新核素^239Pa的分离和鉴别

用５０ＭｅＶ／ｕ１８Ｏ离子照射厚天然铀靶，用ＨＰＧｅ探测器测量化学分离后的Ｐａ样品源，观察到了２３９Ｐａ的β－衰变子体２３９Ｕ的７４．６６ｋｅＶγ射线的生长和衰变，首次鉴定了新丰中子核素２３９Ｐａ，并确定了２３９Ｐａ的半衰期为（１０６±３０）ｍｉｎ。     

新重丰中子核素^239Pa的观测

以５０ＭｅＶ／ｕ丰中子炮弹＾１８Ｏ轰击天然铀靶，通过奇异的多核子转移反应产生了＾２３９Ｐａ用放射化学分离方法从复杂的反应产物中分离出Ｐａ活性，借助于＾２３９Ｐａ及其子体＾２３９Ｕ衰变的观察，鉴别了新重丰中子核素＾２３９Ｐａ，并测定其半期为１０６±３０ｍｉｎｌ同时，还发现了能量为５２２．０，５６２．０，６３８．５，６８１．０ｋｅＶ的＾２３９Ｐａ的四条衰变γ射线。     

用于微剂量学研究的无壁正比计数器系统

本文介绍了为模拟荷能重离子在等效生物组织中径迹和能量沉积分布研究而设计，制造的无壁正比计数器和探测系统，并利用放射源＾２３９Ｐｕ的α粒子（能量为５．１５５ＭｅＶ）在５００Ｐａ气压及工作气体为ＣＨ４（１０％）＋Ａｒ（９０％）下，对本探测器系统的分辨率与所加高压关系进行了实验，并就利用此探测器系统研究微剂量学的研究方法进行了讨论。     

14MeV中子在φ600mm贫化铀球中造钚率测量

使用中子活化技术对２３８Ｕ（ｎ，γ）２３９Ｕ反应产物２３９Ｕ衰变后的２３９Ｎｐ子体的２７８ｋｅＶγ射线的绝对测量，获得了１４ＭｅＶ中子在６００ｍｍ贫化铀球中的造钚率。其实验测量值为２．４６±０．０９。２７８ｋｅＶγ射线用高纯锗探测器测量，探测器的有效计数效率用２４３Ａｍ源刻度。６００ｍｍ贫化铀球由７层贫化铀球壳组成，球心有一８０ｍｍ源腔，总重约２．１ｔ。     

在NH4F介质中电沉积^233Pa源

介绍了在ＮＨ４Ｆ介质中制备薄而均匀的＾２３３Ｐａ镀层的实验方法。对＾２３３Ｐａ电沉积的主要影响因素（电流密度、搅拌速度、电镀时间和溶液的ｐＨ等）进行了实验，得到了在不锈钢片上电沉积厚度为１ｍｇ／ｃｍ＾２的＾２８３Ｐａ源。同时观察了用不同阴极材料对电沉积＾２３３Ｐａ源厚度及电沉积效率的影响，提出了在不锈钢片上制备＾２３３Ｐａ源的工艺流程。     

用超铀核素复制骨肉瘤模型

本实验用７４８只ｗｉｓｔａｒ大鼠进行超铀核素２４１Ａｍ、２３９Ｐｕ、２３８Ｐｕ和２３７Ｎｐ复制肿瘤模型的研究。动物分成（１）２４１Ａｍ中毒组，２０８只，中毒剂量为０．７５×１０～３１．４５×１０４Ｂｑ·ｋｇ－１；（２）２３９Ｐｕ中毒组，１４５只，中毒...     

低压下两相自然循环流动不稳定性的实验研究──（Ⅰ）机理探索

对两相自然循环流动不稳定性问题进行了机理性实验研究,系统压力范围为０．１ＭＰａ－０．４ＭＰａ。通过实验,分析了不稳定流动的机理,并根据其内在特性总结出两类主要的不稳定流动,为深入进行理论研究打下了良好基础。     

电镀法制备Pa测量源

用＾２３３Ｐａ作示踪剂，对影响电镀Ｐａ的主要因素（如ｐＨ值，电镀时间和电流密度等）进行了实验和讨论，用ＨＰＧｅ能谱仪对镀源进行测量，以确定化学效率，并在不锈钢片获得了薄而均匀的Ｐａ镀源，其厚度为１ｍｇ／ｃｍ＾２。     

Pu在不锈钢基底上的电沉积

对在不锈钢基底上用电沉积法制备＾２３９Ｐｕ（α）参考源作了详细研究。试验中选择ＮＨ４Ｃｌ－ＨＣｌ体系，观察了铵盐浓度、电解质酸度、电解质体积、电流密度、电镀时间、不锈钢基底材料和单面电解槽尺寸对＾２３９Ｐｕ电沉积率的影响，从而确定了最佳工艺条件，并已用于＾２３９Ｐｕ（α）参考源的批量生产中。该电镀工艺的优点是简便、快速，且获得的镀层均匀、牢固。该工艺也已成功地用于制备＾２４１Ａｍ（α）源和＾２４４     

^239Pu,^241Am,^99Tc和^137Cs在高压实缓冲材料中的扩散系数

本文从物质的一维非稳态扩散规律出发，在常温，纯氮条件下，测定了＾２３９Ｐｕ，＾２４１Ａｍ，＾９９Ｔｃ和＾１３７Ｃｓ在作为高放废物深地质处置库缓冲材料的高压实钠质膨润土中的扩散系数，９０ｄ的实验测定结果表明，在膨润土的干密度为１．９ｇ／ｃｍ＾３时，＾２３９Ｐｕ，＾２４１Ａｍ扩散系数为在１０＾－１５ｍ＾２／ｓ，＾９９Ｔｃ约为１０＾－１３ｍ＾２／ｓ，而＾１３７Ｃｓ约为１０＾－１２ｍ＾２／ｓ，都随缓冲材料     

Nuclear data sheets for A = 138

The experimental nuclear structure data available through December 1980 have been reviewed. A summary of information obtained in various reaction and decay experiments is presented, together with adopted level schemes. Where there was no new data the 1976 evaluation of S. Pancholi and M. Martin (76Pa04) was adopted.     

