DETERMINING CARBON—13 ENRICHMENT USING LOW ENERGY PROTONS

The proton-capture reactions 12C(p,γ)^13N and 13C(P,γ)^14N have been studied to determine 13C enrichments.The system has been calibrated by measuring the gamma-rays yield from the 12C(p,γ)13N and 13C(p,γ)^14N reactions as a function of known 13C enrichment.This technique is applicable to the analysis of samples with 13C enrichments between 1% and 90%.     

主动法探测炸药的实验研究

阐述了采用主动法探测炸药的原理,综合分析屏蔽体、自然界本底和反应截面对炸药中^1H、^12C、^16O和^14N核素的测量影响.并利用^252Cf中子源辐照模拟炸药半球,采用高纯锗γ探测器探测了由中子与^1H、^12C、^16O和14N核素发生（n,γ）俘获反应产生的γ射线.通过实验研究了主动法探测炸药的可行性,分析了探测^1H、^12C、^16O和^14N四种核素的瞬发γ射线的优缺点.     

41 ^11C（p，g）^12N的核天体反应率以及^3He至CNO的转换

核合成链^3He（a，γ）^7Be（a，γ）^11C（p，γ）^12N到CNO循环可能是另外一条途径替代^3He经由3^4He→^12C到CNO。这一点在某些特定的天体环境中显得很重要，例如贫金属的大质量星。其作用的大小，决定于它所包含的核反应的反应率，其中重要的是^11C的质子俘获反应与其β衰变的竞争。^11C（p，γ）^12N的直接俘获的核天体S因子在我们以前的工作中用实验进行了测量。     

基于14 MeV μs脉冲中子发生器与NaI(Tl)和BGO闪烁探测器的爆炸物检测系统的研制

介绍了利用14MeV μs脉冲中子发生器、NaI(Tl)和BGO闪烁探测器建立的爆炸物检测实验系统。研究了中子感生瞬发γ能谱的时间特性，分别测量了快中子的非弹性散射γ能谱和热中子辐射俘获γ能谱。使用了NaI(T1)和BGO两种探测器测量γ能谱；NaI(Tl)探测器在测量“N的热中子辐射俘获γ10、835MeV时表现出了很好的性能，而BGO探测器则在测量^12C和^16O的快中子非弹性散射γ时得到了较好的结果。利用这两种探测器测量了22种样品，其中包括RDX、TNT、NQ3种炸药。根据NaI(Tl)和BGO测量到的中子感生瞬发γ能谱，在分析了^1H、^12C、^14N、^16O的元素含量之后，有效地实现了对炸药与普通物品的分辨。     

Feasibility Analysis of ^13N＋p Elastic Resonance Scattering

13N（p, γ）^14O is one of the key reactions involved in the hot CNO cycle that takes place in the evolution of massive stars. Its reaction rates are dominated by a 1^- broad resonance state which lies at 5.17 MeV in 14O. However, there are several low-lying levels above the ^13N＋p threshold which might be of relevance to the reaction rates and of importance to the nuclear structure of ^14O. The properties of these levels are not well known, in particular, there is a O^- level missing when comparing with the mirror nucleus ^14C. These incomplete information can be complemented by a study of ^13N＋p elastic resonance scattering.     

Proton induced gamma ray emission analysis of nitrogen

The proton-capture reactions 14N(p,γ)15O and 15N(p,αγ)^12C have been studied to determine their applicabilities to the analysis of materials for 15N enrichment,It is true that precision of the measurement concerned in these techniques cannot compete with mass spectrometry,but their ease of application is of great advantage to the fast handling of very large batches of samples from stable nuclide tracer experiments.     

^8Li（p，d）^7Li角分布的测量

^8Li（p，d）^7Li是大爆炸原初核合成非标准模型和r过程种子核合成反应网络中的关键反应。在非标准模型中，A=8处稳定核空隙可以通过^4He（t，γ）^7Li（n，γ）^8Li（α，n）^11B（n，γ）^12B（e-v）^12C…、^8Li（α，n）^9Li（e-v）^9Be（n，γ）^10Be（e-v）^10B（n，γ）^11B（n，γ）^12B（e-v）^12C…等一系列反应链跨越过去，从而使核合成的反应能够向更重的核区发展。     

^14C标记利多卡因（二乙基甘氨酰二甲苯胺）的合成

^14C－利多卡因由^14C－二乙胺和ω-氯乙酰－2，6－二甲基苯胺缩合制得，而^14C－二乙胺由Ba^14CO3途径K^14CN和CH3^14CN氢化而制得。^14C－二乙胺和^14C－利多卡因各自用HPLC和TLC检定放化纯度＞99％。它为研究肝储备功能动物呼气试验提供了有力的手段。     

