用BF3探测器阵列测量"神光Ⅱ"辐射驱动DD中子产额

利用激光辐射驱动充纯氘燃料的内爆靶丸,完成了"神光Ⅱ"激光装置辐射驱动内爆出中子实验.通过BF3探测器阵列测到了DD中子产额.中子产额103～105,测量误差±20%到±100%.实验结果表明燃料中加杂质后,中子产额明显下降.     

“神光Ⅲ原型”装置首轮实验中子产额诊断

利用激光辐射驱动充D-D燃料的内爆靶丸,完成了"神光Ⅲ原型"大型激光装置首轮出中子实验。通过塑料闪烁探测器测到了辐射驱动内爆中子产额。中子产额107~108,测量不确定度~10%。     

利用次级中子诊断燃料面密度

介绍了一种用于测量在低中子产额下的压缩燃料面密度诊断方法,并且这种方法在实验中得到了实现。它是利用塑料闪烁体探测器对辐射驱动充纯D的内爆靶所产生的初级中子和次级中子进行测量,在中子产额较低的情况下,实现了利用次级中子和初级中子的产额比值法来诊断燃料面密度〈ρR〉,并获得了实验数据。这个工作对我们以后开展燃料面密度的诊断奠定了基础。     

"神光Ⅱ"基频直接驱动内爆出中子靶制备工艺

描述了"神光Ⅱ"基频直接驱动内爆出中子靶制备工艺.用该工艺制备的爆推靶、烧蚀靶在"神光Ⅱ"装置上用基频光进行物理实验,分别获得了4×109个中子和6×108个中子的高中子产额,与理论计算的中子产额值符合较好.     

中子计数器探测效率的校准

设计制作了一个 BF3长硼中子计数器 ,采用伴随粒子法标定了其中子探测效率 ,约为 3.17×10 -4 ( 1± 18% )。利用这个中子探测器测量了中子管脉冲中子产额 ( 10 7/ pulse)     

44GeV或18GeV ^12C离子轰击Cu靶或Pb靶时中子产额的研究

用ＣＲ－３９迭层探测器测量了４４ＧｅＶ或１８ＧｅＶ１２Ｃ离子轰击Ｃｕ靶或Ｐｂ靶时中子产额与入射粒子能量以及靶核质量的关系。当入射能量由１８ＧｅＶ增至４４ＧｅＶ时，Ｃｕ靶的中子产额增大２．１２±０．１９倍，Ｐｂ靶的中子产额增大２．０４±０．１５倍。Ｐｂ靶和Ｃｕ靶中子产额之比在４４ＧｅＶ和１８ＧｅＶ分别为２．５４±０．２０和２．５６±０．２０。     

用于中子测井的自成靶密封中子管性能评价

采用自成靶工艺,研制了SNT-DT/25型密封氘氚中子管,对其工作温度、使用寿命、功耗、中子产额及其稳定性等性能参数进行了测试。结果表明:中子管使用温度可达175℃,最高中子产额≥1×109 n/s,中子产额浮动≤10%;在靶极电压-80kV、阳极电流300μA、靶流80μA的工作条件下,中子产额可达1×108 n/s,中子管的性能指标完全满足中子测井使用要求。此外,本文还对中子产额随靶极电压、阳极电流的影响进行了分析。     

分析束强流中子发生器中子比产额及靶寿命

将在分析束(D_1~-)轰击下,大面积高速旋转靶半寿命、中子比产额等指标与非分析束作了比较。中子比产额从1.1×10~(11)s~(-1)·mA~(-1)提高到1.6×10~(11)s~(-1)·mA~(-1),氚钛靶半寿命提高一个数量级,靶寿期由1mA·h/cm~2提高到6.9 mA·h/cm~2。     

辐射驱动低产额中子诊断数据处理

本文介绍了在“神光”装置上用塑料闪烁探测器测量辐射驱动内爆低产额中子的数据处理方法,将实验数据输入计算机模拟出了所测中子产额几率分布公式及曲线,对测量结果的可信号度进行了分析讨论。     

中子活化分析法测定热中子诱发^235U裂变中^135Cs的产额

应用裂变反冲法和中子活化分析法测定了热中子诱发＾２３５Ｕ裂变中＾１３５Ｃｓ的裂变产额，主要研究内容包括：＾２３５Ｕ靶的制备，反冲捕集装置的设计加工；用Ａｕ作为中子监测器监测＾１３５Ｃｓ活化时的中子注量率，＾１３７Ｃｓ和＾１３６Ｃｓ的放化分离和测量，以＾１３７Ｃｓ的裂变产额主标准得到＾１３５Ｃｓ的裂变产额值为（６．３４±０．４６）％。     

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.