An exclusive event generator for e＋e- scan experiments

An exclusive event generator is designed for e＋e- scan experiments, including initial state radiation effects up to the second order correction. The generator is coded within the framework of BesEvtGen. There are seventy hadronic decay modes available, with effective center-of-mass energy coverage from the two pion mass threshold up to about 6 GeV. The accuracy achieved for the initial state radiation correction reaches the level achieved by the KKMC generator. The uncertainty associated with the calculation of the correction factor to the initial state radiation is dominated by the measurements of the energy-dependent Born cross section.     

Production of charmonium（like）states in e^＋e^- interactions

We present a search for new charmonium like states in e~ e~- annihilation using the initial-state radiation and the process e~ e~-→J/ψD~(*)~(*).The analyses are based on a huge data sample recorded near theγ(4S)resonance with the Belle detector at the KEKB e~ e~- asymmetric-energy collider.     

Hidden-charm Pentaquark Production at e~+e~- Colliders

We study one possible production mechanism for the hidden-charm pentaquark via a color-octet cc pair fragmentation in e~+e~-collision.The pentaquark production at B factory energy is dominated by e~+e~-→ccg→P_c+X,while at Z~0pole energy,there are several partonic processes playing significant role.Our results show that it is possible to search for the direct pentaquark production signal at e~+e~-colliders,which is important to understand the properties of pentaquark.     

Physics cross sections and event generation of e~+e~- annihilations at the CEPC

The cross sections of the Higgs production and the corresponding backgrounds of e~+e~- annihilations at the CEPC(Circular Electron and Positron Collider) are calculated by a Monte-Carlo method, and the beamstrahlung effect at the CEPC is carefully investigated. The numerical results and the expected number of events for the CEPC are provided.     

Tuning and validation of hadronic event generator for R value measurements in the tau-charm region

To measure the R value in an energy scan experiment with e⁺e^- collisions, precise calculation of initial state radiation is required in the event generators. We present an event generator for this consideration, which incorporates initial state radiation effects up to second order accuracy. The radiative correction factor is calculated using the totally hadronic Born cross section. The measured exclusive processes are generated according to their cross sections, while the unknown processes are generated using the LUND Area Law model, and its parameters are tuned with data collected at √s=3.65 GeV. The optimized values are validated with data in the range √s=2.2324-3.671 GeV. These optimized parameters are universally valid for event generation below the DD threshold.     

A method for measuring D~* electromagnetic form factors in e~+e~- annihilation

We describe a method for measuring the electromagnetic form factors of the D~* meson at time-like momentum transfer in e~+e~-annihilation.This is to study the joint angular distribution of the e~+e~-→γ~*→D~*+D~*-,D~*~+→D~0π~+,and D~*-→D~0π-processes.The magnitudes and relative phases of the charge,magnetic and quadrupole form factors can be determined.The method can also be applied to other vector particles.     

紧凑型X箍缩脉冲功率发生器

为研究丝阵负载对X箍缩的影响,设计了一台紧凑型脉冲功率发生器。介绍了该脉冲功率发生器的设计及初步实验。根据装置的结构特点,研制了一种利用金属膜连接传输线外筒与负载内筒,构成回路测量负载电流的探头。结果表明:在对Marx电容器充电60 kV时,输出电流峰值117 kA,脉宽 60 ns,上升沿22 ns,该装置已经成功箍缩出X射线。     

紧凑型X箍缩脉冲功率发生器

为研究丝阵负载对X箍缩的影响,设计了一台紧凑型脉冲功率发生器。介绍了该脉冲功率发生器的设计及初步实验。根据装置的结构特点,研制了一种利用金属膜连接传输线外筒与负载内筒,构成回路测量负载电流的探头。结果表明:在对Marx电容器充电60 kV时,输出电流峰值117 kA,脉宽 60 ns,上升沿22 ns,该装置已经成功箍缩出X射线。     

Uncertainty of the beam energy measurement in the e~+e~- collision using Compton backscattering

The beam energy is measured in the e+e-collision by using Compton backscattering. The uncertainty of this measurement process is studied by virtue of analytical formulas, and the special effects of variant energy spread and energy drift on the systematic uncertainty estimation are also studied with the Monte Carlo sampling technique. These quantitative conclusions are especially important for understanding the uncertainty of the beam energy measurement system.     

Complementary studies on N~* from e~+e~-, pp and pp(-) collisions

Complementary to the conventional experimental studies on N~* from πN and γ(~*)N reactions, the e~+e~-, pp and pp collisions can give novel insights into these N~* resonances. While the e~+e~- collisions through production and decay of vector charmonium ψ provide a nice isospin filter for a simultaneously study of N~*, △~*, Λ~*, ∑* and Ξ~*, the pp collisions should be the best place for producing those △~(*++) with large coupling to p+p though pp→n△~(*++) reaction, and the pp(-) collisions should be the best place for looking for those N~* with large coupling to σN.     

