36Cl exposure dating with a 3-MV tandem

³⁶Cl AMS measurements at natural isotopic concentrations have yet been performed only at tandem accelerators with 5 MV terminal voltage or beyond. We have developed a method to detect ³⁶Cl at natural terrestrial isotopic concentrations with a 3-MV system, operated above specifications at 3.5 MV.An effective separation was obtained with an optimized split-anode ionization chamber design (adopted from the ETH/PSI Zurich AMS group), providing a suppression factor of up to 30,000 for the interfering isobar ³⁶S. Despite the good separation, a relatively high sulfur output from the ion source (³⁶S^?/³⁵Cl^? ≈ 4 × 10^?10 for samples prepared from chemically pure reagents), and a possibly cross contamination resulted in a background corresponding to ³⁶Cl/Cl ≈ 3 × 10^?14. The method was applied to samples containing between 10⁵ and 10⁶ atoms ³⁶Cl/g rock from sites in Italy and Iran, which were already investigated by other laboratories for surface exposure dating. The ³⁶Cl/Cl ratios in the range from 2 × 10^?13 to 5 × 10^?12 show a generally good agreement with the previous results.These first measurements demonstrate that also 3-MV tandems, constituting the majority of dedicated AMS facilities, are capable of ³⁶Cl exposure dating, which is presently the domain of larger facilities.     

纳米孔径重离子微孔膜的制备

应用中国原子能科学研究院HI 13串列加速器产生的重离子32S和79Br轰击聚对苯二甲酸乙二醇酯（PET）薄膜,再对薄膜进行化学蚀刻处理使由重离子辐照损伤产生的潜径迹形成微孔,制备出孔径为100～900nm的重离子微孔膜。为增加径迹蚀刻速率与体蚀刻速率之比,化学蚀刻前采用紫外光辐照薄膜。蚀刻过程中采用电导蚀刻法监测膜孔径生长过程。对32S和79Br辐照制备的重离子微孔膜进行了比较,79Br离子辐照制备的微孔膜与32S离子辐照制备的微孔膜相比,孔型圆整,锥角更小;在制备纳米微孔膜方面79Br离子优于32S离子。     

ANL survey of LWR containment penetrations: A progress report

Argonne National Laboratory is currently working on specific tasks in a containment penetration integrity program funded by NRC and managed by the Sandia National Laboratories. The first of these tasks is called “Characterization of Existing Penetration Designs”. The objective of this task is to identify those penetrations in nuclear reactor containments which, because of historical data or expected behavior under accident loads, are believed to have a relatively high probability of developing leakage when subjected to temperatures and pressures well beyond the containment design basis values. The program focuses on large and operating penetrations — such as personnel airlocks, equipment hatches, and bellows seals — and excludes electrical penetration assemblies and valve penetrations. (Sandia is working on electrical penetrations and EG&G is studying valve penetration assemblies.) This task will determine which penetrations require detailed study to determine leakage characteristics, and will identify which types of penetrations may require specific model and/or large-scale testing to obtain such characteristics. The survey is concentrating on containments built primarily between 1970 and 1982, and includes a comprehensive sample involving not only all types of containment types and materials, but also includes work performed by a large number of A-E design firms. The survey includes a good sample of containment penetration fabrication vendors. About 40 containments have been completed mid-August 1984.     

Inertial Confinement Fusion with a Heavy-Ion Driver-Accelerator and a Cylindrical Target

An economically efficient power plant burning deuterium-tritium fuel can be built using a powerful heavy-ion accelerator of a new type. A multilinear cryogenic cylindrical target, 1 cm long, 0.44 cm in radius, and containing 7.8 mg equimolar DT fuel, is studied as an example. The driver-accelerator gives two different target irradiation regimes. In both regimes, the beams consist of platinum ions, accelerated up to 100 GeV, with different isotopic composition, charged in the first regime only positively and in the second regime positively and negatively. In the first regime, the beam energy is 4.8 MJ and the beam heats in 60 nsec only the target shell. High heating symmetry is achieved by rapidly rotating the beam around the target axis with frequency 1 GHz. The fuel is compressed into a dense filament, where the condition for propagation of a fusion burn wave is satisfied – R 0.4 g/cm². In the second regime, a beam with 0.4 MJ ions heats in 0.2 nsec compressed fuel with power density 2.5·10⁷ TW/cm² up to ignition temperature. The computed energy amplification factor in the target is 200.     

