Characteristics of Double Gamma-Ray Bursts

Double gamma-ray bursts （DGRBs） have two well-separated sub-bursts in the main prompt emission and the typical time interval between them is in the hundreds of seconds. Among DGRBs, gamma-ray bursts （DGRBs） 110801A and 120716A are the ones with known redshifts. However, unlike GRB 110801A, we show that the two sub-bursts of GRB 120716A is severally similar to the short- and long-duration GRBs, thus it is difficult to explain the origin of GRB 120716A by the popular models on the central engine of GRBs. We suggest that some mechanisms of x-ray flares in GRBs, i.e., a post-merger millisecond pulsars or the jet precession in a black hole hyperaccretion system may produce the DGRB.     

973 RFQ 水冷调谐系统(英文)

由于束流的传输效率对射频四极场加速器(RFQ) 中射频场的分布极其敏感,所以在RFQ 的运行过程中不再采用传统的调谐器调谐RFQ。水冷调谐的方法基本上不影响RFQ 射频场的分布,所以适用于RFQ 的调谐。中国科学院高能物理研究所为C-ADS、CSNS 预研RFQ 项目开发建造了一套水冷调谐系统,使用RF 相位差作为控制量进行RFQ 水冷调谐,相位差的控制精度达到了1°运行结果显示该系统满足了RFQ 的调谐需求。介绍了该系统的水冷系统、调谐控制系统和一些运行经验。Since the beam transmission of a Radio Frequency Quadrupole(RFQ) Accelerator is very sensitive to the field profile, the ordinary frequency tuning method by the local movable tuner is no more adopted in an RFQ operation. The tuning method by controlling cooling water temperature is widely adopted to tune the RFQ due to the less affect on the RFQ field profile. A Resonance Control Cooling System (RCCS) is developed and commissioned for the 973 RFQ,which is a R&D project for C-ADS and CSNS RFQ at IHEP. This system adopts the RF phase difference as control variable to tune the RFQ. The control accuracy of the RF phase difference is about 1°. The running of the 973 RFQ shows that the RCCS works very well and fully satisfies the operation requirement of the RFQ. In this paper, the water skid, resonance control system of the RCCS and the operation experiences will be presented.     

高功率腔内双共振2μm光参量振荡器特性研究

报道了一种稳定的高功率双共振2?μm 光参量振荡器（OPO）. 该OPO使用调Q的线偏振全固态Nd∶YAG激光器作为抽运源,利用双棒串接补偿热致双折射和双Q开关正交放置技术提高了抽运源的输出功率和光束质量,通过腔内抽运单块KTP晶体实现了稳定的高功率2?μm 激光输出. 在调Q频率为5?kHz时,得到了295 W的2?μm 激光输出. 研究了OPO输出功率同KTP晶体温度和声光Q调制频率的关系,并测量了在29W时2?μm激光的功率稳定性. 在1 h内该OPO的功率起伏小于1.4%. 关键词： 光参量振荡器 2?μm激光器 KTP晶体 双共振     

手性氮杂卡宾金属络合物的合成及其在不对称催化反应中的应用

手性氮杂卡宾金属络合物在多种催化反应中得到了广泛的应用, 并取得了很好的研究成果. 综述了手性氮杂卡宾金属络合物的合成以及它们在催化不对称反应中的应用研究进展, 如催化α,β-不饱和酮的1,4-加成反应、酮的氢硅烷化反应、烯烃的氢化反应和烯烃的复分解反应等.     

Spectroscopic measurements and terahertz imaging of the cornea using a rapid scanning terahertz time domain spectrometer

Spectroscopic measurements and terahertz imaging of the cornea are carried out by using a rapid scanning terahertz time domain spectroscopy(THz-TDS) system.A voice coil motor stage based optical delay line(VCM-ODL) is developed to provide a rather simple and robust structure with both the high scanning speed and the large delay length.The developed system is used for THz spectroscopic measurements and imaging of the corneal tissue with different amounts of water content,and the measurement results show the consistence with the reported results,in which the measurement time using VCM-ODL is a factor of 360 shorter than the traditional motorized optical delay line(MDL).With reducing the water content a monotonic decrease of the complex permittivity of the cornea is observed.The two-term Debye relaxation model is employed to explain our experimental results,revealing that the fast relaxation time of a dehydrated cornea is much larger than that of a hydrated cornea and its dielectric behavior can be affected by the presence of the biological macromolecules.These results demonstrate that our THz spectrometer may be a promising candidate for tissue hydration sensing and practical application of THz technology.     

