从递次误变子体的γ放射性提取同位素独立截面

研究了从放射性产物或其递次衰变子体的γ放射性测量来提取第一代产物独立截面的技术。它适用于在束快化学元素分离样品同位素独立截面的确定。运用这套技术进行了６００ＭｅＶ６１８Ｏ轰击厚天然铅靶后分离出来的汞同位素分布的测量,共得到从＾１８０Ｈｇ至＾２０９Ｈｇ２０余种同位素的独立截面。     

从递次衰变子体的γ放射性提取同位素独立截面

研究了从放射性产物或其递次衰变子体的γ放射性测量来提取第一代产物独立截面的技术。它适用于在束快化学元素分离样品中同位素独立截面的确定。运用这套技术进行了６００ＭｅＶ１８Ｏ轰击厚天然铅靶后分离出来的汞同位素分布的测量,共得到从１８０Ｈｇ至２０９Ｈｇ２０余种同位素的独立截面     

从30MeV／核子^12C离子辐照过的铅靶中分离汞和铊

用３０ＭｅＶ／核子＾１２Ｃ离子辐照天然铅厚靶，使用熔化铅靶－热色谱装置使汞元素从含许多元素产物的铅靶中分离出来。利用“母牛法”，通过液－液萃取周期性地提取出Ｔｌ。通过观察＾２０８Ｈｇβ＾－衰变子体＾２０８Ｔｌ的存在，确证新核素＾２０８Ｈｇ已被合成。     

85 气体射流反冲传输装置的建立

为了对短寿命裂变产物核素进行连续收集，我们在中国原子能科学研究院重水反应堆上建立了一套气体射流反冲传输装置。该装置能将短寿命裂变产物从辐照靶所在的高辐射场区快速而有效地传输到远离靶的低本底区进行测量或进一步分离。该装置的特点是：辐照靶可反复使用，且不需对靶进行处理；传输快，适宜对裂变产物进行在线分离采集。气体射流反冲传输装置的原理基于轰击粒子（或裂变过程）使反应产物原子得到足够的反冲动能而与固体靶实现瞬间物理分离.     

气体射流反冲传输装置的建立

为了对短寿命裂变产物核素进行连续收集,我们在中国原子能科学研究院重水反应堆上建立了一套气体射流反冲传输装置。该装置能将短寿命裂变产物从辐照靶所在的高辐射场区快速而有效地传输到远离靶的低本底区进行测量或进一步分离。该装置的特点是:辐照靶可反复使用,且不需对靶进     

钚及其裂变产物钯、银、镉、锡、锑、锆的系统分离方法

描述了钚及其6种裂变产物钯、银、镉、锡、锑、锆的系统分离方法：在强碱性阴离子交换树脂柱上将盐酸介质的辐照靶溶解液中的这些元素分为5组，然后再针对各组目标元素进行分离和纯化，可简便快速地从同一份靶溶解液中分离以上7种元素。采用辐照铀靶对分离方法进行了验证，结果表明，分离流程对6种裂变产物的化学回收率均大于70%，对γ谱仪测量干扰的主要核素去污因子均大于1.0×10³，可满足²³⁹Pu裂变谷区核素裂变产额测量对化学分离的要求。     

中能^12C离子轰击铯靶的超靶余核截面测量

用核化学方法测量了入射能量的４７ＭｅＶ／Ａ＾１２Ｃ离子轰击铯靶的超靶产物钡的生成产额，并用放射化学分离方法和离线γ谱方法进行确定，从测量结果可知，获得的超靶产物的载段都比较大（与低靶产物相比），而且钡同位素的分布峰位的最可几质量数为Ａｐ＝１２９．７±０．２其分布宽度参数σｚ＝２．７６±０．２８。     

钚及其裂变产物钯 、银 、镉 、锡 、锑 、锆的系统分离方法

描述了钚及其6种裂变产物钯、银、镉、锡、锑、锆的系统分离方法：在强碱性阴离子交换树脂柱上将盐酸介质的辐照靶溶解液中的这些元素分为5组,然后再针对各组目标元素进行分离和纯化,可简便快速地从同一份靶溶解液中分离以上7种元素。采用辐照铀靶对分离方法进行了验证,结果表明,分离流程对6种裂变产物的化学回收率均大于70%,对γ谱仪测量干扰的主要核素去污因子均大于1.0×10³,可满足²³⁹Pu裂变谷区核素裂变产额测量对化学分离的要求。     

中能^12C离子同厚铋靶反应近靶产物的产额测定

用放射化学分离及γ谱学技术测量了入射能量为４７ＭｅＶ／ｕ＾１２Ｃ离子轰击厚靶反应产物的平均产额，获得了近１００个核素的平均生成截面。基于这些数据并借助于电荷分布母子体关系的修正，从许多累积及部分累积产额获得了独立产额同时得到了比靶核少３、４、５个电荷数的产物的同位素分布曲线，由此得到了中能较轻重离子引起的溶部非弹转移反应产生丰中子同位素的有效产额。     