36Cl-AMS measurements with 3-MV tandem accelerator

36Cl is one of the most interesting nuclides in accelerator mass spectrometry (AMS) measurements. The application of 36Cl has been widely applied in various fields. All most all of 36Cl AMS measurements at natural isotopic concentrations have yet been performed at tandem accelerator with 5 MV or higher terminal voltage. The measure improvement of 36Cl and other medium heavy isotopes performed at 3 MV in AMS facilities is one of the hottest topics in AMS measurements. In order to increase the suppression factor of 36S, the energy loss straggling and angular straggling of 36Cl and 36S ions in various counter gases (P10, isobutane and propane) were investigated. Some groundwater samples were measured with energy of 32 MeV, and the results were in good agreement with the result obtained with ion energy of 72 MeV. The results indicate that the approximate detection limit of 36Cl in 3 MV AMS facility is 36Cl/Cl=1×10-14 , and the uncertainty is 30% when the sample with isotopic ration 36Cl/Cl≈10-13.     

Power Plant for Heavy-Ion DT Fusion with Targets Containing Fissioning Materials

The special features of the concept of a hybrid power-generating plant, which combines the fusion and fission processes in a cylindrical target initiated by a high-power heavy-ion accelerator, are analyzed. The main advantages of the proposed setup are: burning of unenriched ²³⁸U in the reactor cavity, continuous removal of fission products from the core, and impossibility of an uncontrollable nuclear reaction. The characteristics of matched heavy ion accelerator, target, reactor chamber, and blanket with circulating coolant in the blanket are presented, and the power parameters of the electric power plant are estimated. __________ Translated from Atomnaya Energiya,Vol. 99, No. 3, pp. 190–198, September, 2005.     

重离子微束装置中真空窗的研究

中国科学院近代物理研究所（IMP）正在兰州重离子加速器（HIRFL）系统中研制中能重离子微束终端,以对重离子进行准确定位和精确计数。应用有限元分析软件对不同结构、不同材料的真空窗进行受力分析,模拟真空窗的形变和等效应力,运用强度理论考察候选真空窗的安全性;运用SRIM程序模拟离子的小角散射、横向射程,详细计算入射离子的能量、真空窗材料和厚度及空气层对束斑展宽的影响;最后提出真空窗适宜的结构、材料及厚度范围。     

Vibration-RF Control of Superconducting-Helix Resonators for Heavy-Ion Acceleration

An electronic system for the control of the effects of RF frequency oscillations caused by mechanical vibrations in a superconducting helix are described. A combination of frequency modulation and amplitude modulation is used to lock the phase of a self-excited accelerating structure to that of a controlling master oscillator. The system has been used successfully during beam acceleration with a superconducting helix.     

Development of synchrotron control for Heavy-Ion Medical Accelerators

The power supplies for the main bending and quadrupole magnets of the Heavy-Ion Medical Accelerator (HIMAC) in Chiba are controlled by preset current and voltage patterns, which are created by a pattern-creation program. It has been observed that a deviation between the preset current and the actual one becomes very large when newly created patterns are applied to the power supplies. This deviation is attributed to the incorrect parameters used for calculations of the voltage pattern in the pattern-creation program. In order to reduce the deviation, we have analyzed the values of resistance and inductance using the actual data of the current and voltage patterns. As a result, more than 10% difference was found between the conventional and newly calculated parameters. By applying the new parameters to the pattern-creation program a reduction of the deviation was confirmed.     

Production of Ultra-High Charge States in Heavy-Ion Collisions

Charge-state fractions have been determined for iodine, selenium and bromine ions traversing oxygen, argon, krypton, xenon, carbon-foil and gold-foil targets. Particular attention has been paid to high charge states, some containing as little as 10-6% of the primary beam intensity. The measurements indicate that a TU tandem accelerator is capable of delivering useful beams of heavy elements up to bromine (including 82Se and 48Ca) with energies suitable for the research of super-heavy elements.     

