质子与裂变核238U反应的理论计算

利用球型光学模型、耦合道理论、核内级联、激子模型、蒸发模型、带宽度涨落修正的Hauser-Feshbach模型,Bohr-Wheeler裂变理论,对入射能量从阈能到200 MeV的p+²³⁸U各种反应进行了计算,计算结果和实验符合较好.     

Fluorescence quenching using plasmonic gold nanoparticles

This communication describes the study of fluorescence quenching in a new fluorescent laser dye ADS680HO is attached to gold nanoparticles of size 4-12 nm. Photo physical properties confirms that it is due to size, shape, coupling between nanoparticles with laser dye ADS680HO, and energy transfer between dye and nanoparticles. Fluorescence quenching leads to advancement in biomolecular labeling and fluorescence patterning.     

联邦滤波在飞机组合导航中的应用

研究了中等精度捷联惯导系统(SINS),大气数据系统(ADS)和塔康系统(TACAN)构成的机载组合导航系统.在分析SINS、ADS、TACAN各自特点的基础上,提出了SISN/ADS/TACAN组合导航系统的联邦滤波方案,并建立了相应的组合导航系统的数学模型.以一条典型的飞行轨迹进行了全航线的仿真研究,仿真结果为:基于联邦滤波的SINS/ADS/TACAN组合导航系统的位置精度约为70 m(CEP),速度精度约为0.75 m/s(1),航向精度为约为 (1)和姿态精度约为 (1),由此可见基于联邦滤波的SINS/ADS/TACAN组合导航系统可以充分利用各机载导航子系统信息,满足飞机导航定位的精度要求.     

MPI在蒙特卡罗程序GMT中的应用和发展

针对ADS颗粒靶概念的研究和设计,中国科学院近代物理研究所自主研发了蒙特卡罗模拟软件GMT。为了提高GMT程序的计算效率,研究了MPI在GMT中的应用和发展,实现了大规模随机数在进程中的随机分配,并采用快速读写文件的方式替代了MPI相关数据通信函数,极大地提高了计算效率。并研究了不同规模计算实例进程数、加速比、效率之间的关系,确定了最大加速进程数及并行效率最高时的进程数,为科研工作者在计算资源和计算效率之间选择最优计算方案提供了科学依据。MPI在GMT中的成功应用使计算资源得到了充分、高效的利用,极大地提高了计算效率,解决了蒙特卡罗方法中大规模事件模拟计算时间长、计算不稳定等问题,在散裂靶大规模扫描计算中发挥了重要的作用。For the research and design of the ADS granular-flow target concept, the Institute of Modern Physics, CAS has developed a Monte Carlo simulation software (GPU-accelerated Monte Carlo Transport program, GMT). In order to improve the computational efficiency of the GMT program, development and application of MPI in GMT were studied, to realize random distribution of the large-scale random number in the sub processes. Rapid reading and writing files were employed instead of the MPI data communication function, which greatly improves the computational efficiency. Different scale calculations were performed to study the relationship of process instance number, speedup to find the maximum acceleration process number and the number of processes when parallel efficiency is highest, which provides a scientific basis for researchers to optimize the computational program between computational resources and computation efficiency. The successful application of MPI in GMT, utilizes the computing resources fully and efficiently, improves the computational efficiency, solve the long time cost and unstable problem of Monte Carlo method in large-scale event simulations, plays an important role in the large-scale scanning calculation of the spallation target.     