低温冷阱法分离裂变产物中的^88Rb和^89Rb

为将短寿命核素^88Rb和^89Rb分别从裂变产物中分离出来，需考虑从它们的母核放射性惰性气体核素融开始分离。利用同位素交换方法将裂变产物中的Kr、Xe同位素从靶室载带至低温冷阱分离装置，基于Kr、Xe的饱和蒸汽压不同，即通过Kr、Xe在一定的分压下其熔沸点相差较大而形态不一进行分离。载气采用掺有0．5％Kr、0．5％Xe的N2，工作压力为0．2-0．3MPa。     

Generalization of Smorodinskii's Solution for the Separation Potential of a Multicomponent Mixture of Isotopes

A new approach is proposed for determining the multicomponent potential. The method is based on calculating the number of elementary separation effects produced by the separation apparatus. Relations are found for the potential which contain arbitrary constants that depend on the special features of the separation process under study. In a particular case, the solution obtained corresponds to Smorodinskii's formula. The practical application of various forms of the potential is analyzed. The form of the potential suitable for enrichment of target isotopes is established. Recommendations are made for estimating the separation efficiences for elements, steps, and cascades.     

自动固相萃取仪在尿中钚分析方法中的应用

为了对钚操作者内照射剂量进行有效监测和估算,国际辐射防护委员会(ICRP)推荐测量工作人员的排泄物,比如对尿液中钚进行分析。本研究采用自行研制的自动固相萃取仪分离纯化尿中的钚,并优化实验方案,实现自动化操作。分离纯化的优化实验条件为:料液硝酸浓度为7~8mol/L、吸附速度为0.5mL/min、解吸速度为0.3mL/min和解吸液为10mL 0.36mol/L HCl-0.01mol/L HF溶液。采用优化条件处理后,全程平均回收率为75.70%,相对标准偏差为7.98%。结果表明,在尿中钚分析的前处理中,采用自动固相萃取仪进行分离纯化,能够显著提高分离效率,提高样品前处理的稳定性。     

中子辐照后镍靶件中63Ni分离提纯技术研究

63Ni是通过在反应堆中子辐照62Ni而产生的,产生的63Ni再经过分离提纯,制成高纯63NiCl₂溶液。以在高通量工程试验堆内辐照逾30 a的镍靶件为实验对象,采用ZGANR170核级阴离子树脂对辐照后镍靶件溶解液中的63Ni进行提纯,最终得到高纯度的63NiCl₂溶液产品。详细介绍了分离提纯原理、热实验分离步骤和最佳分离条件。酸度对分离的影响实验研究表明,当HCl浓度大于等于9 mol/L时才能获得了良好的分离效果。镍纯化过程对γ核素的去污系数为2.33×103,63NiCl₂产品核纯度大于99.9%。辐照后镍靶件经溶解、体系转换、分离提纯全流程63Ni的回收率为86.5%。      

An electromagnetic apparatus with a high resolving power for the separation of the isotopes of the heavy elements

The operating principles and the main features of an electromagnetic apparatus which has been designed and constructed for the separation of isotopes with a relative mass difference of about 1/240 are here described. An axially-symmetric magnetic field is used (focussing angle 225 °) in which the dispersion is proportional to the square of the focussing angle. The dispersion obtained with the separation apparatus is 20 mm for a 1% relative difference in mass. The magnetic field of the apparatus is stabilized to within 0.005% with the help of a circuit containing electron-beam regulators. Ion sources, with a discharge in the vapor of the working and auxiliary substances, were developed for the separation of large and small quantities of the raw material. General-purpose ion collectors were also developed. Some results of the separation of lead, uranium and plutonium isotopes are given. The enrichment factor in the separation of lead isotopes reaches 300, while for uranium and plutonium it is ～ 1000.     

级联中部设置净化级的可行性研究

级联分离同位素的过程中,不可避免的存在轻杂质,需要在级联的中间设置净化级。如果工质中轻杂质含量较多,运行级联较长时,轻杂质的存在会影响级联的正常运行。为探索在级联中部设置净化级的可行性,采用非定常态法计算求解级联分离方程组,研究净化级的位置、净化比和级联分流比对产品中轻杂质和目标组分丰度的影响。结果表明,在级联中部设置净化级,通过选取合适的级联参数,可以提高目标组分丰度,同时去除轻杂质,实现分离和净化。     