Energy Dependence of Dynamic Barrier in Heavy-Ion Fusion Reactions

投影壳模型（PSM）给出的波函数具有好的角动量和宇称，并且不断证实它可以很好地描述原子核的多方面性质。本工作期望采用PSM波函数计算Beta衰变矩阵元能够给出较好的结果。最近，应用投影壳模型初步建立了Gamov—Teller（GT）跃迁的计算程序。     

脉冲激光能量等效重离子LET研究

基于重离子和脉冲激光与Si材料相互作用的机理分析,提出了脉冲激光能量等效重离子LET的等效判据。该判据认为:如果半导体材料每吸收1个光子就能产生1个载流子,则脉冲激光和重离子诱发1个载流子所需的能量是等效的。利用该等效判据及Beer定律,推导出线性吸收条件下脉冲激光能量与重离子LET之间等效换算公式。本工作计算的脉冲激光能量等效LET结果与国外文献结果一致。     

Development and Operation of a Prototype Superconducting Linac for Heavy-Ion Acceleration

A prototype superconducting-helix accelerator is described and design considerations are discussed. The results obtained during 120 hours of beam acceleration are given. These include a wealth of practical engineering experience, the demonstration of stable operation with external phase control, and measurements of various kinds of accelerator-physics data.     

Transient analysis of Ghana Research Reactor-1 using PARET/ANL thermal–hydraulic code

PARET/ANL (Version 7.3 of 2007) thermal–hydraulic code was used to perform transient analysis of the Ghana Research Reactor-1. The reactivities inserted were 2.1 mk, 4 mk and 6.71 mk. The results obtained are similar to experiment and theoretical studies performed to demonstrate that the reactor is safe to operate. The PARET/ANL (Version 7.3 of 2007) could not simulate the reactivities above 5 mk insertions which were successfully performed in earlier theoretical and experimental studies. This may be attributed to different fluid flow and heat transfer regimes within the flow channels of the reactor that were considered by the codes.     

重离子微米孔膜防尘口罩滤芯的研制

本文以重离子微孔膜作为主要过滤材料,研制出一款梳格结构的新型防尘口罩滤芯。经国家权威机构测试,该口罩滤芯过滤效率为99.7%,达到国家标准GB 2626-2006《呼吸防护用品--自吸过滤式防颗粒物呼吸器》KN95的标准;呼吸阻力小于180 Pa,低于国家标准350 Pa。     

Performance of a New Ion Source for KSTAR Tokamak Plasma Heating

In the experimental campaign of 2010 and 2011 on KSTAR, the NBI-1 system was equipped with one prototype ion source and operated successfully, providing a neutral beam power of 0.7-1.6 MW to the tokamak plasma. The new ion source planned for the 2012 KSTAR campaign had a much more advanced performance compared with the previous one. The target performance of the new ion source was to provide a neutral deuterium beam of 2 MW to the tokamak plasma. The ion source was newly designed, fabricated, and assembled in 2011. The new ion source was then conditioned up to 64 A/100 keV over a 2-hour beam extraction and performance tested at the NB test stand （NBTS） at the Korea Atomic Energy Research Institute （KAERI） in 2012. The measured optimum perveance at which the beam divergence is a minimum was about 2.5μP, and the minimum beam divergent angle was under 1.0° at 60 keV. These results indicate that the 2.0 MW neutral beam power at 100 keV required for the heating of plasma in KSTAR can be delivered by the installation of the new ion source in the KSTAR NBI-1 system.     

Comparison of detector systems for the separation of 36Cl and 36S with a 3-MV tandem

The possibility of detecting ³⁶Cl for geological exposure dating has been explored for several years at VERA (the Vienna Environmental Research Accelerator). First results on real samples were obtained with an ionization chamber (developed at the ETH/PSI, Zürich, Switzerland) with two anodes. To improve the suppression of ³⁶S, we equipped the ionization chamber with an exit window and added a Time-of-Flight (TOF) system with a double-sided silicon strip detector (50 × 50 mm²) as stop detector. We optimized the TOF setup by using silicon nitride foils to reduce scattering tails in the energy spectra.At 3 MV terminal voltage, corresponding to a particle energy of 24 MeV of ³⁶Cl⁷⁺, we achieved a ³⁶S⁷⁺-suppression of 21,500 (50% ³⁶Cl-detector-efficiency).