强辐射对Yb∶YAG超快无机闪烁探测器灵敏度影响的实验测量

为了给强脉冲辐射场中应用超快闪烁探测器进行精密物理测试以及相关晶体抗核加固提供实验测量数据参考,针对近年新研制的Yb∶ YAG超快无机闪烁体与GD40光电管构成的快闪烁探测器,在源强近万居的强稳态辐照场中,细致测量了辐射累计伽马剂量从约1 Gy开始到最高约1 kGy全过程中Yb∶ YAG超快闪烁探测器输出电流的变化数据;在测点注量率大于1017cm-2·s-1的“强光一号”短γ脉冲辐射场中,测量了Yb∶ YAG超快闪烁探测器输出脉冲波形响应情况.实验测量结果表明:在强稳态辐射场情况下,对应累计剂量5 ～ 10Gy时,YAG(Yb)闪烁探测器灵敏度下降约5～10;(相对辐照IGy时的情况);测点累计伽马剂量约1 kGy时,Yb∶ YAG超快闪烁探测器的电流输出与约1 Gy时的比值约50;;短γ脉冲辐射情况下,测点累计注量约4×109 cm-2,Yb∶ YAG超快闪烁探测器输出电流约1A时,灵敏度下降约10;(相对累计注量约3×109 cm-2的情况),当测点注量大于1010 cm-2(累积剂量超过100 mGy),Yb∶ YAG超快闪烁探测器会出现较明显的损伤现象.     

A_n型非退化仿射Hecke代数的Gr?bner-Shirshov基

我们讨论了A_n-型非退化仿射Hecke代数的Gr?bner-Shirshov基和线性基.构造代数的Gr?bner-Shirshov基的方法主要有两种:一是通过计算合成;另一种方法是用线性基和钻石合成引理.因为我们还不知道A_n-型非退化仿射Hecke代数的线性基,因此我们使用第一种方法,也就是先通过计算合成给出A_n-型非退化放射Hecke代数的Gr?bnerShirshov基,然后用此Gr?bner-Shirshov基和结合代数的钻石合成引理,给出A_n型非退化仿射Hecke代数的一组线性基.     

2-μm singly resonant optical parameter oscillator

We experimentally realize a singly resonant optical parameter oscillator （OPO） which operates at the degenerate point of KTiOPOa （KTP） crystal. A thin film plate polarizer （TFP） is used as the output coupler to obtain linearly polarized 2.12 μm laser. A maximum output power of 2.2 W at 2.12 μm is obtained from a near-degenerate, type-II KTP OPO by utilizing a Q-switched diode-pumped Nd：YAG laser operating at 5 kHz.     

Design of the low energy beam transport line for the China spallation neutron source

The design of the China Spallation Neutron Source (CSNS) low-energy beam transport (LEBT) line, which locates between the ion source and the radio-frequency quadrupole (RFQ), has been completed with the TRACE3D code. The design aims at perfect matching, primary chopping, a small emittance growth and sufficient space for beam diagnostics. The line consists of three solenoids, three vacuum chambers, two steering magnets and a pre-chopper. The total length of LEBT is about 1.74m. This LEBT is designed to transfer 20mA of H-pulsed beam from the ion source to the RFQ. An induction cavity is adopted as the pre-chopper. The electrostatic octupole steerer is discussed as a candidate. A four-quadrant aperture for beam scraping and beam position monitoring is designed.     

Design of magnet and control of the beam emittance for Penning H－ ion source

The design requirement and principle of the deflection magnet for Magnetron and Penning H^－ ion source are discussed. It is proved that there exists a maximum emittance for the beam that may be transformed by the magnet into a state with equal Twiss parameters of α_r=α_y and β_r=β_y, which is the requisite condition to get a minimum emittance at the entrance of RFQ after transporting by a LEBT with solenoids. For this maximum emittance, the corresponding magnetic field gradient index is 1.