电流型半导体探测器收集特性的测定

利用2.5MeV质子静电加速器调制成微秒宽度的单次脉冲束流,照射国产离子注入PIN及Au-Si面垒型探测器表面后,观察从示波器屏幕上同时拍摄的探测器输出波形和束流波形并加以比较,由此观察耗尽区内部电荷积累对平顶畸变、收集时间大小的影响及收集效率等参数。     

北京正负电子对撞机(BEPCⅡ)束流注入区辐射场研究

北京正负电子对撞机(BEPCⅡ)正负电子束流注入阶段的束流损失,影响储存环束流注入区及防护区辐射场。本文利用束流损失监测系统(BLM系统)分析了束流注入阶段注入区束流损失的位置和束流损失率,并结合FLUKA软件模拟计算对撞实验模式下束流注入阶段注入区的辐射场。结果表明:注入阶段注入区及其下游束流损失明显;辐射场内粒子能谱情况是中子为宽能谱且各向同性,切割磁铁 (铁靶)出射蒸发谱峰窄,峰值约为0.9 MeV,直接发射谱不显著;真空管(铝靶)出射蒸发谱峰宽且直接发射谱显著,峰值分别为4 MeV和20 MeV;光子能谱峰窄且前向性明显,能量在5 MeV以下分布集中;中子与光子剂量率水平相当;注入阶段比非注入阶段剂量率高约2个数量级;对撞实验模式下,实验测量整个运行阶段储存环光子剂量率平均水平约为1 000 μSv/h,中子剂量率比光子剂量率低1个数量级。     

组合PIN探测器对γ、中子脉冲辐射补偿效果研究

提出了一种新的硅PIN探测器组合结构,使其适用于n、γ混合脉冲辐射场中脉冲中子的测量。分别利用三通道脉冲γ发生器和DPF脉冲中子发生器对组合PIN探测器的γ和中子辐射补偿效果进行了测量研究,实验结果表明组合PIN探测器的γ和中子辐射补偿效果均达97％以上。     

平面型硅光电二极管PIN的研制及其基本性能测试

为满足CERN/ALICE超高能重离子对撞实验光子谱仪的需要,首次采用高阻硅材料,并利用一些特殊工艺,研制了用于钨酸铅晶体探测器读出单元的硅光电二极管PIN。PIN的灵敏区面积为16mm×17mm,常温漏电流小于5nA,紫光区量子效率82%,全耗尽结电容为110—120pF。由PIN与电荷灵敏前置放大器组成的读出系统的噪声水平,在-25℃下小于600个等效噪声电荷,并经过了长期性能稳定性的考验。开发研制的大面积PIN硅光管全面达到ALICE/PHOS国际招标所规定PIN硅光管性能的指标。     

PIN硅光二极管在n/γ混合辐射场中的探测技术研究

PIN硅光型半导体探测器较传统辐射探测器具有响应快、抗干扰强、体积小、灵敏度高、能量分辨率高以及无需高压等优点,在个人剂量仪、X射线荧光分析、镀层测厚、放射诊断等粒子辐射测量领域中被广泛采用.采用6LiI与BGO晶体把n和γ射线转换至PIN的有效光谱探测范围内,同时参考PIN硅光二极管的电路等效模型,设计与之匹配的电荷...     

基于半导体集成电路辐射效应的空间辐射环境探测器

空间辐射环境能够引起半导体集成电路发生的总剂量效应、单粒子效应等辐射效应,可以被用来进行空间辐射环境监测。在一定条件下,基于此原理的探测器具有常规的面垒型探测器以及PIN型探测器等所不具备的优点。尤其适合航天器舱内带电离子探测和用于航天医学的个人辐射剂量探测。介绍了三种基于半导体器件辐射效应的探测器。     

用“脉冲响应法”确定PIN探测器的电容

利用W.C.Dikinson推导的PIN探测器的时间响应公式计算的波形与实测波形进行比较,反推探测器的电容值C,这种方法称为脉冲响应法。这种方法获得的PIN电容大约是探测器结区电容的1.3-1.4倍。分析表明,由于包含了杂散电容等的影响,这种方法比公式法在确定PIN探测器的电容时具有更好的准确性,可以用这种方法确定的电容来计算PIN探测器的脉冲响应波形。     

CZT探测器辐射性能实验研究

使用高电阻率CZT(碲锌镉)晶体制备了适用于脉冲γ辐射探测的探测器。通过在脉冲γ发生器和60Co放射源上开展实验,获得了CZT探测器的时间响应和1.25MeVγ辐射灵敏度。结果表明,CZT探测器较传统Si基PIN探测器有暗电流低、时间响应好、灵敏度高的优势,适用于低强度γ辐射脉冲测量。     

PIN探测器贯穿辐射与非贯穿辐射线性特性

采用脉冲X射线源和脉冲氙灯光源实验研究了PIN探测器对贯穿辐射和非贯穿辐射响应的最大线性电流输出特性,并与理论计算结果进行了比较。PIN探测器输出的最大线性电流随外加反向偏置电压线性变化,对贯穿辐射响应的最大线性电流输出比对非贯穿辐射响应的最大线性电流输出约大20%,理论计算的最大线性电流值比实验值小。在脉冲辐射探测中,采用可见脉冲光源获得的PIN探测器最大线性电流不会超出探测器对贯穿辐射的线性响应。     

脉冲慢正电子束流的检测

本工作设计了一种通过测量脉冲慢正电子湮没辐射在闪烁探测器的积分效应进行测量和标定脉冲正电子束流强度的方法.通过对探测器的刻度,定量测量了北京慢正电子强束流项目中慢正电子束流的流强和能谱发布,为脉冲正电子束流的直流化设计提供了依据.     

