Performance of and experiments with the recoil separator CARP at RCNP

A recoil mass separator (CARP) in operation at RCNP is described. The optimization of the operational parameters of the separator has been carried out experimentally. The procedure and the resulting performance of the system are presented. The mass resolution has been observed to be about 800 for the fusion-evaporation residues for a solid angle of 2 msr. The practical solid angle has been found to be limited to about 5.5 msr, due primarily to a presence of one of the third order aberrations. The current experiments with the separator are briefly described.     

高纯气体制备膜分离级联的组分分布模拟

膜分离技术已广泛应用于气体纯化。由于单台膜分离器的分离能力有限,使用时需将多台分离器连接构成级联。根据同位素分离级联理论并结合膜分离级联实验结果,建立了膜分离级联的计算模型,在此基础上完成了级联参数的数值模拟。模拟结果表明,净化后的产品纯度可达99.999%以上,而杂质端取出的物料中基本不含目标成分。可通过增大杂质端取料量来提升级联对摩尔质量较大的杂质成分的净化效果以获得更纯的产品。只要目标成分与杂质成分的摩尔质量差达到一定程度,即可通过膜分离级联进行气体纯化。总体看来,利用膜分离级联制备高纯气体具有净化效果好、工艺简单、目标成分损失率低的优点,有很大的实用价值。     

新型旋叶分离器分离特性与机理研究

为定量地获得熔盐反应堆旋叶分离器中气泡的分离行为,采用计算流体力学(CFD)方法获得了分离器液相流场分布,基于涡旋模型耦合相间作用力的气泡分离模型开发了气泡运动的数值计算程序,快速预测了分离器内熔盐介质中气泡的临界分离直径。通过对气泡受力的量化,阐述了气泡的分离机理。分析表明,气泡受到的相间作用力的大小与其运动到分离器内不同半径位置密切相关;气泡在轴向上受到的附加质量力分力和曳力分力决定着气泡分离长度;气泡在径向上受到的压力梯度力、升力与曳力、附加质量力相平衡时,其不能再向心运动进入气芯被捕获分离。     

Ion-optical design of the high-resolution mass separator for the Japanese Hadron Project

An ion-optical design of the JHP-ISOL is presented. This separator consists of a beam guidance system, a main magnetic separator stage and an electrostatic energy focusing stage. This separator is to be coupled with a heavy-ion linac for post-acceleration of mass separated ions up to 6.5 MeV/u. The design goal of the separator is to realize a mass resolving power of R_M = 20000 (basal) at a transmission approaching 100% with the initial phase space of ± 0.2 mm × ± 20 mrad.     

立式蒸汽发生器中蒸汽干燥器的研究与进展

对国内用作立式蒸汽发生器中蒸汽干燥器的同心分圈立式波形板分离器、锥形离心分离器和带钩波形板分离器在结构型式、试验状况和试验结论等方面的进展作了介绍。指出带钩波形板分离器是立式蒸汽发生器用蒸汽干燥器中较好的一种结构型式。对蒸汽干燥器在试验研究、疏水结构和阻力等方面提出了几点看法。     

Status report of the Leuven isotope separator on-line (LISOL)

The mass separator LISOL, on-line to the CYCLONE cyclotron, is described as it is presently configured. The main development has been in the ion-guide operation in conjunction with light-ion induced fusion and fission. The plans to obtain intense (nA) beams of light (A ≤ 30), short-lived nuclei in the framework of the ARENAS³ project are also described.     

The production of neutron-rich heavy nuclei of astrophysical interest at the IRIS facility

Targets of ThC_x and UC_x have been used for production of Fr, Ra(Ac) nuclides of astrophysical interest at the IRIS mass separator on line with the 1 GeV proton synchrocyclotron at LNPI. A fine-grained powder of a target has been prepared using a special technology based on high temperature destruction of the thermostable organometallic compounds of U, Th or Cm (diphtalocyanine). New neutron-rich nuclides have been identified: ²³²Fr (5 ± 1 s), ²³³Ra (30 ± 5 s), ²³⁴Ra (30 ± 10 s). The yields of some nuclides from a CmC_x target have been also determined.     

PILIS: post-ISOCELE laser isobar separation; a high efficiency apparatus for laser spectroscopy

A new experimental setup PILIS II has been installed on-line with the ISOCELE isotope separator (IPN, Orsay). The mass-separated ions are slowed from 30 kV to 500 V and implanted on a graphite collecting disk. The atoms are then thermally desorbed at the implantation region by Nd: YAG laser pulses and selectively ionized by three laser beams. The ions created are mass identified by a time-of-flight (TOF) system. Two versions of the TOF system with accelerating voltages of 1.5 and 30 kV were used to carry out hyperfine structure measurements. With the 30 kV system we obtained an overall detection efficiency of 1.4 × 10⁻⁵. First measurements were performed on very light gold and platinum isotopes. It has been shown that PILIS II is well adapted to study very short half-life isotopes ( ).     

双钩波形板汽水分离器疏水钩优化研究

为提高双钩波形板汽水分离器的分离性能，采用计算流体力学方法建立波形板内的两相流动模型，并对不同结构疏水钩的波形板汽水分离器进行研究。通过数值计算得到了波形板内的速度云图和液滴运动轨迹，并分析了不同进口速度下疏水钩结构对压降和分离效率的影响。结果表明：大部分液滴在前两级通道被分离，进口速度为0.922 m/s时其质量份额可超过50%；疏水钩通过影响流场的局部流速和湍流强度进而影响压降和分离效率，疏水钩对液滴的直接拦截作用有利于提高分离效率。综合考虑分离效率和压力损失获得了综合性能良好的双钩波形板汽水分离器结构型式。     

弹性碰撞对质量分离过程的影响

本文根据快速离子在束等离子体中损失能量的速率,结合同位素电磁分离的过程,讨论了带电粒子间弹性碰撞对质量分离效果的影响。     

Energy compensation of an ISOLDE-type isotope separator

The placement of an electric dipole following the magnet in an ISOLDE-type isotope separator can compensate for the energy dispersion introduced by the magnet. This allows the injection into such a separator of ion beams with energy spreads of up to ±3% at mass A = 120, an order of magnitude larger than previously possible. Calculations are presented applying this technique to an IGISOL (ion guide isotope separator on-line) facility, where such energy spreads occur under the conditions where the highest yields are available.     