Beam experiments with a non-intercepting beam induced f luorescence profile monitor for the ADS LINAC

An accelerator-driven subcritical system(ADS) project was launched in China in 2011, aiming to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power. The driver linac is defined to be a 10 m A current of high energy protons at 1.5 Ge V in continuous wave operation mode. To meet the extremely high power and intense beam accelerator requirements, non-interceptive monitors for the beam transverse profile are required for this proton linac. Taking advantage of the residual gas as active material, the Beam Induced Fluorescence(BIF) monitor exploits gas-excited fluorescence in the visible spectrum region for transverse profile measurements. The advantages of this non-intercepting method are that nothing is installed in the vacuum pipe,component design is compact and there is no need for expensive signal processing electronics. Beam experiments have been performed under constant beam conditions. The helium spectrum has been verified with different optical filters, showing that a proper optical band-pass filter covering 400–500 nm is necessary for fluorescence experiments with helium. By changing gas pressure, it is shown that gas pressure is proportional to the signal amplitude but has no influence on detected profile width. Finally, a comparison experiment between the BIF monitor and a wire scanner shows that the detected profile width results of both methods agree well.     

Beam-based calibrations of the BPM offset at C-ADS Injector Ⅱ

Beam-based BPM offset calibration was carried out for Injector II at the C-ADS demonstration facility at the Institute of Modern Physics(IMP), Chinese Academy of Science(CAS). By using the steering coils integrated in the quadrupoles, the beam orbit can be effectively adjusted and BPM positions recorded at the Medium Energy Beam Transport of the Injector II Linac. The studies were done with a 2 m A, 2.1 Me V proton beam in pulsed mode.During the studies, the "null comparison method" was applied for the calibration. This method is less sensitive to errors compared with the traditional transmission matrix method. In addition, the quadrupole magnet's center can also be calibrated with this method.     

The spatial distribution of thermal and epithermal neutrons in a graphite moderated spallation neutron field

The Gamma-3 assembly is located at the Joint Institute for Nuclear Research, Dubna, Russia. It consists of a cylindrical lead target (ø = 8 cm, L = 58.8 cm) surrounded by reactor grade graphite (110 × 110 × 60 cm). The target was irradiated with a beam of 1.6 GeV deuterons from the Nuclotron accelerator and CR-39 track detectors coupled to LR-115 2B film were used to measure the slow neutron distribution on the surface of the graphite. The detection efficiency of the CR-39 in the CR-39/LR-115 2B system was measured using a custom made calibration setup and found to be (1.12 ± 0.05) × 10⁻³ and (6.1 ± 1.2) × 10⁻⁴ tracks per neutron, for thermal and epithermal neutrons respectively, under the etching and counting procedures described in this work. The irradiation of the Gamma-3 was also simulated using MCNPX 2.7 Monte Carlo code and good agreement between the experimental and calculated track densities was found. This serves as a good validation for the computational models used to simulate spallation neutron production, transport and moderation.     

中能质子入射的裂变产物质量分布计算

采用量子分子动力学(QMD)、统计衰变模型(SDM)和半经验的多模裂变模型方法计算了能量在200MeV附近的中能质子入射重核引起裂变的裂变产物质量分布,得到了与实验相符合的结果;同时对锕系核素和非锕系重核素分别给出了一组合理的多模裂变模型参数.     

Radicals whose semisimple classes satisfy a generalised ADS condition

A class K of rings has the GADS property (i.e., generalized ADS property) if wheneverX&;ltri; I&;ltri; R with X&;isin; K, then there exists B &;ltri; R with B &;isin; K such that X &;sube; B &;sube; I. Radicals whose semisimple classes have the GADS property are called g-radicals. In this paper, we fully characterize the class of g -radicals. We show that ? is a g-radical if and only if either ? &;sube; I or S? &;sube; I , whereI denotes the class of idempotent rings and S? denotes the semisimple class of ?. It is also shown that the (hereditary) g-radicals form an (atomic) sublattice of the lattice of all radicals.     

Conformal quantum mechanics as the CFT1 dual to AdS2

A (0+1)-dimensional candidate theory for the CFT₁ dual to AdS₂ is discussed. The quantum mechanical system does not have a ground state that is invariant under the three generators of the conformal group. Nevertheless, we show that there are operators in the theory that are not primary, but whose “non-primary character” conspires with the “non-invariance of the vacuum” to give precisely the correlation functions in a conformally invariant theory.