Collection, cooling and delivery of ISOL beams

The collection of an ISOL beam in a Penning trap using implantation on a surface that is subsequently manipulated so as to become part of an end electrode of a Penning trap and reionization of the implanted material by heat has already been very productive for high-precision nuclear-mass measurements, even though it is limited to elements that are surface ionizable and the collection efficiencies are never better than about 0.1%. More recently, in 1990 a Paul trap system for electric collection of ions was installed at the ISOLDE-3 facility and collection was demonstrated for a 60 kV beam of ¹³²Xe ions. The purpose of this test setup was to determine the relationship between phase space volume of a typical trap and the collection efficiency that could be obtained in direct capture. For the modest trap used, collection efficiencies of up to 0.2% were achieved. A beam of negative bromine ions was collected by simply reversing the polarities of all voltages used. From the experience with this system it appears feasible to build a Paul trap which is about three times as large in linear dimensions as the existing one and which could be driven at up to 10 kV peak at 1 MHz using a modest rf amplifier (300 W). With moderate prebunching of the injected beam at 1 MHz, this system should achieve collection efficiencies approaching 100%. Based on these results, preliminary design work is being carried out on the collection system to be installed at the ISOLDE Booster facility. Suggestions for other uses of a Paul trap collection system for ISOL beams are presented.     

An Experimental Apparatus for Low Energy High Charge Heavy Ions to Study Collisions on Atomic Hydrogen

The design and performance of a recoil ion source system which includes a recoil ion source, atomic hydrogen thermal oven target and an electrostatic analysis system will be discussed. The recoil ion source produces low velocity highly charged ions via collisions between heavy fast pump beams from the EN tandem accelerator and target gases. Time-of-flight techniques provide initial recoil charge state separation. Collisions of the recoils with atomic hydrogen are being studied. The atomic hydrogen is provided by a thermal oven which features long life time operation and low input power requirements. Dissociation fractions of 80% are achieved for 300 watts of input power. A hemispherical electrostatic analyzer allows the final charge states of the recoil ions to be determined thereby allowing the measurement of charge exchange processes for an energy range of 100 eV/q to 5000 eV/q for the incident recoil ions.     

An electromagnetic apparatus with a high resolving power for the separation of the isotopes of the heavy elements

The operating principles and the main features of an electromagnetic apparatus which has been designed and constructed for the separation of isotopes with a relative mass difference of about 1/240 are here described.An axially-symmetric magnetic field is used (focussing angle 225 °) in which the dispersion is proportional to the square of the focussing angle. The dispersion obtained with the separation apparatus is 20 mm for a 1% relative difference in mass. The magnetic field of the apparatus is stabilized to within 0.005% with the help of a circuit containing electron-beam regulators. Ion sources, with a discharge in the vapor of the working and auxiliary substances, were developed for the separation of large and small quantities of the raw material. General-purpose ion collectors were also developed.Some results of the separation of lead, uranium and plutonium isotopes are given. The enrichment factor in the separation of lead isotopes reaches 300, while for uranium and plutonium it is 1000.We express our gratitude to the personnel of the laboratory who took part in the work and also to G. N. Iakovlev and his collaborators for the preparation of the working substances and for the extraction of the separated isotopes.     

Influences of Gas Stream Conditions on Efficiency of Tritiated Moisture Collection with P2O5-Desiccant and Isotope Effect

A method was proposed previously for collection and measurement of tritiated moisture in gas stream using P₂O₅-desiccant. Influences of the gas humidity, the gas flow rate and the distance between gas nozzle and P₂O₅-desiccant layer surface on the moisture collection efficiency have been examined through experiments, and the isotope effect on the collection has been investigated. The collection efficiency is the ratio of collected to supplied moisture, and the moisture supplying rate is in proportion to the humidity and flow rate of feed gas. The experiments show that; the collection efficiency does not depend on the gas humidity, but is affected by the gas flow rate and by the nozzle-layer distance. The effects of the flow rate and the nozzle position are related to the mass transfer distance from the bulk of gas stream to the desiccant layer surface in the collection cell. The moisture collecting rate is promoted by the approach of the gas stream to the layer surface. An expression of effective separation factor has been derived to explain the isotope effect on the moisture collection. Experimental data distribution of the separation factor have been reasonably simulated by the analysis.     

Ion Collection from Resonance-Photoionized Plasma by Applying Radio-Frequency Voltage

Ions were collected on electrodes from laser resonance photoionized plasma by applying 2 MHz radiofrequency voltage to the electrodes. It was demonstrated that the ions are collected in a shorter time at the same kinetic energy of the collected ions compared with ion collection by applying DC voltage to the electrode. A simple one-dimensional model was extended for prediction of ion collection times in the cases of applications of not only DC voltage but also radio-frequency voltage. The ion collection times estimated with the simple one-dimensional model agreed with the experimental values in the case of application of radiofrequency voltages as well as DC voltage. Though the experimental conditions such as ion density are far from those of the plant of atomic vapor laser isotope separation (AVLIS), the simple one-dimensional model shows that radio-frequency voltage method is effective under the conditions close to those of the AVLIS plant.