39 ^8B（p，γ）^9C反应的天体物理S因子

^7Be（p，γ）^8B（p，γ）^9C（α，p）^12N反应链是通向高温CNO循环的重要路径之一，^8B（p，γ）^9C是该反应链中的关键反应。^8B（p，γ）^9C反应对于大质量贫金属星体的衍化有重要意义，该类星体中丰质子反应链的反应速率超过3α过程。在天体物理感兴趣的温度，直接俘获在。^8（p，γ）^9C反应中占主要贡献。     

在柱甲基化法自动合成(S-[11C]甲基)-L-蛋氨酸和(S-[11C]甲基)-L-半胱氨酸

用PET trace回旋加速器通过核反应^14N(P,q)^11C生产^11CO2,经甲烷循环碘化法和”CH3I全自动合成系统制备^11CH3I,合成时间约为12min,未校正放化产率大于30％。采用(S-[^11C]甲基)-L-蛋氨酸(^11C-MET)半自动合成装置,使^11CH3I与前体L-同型半胱氨酸硫内酯盐酸盐的碱性溶液在Sep Pak Plus C18小柱上发生烷基化反应,并经Sep Pak Plus C18小柱分离,得^11C-MET注射液,烷基化反应时间约6min,放化产率大于85％,放化纯度大于99％,对映纯度约为90％。采用PET-CS-I型全自动合成模块,使^11CH3I与前体L-半胱氨酸发生在柱烷基化反应,并经柱分离后得到(S-[^11C]甲基)-L-半胱氨酸(^11C-CYS)注射液,烷基化反应时间约2min,未校正放化产率大于50％,放化纯度大于99％,对映纯度大于90％。制得的^11C-MET和^11C-CYS注射液可用于动物和人体研究。     

Thermally and plastically induced residual strains in textured Zircaloy-2 plate

The residual intergranular strains in textured Zircaloy-2 plate samples induced by cooling from 823 K to ambient temperatures, by cold-rolling by 1.5% and 25% and by deforming in tension by 1.5% were measured by neutron diffraction. The strong rolling texture, which gives rise to two ideal orientations, permitted the interpretation of much of the data in terms of strain tensors for the two orientations. The experimental results were compared with calculations based on the elasto-plastic self-consistent model with no adjustable parameters. Close agreement was obtained for samples in the as-cooled state and deformation in tension by 1.5% but the agreement is less satisfactory for cold-rolling.     

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。     

电荷耦合器件的~(60)Coγ射线和电子辐射损伤效应

对东芝公司生产的TCD1209D线阵电荷耦合器件(CCDs)进行了60Coγ和1 MeV电子辐照实验,获得了CCDs的像元信号输出波形、像元光强量化值及器件功耗电流随辐照剂量的变化规律。比较了两种射线产生的CCDs辐射损伤。结果显示,60Coγ和1 MeV电子导致的CCDs辐射损伤不仅在程序上存在差异,而且二者的表现形式也有所不同。分析了电离辐射和位移损伤对CCDs内部不同单元的影响,表明了电子辐照产生的位移损伤是造成上述差别的重要原因。     

动态离子束混合技术制备氧化铬薄膜的X射线光电子能谱与俄歇电子能谱研究

本文介绍的动态离子束混合技术制备氧化铬薄膜系在不锈钢基体上进行1keV氩离子束溅射沉积铬(同时通入一定量的O),并用100 keV的氩离子束或氧离子束轰击该样品.对两种离子束轰击形成的氧化铬薄膜进行了X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)和俄歇电子能谱(Auger electron spectroscopy,AES)的分析研究.发现Ar 离子束制备的氧化铬薄膜主要是Cr2O3化合物,而O 离子束制备的氧化铬薄膜含有其它价态的铬氧化物.Ar 离子束制备氧化铬薄膜的污染碳少于O 离子束制备.与O 离子束制备相比较,相同能量的Ar 离子束轰击更有利于提高沉积的Cr原子与周围O2的反应性;Ar 离子束制备的氧化铬薄膜过渡层的厚1/3左右,较厚的过渡层显示了制备的薄膜具有较好的附着力.     

