Application of SSNTDs to investigations of radiation accident after-effects

Track methods and devices used for studies conducted after radiation accidents are considered. Solid State Nuclear Track Detectors (SSNTDs) are applied for measurements of contamination in soil, water, biological and other objects of alpha-emitting radionuclides, as well as for estimation of neutron doses by means accident dosimeters. Known radiation accidents (Chernobyl a.o.) and potential emergencies (sunken submarine “Komsomolets”, nuclear reactors) are discussed. Some result of SSNTD application at after-accident period are presented.     

中能重离子碰撞中的中子(质子)发射的同位旋效应

利用同位旋相关的量子分子动力学,对中能重离子碰撞过程中的中子和质子发射的同位旋效应进行了分析.计算结果表明在有动量相关作用条件下,在很宽的能量和碰撞参数范围内,缺中子碰撞系统的中子(质子)发射数强烈地依赖于同位旋相关的核子–核子碰撞截面,而较弱地依赖于对称势.在对丰中子碰撞系统的研究中,上述规律减弱.这样就可以通过实验上对缺中子碰撞系统的中子(质子)发射数的探测,来提取介质中同位旋相关核子–核子碰撞截面的知识.     

Crystallography Without a Lattice

Molecular structure determination in crystals depends on the presence of the crystal lattice. In liquids, there is no underlying lattice, so phase relationships between scattered X-rays or neutrons are not preserved. Hence, only pair-distance distributions can be obtained from simple diffraction experiments. Advances in the past 30 years in radiation sources, instrumentation, and computing have enabled us to go beyond this apparent limitation. We can now obtain detailed structural information on relatively complex liquids and thus see clearly for the first time how molecules actually interact in solution, and how the solvent is perturbed by the presence of the solute. Using as an example recent work on aqueous solutions of tertiary butanol, the ways in which we can obtain high quality structural information in the absence of a lattice are summarized. Not only can we see how intermolecular interactions are influenced by changes in temperature and concentration, we can also begin to see where the structural source of the entropic driving force for the hydrophobic interaction may be found.     

富勒烯-PVP聚合物链团结构的中子小角散射实验研究

应用中子小角散射技术研究了水溶液中富勒烯-PVP聚合物的链团结构及其大小以及它们在不 同富勒烯含量下的变化.结果表明：当加入富勒烯后，不论是PVP单体分子链还是大分子链团 ，其相关长度与纯PVP溶液相比均变小，且大分子链团的变化更为明显；在不同富勒烯含量 情况下，高富勒烯含量的富勒烯-PVP分子链团的体积更小. 关键词： 中子小角散射 富勒烯 PVP聚合物     

个人中子剂量气泡探测器研制

中子固体气泡探测器被认为是唯一能够满足国际辐射防护委员会ICRP60要求的个人中子剂量计，它具有从低能中子到高能中子的平坦响应曲线和对γ射线不灵敏的优点.本工作将过热液滴均匀地分布在一种软聚合物中，制成了个人中子气泡剂量计,其灵敏度达到每毫雷姆40个气泡.还介绍了个人中子剂量气泡探测器的原理和制作过程.Neutron solid bubble detector was considered as a unique one for meeting the need of the personal neutron dosimeter recommended by International Committee of radiation protection,ICRP60.It has the flat response for neutron from low energy to high energy,and insensitive for gamma rays. In this work,superheated liquid drops were dispersed into a kind of soft polymer homogeneously.A personal neutron bubble dosimeter has been made,and the sensitivity reached to about 40bubbles/mrem.The principle and the processing procedure of bubble detector were also introduced in this paper.     

Influence of the surface chemistry on the structural and mechanical properties of silica‐polymer composites

Poly(vinyl alcohol) (PVA) composite films filled with nanometric, monodisperse, and spherical silica particles were prepared by the mixing of an aqueous PVA solution and SiO₂ colloidal suspension and the evaporation of the solvent. Adjusting the solution pH to 5 and 9 controlled the PVA‐SiO₂ interaction. Adsorption isotherms showed a higher PVA/surface affinity at a lower pH. This interaction influenced the composite structure and the particle distribution within the polymer matrix, which was investigated by small‐angle neutron scattering, electron microscopy, and swelling measurements. Most of the mechanical properties could be related to the composite structure, that is, the distribution of clusters within the polymer matrix. The progressive creation of a cluster network within the polymeric matrix as the silica volume fraction increased reduced the extensibility or swelling capacity of the composite. The effect was more acute at a higher pH, at which the surface interaction with PVA was weaker and promoted the interconnection between clusters. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3127–3138, 2003     

超强激光与等离子体相互作用产生中子的计算

对超强激光与等离子体相互作用过程中发生的氘-氘反应的中子能谱进行了计算.并将计算结 果与实验结果相比较.采用麦克斯韦能量分布和高斯形式的角分布对实验结果进行拟合，从 而确定了入射氘离子的温度和角分布，为研究离子的加速机制提供了依据. 关键词： 中子能谱 激光与等离子体相互作用     

Relativistic theory of inverse beta-decay of polarized neutron in strong magnetic field

The relativistic theory of the inverse beta-decay of polarized neutron,ν _e +n → > p +e ^-, in strong magnetic field is developed. For the proton wave function we use the exact solution of the Dirac equation in the magnetic filed that enables us to account exactly for effects of the proton momentum quantization in the magnetic field and also for the proton recoil motion. The effect of nucleons anomalous magnetic moments in strong magnetic fields is also discussed. We examine the cross-section for different energies and directions of propagation of the initial neutrino accounting for neutron polarization. It is shown that in the super-strong magnetic field the totally polarized neutron matter is transparent for neutrinos propagating antiparallel to the direction of polarization. The developed relativistic approach can be used for calculations of cross-sections of the other URCA processes in strong magnetic fields.     

Techniques to investigate the characteristic of CR-39 detectors using Am---Be neutron source

Two techniques have been developed to investigate the characteristic of the sensitivity of CR-39 (polyallyldiglycol carbonate) track detector using Am---Be neutron source. The firstis to measure volume track density created by fast neutrons in CR-39 detectors. The second is to measure areal asymptotic track density on the surface of CR-39 sheets. Two types of CR-39—SY-2 CR-39 made in China and another made in USA were calibrated using the techniques. It shows that the two types of CR-39 detectors have nearly the same sensitivity to detect fast neutrons. The techniques developed in this work can be applied to calibration of other track detectors.