PIN硅光电二极管用于γ射线探测的试验研究

在X、γ射线的剂量或剂量率测量场合,常用到PIN硅光电二极管.比起传统的电离室等,它有体积小、灵敏度高、成本低、不需要高压等优点;与计数管、闪烁探测器相比,其电流输出的特性可以避免脉冲场下的死时间问题.但大剂量照射造成的辐射损伤是影响其性能的最大因素.以XRB100s-CB380为例,通过试验研究了PIN硅光电二极管的特性,包括灵敏度、偏压影响、温度补偿、辐射损伤及退火等,并简单介绍了实际应用中对输出电流信号的处理方法.     

BESIII剂量率在线检测和保护系统读出电子学设计

为保护束流管, BESIII将使用PIN硅光电二极管来实时检测对撞点附近的剂量率水平,其中的信号读出电子学采用电流A/D转换方案.对几种弱电流放大与测量方法进行了比较,主要介绍了电流A/D方法的工作原理、软硬件实现以及实际性能.     

An intense channeling radiation source

A non-conventional X-ray source which is based on the production of electron channeling radiation in a diamond crystal has been installed at the radiation source ELBE. The brilliant electron beam with an average current of up to 200 μA allows to reach photon rates of quasi-monochromatic channeling radiation between 10¹⁰ s⁻¹ and 10¹¹ s⁻¹ per 10% bandwidth. The photon energy can be tuned by variation of the beam energy. On-line X-ray monitoring was realised at high beam currents using a Compton spectrometer. Monochromisation of channeling radiation and bremsstrahlung background reduction has been investigated applying X-ray diffraction at a highly ordered pyrolytic graphite crystal.     

Design of a prompt-gamma neutron activation analysis system on China Advanced Research Reactor

In this paper,computational methods are used to optimize the design of a prompt-gamma neutron activation analysis(PGNAA) system on China Advanced Research Reactor(CARR).Approaches are adopted for obtaining accurate neutron beam parameter and saving the computing time.For the radiation shielding design,the optimizing factors include the cost,weight,volume,machining convenience and background radiation at the detector position.Low background spectrum and high sensitivity are expected.The simulation results...     

Heavy-ion microbeam system for cell irradiation at Kyoto University

We have developed a heavy-ion microbeam system for cell irradiation that uses an 8-MV tandem Van de Graaff accelerator at Kyoto University. Using a pair of apertures as the final collimator, microbeams of carbon, fluorine, and silicon were extracted to the atmosphere with few background particles. We used a thin transmission scintillator and a photomultiplier detector to accurately measure the number of extracted particles. To examine beam spreading, the beam profile was measured by observing tracks of an irradiated CR-39 track detector. The two disks with holes which were added to the collimating apertures reduced background radiation due to secondary X-rays and electrons from the apertures.     

Sensitivity of a new-developed neutron detector

We develop a kind of neutron detector, which consists of a polyethylene thin film and two PIN semiconductors connected face-to-face. The detector is insensitive to γ-rays. Its sensitivity to neutron has been calculated with MCNP program and calibrated by experiments, and the results indicate that the neutron sensitivity of the compensation detector will vary with polyethylene convel‘ter. The compensation PIN detector can be employed to measure pulse neutron in neutron and gamma mixture radiation field.     

The New 5 MeV Electrostatic Ion Accelerator at the Central Research Institute for Physics, Budapest, Hungary

The new 5 MeV electrostatic ion accelerator, projected, built, and tested at the Central Research Institute for Physics in Budapest, with some necessary aid from Hungarian industry /pressure vessel etc./ is described. The accelerator's main specifications are detailed and an account is given of the experiences with glass and porcelain accelerating tubes. By careful design, the intensity of radiation in the range of 4-5 MV has been reduced by 2-3 orders of magnitude. Without an ion beam there was only 3-5 times the intensity of the natural radiation background /i.e. less than 0.5 mR/h/ on the outer surface of the generator vessel when operated at 4-5 MV. The radiation level with the accelerated ion beam is accordingly also very low. During a 7-month period in 1970 the generator ran for 3,250 hours of measurements in nuclear physics.     

光敏晶体管的中子位移损伤效应研究

通过开展光敏晶体管的反应堆中子辐照实验,获得位移效应实验结果,并分析位移损伤机理。研究发现,在3×10¹¹~5×10¹²cm^-2中子注量范围内,光敏晶体管增益和光响应度的下降导致集电极输出电流下降。增益的倒数与注量的增加呈线性关系,注入电流越大,线性关系的斜率越小。理论分析表明,通过提高基区掺杂水平或减小基区宽度,可提高增益的抗辐射水平;不同反向偏置电压下的初级光电流辐照前基本相同,随着辐照注量的增大,差异逐渐增大,反向偏置电压越大,初级光电流的退化越小;通过采用PIN结构或加大反向偏置电压来展宽耗尽区以减少受位移效应严重影响的扩散电流份额,可提高初级光电流的抗辐射水平。与PIN光电二极管不同,本实验注量范围内,光敏晶体管的暗电流随注量的增大而减小。