Attachment of Membrane Separator for Removal of Radon to Ionization Chamber Installed for Tritium Stack Monitor

The effect of background counts induced by α-particles mainly from Rn in air was removed by the attachment of a water-permselective membrane separator to a tritium stack monitor equipped previously. Water vapor, after permeating the membrane selectively, was carried by N₂ gas into an ionization chamber where the activity of tritium was measured. The consumption of N₂ gas for carrier was reduced by recycling the gas through dehumidification processes; (1) condensation by pressure, (2) condensation by refrigeration and (3) adsorption (by adsorbents), so that there is no added daily work arising from the attachment for maintenance of the tritium monitor.     

电子束加热与电阻加热蒸发锆膜的结构分析

采用XRD与SEM分析了在钼衬底上电子束加热蒸发与电阻加热蒸发制备的锆膜的结构。结果表明,电子束加热蒸发与电阻加热蒸发在钼衬底上制备的锆膜为hcp结构;电子束加热蒸发的锆膜以（002）晶面生长为主,而电阻加热蒸发的则以（101）与（002）晶面生长为主;电阻加热蒸发的锆膜晶粒呈不规则堆积,大部分尺寸约为1 μm,少部分约为500 nm;电子束加热蒸发的锆膜织构强烈,晶粒规则,呈六棱柱型,尺寸约为300 nm。     

沉默生存素基因增强人肝癌细胞SMMC-7721放射敏感性

为探讨沉默生存素(Survivin)基因对人肝癌细胞SMMC-7721放射敏感性的影响,利用靶向Survivin基因的RNA干扰(RNA interference,RNAi)质粒pGenesil-survivin,采用阳离子脂质体介导法转染SMMC-7721细胞后48 h,分别以RT-PCR和Western blot法检测Survivin基因mRNA和蛋白表达,以四甲基偶氮唑盐(MTT)法检测细胞增殖活性,流式细胞术检测细胞周期和细胞凋亡,克隆存活实验检测细胞放射敏感性的变化。结果表明,转染质粒pGenesil-survivin后48 h,SMMC-7721细胞Survivin基因mRNA和蛋白表达水平与对照和阴性干扰组相比明显降低(p0.05);转染后第1—4 d,细胞增殖活性与对照组相比明显降低(p0.05或p0.01);转染后48 h,细胞阻滞于G2/M期(p0.001),凋亡百分率明显高于对照组(p0.001);转染后SMMC-7721细胞D0值减小,放射敏感性增强,增敏比为1.24。结果提示,沉默生存素基因可增强人肝癌细胞SMMC-7721放射敏感性。     

Three dimensional measurement of nanostructures by single event TOF-RBS with nuclear nano probe

Single, double and triple-layer test structures were measured by time of flight (TOF) Rutherford backscattering spectrometry (RBS) for checking the sensitivity and resolution. A single-layer nanostructure with Au stripes on a Si substrate was resolved by TOF-RBS measurement within a short time of 256 s. The spatial resolution, measured by the edge of the Au stripes, was 42 nm. Another single-layer nanostructure with Pt stripes fabricated by electron beam (EB) induced deposition on a Si substrate was resolved by TOF-RBS measurement even at a thickness of Pt stripes less than one mono-layer. Ga embedded layers implanted by a focused ion beam under the Pt stripes fabricated by EB induced deposition on a Si substrate could be detected for a double-layer nanostructure. Furthermore, a triple-layer nanostructure with two Pt stripe layers isolated by a SiO₂ layer fabricated by EB induced deposition on a Si substrate could be resolved and cross-sections shown.     

切尔诺贝利核电厂事故后污染地区居民避迁的问题

本文介绍原苏联当局及有关部门在切尔诺贝利核电厂事故后恢复期为生活在该事故污染区的居民所制订的剂量限值以及避迁的干预水平。根据1989年底以前的监测结果和原苏联最高苏维埃通过的新法律,居民要避迁的地域面积约1万 km~2,人数约25万人。避迁计划已经开始执行。国际咨询委员会肯定了原苏联当局在制订避迁标准及其执行中首创的经验;但同时指出,仅从放射学角度而言,现行的避迁干预水平偏严,会造成负效应;还强调了考虑社会因素的必要性。     

热释光法测量环境累积剂量不确定度分析

通过分析热释光法测量环境累积剂量测量过程中可能对测量结果有影响的因素,对各环节不确定度分量进行了评估。结果表明:热释光法测量环境累积剂量各不确定度分量中,主要考虑不确定分量为测量重复性引起的A类不确定度、刻度因子引起的B类不确定度以及TLD片在布放过程中所引起的A类不确定度;此外,TLD片筛选和宇宙射线响应引起的不确定度也较大。