Overview of COSY

The COSY facility is sketched together with its experiments. The hadron physics program is discussed highlighting recent results with particular emphasis on nucleon-nucleon interaction, precision experiments, and meson and strangeness production.     

FAZIA: Prototyping a next-generation 4π array for nuclear reaction-dynamics studies

The international FAZIA (Four π A and Z Identification Array) Collaboration, presently involving researchers and institutions from France, Italy, Poland, Romania, Spain, India, Canada and USA, is currently investigating the use of new detector types/configurations (nTD Si detectors, single chip telescope) and new electronics (charge/current preamplifiers, digital sampling and signal processing) in view of defining a next-generation detection array with improved particle identification capability to study nuclear reaction dynamics and thermodynamics exploiting the Radioactive Nuclear Beam (RNB) facilities. The present main R&D activities inside the Collaboration are brielfly described.     

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分析了紧凑等离子体环(CT)加速的原理,给出了加速过程的辐射磁流体力学描述。采用Lagrange方法编写了二维计算程序,计算了10mg的氩CT在同轴加速器内的加速过程,得到了加速电流和辐射功率随时间的变化曲线,给出CT等离子体内部的速度和温度等物理量的分布。     

Strong curvature naked singularities in generalized Vaidya space-times

In this paper, following recent results on generalized Vaidya solutions by Wang, we prove that under certain conditions on generalized mass function, strong curvature naked singularities exist in radiation collapse in monopole-Vaidya space-times and also in charged-Vaidya space-times. We thus unify and generalize results of Dwivedi-Joshi and Lake-Zannias. The general case also covers de Sitter-Vaidya space-time recently treated by Wagh-Maharaj with a view to study existence of naked singularities.     

Radiation-induced chemical evolution of biomolecules

Chemical evolution in glycilglycine (Gly2) films irradiated with 146 nm vacuum ultraviolet light was studied. It is found that quantum efficiency of chemical evolution from Gly2 to glycilglycilglycine (Gly3) is smaller than that to glycilglycilglycilglycine (Gly4) due to the multiple step of reaction. Furthermore, we have carried out measurement of soft X-ray natural circular dichroism spectra for serine and alanine films in the energy region of oxygen 1s transition and we report the splitting of 1s→π* transitions.     

Radiation-induced decomposition of explosives under extreme conditions

We present high-pressure and high temperature studies of the synchrotron radiation-induced decomposition of powder secondary high explosives pentaerythritol tetranitrate (PETN) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) using white beam synchrotron radiation at the 16 BM-B and 16 BM-D sectors of the HP-CAT beamline at the Advanced Photon Source. The radiation-induced decomposition rate TATB showed dramatic slowing with pressure up to 26.6 GPa (the highest pressure studied), implying a positive activation volume of the activated complex. The decomposition rate of PETN varied little with pressure up to 15.7 GPa (the highest pressure studied). Diffraction line intensities were measured as a function of time using energy-dispersive methods. By measuring the decomposition rate as a function of pressure and temperature, kinetic and other constants associated with the decomposition reactions were extracted.     

Structural study of (As2S3)0.6(GeS2)0.4 glass

(As₂S₃)_0.6(GeS₂)_0.4 glass in non-irradiated and γ-irradiated states has been studied by using high-energy synchrotron X-ray diffraction, extended X-ray absorption fine structure spectroscopy, and positron annihilation lifetime spectroscopy. The experimental results are explained by the local changes around As and Ge atoms upon irradiation. These changes are suggested to involve chemical bonds distortion, formation of defective bonds with wrong coordination, rotation of structural units and appearance of additional free volume in the glass network.     

UV-A区段紫外辐射对DNA影响的拉曼光谱研究

检测了小牛胸腺 DNA水溶液经 2 h和 16 h UV- A区段紫外辐射的拉曼光谱。实验结果表明 ,该区段紫外辐射对 DNA的影响要比全波段紫外辐射的影响小得多。主链构象基本上没有受到影响。经过较长时间的 UV- A区段紫外辐射后 ,DNA受到了较轻的损伤。 80 3— 816 cm-1间峰的变化表明 DNA链不同区段的构型处于不断的变化之中。脱氧核糖的特征峰 ,或强度有所下降 ,或峰发生了位移 ,或者两种变化皆有 ,表明 A区段紫外辐射对 DNA的脱氧核糖有所损伤。胸腺嘧啶的 6 81cm-1、75 2 cm-1和 1177cm-1谱线都发生了变化 ,表明胸腺嘧啶也受到了影响。但嘌呤碱基和胞嘧啶基本上没有受到影响。     

一维晶化束的辐射能损与束流冷却

 用Jacobian椭圆函数求解了一维晶化束的非线性动力学方程，并用第一类全椭圆积分表示了粒子振动周期。在经典物理学框架内，讨论了储存环中作相对论运动的带电粒子的辐射能损，以及由于辐射能损导致的束流冷却。结果表明, 由于辐射损失束流将进一步冷却。     

A simplified model of mouth radiation impedance closed by mask cavity

Acoustic radiation impedance of the mouth is an important parameter when the vocal tract is modelled by the equivalent electrical circuit. If the vocal tract is closed by a cavity, as when the speaker wears some kind of mask, total impedance acoustically loading the vocal tract becomes serial connection of the mouth radiation impedance and the mask impedance. In that case the mouth radiation impedance has to be changed compared to free field conditions. This paper introduces a simplified approach to the modelling of that change by an appropriate reduction coefficient. The analysis based on an experiment preformed by measurement in the vocal tract physical model accompanied with analytical estimation has shown that the value of such reduction coefficient is 0.5. The results reveal that for a vocal tract closed with mask cavity the change in mouth radiation impedance introduced in an equivalent electrical circuit can be approximated by the value for free field radiation decreased by about 50%.