薄膜型纳秒壁流探测器的研制及应用

国家同步辐射实验室和安徽光学精密机械研究所共同研制的薄膜研究纳秒壁流探测器以其占有空间小,电阻膜特性连续、均匀等优点在ＨＬＳ中得到实际应用,并获得了满意的实验结果。     

兰州重离子研究装置的辐射监测系统

介绍了兰州重离子研究装置工作场所辐射监测系统的组成及性能,通过多年的现场使用,具有良好的稳定性和抗干扰能力,可以满足大型加速器或其他核装置的现场辐射剂量监测的需要。     

PET系统中Lu-176本底辐射的影响

正电子发射断层（positron emission tomography, PET）成像系统的探测器广泛采用具有高阻止本领、高光输出和较短发光衰减时间特性的含镥闪烁晶体。天然镥（Lu）元素中含有丰度2.6%的Lu-176长半衰期放射性同位素,包括一个β衰变和三个级联的γ衰变。Lu-176本底辐射对PET探测器引入随机事件,影响系统成像性能,但该特性又可以被合理的开发应用。本文主要介绍Lu-176本底辐射在PET系统中的特性,由此带来的不利影响,以及其有利的应用开发。     

~(99m)Tc诊断过程中辐射场特征及其源强测量

为了掌握~(99m)Tc诊断全过程中所产生辐射场特征和源强,利用HPGeγ谱仪及其无源效率刻度技术,分析了99Mo和~(99m)Tc发射的主要γ射线对辐射场的贡献。使用主动测量和被动测量相结合的方式,测量了~(99m)Tc诊断过程中各个操作环节中的辐射源强。实验结果表明:99Mo-~(99m)Tc发生器淋洗前、后主要的γ射线发射率之比变化较大;随着距离的增加,99Mo-~(99m)Tc发生器、注射器和病人表面的γ辐射空气吸收剂量率快速衰减;~(99m)Tc诊断一天,放射性药品操作人员手部剂量达到0.41 m Sv。     

N,N-二甲基羟胺用于铀钚分离多级反萃实验研究和相应的计算机程序

建立了多级混合澄清槽稳态趋近数学模型 ,并在此基础上编写了计算机模拟程序MIXEX2。进行了N ,N 二甲基羟胺 (DMHAN)作为 1B槽还原反萃剂微型槽实验和MIXEX2计算程序的验证实验。结果表明 :以DMHAN为反萃剂的 1B槽 ,在设定工艺条件下能够有效地实现铀钚分离 ,钚中去铀的分离系数和铀中去钚的分离系数高达 1 0 4 以上 ;程序计算的酸、铀和钚的浓度剖面与实验浓度剖面符合良好 ,表明计算机模拟程序MIXEX2可以很好地预期萃取器的运行结果     

我国抗辐射电子学发展的回顾与展望

本文扼要地介绍抗辐射电子学的主要内容,并回顾了这门新科学在我国的发展概况。由于电子器件及系统对于核或空间辐射以及核电磁脉冲十分敏感,它们必须进行加固以保证在空间及强辐射环境中能生存和正常工作,因此逐渐形成了抗辐射电子学这门新的核电子学分支。     

广西伴生放射性矿开发利用中的放射性水平初步调查

本文围绕广西境内17类矿产资源的开发利用展开调查,并对280家详查企业开发利用中的放射性水平进行了监测分析。结果表明:在原料与产品中,锆石和氧化锆、铅/锌、锗/钛、钒等行业²³⁸U、²²⁶Ra、²³²Th任一核素比活度大于1 000 Bq/kg。在固体废物中,稀土、锆石和氧化锆、铅/锌、锗/钛、锡、钒等行业²³⁸U、²²⁶Ra、²³²Th任一核素比活度大于1 000 Bq/kg。花岗岩企业的废水中总α、总β放射性水平偏高。研究发现,在对矿产开发利用企业开展放射性水平调查时,将γ辐射剂量率现场监测筛选标准下调50 nGy/h,即设定为在固体表面1 m处的γ辐射剂量率超过"当地本底水平"+100 nGy/h时,可更为保守地避免出现遗漏放射性水平较高企业的情况。     

Analysis and improvement of the influence of sample shape on Pu measurement results

ABSTRACT

The analysis method of Fast Neutron Multiplicity Counting (FNMC) plays an increasingly important role in the measurement of nuclear material properties. Based on the assumption of point model, fast neutron multiplicity measurement equation is derived which can be used to measure the mass of Pu sample. However, the deviation of the simulated measurement of 1 kg Pu sample reaches 16.6% and increases with mass. Because nonpoint source samples of different shapes do not fully satify the hypothesis. To correct this deviation, a set of fast neutron multiplicity counters was built by Geant4 to simulate and study the mass attribute of Pu samples.The cylindrical sources of different shapes and different masses were simulated, the self-multiplication factor and α coefficient were corrected.And the corresponding third-order polynomial fitting equation was obtained, the goodness of fit was greater than 0.970. In the same way, the spherical and spherical shell source samples in the mass range of 0–5 kg were analyzed, the corrected mass deviation of samples was less than 10% in this interval. The results show that the combination of the fast neutron multiplicity counter and parameter correction can accurately measure the sample mass attribute.     

滤光片及X射线二极管响应面均匀性研究

介绍了用于软X光能谱测量的滤光片及X射线二极管能量应均匀性研究。实验利用北京同步辐射装置3WIB束线,流强40－80mA的运行条件,在100－1600eV能区对滤光片及X射线二极管（XRD）作能响曲线标定。重点对C滤片及Al阴极XRD的灵敏面作能响面均匀性研究,最后给出响应面均匀性测量结果及计算分析。     

Structural Analysis and Calculation for the Radiation Baffle of Cryopumps

To decrease the radiation heat load of the cryopanel is considered to be necessary for the design of cryopumps. In general, a radiation baffle is mounted between the cryopanel and the heat source. The radiation baffle absorbs the majority of the radiated heat load. However, the motion of molecules to be pumped is baffled and the pumping speed is lowered at the same time. Therefore the selection of a good radiation baffle is a very important issue for the economical operation of the cryopump. By calculating and comprehensively analyzing the thermal transmission coefficients and the molecular transmission coefficients of baffles of different structures, a type of Chevron baffle is found to be more satisfactory. This paper focuses on the application of the Monte Carlo Method involved in the process of analysis and calculation.     

PET/CT在预测及评价实体肿瘤化疗疗效中的应用

本文从评价标准、评价时间和评价参数三方面对PET/CT用于实体肿瘤化疗疗效评价进行总结,结果表明,使用PET/CT进行化疗疗效评价时,应根据不同肿瘤和化疗的特点选择适合的评价手段,对评价手段的确定性需设计完善的研究进一步验证。