两种测量氚靶3He释放方法比较

对开放式离子源四极质谱计和封闭式离子源四极质谱计实验装置进行了标定,并用其对氚靶中3He释放进行了测量.标定与测量结果表明开放式离子源四极质谱计可定量测量3He的最低原子数为6×106,封闭式离子源四极质谱计则为3×1010;对于氚量较大的氚靶,两者均能对其3He释放进行定量测量,测量结果间的相对偏差约为5.3%;对于小氚量氚靶,前者可用于3He定量测量,测量结果的不确定度主要来源于质谱计的标定过程,约为7.2%,后者则难以对其进行定量测量.     

用四极质谱法测定从金属氚化物中释放的^3He

使用自行设计的超高真空金属系统和气体样品净化装置，以引进的Ｇａｓｔｒａｃｅ－ｓ型气体分析四极质谱计为分析器，以纯度为９９．９％的＾３Ｈｅ和＾４Ｈｅ气体为标准气样，对微量气体样品中Ｈｅ同位素的四极质谱峰高比测定法进行了实验研究。结果表明，Ｚｒ－Ａｌ活性气体吸收剂能在３９０ｓ内将活性杂质气体含量为４０．７％的＾３Ｈｅ气体样品净化到接近１００％。     

磁控溅射法制备含氦钛膜及膜中氦的热解吸研究

采用He/Ar复合气氛下磁控溅射方法,在Ti、TiZrYAl 和TiMoYAl等3种薄膜中引入浓度(氦-金属比)高达0.19的氦.引入的氦在膜层内沿深度均匀分布,并主要存在于直径为2～5 nm的高压He泡内.热解吸实验表明,在相同He含量下,TiHe膜中He的解吸峰温度与氚化钛中衰变产生的3He的解吸峰温度基本一致.与纯钛相比,合金膜中氦的热解吸谱宽化明显,表明He在合金膜内的捕获形式更为复杂.     

两种热解吸动力学测试方法的比较

以氢化钛热解吸反应为研究对象,用升温法（初压为零）和恒温法（初压不为零）两种不同的方法,在高真空金属系统上分别测定氢化钛在恒容体系和350～550℃范围内解吸氢的p-t曲线,并应用反应速率分析方法计算解吸反应在不同温度下的速率常数。实验测得氢化钛升温法热解吸和恒温法热解吸的表观活化能分别为（22.1±2.5）和（27.1±0.4）kJ•mol^－1。经分析,用恒温法测得的表观活化能较为准确。     

Ti、Zr、Er及Nd等金属氚化物的3He释放

利用四极质谱计（QMS）法测量了Ti、Zr、Er及Nd等4种单质金属的氚化物³He释放,通过数年监测与数据积累,对这4种金属氚化物的3He释放行为进行了比较研究。结果表明,它们贮存早期的³He释放速率极低,其释放速率均不及生成速率的1%,其中,Ti、Zr氚化物³He释放系数（RF）为10^－6～10^－5量级,Er、Nd氚化物的3HeRF为10^－3量级,随着贮存时间的增加,当金属氚化物内积累较多的3He时,其RF会迅速增长至10^－1量级,释放速率接近生成速率。     

氚钛膜中^3He释放的研究

在极限真空为２×１０＾７Ｐａ的超高真空全金属系统中，用四极质谱计分析了氚钛膜中释放的＾３Ｈｅ气体及其它杂质气体组分。对两块原子比分别为１．６８和１．６９的氚钛膜中释放的＾３Ｈｅ经过长达４１０ｄ的测量。结果表明，当样品中＾３Ｈｅ浓度达到０．１时，＾３Ｈｅ释放系数仍保持为１０＾－５量级。     

氢/氘化钛热解吸的动力学同位素效应

在高真空金属系统上测定了氢化钛和氘化钛在恒容体系中、350~550℃温度下热解吸氢和氘的P-t曲线;应用反应速率分析方法计算了各自在不同温度下的反应速率常数,得到氢化钛和氘化钛热解吸的表观活化能分别为27.1±0.4和42.3±1.9 kJ/mol。氘化钛热解吸氘的表观活化能高于氢化钛热解吸氢的表观活化能,表现出显著的热解吸动力学同位素效应,表明氘化钛热解吸时需要更高的初始能量;同时也说明氘化钛在相同条件下比氢化钛更稳定。     

氘/氚化铀热解吸的动力学同位素效应

在高真空金属系统上测定了氘/氚化铀在恒容体系和225～400℃范围内热解吸的压力-时间等温线,应用反应速率分析方法计算了各自在不同温度下的速率常数。随着温度的升高,热解吸反应的速率增大,反应的平衡压随之增高。由速率常数计算得到氘/氚化铀热解吸的表观活化能分别为(26.3±0.4)kJ/mol和(27.7±0.6)kJ/mol。活化能数据显示,氘/氚化铀热解吸反应的动力学同位素效应不明显。     

1.55 MeV 3He离子辐照单晶Si引起的损伤效应研究

室温下使用1.55 MeV、5×1013-5×1016/cm2注量的3He离子注入单晶Si,采用透射电子显微镜(TEM)观测分析了高温退火后单晶Si中由注入引起的损伤形貌,同时使用核反应分析(NRA)技术研究了3He气体原子的热解吸.结果显示,低注量3He离子注入在Si中产生的缺陷主要为一些小尺寸的位错或位错环;在中等照射剂量,退火导致了气泡和气泡团簇的形成并伴随着高密度的位错环从这些气泡团簇中发射出来;而对于较高的照射剂量,3He离子注入加上随后的高温退火则在离子射程附近产生了一个具有确定边界的空腔带.结合NRA结果对实验现象进行了分析.     

He/H离子辐照损伤及其对ODS钢显微硬度的影响研究

为研究氧化物弥散强化铁素体钢(ODS钢)中的He/H离子协同辐照效应,本文开展了室温条件下ODS钢的He/H离子单一及复合辐照实验,并研究了辐照损伤对其显微硬度的影响。实验结果表明:He/H离子主要分布在损伤峰值附近;H离子辐照对ODS钢显微硬度的影响大于He离子;H离子的引入导致He离子低温解吸峰消失,而He离子的注量减半则使其热解吸起始温度升高;He、H离子与材料中缺陷相互作用不同是影响显微硬度及正电子寿命结果的主要因素。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.