嫦娥二号γ谱的非线性谱漂校正

针对嫦娥二号γ谱的非线性谱漂特点,提出了一种基于能量对应的谱漂校正方法。选取了嫦娥二号γ谱线作为研究对象,进行谱漂校正实验。结果显示:该方法能够有效校正嫦娥二号γ谱的非线性漂移,使Fe峰和Mg/K峰的峰位漂移范围控制在±1道范围内。     

基于全谱特征的谱线漂移校正方法研究

建立谱漂模型,构造了一种可以利用全谱数据对谱漂参数进行估计的方法。以Na I(Tl)晶体闪烁探测器γ能谱仪测量放射性矿物样品得到的仪器谱为例,在保证谱漂规律的前提下,使用一定的谱漂参数对实测谱线进行变换,对谱漂估计算法进行了理论验证;同时在对能谱仪实际应用中出现的谱线漂移进行谱漂校正,并得到了良好的校正效果。提出的谱漂校正方法无需寻峰,能够充分利用全谱数据,易于实现自动化稳谱操作,在野外及原位光谱测量分析中具有实际应用价值。     

基于时延估计法的自然伽玛能谱自动稳谱

传统的软件稳谱方法基于谱漂为线性漂移的假设,只利用一个主峰峰位进行校正,论文将时延估计中的相关法应用到软件稳谱,通过构造标准特征谱峰,与实际光滑后的谱峰进行相关计算寻找漂移道数。实例证明了该方法对于非线性谱漂校正性优于传统方法。     

基于奇异值分解方法的嫦娥一号γ射线谱仪谱线定性分析

针对嫦娥一号γ射线谱仪(CE1-GRS)探测数据难以从谱形特征直接进行定性分析的问题,提出采用噪声调整的奇异值分解(NASVD)方法提取CE1-GRS数据中相互正交的谱线主成分,然后分别分析月表各区域对应谱线的低序层谱线中的峰信号,通过鉴别各峰信号对应的能量值是否等于特定元素的特征γ射线能量来确定月表各区域的元素种类。结果表明,该方法能够识别出的月表可能元素包括U、Th、K、Fe、Ti、Si、O、Al、Mg、Ca和Na等11种元素。     

质量控制谱法校正惰性气体氙β-γ符合谱能量漂移

针对CTBT放射性核素台站惰性气体氙β -γ符合谱能量漂移问题,提出了一种基于质量控制(QC)谱的谱能量漂移校正方法,利用质量控制谱中的γ能谱和二维β -γ符合谱分别对γ探测器和β探测器的能量漂移进行校正,确定氙样品二维β -γ符合谱中四种放射性氙同位素(131mXe,133mXe,133Xe和135Xe)的符合能量区域,实现了放射性氙同位素活度浓度的准确定量分析。     

实验室高纯锗γ谱仪的“稳谱法”研究

“峰漂”是影响γ谱仪测量准确度的重要因素.文中详细介绍了“天然放射性核素特征峰稳谱法”,采用天然放射性核素K-40的特征峰识别“峰漂”,并使用该峰对谱仪进行矫正.该方法具有操作简单、识峰快捷、实时准确矫正等优点,适合于实验室工艺系统样品γ核素测量.     

NASVD方法在CE1-GRS谱线分析中的应用研究

直接从谱形特征上对嫦娥一号伽玛射线谱仪(CE1-GRS)的3级谱线数据进行分析,难以确定月表元素的种类。提出采用噪声调整的奇异值分解(NASVD)方法对CE1-GRS谱线进行定性分析。分析结果表明,该方法能够识别出的月表可能元素包括U、Th、K、Fe、Ti、Si、O、Al、Mg和Ca等10种元素,也能够通过各观测谱线对应于第一主成分的幅度绝对值大小反映对应月表区域的总放射性活度强弱。     

航空γ能谱测量谱线比法大气氡校正的理论研究

本文介绍了在航空γ能谱测量中,校正航空γ能谱所包含大气氡本底的谱线比法理论基础及其数学模型。通过对谱线比法校正系数的探讨,分析不同组分校正系数和高度之间的关系。在此基础上,提出了校正系数获取的实验途径,避免了谱形数学拟合方法可能引起的问题。     

X射线管原始谱和透射谱的测量及应用

本文基于COMET公司MXR225/22型X射线管,使用高纯锗探测器测量了X射线管大、小焦点几种管电压的X射线原始谱,并测量了小焦点下的初始透射谱,在此基础上测量了X射线穿过几种不同材质(铝、钛、铁和铜)吸收片的透射谱。结果表明：X射线管大、小焦点能谱近似相同,低能端X射线比重较大,原始谱中包含铜、银、钨和铅元素的特征峰;初始透射谱低能端硬化明显,并随着管电压升高,高能端所占比重增大,钨特征峰变得明显,X射线平均能量升高,能谱的X射线强度最大区域在最高能量的1/3附近;金属吸收片对X射线硬化明显,硬化效果强烈依赖于其原子序数。相关结果已在工业CT硬化校正中应用,重建图像质量得到改善。     

大量铀溶液中^237Np含量的γ谱法测量

研究建立了γ谱法直接测定大量铀溶液中^237Np的方法。利用^237Np在86keV附近的γ射线峰扣除其子体^233Pa的影响,可以定量测定^237Np。铀溶液中的大量铀对86keV附近的γ射线有较强吸收,86KeV附近峰面积的对数与铀浓度呈线性关系,用最小二乘法进行拟合线性,对铀的影响加以校正。     

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.     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 15 (2013)

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