Isoscaling behavior studied by HIPSE model

The isoscaling behavior in the reaction system of ^58,64Ni+⁹Be has been studied by using the heavy-ion phase-space exploration(HIPSE) model. The extracted isoscaling parameters α and β for both heavy and light fragments for HIPSE model calculations are in good agreement with recent experimental data. The investigation shows that the parameters in the HIPSE model have some effect on the isoscaling parameter. The isoscaling parameters for hot and cold fragments have been extracted.     

原子核高K同质异能态的诱发γ辐射

介绍了原子核高K同质异能态潜在的应用价值及国内外研究的进展。 总结了形成同质异能态的3种主要物理机制。 说明了高K同质异能态的应用原理是将其激发到更高的不稳定的K混合态上, 再发生诱发退激, 形成γ瀑, 释放其存储的能量。 同时又介绍了K混合态的3种主要产生机制。 最后分析了178Hfm2诱发退变的实验, 讨论了这些实验的区别和与角动量投影壳模型计算结果的差异。The nuclear isomer states have great potential value of application. The important experimental and theoretical researches are presented here. There are three kinds of physics mechanism for the formation of the isomer states. The principle of releasing the energy stored in the isomer is to excite it to higher states, K mixing states, which can spontaneously decay to the ground state forming the γ cascade. After introducting the three ways to form the K mixing states, we analyzed experiments on the most prospective isomer 178Hfm2, discussed the key differences between these experiments and suggested that the Projected Shell Model (PSM) can be helpful to confirm the occurrence of the  K mixing states and would work out characteristics of the induced decay.     

中高能重离子碰撞中的电磁场效应和手征反常现象

重离子碰撞可以产生极强的电磁场和高温高密量子色动力学(QCD)物质,诱导很多重要手征反常现象,例如手征磁效应和手征磁波.本文围绕手征反常现象中的诸多物理要素,详细介绍包括相对论重离子碰撞中不同碰撞系统和能量下的电磁场特性、同质异位素碰撞中寻找手征磁效应、手征磁波特性、中低能重离子碰撞中磁场效应等一系列与电磁场和手征反常现象相关的理论研究成果.相关研究有助于实验中寻找强相互作用中的电荷宇称(CP)破缺的证据,加深对QCD真空涨落和宇宙中正反物质不对称问题的理解.     

液体粘滞系数测量实验中鉴别小球运动状态的设计与实现

介绍了利用光电阵列法鉴别液体中小球的运动状态,从而保证液体粘滞系数实验测量精度的设计与实现方法。     

中能重离子碰撞中的各向异性流标度

用同位旋相关的量子分子动力学(IQMD)模型, 研究了25MeV/A的⁸⁶Kr+¹²⁴Sn碰撞系统在较大碰撞参数下的轻碎片的各向异性流(v₂和v₄), 发现横向动量依赖的椭圆流(v₂)存在对轻碎片核子数的标度律(number-of-nucleon scaling)现象, 以及不同轻碎片的v₄/v₂²比值都近似等于一个常数0.5. 这种标度律现象可以用核子层次碎片形成的组合(coalescence)模型来解释.     

Proton Halo or Skin in the Excited States of Light Nuclei

Properties of nuclei 13,15,N and 9B are investigated in the relativistic mean-field theory with NLz and NL3 force parameters.The calculated binding energies are very close to the experimental ones.The calculations show that the first excited state (1p1/2) in 9B,the first excited state (2s1/2)in 13 N and the second excited state(2s1/2) in 15N are weakly bound .In particular,for 13N and 15N,the proton density distributions in the two above excited states have a long tail and the rms radii of the last proton are greatly larger compared with their respective matter radii.It is predicted that a proton halo exists in the first excited state of 13N and in the second excited state of 15N,respectively.It also indicates that the first excited state in 9B is a proton skin state.     

Photons from a Chemically Equilibrating Quark-Gluon Plasma at Finite Baryon Density

We study hard photon production in a chemically equilibrating quark-gluon plasma at finite baryon density based on the Juttner distribution of partons of the system. We find that the photon yield is a strongly increasing function of the initial quark chemical potential.     

质子滴线附近的β缓发质子衰变

简要回顾了实验小组在过去8年中获得的实验结果, 即采用氦喷嘴快速带传输系统 +“p-γ”符合方法, 在稀土区质子滴线附近首次观测了9种新核素的β缓发质子衰变, 在A=90核区的N=Z线附近获得了5种核素的β缓发质子衰变的新数据. 并把这14种核素的半衰期, 自旋宇称, 形变以及生成反应截面的实验值与流行的核模型理论预言进行了系统地对比讨论. 从中看出:(1)⁸⁵Mo, ⁹²Rh以及“等待点”核⁸⁹Ru和⁹³Pd半衰期的实验值比近期Moller等人的宏观-微观理论预言值[At. Data Nucl Data Tables, 66, 131(1997)]长5—10倍, 因而明显地影响天体rp过程生成的核素丰度;(2)实验指认的质子滴线核¹⁴²Ho和¹²⁸Pm的自旋宇称与流行理论预言不符, 但用Woods-Saxon-Strutinsky方法可以计算得到相符的位能面;(3)实验估计的9种稀土核的生成截面比通用的Alice和HIVAP程序的计算值要小1—2个数量级.     

A Proposed Reaction Channel for the Synthesis of the Superheavy Nucleus Z=109

We apply a statistical-evaporation model (HIVAP) to calculate the cross sections of superheavy elements, mainly about actinide targets and compare with some available experimental data. A reaction channel ^30Si 4 ^243Am is proposed for the synthesis of the element Z=109 and the cross section is estimated.