用大角度伴随粒子法测量聚变中子产额及其校对实验

描述了用大角度（178.2°）伴随α粒子方法测量绝对D-T 聚变中子产额及其校对实验。为此,设计和加工了一套三叉管校对靶室,α粒子探测器分别置于与D∧ 束成90°、135°和178.2°的方向上,测量和比较了三个方向的α粒子谱和绝对中子产额。分析了实验误差来源,并对实验结果进行了讨论。     

密封中子管氘-氘产额及二次电子抑制

中子管的工作参数是影响中子产额的重要因素.为了更准确地调控D-D中子管的中子产额,对中子管的工作参数与产额关系进行了研究,同时为了提高中子管束流品质及寿命,对中子管的二次电子抑制进行实验.采用控制参数变量的方法分别研究了D-D中子管的热子电流、阳极高压、靶极高压对中子产额的影响,以及二次电子抑制电阻阻值与靶极电流之间的...     

150MeV质子入射固态金属靶性质研究

对150MeV质子入射钨、铅和铅－铋合金固态金属靶的性质进行了研究。就靶的几何设计、靶材料选择、150MeV质子入射靶中子产额和从靶中泄漏的中子产额、泄漏中子的能谱和空间分布、靶的放射性活度累积以及靶的辐射损伤进行了研究。     

加速器驱动次临界系统的中高能质子轰击厚靶中子学实验研究

利用俄罗斯杜布纳联合核子研究所的高能加速器进行加速器驱动次临界系统 (ADS)靶区中子学研究。用 0 .5 33、1 .0、3.7和 7 4GeV质子轰击U(Pb)、Pb和Hg靶的测量结果表明 :U(Pb)和Pb与Hg靶的中子产额比分别为 ( 2 0 1± 0 1 0 )和 ( 1 76± 0 33) ,从获得较强中子的角度看 ,Hg作为ADS靶是不利的 ;沿厚 2 0cm靶的中子产额随入射质子穿透深度增大而下降 ,质子能量越低 ,中子产额下降越快 ,为在较大厚度范围内获得较均匀的中子场 ,质子能量不应低于 1GeV ;不同能量质子产生的次级中子能谱相近 ,但随质子能量提高 ,较高能量中子的比例逐渐增大。     

厚铍靶9Be(d,n)反应中子产额测量

能量在3MeV以下厚靶D-Be反应的中子产额实验数据至关重要,但较为缺乏。本工作在北京大学4.5MV静电加速器上对氘束轰击厚铍靶的中子产额进行测量。对入射氘核能量在0.35~2MeV之间的若干能量点用长中子计数管进行了0°方向中子产额、中子角分布及中子总产额的测量。与已有的测量结果和经验公式进行了比较,并拟合出氘束轰击厚铍靶中子总产额的经验公式。     

带伴随粒子中子发生器研制

为研制带伴随α粒子法检测隐藏爆炸物,我们研制了外形尺寸为Φ76 mm×1100 mm的中子发生器,采用中子管离子源加高压,靶接地的设计方式,便于安装α粒子探测器.靶与束流入射方向成45°角,以便探测器接收更多的α粒子,提高探测效率.试验测试表明,中子产额在3×107n/s-5×107n/s范围,中子发生器稳定工作已超过...     

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。     

ENT2465长寿命中子管设计及性能测试

中子管是可控中子源测井仪的核心部件,其工作的稳定性、耐高温、中子产额等指标对仪器的工作性能有重要影响。目前,随着深地探测的发展,应用于石油测井的中子管中子产额、耐高温性能、寿命、工作稳定性均有待提升。从结构、材料、制造工艺三方面,对自成靶中子管进行优化设计,进一步降低功耗,提高工作时间。通过耐高温、寿命和中子产额三项指标对外径为25 mm的ENT2465样管进行了性能评估测试,将样管置于中子实验测试平台的油槽内,连接激励线缆,记录样管工作过程中的温度、累计工作时间、中子产额、靶压、靶流和阳极电流。结果表明：在靶压为80 kV、靶流小于60μA条件下,该样管累计使用寿命超过了1 000 h,其中175℃下连续工作时间持续23 h、累计工作超过500 h,室温下连续工作时间持续36 h。在相同靶压、靶流条件下,1 000 h后中子产额仅下降5.3%。     

135°伴随粒子法D-T中子产额测量研究

研究了伴随粒子法D-T中子产额测量的各向异性修正因子的计算方法,计算给出了D束流能量20 ～ 600 keV范围135°随粒子法中子产额测量的各向异性修正因子数据,数据的不确定度约为1.4％.在兰州大学Z -300强流中子发生器上建立了135°伴随粒子测量法中子产额测量系统,并进行了实验测试,结果显示,在较长的测量距离下,α粒子多道幅度谱清晰,快中子与Si探测器反应产生的带电粒子的影响可忽略,D-T中子产额测量的不确定度不大于2％.     

用不同程序模拟计算ADS散裂靶结果的比对(英文)

利用不同的程序对ADS散裂靶进行了模拟计算。用SNSP,SHIELD,DCM\CEM(Dubna Cascade Model\Cascade EvaporationMode)和LAHET等程序计算了长60 cm,直径20 cm的圆柱形铅靶,分别在800,1000,1500 and 2000 MeV的质子轰击下所产生的泄漏中子产额和能谱分布。模拟结果与实验数据进行了比较,对泄漏中子产额而言,SNSP模拟的结果与实验符合较好,SHIELD,DCM\CEM和LAHET计算的泄漏中子能谱分布比较一致。     

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.     

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.     

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.