Status report of the SARA IGISOL used in the study of the U(α 40 MeV, ƒ) reaction

A new ion guide isotope separator on-line (IGISOL), operating with the SARA facility, has been constructed. Using the ²³⁸U(α 40 MeV, ƒ) reaction to produce very neutron-rich radioisotopes, all mass chains from A = 96 to 122 have been scanned by conventional methods of nuclear spectroscopy. Provided the stopping volume is separated from the primary beam, it has been proved that the yield is nearly proportional to the He pressure. In addition to the usual advantages (quasi-independence from physical and chemical properties of elements), this makes IGISOL a powerful technique for high energy recoil products. During the experiments the boundary of known neutron-rich nuclei was reached such as ¹¹⁷Rh(440 ms) and several unknown activities were detected in the range A = 113–118.     

Design study of the secondary-beam line at RCNP

A beam line for use with the new RCNP ring cyclotron (K = 400) has been designed to separate unstable nuclei produced in high energy heavy-ion reactions. The separation principle takes advantage of A- and Z-dependence of the energy loss of ions in matter (energy degrader), and enables us to obtain the reaction products in the form of a secondary beam. Ion-optical consideration has been made for the separator by treating the degrader as one of the ion-optical elements. By this new treatment it has been made possible to optimize the optics of the system according to experimental requirements. The methods (i) to achieve an achromatic focusing of the secondary beams and (ii) to obtain beams with small energy spread are discussed. The effects of energy straggling in the degrader are shown to be the principal factor to limit the isotopic resolution of the separator. Ion-optical calculations have been performed for the secondary-beam line taking into account the transfer matrix elements up to third order. The design specifications are described and the expected profiles of the secondary beams are presented.     

核级除雾器除雾效率的测量

除雾器除雾效率的测量是除雾器研制过程中必不可少的重要环节.本文通过对国内新研制除雾器以及国外MSA型除雾器除雾效率的测量研究,建立了一套准确、稳定的除雾器除雾效率检测系统,该系统采用水量称量法计算计重效率,利用撞击采样和显微镜观测法计算计数效率.实验结果表明,系统具有稳定、可靠以及测量数据准确等优点.     

Measurement of β-ray maximum energy with an HPGe detector by means of β-annihilation photons coincidence

A β⁺-ray detection system free from summation of annihilation photons has been constructed for the determination of Q_EC-values. It consists of an HPGe β-ray detector and two pairs of BaF₂ scintillation detectors for annihilation photons. A Q_EC-value of 4.83(4) MeV is obtained for ¹²⁶Cs separated with the JAERI on-line isotope separator.     

Experimental complex to study nuclei far from the beta-stability line — ISOL-facility YASNAPP-2

A complex of physics installations (YASNAPP-2 complex) developed for spectroscopic investigations of short-lived isotopes in the proton beam of the JINR phasotron is briefly described. The complex consists of a proton line, a target unit, an electromagnetic mass separator, an ion beam transport system and different spectrometric installations. Some physics results of investigations of short-lived nuclides in the rare earth region are presented.     

High-current sputtering ion source for refractory metals

The Chavet-Bernas ion source of the MEIRA isotope separator has been modified to a gas sputtering source for the production of intense refractory metal ion beams. The source has produced a molybdenum ion current of 8 mA; the ratio of this current to the total current, including the argon carrier, is 0.46. A metal ion density of 5.8 mA/cm² has been achieved at the source from an emitting area of 55×2.5 mm². This ion density is significantly higher than the figures which have been reported for such sources.     

Ion traps — recent applications and developments

Paul and Penning traps are now widely applied in chemistry and physics laboratories. They are used as storage devices, as tools for precision spectroscopy and metrology, and as mass spectrometers. Direct mass measurements of short-lived Rb, Sr, Cs, Ba, Fr and Ra isotopes were performed at the on-line mass separator ISOLDE at CERN, Geneva, by means of a tandem Penning trap system. The ions from ISOLDE are captured and cooled in a first trap and trasnferred to a second trap. Here the mass of the trapped ions is determined by measuring their cyclotron frequency. Resolving powers exceeding m/Δm (FWHM) = 10⁶ could be achieved. Mass values of about 60 isotopes have been determined with accuracies of typically δm/m = 10⁻⁷. For the first time in the history of mass spectrometry the isomeric and ground states of a nucleus have been resolved.     

两级旋风式汽水分离器的分离性能研究

在研究国内外相关资料的基础上,设计了一种两级旋风分离器结构并针对该结构的分离性能进行了详细的数值模拟研究:依据两级旋风式汽水分离器的结构建立计算分析模型,采用数值模拟分析计算了汽水分离器的分离性能,研究不同入口速度、不同湿度对分离器分离特性的影响,搭建了气-水冷态试验回路对模型进行了验证。分析结果表明数值模拟计算结果与冷态试验结果趋势一致,分离效率计算结果偏差小;设计工况中,分离器总体分离效率优于99.5%;一级分离器适用于粗分离,其分离效率随入口湿度和速度的增大而减小;二级分离器适用于小液滴分离,其分离效率与入口速度呈正相关,与入口湿度呈非线性关系。