重离子碰撞中超重核的形成机制(英文)

在双核模型框架下,用数值解主方程方法计算了超重核的熔合几率。明确描述了包含能量、角动量和碎片形变弛豫的相对运动,并与核子扩散过程相耦合。因此,用微观方法推导出的核子跃迁几率是与时间相关的。所计算的以Pb为靶的冷熔合超重核形成截面和以48Ca为弹核的热熔合超重核形成激发函数与已知的实验值在合理的范围内符合。

离子束生物效应及应用中值得研究的几个问题

重离子束生物效应及重离子束在生命科学中的应用研究,在国内外物理学与生命科学领域中得到了广泛的开展,但对出现的一些现象还没有深刻地揭露其本质,作出机理性解释。为了深入研究,本文提出一些值得研究的问题供参考,如:重离子径迹结构及能量沉积分布模型,DNA辐射敏感位点,质量沉积-分子改造,直接作用与间接作用,放射性核束的应用等。

重离子加速器冷却储存环监视系统的设计及其应用

在兰州重离子加速器冷却储存环(HIRFL-CSR)控制系统中,需要监视现场和环境的场合很多。设计了以微处理器为核心的现场智能控制设备,阐述了系统结构、工作原理、硬件结构、软件设计,描述了监视系统的功能及实现方法。该系统具有人机交互性好、研制成本低且操作使用简便等优点,取得了良好的监视效果。

~(19)F+~(27)Al深部非弹性碰撞产物的角分布

完成了19F+27Al深部非弹性碰撞产物的角分布测量.初步分析了反应产物B,C,N,O,F,Ne,Na,Mg和Al的实验室系角分布,展现出深部非弹性反应机制的特点,显示了反应系统随时间的演化过程.

黄土细颗粒单测片再生法光释光测年的进展

IEECAS SKLLQG

丰中子核~6He在~(28)Si靶上的反应总截面测量

实验测量了20—40MeV u的轻丰中子核6He在Si靶上的反应总截面,并且结合6He的高能实验数据,采用双参数HO密度分布形式用Glauber模型计算得到较好的拟合.与Warner的实验数据比较,反应总截面数据系统性好,并与能量有明显的依赖关系.

Theoretical calculation of photoionization cross sections of B-like ions: N2+, O3+ and F4+

There can be found some notable discrepancies with regard to the resonance structures when R-matrix calculations from the Opacity Project and other sources are compared with recent absolute experimental measurements of Bizau et al [Astron. Astrophts. 439 387 (2005)] for B-like ions N2+, O3+ and F4+. We performed close-coupling calculations based on the R-matrix formalism for the photoionizations of ions mentioned above both for the ground states and first excited states in the near threshold regions. The present results are compared with experimental ones given by Bizau et al and earlier theoretical ones. Excellent agreement is obtained between our theoretical results and the experimental photoionization cross sections. The present calculations show a significant improvement over the previous theoretical results.

The experimental measurement of the relative biological effectiveness of carbon ions with different qualities

The relative biological effectiveness (RBE) of carbon ions with linear energy transfer (LET) of 172 keV/mu m and 13.7 keV/mu m were determined in this study. The clonogenic survival and premature terminal differentiation were measured on normal human. broblasts AG01522C and NHDF after exposure of the cells to 250 kV X-rays and carbon ions with different qualities. RBE was determined for these two biological end points. The results showed that the measured RBE10 with a survival fraction of 10% was 3.2 for LET 172 keV/mu m, and 1.33 for LET 13.7 keV/mu m carbon ions. RBE for a doubling of post-mitotic. broblasts (PMF) in the population was 2.8 for LET 172 keV/mu m, and 1 for LET 13.7 keV/mu m carbon ions. For the carbon ion therapy, a high RBE value on the Bragg peak results in a high biological dose on the tumour. The tumour cells can be killed effectively. At the same time, the dose on healthy tissue would be reduced accordingly. This will lighten the late effect such as fibrosis on normal tissue.

A transverse field gas ionization chamber performed at RIBLL

A transverse field gas ionization chamber as Delta E detector at the Radioactive Ion Beam Line in Lanzhou (RIBLL) is described. A high detection efficiency and long plateau are achieved with the mixed gas Ar(80%)+CO2(20%). The energy resolution is 3.25% for 4.94MeV alpha particle. This ionization chamber has been tested in the experiment with 50MeV/u Ni-58 bombarding Ta at RIBLL. All the fragments can be identified clearly by the ionization chamber.

气相C60在纳秒激光场中的内能分布以及退激研究

本工作建立了激光飞行时间质谱仪，与示波器获取质谱全图技术联合运作，研究了气相C60分子在具有不同空间分布的纳秒激光场中的内能分布规律以及退激产物的分布特征。研究表明，C60分子的内能分布在较低内能区遵循幂指数衰减形式E-b，并且幂指数值b随激光场发散度的增加而增加；在较高内能区的内能分布迅速偏离各自对应的幂指数规律。实验结果与把激光束和分子束看作高斯分布的理论预言符合的很好。对碎片质谱的研究表明，质谱具有明显的双峰分布特征，且激光通量较低时，碎片表现出明显的幻数结构，随着激光通量的增加，幻数结构在质谱中逐渐消失。碎片离子的产额分布表明，激光场的发散度越大，C60分子的碎裂程度随激光通量变化趋势就越快；分析轻碎片离子的峰形分布得到，所有轻碎片离子具有相同的平均初始动能；在近似认为富勒烯离子蒸发一个C2分子具有相同的动能释放的情况下，得到该动能释放值约为0.40±0.02eV。不同激光场中延迟电离与非延迟电离的产额分布表明，激光场发散度越大，两种电离成分随激光通量变化趋势越快，延迟电离成分占总电离成分的百分比越高。通过分析不同激光场中延迟电离离子飞行质谱，实验测量C60分子蒸发中性C2对应的蒸发势垒为10.59±0.17eV