电磁脉冲传感器γ射线干扰阈值实验研究

基于光纤传输的强电磁脉冲传感器具有良好的抗电磁干扰性能.核爆炸以及核爆炸模拟装置激励的电磁脉冲是γ射线与空气分子作用散射的康普顿电子激励的,γ射线能穿透屏蔽壳体进入传感器内部,作用在集成电路上会产生干扰、闭锁或毁伤等效应,影响传感器的性能指标.介绍了在强光I号加速器上开展强电磁脉冲传感器γ辐照效应实验方法.实验结果表明该传感器的γ剂量率干扰阈值为2×106Gy/s.     

核电磁脉冲信号向卫星轨道传播数值计算

采用射线追踪法对核电磁脉冲(NEMP)信号穿过电离层后传播到卫星轨道的波形进行了数值计算.由于电离层的色散与时延作用,NEMP波形转变成-个震荡的波包.计算结果表明,在卫星轨道上,核电磁脉冲信号是可以监测到的.     

火工品的内电磁脉冲效应研究

介绍了核爆炸条件下γ射线作用于系统并在系统腔体内所产生的内电磁脉冲特性,研究了火工品的内电磁脉冲作用机制,利用电磁耦合理论建立了火工品在系统腔体内的电磁感应电路模型及相应的电磁感应电压及电流计算方法,分析了火工品的电磁脉冲效应的影响因素.     

关于天基探测近地核爆瞬发辐射的思考

分析探讨了利用瞬发辐射天基探测核爆炸(包括空间核爆和近地核爆)的可行性,概略估算了近地核爆某些瞬发辐射粒子(含X,γ射线及中子等)自爆点垂直传播至同步探测卫星处的传输总衰减倍数A及相应的辐射厚度B和物理衰减因子Aph等.得出结果:利用γ射线与中子可探测高于10km的核爆;利用10keV X射线可探测高于40km的核爆炸,利用1keV X射线可探测高于80km的核爆炸.     

神经网络识别算法去除核爆电磁脉冲探测闪电干扰

为解决在核爆电磁脉冲(NEMP)探测中经常出现的闪电电磁脉冲(LEMP)干扰问题,提出一种基于广义回归神经网络(GRNN)的识别分类算法.通过对收集到的LEMP与NEMP波形的时域分析,定义9个特征参数用以表征、区分二者波形.通过对GRNN的训练使正地闪、负地闪、云闪、先导四种LEMP波形的识别准确率达到92％以上,L...     

星载核爆X射线探测技术进展

卫星有效载荷对核爆炸的探测是实现国土及全球核爆监测的最佳手段，核爆传感器也可为空间科学研究积累数据。而星载X射线探测的途径，可较理想地实现对近地太空核爆的探测、识别、定位与确定核爆炸的当量。主要介绍利用X射线探测太空核爆在国外的发展历史及现状，并且预测了今后的发展趋势。     

柱二维内电磁脉冲的非自洽源计算方法

本文给出在核爆炸条件下,计算瞬发γ光子在金属柱腔体中产生的内电磁脉冲的计算方法,并且把这种方法的计算结果同质点网格方法、拉格朗日方法和欧拉方法的计算结果作了比较。在电场强度E≤10~5V/m的条件下,非自洽源方法的计算结果同其他三种方法的计算结果符合较好。     

利用MCNP程序对充气电离室探测性能的研究

利用MCNP程序研究了充气电离室的探测径能，计算了探测器内工作气体和电扳片在射线探测中各自的作用，得到该电离室的探测效率．然后计算不同偏角入射时探测器的信号输出值，并给出计算的探测灵敏废。计算结果表明，高压充气电离室探圈^60Co源γ射线也可达到高的探测效率和灵敏度．     

核爆电磁脉冲信号的分形特征分析

针对核爆电磁脉冲(NEMP)信号的非平稳、非线性特点．将小波变换和分形方法引入到NEMP信号的分析处理中,提取了多分辨率能量分形特征及盒维数．并在实验的基础上对所提取的特征与NEMP传播距离及当量之间的关系进行了分析．从而为NEMP信号分析与处理提供了一种新的方法。     

核辐射条件下磁性器件的动态效应

核爆炸瞬间释放的中子、γ射线和核电磁脉冲对磁性材料及器件会产生各种影响,引起性能变化。中子能使磁性材料产生永久性损伤的主要原因是高能中子与材料相互作用使晶格原子产生位移效应。γ辐射可引起电离效应,产生瞬时光电流,对材料及器件造成瞬时干扰,甚至永久性损伤。静态实验证明,当中子流量达10~(16)中子/厘米~2、γ剂量率为10~8拉德(硅)/秒时,磁性器件的性能无显著改变。核爆瞬间,在相当大的范围内产生强大的电磁脉冲,其电场强度为10~4—10~5伏/米,脉冲波形持续时间为几百10~(-9)秒,频谱范围从10~2千赫兹到10~2兆赫兹。由于磁性器件外部屏蔽不完善或结构本身的孔隙,使外部电磁脉冲可以渗透到内部。即使屏蔽很完善,在几百公里范围内的强γ辐射也会在器件内部感生内电磁脉冲。这些都会干扰或破坏磁性器件的正常工作性能。因此在核辐射条件下,研究这些材料和器件的动态性能具有重要意义。     

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.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

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.