Neutron dose equivalent rate for heavy ion bombardment

The fluence rate distribution of neutrons in the reactionsof 50MeV/u ^18O-ion on thick Be,Cu and Au targets have been measured with an activation method of threshold detectors andthe neutron dose equivalent rate distributions at 1m from the tqrgets in intermediate energy heavy ion target area are obtained by using the conversion factors from neutron fluence rate to neutron doseequivalent rate.     

Neutron yields and emission rates in the forward direction for 50MeV／u ^18O—ion on thick Be,Cu,Au targets

Total neutron yields and neutron emission rates in the forward direction for 50MeV/u ^18O-ion on thick Be,Cu,Au targets have been measured using an activation technique.The results indicate that neutron yields and emission rates in the forward direction depend on the atomic number of target nuclei,i.e.the lighter target the greater neurtron yield and neutron emission rate.Meanwhile,the neutron yield of ^18O-ion is greater than that of 12C-ion when target nucleus and incident energy per nucleon are identical.     

Neutrons produced by 75MeV／u ^12C—ion on thick targets

Fluence rates and angular distributions of the neutron emitted by 75MeV/u ^12C-ion bombardment on thick Be and Au targets have been measured by means of the threshold detector activation method.Based on that,the neutron yields,emission rates in the forward direction and neutron dose equivalent rate distributions were deduced.     

A ctivation measurement of neutron distribution in intermediate energy heavy ion target area

The distribution of neutrons produced by the reaction of 50MeV/u ^12C-ion on a thick Cu target are studied.The neutrons are measured with threshold activation detectors.Al.F,C,Al and In activation samples were used to measure neutrons with energy greater than 7,11,20,50MeV and thermal neutrons,respectively,The fluence rate,energy and angular distributions of neutrons,total neutron yield of 12C-ion and the emission rate in the forward direction of neutrons over 11 and 20MeV were obtained.     

Experimental test of a new neutron threshold detector and its application

The Possibility of using 209Bi as a new threshold detector to measure high-energy neutrons was investigated for the first time.At the same time the experiment measured successfully the emitted neutron fluence rate,energy spectrum and dose equivalent rate distributions in the heavy ion target area using a detector complex including 209Bi,^115In,^27Al,^19Fand ^12C samples.     

Analysis of the Delayed Neutron Detection System of CEFR

The delayed neutron detection（DND） system is one of the failed fuel detection systems designed for China Experimental Fast Reactor （CEFR）. This paper gives the analysis results of the delayed neutron flux and the fission neutron flux compared to background. The code package which contains codes such as VVER, VITAMIN-C, PASC-1 and MORSE, was used to analyze. The VVER code was used to calculate the releasing rate of volatile fission products （^87Br, ^88Br and ^137I） from fuel pellet to the gas plenum of fuel rod. The VITAMIN-C library and the cross section processing system PASC-1 were used to produce the ANISN format library for neutron transport calculation. The MORSE code was used to transport calculation of the fission neutron and the delayed neutron, respectively. For CEFR,     

Measurement of fast－neutron capture cross sections for ^75As

The cross sections of the ^75As(n,γ)^76As reaction were measured in the neutron energy range from 0.50 to 1.50 MeV by using the activation technique.Neutrons were produced via the T(p,n)^3He reaction and the cross sections of the ^197Au(n,γ)^198Au reaction were used to determine the absolute neutron flux.Present results are compared with existing measurements and evaluations.     

Calculation and Analysis of n ~(69,71)Ga Reaction

Ga is an important nucleus in nuclear science and engineering. However, its experimental data are less and the calculation is necessary. Based on the available experimental data of ~(69,71,Nat)Ga and the nuclear reaction semi-classical theory code SUNF, neutron induced reaction cross sections, angular distributions and the energy spectrum were calculated for ~(69,71)Ga at incident neutron energy below 20 MeV. The calculated results were compared with the experimental data.     

Calculation and Evaluation of Neutron-Induced Reactions on ^60Ni Below 150 MeV

Based on the experimental data of total, nonelastic, elastic cross section and elastic scattering angular distributions for n＋^60Ni reactions, a set of neutron optical model potential parameters is obtained in the region of incident neutron energy from 0.456-150 MeV. The reaction cross sections, angular distributions, energy spectra, gamma-ray production cross sections, gamma-ray production energy spectra, are calculated and evaluated by optical model,     

Nuclear Safeguards Techniques Non-destructive Assaying for Attributes of Fast Neutron Reactor＇s Fresh Fuel

We have adopted active neutron coincidence method and y-ray measurement method in order to measure the attributes of fast neutron reactor＇s fresh fuel. An improved uranium neutron coincidence collar （UNCC） was used for measuring the ^235U enrichment distribution of the 2 pieces fuel assembles. The measured results show curve＇s trend is the same as the fact of distribution. Fig. 1 shows the assembly＇s neutron coincidence counting rate.     

重离子加速器实验靶区的中子剂量当量率

用阈探测器中子活化法测量了５０ＭｅＶ／ｕ＾１８Ｏ离子轰击Ｂｅ、Ｃｕ、Ａｕ厚靶出射中子的注量率分布,并利用中子注量率对剂量当量率的转移因子,得到了重离子实验靶区的中子剂量当量率分布。     

中能^12C重离子在Fe等厚靶上核反应的中子产额和能谱

本文调研了由测量和核内级联-蒸发模型理论计算得到的中能区重离子核反应中子发射微分截面数据,并依据这些结果计算给出了单核能为58.3和100MeV 的~(12)C 离子轰击~(56)Fe 厚靶产生的次级中子能谱、角分布和总产额。同时对现有数据做了较为细致的分析,为重离子的防护提供了一些基础资料。     

中子能谱快速测量

为了实现中子能谱的快速获取,准确测量中子辐射场的剂量率,设计了一款一体化多球中子能谱仪。该系统能进行中子能谱的在线测量,实时显示中子剂量率。谱仪在Am-Be参考辐射场进行了验证,测量能谱与标准谱符合较好,转换后剂量率测量值与真值偏差<±7%。     

双闪烁体快中子飞行时间谱仪

一台由散射闪烁体和中子探测器及其屏蔽准直系统、α粒子探测器和相应的电子学仪器组成的双闪烁体快中子飞行时间谱仪已经建立,并在研究D(n,n)D和D(n,2n)P反应中获得了满意的结果,文章介绍了它的工作原理、结构、主要性能和应用。     

中子标准的国际比对

本文介绍了国际计量局(BIPM)组织的最近进行的中子标准的国际比对,包括中子源的发射率,中子注量和能量,中子剂量的比对。并给出了部分比对结果。     

Measurements of induced activity in concrete by secondary particles at forward direction produced by intermediate energy heavy ions on an Fe target

Spallation and neutron capture reaction rate distributions were measured using activation detectors inside a 90-cm thick ordinary concrete pile exposed to a field of secondary particles escaping a thick (stopping length) iron target bombarded with various intermediate energy ions, 230 MeV/u He, 400 MeV/u C, and 800 MeV/u Si. Activation detectors of aluminum, bismuth, gold, and gold covered with cadmium were inserted at various depths in the concrete pile. In addition, the distributions of activation reaction rate were simulated by FLUKA and PHITS Monte-Carlo codes. Generally, comparison of measured and calculated reaction rates show agreement within a factor of two. The experimental data will be useful for benchmarking Monte-Carlo radiation transport simulation code capabilities in estimating radioactivity induced in accelerator radiation shielding.