 3 matrix spectral problem is proposed. By using the trace identity, the bi-Hamiltonian structures of the hierarchy are established with two skew-symmetric operators. Based on two linear spectral problems, we obtain the infinite many conservation laws of the first member in the hierarchy.     

Balmer-alpha and Balmer-beta Stark line intensity profiles for high-power hydrogen inductively coupled plasmas

We compare Balmer-alpha(Hα) and Balmer-beta(Hβ) emissions from high-power(1.0–6.0 kW) hydrogen inductively coupled plasmas(ICPs), and propose region I(0.0–2.0 kW), region II(2.0–5.0 kW), and region III(5.0–6.0 kW). In region I, both Hαemission intensity(Iα) and Hβemission intensity(Iβ) increase with radio frequency(RF) power, which is explained by the corona model and Boltzmann’s law, etc. However, in region II, Iαalmost remains constant while Iβrapidly achieves its maximum value. In region III, Iαslightly increases with RF power, while Iβdecreases with RF power,which deviates significantly from the theoretical explanation for the Hαand Hβemissions in region I. It is suggested that two strong electric fields are generated in high-power(2.0–6.0 kW) hydrogen ICPs: one is due to the external electric field of high-power RF discharge, and the other one is due to the micro electric field of the ions and electrons around the exited state hydrogen atoms in ICPs. Therefore, the strong Stark effect can play an important role in explaining the experimental results.     

Implementation of the direct demodulation method for natural gamma ray spectral logging

Spectrum analysis of natural gamma ray spectral logging (SGR) data is a critical part of surface information processing systems. Due to the low resolution, which is an inherent weakness of SGR, and the low signal-to-noise ratio problem of logging measurements, SGR is usually treated with a low confidence level. The Direct Demodulation (DD) method is an advanced technique to solve modulation equations interactively under physical constraints. It has higher sensitivity and spatial resolution than the traditional methods and can effectively suppress the logging noise. Based on standard count rate spectral data obtained from the China Offshore Oil Logging Company SGR Calibration Facility, this paper presents the application of the DD method to gamma-ray logging. The results are compared with four traditional algorithmic methods, showing that the DD method is a credible choice, with higher sensitivity and higher spatial resolution in gamma-ray log interpretation. The Point-Spread-Function of the Shengli Oil Logging Company's natural gamma ray spectroscopy instrument is obtained for the first time. The quantities of various radionuclides in their calibration pits are also obtained. The DD method was applied successfully to gamma-ray logging, offering a new option for SGR logging algorithm selection.     

Phase-locked all-optical differential polarization demodulation

A novel scheme of differential polarization demodulation is presented and demonstrated based on a polarized asym- metrical Mach-Zehnder interferometer configuration with polarization control. To enhance the stability of the demodulator, a phase-lock device is designed, and it is composed of a symmetric 3 × 3 coupler and a feedback circuit. For further estab- lishing a differential polarization-shift keying （DPolSK） transmission system, we successfully carry out the demodulation experiments on 10-Gb/s DPolSK optical signals for the first time. Due to the all-optical structure with phase-lock, our scheme is available to realize the DPolSK optical communication in practical optical fiber systems.     

A prototype of trigger electronics for LAWCA experiment

The Large Area Water Cherenkov Array （LAWCA） experiment focuses on high energy gamma astronomy between 100 GeV and 30 TeV. Invoked by the idea of hardware triggerless structure, a prototype of LAWCA trigger electronics is implemented in one single VME-9U module which obtains all the data from the 100 Front End Electronic （FEE） endpoints. Since the trigger electronics accumulate all the information, the flexibility of trigger processing can be improved. Meanwhile, the dedicated hardware trigger signals which are fed back to front end are eliminated; this leads to a system with better simplicity and stability. To accommodate the 5.4 Gbps system average data rate, the fiber based high speed serial data transmission is adopted. Based on the logic design in one single FPGA device, real-time trigger processing is achieved; the reprogrammable feature of the FPGA device renders a reconfigurable structure of trigger electronics. Simulation and initial testing results indicate that the trigger electronics prototype functions well.     

类型γ射线能谱指纹的识别机理

放射源的辐射指纹能起到标识和鉴别放射性物体的作用.在涉及核弹头不可逆销毁过程的深度核裁军核查中,核弹头的辐射指纹对标识和鉴别裁减下来的核弹头将起到关键作用.预先研究辐射指纹的有关技术,如识别机理的研究,将有助于深度核裁军的核弹头核查技术发展.以实验室放射源为研究对象,探索了类型γ射线能谱指纹的同一性识别机理.类型γ射线指纹识别机理的研究,就是要找出一种合适的方法,以较高的置信度,描述两个正在进行比较的γ射线指纹是否为同一放射源的指纹.采用了谱形比较法,并用谱相似度概念来描述两个指纹的相似程度.在谱形比较思想的指导下,编制了放射源类型指纹识别软件,并通过放射源同一性的识别实验验证了软件的有效性,同时研究了谱相似度随统计涨落和测量条件,如时间、源强和本底等因素的变化情况.研究结果表明:1)用相似度概念来描述两个指纹的相似程度,回答两个待比较的γ射线能谱是否代表同一类型放射源,是切实可行的;2)该识别机理只具备识别放射源类型的能力,而对同一类型、差异甚微的放射源个体还不能识别 关键词： γ射线能谱指纹 辐射指纹 识别机理 核查技术     