Searching for a neutral top-Higgs in association with top-quark pairs at an e~+e~- collider in the TC2 model

We investigate the associated production of the neutral top-Higgs h_t⁰ with a pair of top-quarks in the context of the topcolor-assisted technicolor (TC2) model at the future e⁺e^- Linear Colliders (LC) i.e. e⁺e^- → tt h_t⁰. We calculate the production rate and present the distributions of the transverse momenta of top-Higgs and top-quarks. The results show that the total cross section is typically of the order of 1.0-7.5 fb in the energy range between 1000 GeV and 2000 GeV of the LC for the whole top-Higgs mass region of interest. It should be distinctly possible that hundreds or even thousands of h_t⁰ signals can be produced per year at the LC given the luminosity L=500 fb^-1.     

在s~(1/2)=4.03GeV的e~+e~-湮没中D_s~+单标记的研究及D_s~+D_s~-对产生截面的测定

利用北京正负电子对撞机 (BEPC)和北京谱仪 (BES) ,基于在质心系能量s=4.0 3GeV的e+ e-湮没中 ,D+ s 单标记的分析结果 ,测定了D+ s →K 0 K+ 和D+ s →K0 K+ 衰变的分支比。其结果Br(D+ s →K 0 K+ ) =(3.0 2± 0 .94±0 .91) % ,Br(D+ s →K0 K+ ) =(3.2 8± 1.2 2± 0 .94) %与世界平均值在误差范围内一致 .用π+ ,K 0 K+ ,K0 K+ 作为单标记 ,共观测到 94± 13个D+ s 事例 ,测得在e+ e-湮没中D+ s D-s 对产生的截面为σprodD+s D-s =45 1± 6 3± 118pb .     

流体动力学实验用闪光X光机研究进展

闪光X光机是流体动力学等研究领域必不可少的实验诊断装置, 物理需求推动其向更高剂量和更小焦斑发展。叙述了几种X光二极管研究现状和关键问题,阐述了适用于不同功率水平的闪光X光机驱动源,分析了阳极杆箍缩和磁浸没二极管的应用前景,讨论了阳极杆箍缩二极管、驱动源发展方向以及实现多幅照相涉及的关键技术。     

ENSO事件随机动力学模型的渐近分析

利用边界层型函数，研究了ENSO事件随机动力学的某一模型，给出了这一问题的n阶渐 近展开式，将相关结论应用于特殊的ENSO事件，并得到了零阶渐近解，为分析ENSO事件的变 化状态提供了依据. 关键词： ENSO事件 边界层型函数 渐近展开式     

An event mixing technique for Bose-Einstein correlations of two pions in photoproduction around 1 GeV

We have developed an event mixing technique to observe Bose-Einstein correlations (BEC) between two identical neutral pions produced in photo-induced reactions in the non-perturbative QCD energy region. It is found that the missing-mass consistency cut and the pion-energy cut are essential for the event mixing method to effectively extract BEC observables. A Monte Carlo (MC) simulation is used to validate these constraints and confirms the efficiency of this method. Our work paves the way for similar BEC studies at lower energies where the multiplicity of emitted bosons is limited.     

磁悬浮式电磁-摩擦复合生物机械能量采集器

能量采集技术已经成为智能终端领域的一项关键技术,关于人体机械能采集方式也有大量的研究.针对人体机械能采集的应用需求,本文提出一种基于磁悬浮结构的电磁-摩擦复合式能量采集器.该能量采集器以磁悬浮结构作为核心部件,具有结构简单、感应灵敏、输出功率高的优点.在10 MΩ的外接负载时,两组摩擦发电单元输出功率分别为0.12 mW和0.13 mW;在1kΩ外接负载时,两组电磁发电单元的输出功率分别为36 mW和38 mW.复合能量采集器通过电容储能后,电容器可以输出8 V电压,且输出信号为持续的直流信号,可以为计步器提供持续的能量供给,支撑计步器正常工作.设计的复合能量采集器对于可穿戴电子设备自供电工作模式的实现具有重要意义.     

重复频率纳秒脉冲源程控脉冲发生器

介绍了一种可以完成脉宽、幅值、频率可调、十路脉冲输出且延时可调功能的程控脉冲发生器。硬件主要包括主电源和辅助电源、功率放大电路、控制系统处理器、数字键盘和液晶显示屏。该脉冲发生器输出脉冲宽度可在1~30 s间调节,脉冲幅值在1~15 V间调节,输出脉冲频率范围为1 Hz~30 kHz,十路脉冲输出中每路脉冲之间可以在0~1 ms范围内精确调节。该脉冲发生器可为多个脉冲源的并联运行提供延时触发,为多个绝缘栅双极型晶体管(IGBT)开关串联提供同步触发。     

重复频率纳秒脉冲源程控脉冲发生器

介绍了一种可以完成脉宽、幅值、频率可调、十路脉冲输出且延时可调功能的程控脉冲发生器。硬件主要包括主电源和辅助电源、功率放大电路、控制系统处理器、数字键盘和液晶显示屏。该脉冲发生器输出脉冲宽度可在1~30 s间调节,脉冲幅值在1~15 V间调节,输出脉冲频率范围为1 Hz~30 kHz,十路脉冲输出中每路脉冲之间可以在0~1 ms范围内精确调节。该脉冲发生器可为多个脉冲源的并联运行提供延时触发,为多个绝缘栅双极型晶体管(IGBT)开关串联提供同步触发。