A 300 µA Upgrade for the ISIS Accelerator

The Rutherford Appleton Laboratory (RAL) is home to the world's leading spallation neutron source ISIS [1]. The ISIS neutron producing target is driven by a 50 Hz, 800 MeV, 200 _A proton beam from a rapid cycling synchrotron, which is fed by a 70 MeV H_ drift tube linac (DTL) which in turn accepts beam from an H_ 665 keV Cockcroft-Walton preinjector. The ever increasing international demand for neutrons has motivated a bid to build a second target station at ISIS, for which £100 million funding has recently been approved by the U.K. government [2]. The second target station, operating at 10 Hz, will provide new scientific opportunities in soft condensed matter, biology and advanced materials.     

紫外干涉滤光片2280A’2537A’

一、前言紫外滤光片在生物化学,分析研究中有广泛的应用,目前国内制备还处在实验室阶段。对于2600～4000A波段可以采用和可见区相同的常规制作方法,即用PbF_2、Na_3AlF_6等材料镀出全介质滤光片,再加上紫外滤光玻璃UG5、UG11(德)或ZWB_2(中)组合而成。透过率国外报导可达50%,但由于环氧树脂在低于3700A     

INTERACTION OF A ∧-TYPE THREE-LEVEL ATOM WITH A TWO-MODE FIELD AND A TWO-MODE RAMAN-COUPLED MODEL

The Hamiltonian is derived for the interaction of a ∧-type three-level atom with a two-mode quantum cavity field from the general interaction Hamiltonian between a multi-level atom and a multi-mode radiation field, and it is reduced to an effective two-mode Raman-coupled model under a large detuning condition. We propose a modified effective Hamiltonian for the two-mode Raman-coupled model, find the time-dependent state vectors, and present the validity conditions for the involved interaction Hamiltonians. It is shown that in the study of the two-mode Raman-coupled model it is not enough to retain only the usually used effective Hamiltonian, one must also take into account the ac Stark shift of the atomic levels (at least one of the levels). Finally, we study the atomic dynamics in the interaction of a ∧-type three-level atom with a two-mode quantum cavity field and in the two-mode Raman-coupled model. We find that the number of collapse-revivals, the collapse time and the revival time show new characteristics.     

从A—B效应到A—C效应

本综述了Ａ－Ｂ效应和Ａ－Ｃ效应以及它们之间的对偶关系，并介绍了对Ａ－Ｃ效应的实验验证。     

A New Criterion for Disruption Prediction on HL-2A

A new criterion has been proposed to predict the major disruptions caused by tearing mode instabilities. According to the HL-2A experimental results, the statistical analyses are employed to investigate the relationships between MHD activities and the plasma disruptions. Two kinds of the tearing mode activities can finally cause the disruption on HL-2A operations. By introducing a new parameter, i.e. an integral of poloidal magnetic field over time, as the criterion of disruption precursor, almost all of the disruptions can be predicted.     

One-Dimensional Lattice Dynamics of the Diffusion-Limited Reaction A+A→A+S: Transient Behavior

We use a Boolean cellular automaton model to describe the diffusion-limited dynamics of the irreversible reaction A+AA+S on a 1D lattice. We derive a set of equations for the dynamics of the empty interval probabilities from which explicit expressions for the particle concentration and the two-point correlation can be obtained. It is shown that the long-time dynamics is in agreement with the off-lattice solution. The early-time behavior, however, predicts a slower decay of the concentration.     

p－A和A－A碰撞中重夸克偶素的产生和吸收机制

考虑了色单态和色八重态的贡献后,我们计算了固定靶情况下J/ψ和ψ′的产生截面.并把结果用来研究p–A碰撞中J/ψ压低和ψ′/ψ的产额比值问题.当–核子相互作用的截面对(cc)₈取为σ8abs≈10mb,对(cc)₁取为σ8abs≈0mb时,计算结果和实验数据符合得很好.推广此模型,考虑同行粒子对J/ψ的吸收,并用它来讨论A–A碰撞的情况,计算结果表明,在相同的条件下,这个模型不能同时解释S–U和Pb–Pb碰撞的实验结果.最后讨论了S–U和Pb–Pb碰撞中QGP形成的可能性.     

A New Resonator With A Non─misaligned FourMirorReflectorAndItsEfectOnBeamQualityImprovementOfHighAveragePowerNd：YAGLasers

ＡＮｅｗＲｅｓｏｎａｔｏｒＷｉｔｈＡＮｏｎ─ｍｉｓａｌｉｇｎｅｄＦｏｕｒＭｉｒｏｒＲｅｆｌｅｃｔｏｒＡｎｄＩｔｓＥｆｅｃｔＯｎＢｅａｍＱｕａｌｉｔｙＩｍｐｒｏｖｅｍｅｎｔＯｆＨｉｇｈＡｖｅｒａｇｅＰｏｗｅｒＮｄ：ＹＡＧＬａｓｅｒｓＣ．Ｍ．Ｚｈａｏ，Ｇ...     

A New Quantum State

１ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｗｅｌｋｎｏｗｎｔｈａｔｂｏｓｏｎｒｅａｌｉｚａｔｉｏｎａｐｐｒｏａｃｈｉｓｖｅｒｙｅｆｅｃｔｉｖｅｔｏｓｔｕｄｙｔｈｅｒｅｐｒｅｓｅｎｔａｔｉｏｎｔｈｅｏｒｙｏｆｇｒｏｕｐ，ａｎｄｔｈｅｂｏｓｏｎｒｅａｌｉｚａｔ...     

HL-2Aװ�õ��ӻ���������Ȳ����͹��ʳ�������ķ�������

在HL-2A单零偏滤器条件下,对由弱场侧沿赤道平面垂直注入的电子回旋寻常波(O-模)的波迹和波的功率沉积剖面进行了分析计算。对近磁轴共振情形,需要确定一个有效的物理尺度以正确获得波功率沉积。单一波束的有效吸收层的厚度可以合理地作为这一物理尺度,从而获得统一的功率沉积公式。对比研究了磁轴偏离赤道面和位于赤道面情况下的波功率沉积剖面。     

A Reflected Terahertz-Emission Microscopy

A novel reflected terahertz-emission microscopy is proposed and developed for improving the spatial resolution of THz imaging. When attaching a bow-tie antenna directly onto a thin generation crystal, the reflected THz waves can be collected and detected by a photoconductive antenna, and the spatial resolution is decided by the diameter of focused pump beam. In this way, the detected resolution can be largely improved and tunable. The configuration and characteristics of this microscopy are described in detail.     

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2006年和2008年分别对HL-2A装置的低混杂波传输系统传输特性进行了冷测量和热测量工作。测量结果表明,冷测量传输率达到了94.05%,四个分路的最大相差为11.09°,功率分配也比较均匀;热测量传输率为76%~95%,但功率分配均匀度较差。另外,热测量功率超过230kW时,传输率有明显下降。