表面铀污染量检测仪的研制

介绍了一台测量板形铀元件大面积低水平表面铀污染测量仪。该装置探头是大面积多丝正比计数器,计数器阴极由低本底材料不锈钢制成的,窗由厚6μm双面镀铝的聚脂膜制成。阳极丝是0.025mm镀金钨丝。计数器灵敏面积为1113mm×100mm。实验表明,计数器固有本底为0.002计数/(min·cm~2)(2计数/min)。对浓缩铀源,探测效率为67％,2π方向;24小时稳定度为0.84％(包括计数器、高压、电子学放大器、甄别器、微机、打印和显示系统)。该装置可探测的定量下限为(对20％~(235)U,0.13％~(234)U,79.64％~(238)U)4.6×10~(-10)g/cm~2。通过微机控制,该装置可预置定时,具有显示、自动报警、分类和打印功能。     

表面铀污染量检测仪的研制

介绍了一台测量板形铀元件大面积低水平表面铀污染测量仪。该装置探头是大面积多丝正比计数器,计数器阴极由低本底材料不锈钢制成的,窗由厚6μm双面镀铝的聚脂膜制成。阳极丝是0.025mm镀金钨丝。计数器灵敏面积为1113mm×100mm。实验表明,计数器固有本底为0.002计数/(min·Cm~2)(2计数/min)。对浓缩铀源,探测效率为67％,2 π方向;24小时稳定度为0.84％(包括计数器、高压、电子学放大器、甄别器、微机、打印和显示系统)。该装置可探测的定量下限为(对20％~(235)U,0.13％~(234)U,79.64％~(238)U)4.6×10~-10)g/cm~2。通过微机控制,该装置可预置定时,具有显示、自动报警、分类和打印功能。     

一个简易的正比计数器探测系统

本文介绍了一个低能量γ射线探测器系统,它由端窗型流气式正比计数器和一个具有双极脉冲对基线漂移补偿的前置放大器组成。正比计数器是一个两端用有机玻璃薄窗密封的直径为70mm、长为30mm的薄壁硬铝圆筒。阳极丝用直径为25μm的镀金钨丝直接固定在薄窗的中心,使阳极丝周围的电场分布均匀,减少端点效应,提高能量分辨率。入射的γ射线通过端窗后平行于阳极丝方向,增加了γ射线在工作气体中的作用长度,     

脉冲磁体中不锈钢筒对磁场的影响研究

建立脉冲磁体线圈与不锈钢筒之间电磁耦合分析模型,利用数值分析法,对不锈钢套筒对磁场波形的影响进行理论分析与计算.结果表明,不锈钢套筒增加了放电回路中的等效电阻,降低了等效电感,导致磁场到达峰值时刻的时间缩短,磁场峰值降低.壁厚20 mm的不锈钢筒,磁场峰值降低4.9%,磁场达到峰值时间缩短6.7%.实验结果与理论分析吻...     

对高气压充氙电离室型γ谱仪能量分辨率的优化研究

所研究的高气压氙电离室灵敏探测体积结构如图1所示（12根极丝），它采用共面栅极阳极结构，其灵敏探测体积包括不锈钢外壳，阳极丝及陶瓷绝缘固定端。其中，阴极为不锈钢内壳，高101．6mm，底面直径101．6mm，加偏压一4000V，内充相对介电常数为1．12，电导率为0的高纯高压氙气；不锈钢外壳上下两端为厚12．7mm的陶瓷绝缘体，数目为2、4、8、12或16根不锈钢阳极丝等分成收集极和非收集极两组，相互错开排列，收集极加1400V偏压，非收集极保持接地。     

2π流气正比计数器装置——标定大面积α-板源和β-板源

中国计量科学研究院放射性室于1971年建成2π流气正比计数器装置,该装置用于标定10~2—10~6粒子/分·2π的α-板源及(10~4—10~6)粒子/分·2π的β-板源,给出结果的不确定度±2％,所允许测量的放射源最大活性面积为180×120毫米。 该装置最明显的特点是计数管的几何尺寸大,计数管阴极外壳呈长方盒形(220×160×36毫米),是不锈钢材料制做的。盒高中部沿计数管长轴方向平行地安置五根拉紧的阳极丝(鏮铜丝,直径0.05毫米),丝与丝之间距离30毫米,两侧丝距阴极壳内壁20毫米。待标定     

微剂量学在辐射诱发染色体畸变原发过程分析中的应用

本文根据微剂量学的基本概念,用改变 Rossi 型正比计数器(LET-SW1/2)腔内组织等效气体压力(体积比分别为 CH_4:64.4%,CO_2:32.4%和 N_2:3.2%)的方法,测量了~(60)Coγ射线在50—200mmHg 的气体压力范围内所相应的模拟组织直径(0.92—3.7μm)上的事件大小的分布谱。从而,建立了单次能量沉积事件比能的剂量平均与模拟组织直径的经验关系。并对照辐射诱发染色体畸变产额与吸收剂量的关系,推论得到淋巴细胞辐射敏感区的直径约为0.93μm。     

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%。     

端盖簇射计数器中取样计数管的性能研究

本文对北京谱仪中端盖簇射计数器的取样计数管性能进行了测量和研究。实验结果表明,以内壁截面12.8×12.8mm~2的正方铝管为阴极、直径37μm高阻丝为阳极的工作在Ar+CO_2+n-pentane(1+2+1)混合气中的自猝灭流光管可较好地满足端盖簇射计数器的要求。     

90Y电沉积的实验研究

研究了用电沉积方法从90Sr母液中分离医用90Y的工艺条件。以0.1 mol/L pH 2.5的(NH4)2SO4溶液为电沉积底液，以铂为阳极，铂或不锈钢为阴极，控制阴极电流密度0.5A/cm2，电沉积50min，90Y在阴极沉积率大于95%。阴极上的90Y用0.1~0.5mol/L的热硝酸洗脱后再次电沉积。二次电沉积后90Y/Sr90的分离系数大于8×105，洗脱收率大于70%。铂丝阴极上的90Y可用200~400μL 0.1~0.5mol/L的热硝酸洗脱，制成用于标记药物的90Y溶液；沉积有90Y的不锈钢阴极经热处理后，制成心血管放射性支架或医用敷帖片，其90Y的日浸出率分别小于1%和0.1%。残液中的90Sr经放置一段时间（20天）后，可用来再次分离90Y。     

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.