Study on the optimization of the water Cherenkov detector array of the LHAASO project for surveying VHE gamma ray sources

It is prpopsed that a water Cherenkov detector array, LHAASO-WCDA, is to be built at Shangri-la, Yunnan Province, China. As one of the major components of the LHAASO project, the main purpose of it is to survey the northern sky for gamma ray sources in the energy range of 100 GeV-30 TeV. In order to design the water Cherenkov array efficiently to economize the budget, a Monte Carlo simulation is carried out. With the help of the simulation, the cost performance of different configurations of the array are obtained and compared with each other, serving as a guide for the more detailed design of the experiment in the next step.     

Investigation of high resolution compact gamma camera module based on a continuous scintillation crystal using a novel charge division readout method

The objective of this study is to investigate a high performance and lower cost compact gamma camera module for a multi-head small animal SPECT system. A compact camera module was developed using a thin Lutetium Oxyorthosilicate （LSO） scintillation crystal slice coupled to a Hamamatsu H8500 position sensitive photomultiplier tube （PSPMT）. A two-stage charge division readout board based on a novel subtractive resistive readout with a truncated center-of-gravity （TCOG） positioning method was developed for the camera. The performance of the camera was evaluated using a flood 99roTe source with a four-quadrant bar-mask phantom. The preliminary experimental results show that the image shrinkage problem associated with the conventional resistive readout can be effectively overcome by the novel subtractive resistive readout with an appropriate fraction subtraction factor. The response output area （ROA） of the camera shown in the flood image was improved up to 34%, and an intrinsic spatial resolution better than 2 mm of detector was achieved. In conclusion, the utilization of a continuous scintillation crystal and a flat-panel PSPMT equipped with a novel subtractive resistive readout is a feasible approach for developing a high performance and lower cost compact gamma camera.     

Cl_2~+离子P支高激发振转态的跃迁谱线

基于描述双核分子体系包含转动光谱常数Lv所在高阶项在内的跃迁能谱的经典表达式,采用差分收敛法(DCM)的物理思想,推导获得了求解双核分子体系P支跃迁谱线的另一解析表达形式。对于某一双核分子体系的P支跃迁带,新的谱线表达式仅需要11条精确的实验跃迁谱线就可以正确预言高激发振转态的谱线结构,同时,利用谱线展开系数C还可以进一步给出计算谱线的不确定度以更可靠地预言高激发振转态的跃迁谱线。推导获得了相应的计算公式以正确获得对应跃迁带的转动光谱常数(B_(v′),B_(v″),D_(v′),D_(v″),H_(v′),H_(v″),L_(v′),L_(v″))。应用新的谱线表达式,对~(35) Cl_2~+和~(35) Cl ~(37) Cl~+离子电子态A~2Π_u-X~2Π_g(Ω=1/2)跃迁体系(3,7)跃迁带的P支跃迁谱线进行了详细研究,获得的计算结果不但能完全重复已知的实验数据,还获得了实验上未能获得的包含高激发振转态在内的跃迁谱线。另外,通过计算同时也得到了各跃迁带的高阶转动光谱常数。该研究方法和计算结果为人们进一步正确认识Cl_2~+离子电子态的内部能级结构及物理化学的相关性质提供了更完整的参考数据。     

Post-post-Newtonian deflection of light ray multiple systems with PPN parameters

The post-Newtonian scheme in multiple systems with post-Newtonian parameters presented by Klioner and Soffel is extended to the post-post-Newtonian （PPN） order for light propagation problem in the solar system. Under considering the solar system experiment requirement, a new parameter ε is introduced. This extension does not change the virtue of the scheme on the linear partial differential equations of the potential and vector potential mentioned in previous work. Furthermore, this extension is based on the former work done by Richter and Matzner in one global system theory. As an application, we also consider the deflection of light ray in the global coordinates. And the deflection angle of light ray is obtained with post-Newtonian parameters.     

A comparison of ionizing radiation damage in CMOS devices from ^60Co gamma rays,electrons and protons

Radiation hardened CC4007RH and non-radiation hardened CC4011 devices were irradiated using ^60Co gamma rays, 1 MeV electrons and 1-9 MeV protons to compare the ionizing radiation damage of the gamma rays with the charged particles. For all devices examined, with experimental uncertainty, the radiation induced threshold voltage shifts （△Vth） generated by ^60Co gamma rays are equal to that of 1 MeV electron and 1-7 MeV proton radiation under 0 gate bias condition. Under 5 V gate bias condition, the distinction of threshold voltage shifts （△Vth） generated by ^60Co gamma rays and 1 MeV electrons irradiation are not large, and the radiation damage for protons energy the proton has, the less serious below 9 MeV is always less than the radiation damage becomes. that of ^60Co gamma rays. The lower