单阳极丝位置灵敏探测器

本文报道单阳极丝位置灵敏探测器(SWPC)的制作和性能研究。探测器的灵敏面积为250×70mm~2,两阴极间距离为10mm。在垂直入射的条件下,用5.9keVX射线~(55)Fe源测得的位置分辨为0.7mm(FWHM),最大积分非线性≤0.77%;用~(241)Amα源(约5MeV)测得的位置分辨为0.6mm(FWHM),最大积分非线性≤0.58％。     

小单元多丝漂移室探测器系统研制

为精确测量CSR外靶终端靶前入射粒子的径迹,研制了多套小单元多丝漂移室探测器,该探测器灵敏面积为80 mm×80 mm,每套探测器包括x、x′、y、y′4个探测电极面,每个电极面引出16个阳极丝信号。前端电子学采用基于SFE16芯片的放大器,数据读出系统采用基于HPTDC芯片的数据采集卡。采用两套小单元多丝漂移室对400 MeV/u的¹⁶O束流位置进行了测试,探测器的工作气体为Ar(80%)+CO₂(20%),阳极丝电压为+900 V,场丝与阴极丝均接地,拟合得到的单层电极的位置分辨(拟合残差)为105.9μm,探测效率为99.3%,该指标可以满足现阶段CSR外靶终端大部分核物理实验对反应靶点的定位要求。     

一个二维读出多丝正比室的实验研究

中国散裂中子源(CSNS)反射谱仪中的高精度二维位置灵敏中子探测器以多丝正比室为探测单元.为了深入了解二维读出多丝正比室的性能及为中子探测器多丝室单元设计提供参考和依据,制作了一个二维读出多丝正比室模型.对模型的能量分辨率、正比性、位置分辨率等各种性能进行了较为系统的实验研究.测量得到当阳极高压在1700V～1900V时,多丝正比室模型的能量分辨率在23.5%左右,正比性较好,沿着阳极丝的位置分辨(FWHM)为0.3mm左右.     

一种高性能双维位置灵敏平行板雪崩探测器

本文描述了为兰州放射性离子束流线（RIBLL）研制的一种高性能平行板雪崩计数器（PPAC）。它由中心阳极和X、Y位置阴极构成，阳极间距3mm。阳极为1.5mm厚Mylar膜，双面镀金。阴极为φ25μm镀金钨丝，丝距1mm，位置读出采用电荷分除法。工作气体异丁烷。当工作气压为700Pa，阳极电压为500V时，对3组分α粒子位置分辨0.76mm(FWHM)，探测效率约99.1％。     

2×2阵列H8500光电倍增管简化读出电路的设计

研发了基于两级电阻网络简化电路结合局域重心法定位的简化读出电子学电路,用于2×2阵列的H8500多阳极位置灵敏光电倍增管的前端位置信号读出与处理。实验结果显示:此设计方案能有效将256路读出信号简化至4路处理信号,还能较好分辨出1.2mm像素的NaI(Tl)阵列晶体,同时使探测器的成像视野达到探测器内在的灵敏范围。对各光电管单元边缘及拼接的交界区,需进行有效的光学补偿,才能较好弥补非灵敏区像素的探测性能。     

一个小型△E—E望远镜

一、引言 本望远镜是为在96MeV~(16)O+~(64)Ni系统上探测重离子而研制的。△E探测器是一个纵向电离室,它由阳极、阴极、栅极以及均压环构成。采用的工作气体为P10,使用流气式,气压稳定性为±100Pa。在气压为40kPa,栅极高压为350V,阳极高压400V时,~(241)Amα粒     

LNL的反冲质量谱仪的新型焦面探测器——PS-PPAC

在意大利 L NL实验室 ,研制了两种新型反冲质量谱仪 (RMS)焦面探测器 :灵敏面积均为70 mm× 140 mm的 Padova型和 Argonne型位置灵敏 -平板雪崩计数器 (PS- PPAC)。详细描述了紧密结构的特点及主要特性 ,各自的性能测试方法及结果。对α源 (能量为 5 .5 Me V) ,Padova型 PPAC的 X、Y位置分辨分别为 1.0和 0 .8mm,对应的探测效率分别为 4 9%和 85 % ,Argonne型 PPAC的 X、Y位置分辨分别为 1.8和 1.0 mm,对应的探测效率分别为 12 .7%和 4 .5 %。     

大型位置灵敏探测器的研制

研制了以电荷分配法读出的大型单阳极丝位置灵敏探测器,其灵敏面积为1200×60mm~2。阳极丝采用φ10μm的镍铬合金丝,电阻率为12Ω/mm,两阴极面采用12.5μm的单面蒸铝Mylar膜。工作气体为70％Ar 30％CH_4,在一个大气压下,自然流气式工作。测量前在探测器前窗上贴上1.2m的标尺,将约5MeV的~(241)Amα源,放在一个准直器上,该准直器可以在探测器前窗上面准确、自由地平移。在沿阳极丝方向上,每隔6cm测量一个点,共测量了19个点,测得的平均位置分辨(FWHM)约为0.6mm;最大积分非线性好于0.2％。该探测器已经装配在北京Q3D磁谱仪全焦面探测器系统上准备在串列加速器上进行束流试验。     

两种位置灵敏平行板雪崩探测器

为兰州重离子加速器放射性次级束流线 (RIBLL)设计研制了两种结构双维位置灵敏低压气体平行板雪崩探测器 (PPAC)。用 3组分α粒子辐照 ,传统结构的PPAC ,对于 70 0Pa异丁烷和C3F8工作气体 ,分别得到 0 76mm(FWHM )和 0 64mm(FWHM)的位置分辨 ,探测效率为 99 1 %。新的多级位置灵敏平行板雪崩探测器 (MPPAC) ,对 65 0Pa异丁烷工作气体 ,测得 0 5 8mm (FWHM )的位置分辨、99 2 %探测效率和色散远好于± 0 2mm的位置线性。MPPAC增益较传统PPAC高 ,C3F8较异丁烷阻止本领强 ,适合探测较轻粒子。     

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。     

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.