Nuclear Data Sheets for A=231, 235, 239

The available experimental data pertaining to the nuclear structure of nuleic with mass numbers A=231, 235, and 239 are compiled. The results from various decay and reaction measurements, as available through February 1977 are compared and evaluated. Q-values referenced as 75ScYK are obtained from a least-squares adjustment as explained in Table 3, 76Sc02. The values of r0 parameter, used to calculate α HF, were obtained as in 72ElSc, section A and Figure 1.     

从~(237)Np中分离高纯度的~(233)Pa的新方法

一、引言~(231)Pa是AcU(~(235)U)天然放射系的一个重要成员。在海洋地球化学和地质年代学研究中,它是一个非常重要的核素。但可作为~(231)Pa分离用的产额示踪剂的核素只有~(233)Pa,它是β-γ发射体,半衰期短(27.0 d)。因此如果能够简便地制得示踪剂~(233)Pa,对~(231)Pa年代学的研究和应用以及对镤化学和放射化学的研究无疑是个促进。     

Observation of exotic nuclear decay of (230)~U

(230)~Pa was produced through the 232Th(p,3n)230Pa reaction in the irradiated ThO2 powder targets with 35 MeV proton beam. Pa was radiochemically separated from ThO2 and other reaction products, and then thin sources of230Pa→230U were prepared. The polyethylene-terephthalate (lavsan) films were selected as solid track detectorsearching for the cluster activity of 230U. The gamma activity of 230Pa in the sources was measured using a HPGe detector. The lavsan films were etched in NaOH solution and the etched films were scanned under an optical microscope. The exotic nuclear decay of 230U by emission of 22Ne was observed. A branching ratio relative to a decay was deduced, B =λNe/λα = (1.3±0.8)×10~(-14) for 22Ne emission from 230U.     

Study of delayed neutron decay curves from thermal neutron induced fission of U and Pu

The results of measurements of the delayed neutron decay curves obtained from the thermal neutron induced fission of ²³⁵U and ²³⁹Pu are presented. The data were obtained by the periodical irradiation method on the pulsed reactor IBR-2 during the time interval 5 to 730 msec following irradiation. A comparison of these newly measured decay curves with the curves calculated using several standard delayed neutron sets was then performed. Based on these measurements, a new 7-group delayed neutron model is proposed.     

通用级联衰变动力学简化计算

级联衰变动力学方程是描述放射性同位素衰变规律的基本方程之一,衰变过程的复杂性和衰变子体的多样性,使级联衰变动力学计算十分复杂。本工作分3种情况给出通用级联衰变动力学解析解表达式,用矩阵函数对其进行形式简化,使级联衰变动力学计算简单明了,便于应用;对级联衰变公式进行简单讨论,并利用该公式求解了²³⁹Pu级联衰变中各级子体的原子数及²³⁹Pu的衰变热功率。     

Ge(Li)探测器测定14MeV中子引起~(238)U裂变中稀土核素的裂变产额

在核化学研究中,对稀土核素生成截面的资料是非常感兴趣的。因为在各种能量的轻粒子引起重核的裂变,或者在重离子引起的核反应中,稀土核素都构成了核反应产物中相当大的一部分。此外,处于大的核形变区的稀土核远离任何满核子壳层,因此测量稀土核的反应截面能够获得不受壳效应影响的核反应信息。     

探测短寿命核衰变的一个有效方法

描述了一种新的束流脉冲调制技术，它可用于探测寿命短至微秒的奇异核衰变，并具有较高的探测效率。报道了用此方法得到的６９Ｋｒ衰变研究的新结果。     

An elgenvalue and eigenfunction study of time-dependent fast-neutron spectra in 232Th

The pulsed problem for fast neutrons in Th has been studied using the multigroup diffusion equation and eigenfunction expansion method. The time-dependent fast-neutron spectra have been obtained up to 8000 ns inside Th systems with buckling ranging from 0.0 to 0.015 cm⁻². The results have been obtained using the 27-group BARC data set. It has been shown that for a fast Th system, unlike a fast U system, all the time eigenvalues lie in the continuum and no discrete time eigenvalue exists. A fast Th system behaves more like a non-multiplying system. The spectra shift continuously to lower energies with increasing time. However, pseudo-asymptotic conditions are established in certain time intervals. The start of pseudo-equilibrium conditions and the duration for which they persist is seen to increase with decreasing buckling. The reason for the establishment of pseudo-equilibrium conditions has been discussed. The theoretical results for the instantaneous decay constant inside a 40 cm cube of Th have been compared with the experimental results of Moo et al. (1973). The present results are in good agreement with the above experimental results based on the ²³⁹Pu detector.