SiPM耦合LYSO晶体探测器的能量分辨和时间分辨

本文采用符合测量的方法研究了SENLE公司生产的型号为Micro FC-30035-SMT的Si PM光电转换器件耦合尺寸为3×3×10 mm的LYSO晶体组成的闪烁探测器的能量分辨率和时间分辨。该探测器测得22Na放射源能量为511 ke V光子的能量分辨率(FWHM)为16%,时间分辨达135 ps。     

Linearity and Resolution of Photodiodes

Measurements are reported of the resolution and linearity of Hamamatsu S1337 Photodiodes mounted on a NaI crystal and exposed to electron energy deposits of up to 80 GeV. The results indicate that these diodes can replace photomultipliers in high-light-yield detectors such as NaI and BGO, when operated in multi-element, compact assemblies in the presence of a magnetic field.     

Microbeam RBS on flat panel displays

We have demonstrated the utility of microbeam-Rutherford BackScattering (μ-RBS) in spatially resolved studies of operational plasma effects on the interior surfaces of plasma flat panel displays manufactured by Photonics Imaging. The experiments were performed at the Sandia Nuclear microprobe using a 2.8 MeV He beam with an average beam spot size of less than 8 μm. The interior surface of the top panes of the flat panels is composed of approximately 800 nm of MgO on top of a 2000 nm thick PbO layer. μ-RBS of sample panels operated under varying conditions measured changes in the surface MgO film thickness due to plasma erosion and redeposition as accurately as ± 1.5 nm. The high accuracy in the MgO thickness measurement was achieved by inferring the MgO thickness from the shift of the Pb front edge in the RBS spectrum. An estimate for the thickness accuracy as a function of the acquired statistics is presented. The surface of the flat panels' bottom panes is also comprised of MgO on top of PbO. However, troughs 100 μm wide by 10 μm deep were partially filled with phosphor and cover the entire width of the surface. This leaves only 100 μm long sections of MgO within the trough exposed. Using μ-RBS, we were able to analyze the surface composition of these regions.     

非能动安注箱的设计与分析

介绍了非能动安注箱的设计与实验,并用CATHENA程序分析其特性:注入流量的峰值,高注入流量的持续时间,最低注入流量等。计算结果表明非能动安注箱设计满足主要的性能要求,CATHENA程序计算结果与实验数据基本一致,可用于概念设计与事故分析。     

High Resolution Cryogenic Spark Chambers

A cluster of four narrow gap (2.5 mm) spark chambers containing 8 wires per millimeter has been built and operated at low temperatures (as low as 118°K). Results obtained from these chambers indicate that the width of the spark column is reduced at lower temperatures due to the increased gas density. Electron diffusion and deviation of the spark column from the true particle trajectory are greatly reduced at lower temperatures with narrow gap spark chambers. Space resolutions less than ? = 70 microns (HWHM) has been achieved and even better resolutions are predicted from the observed temperature dependence.     

Time Resolution in Semi-Conductor Detectors

An analytical expression for the prompt time response is compared with available data of prompt cures using surface-barrier detectors, yielding a relation for T? = 0.33 ?1/?n = 0.40 ?2 ?n/N where ?1, ?2 rise and decay times of single-electron response, n/N is the optimum value at minimum time resolution. A preliminary method is proposed for computing the plasma time in these detectors.     

KLOE高分辨电磁量能器

本文描述了ＫＬＯＥ高分辨电磁量能器的设计和结构，着重介绍了获得铅和闪烁光纤取样量能器优良性能的关键技术。为了研究这种量能器的性能，建造了２ｈ和一个全尺寸的量能器模块，其中两个小模块分别是一桶部模块和一个端盖模埠，本文给出了这三个模块的实验结果。     

Linearity and Resolution of Semiconductor Radiation Detectors

The energy linearity for Si(Li) and Ge(Li) has been measured and compared with theory. Good agreement was obtained for x-ray attenuation factors ?md < 100 . The region of the germanium absorption edge was investigated and found to exhibit larger nonlinearities than predicted by the theory. The discrepancy is believed to be due to inefficient charge collection near the detector window leading to excessive fluctuations in the trapped charge. Calculations of the line broadening due to trapping have been shown to agree qualitatively with experimental values for the silicon detector. These calculations do not take into account any position dependent variation of the trapping factor, and must therefore be considered as the best attainable values. The disagreement between theory and experiment for the line broadening in Ge(Li) is particularly evident. The ? seems to be independent of energy in Si to less than 0.2% and in Ge to within at least 2% . Finally, the Fano factor in Si was found to be 0.154 +0.1 -0.2.     

AMS专用高分辨注入器系统研制

研制了北京HI-13串列加速器AMS专用高分辨注入器系统.静电分析器和磁分析器构成能量消色散系统,质量分辨率可达600以上,传输效率好于80%.     

纳秒级时间选通成像系统动态空间分辨率

成像系统动态空间分辨率的下降与静态相比主要发生在光阴极与微通道板输入面之间.本文采用时空传递函数理论,分析了动态下空间分辨率的下降因子,计算得到的结果与实验结果相比基本一致,提出了进一步提高系统性能的方法.     

Air-water multidimensional impingement flow on vertical flat wall

The emergency core cooling (ECC) water is supplied from the direct vessel injection (DVI) system in the Advanced Power Reactor 1400 MWe (APR1400) during a postulated large-break loss-of-coolant accident (LBLOCA). The velocity of ECC water exceeds 10 m/s in the early high pressure phase of LBLOCA and then is decreased to 2-3 m/s in the late phase of reflood. During the injection the flow behavior exhibits a complex mode involving impingement, bypass, entrainment, sweepout and condensation in the reactor downcomer. There is currently no model to accurately simulate the local and complicated flow behavior in the APR1400 downcomer during a LBLOCA. This study is aimed at developing models for the water film flow and deformation, both of which are expected to sizably affect the other multidimensional flow characteristics in the downcomer. Experimental studies are conducted to benchmark the predictive model by furnishing the boundary conditions for the analysis resorting to the Accelerated Liquid Phase Hydrodynamics Apparatus (ALPHA) and the Kinetic Aerodynamic Physics Parallelepiped Apparatus (KAPPA). The Poisson equation and potential theory are applied to formulate the behavior of the water film and air flow. In both the experimental and numerical studies, the temperature-dependent thermodynamic properties and the reactor vessel curvature are neglected to render the problem at hand tractable. The model is found to reasonably describe the downward film flow behavior. The water film is developed in proportion to the initial injection velocity of the ECC water. The downward velocity of water film is increased with the heights of injection. Regarding the film deformation the calculated results tend to deviate from the experimental data as the injected air velocity is increased. The disagreement is attributed to limitations inherent in the two-dimensional treatment and point source approach.     

Time Resolution Measurements with Fast Photomultipliers

A comparision of experimental data and theoretical predictions on time resolution limits of fast photomultipliers has been performed. XP 1020 photomultipliers have been used and measurements were done with a fast electronic system built in our laboratory. This system was tested with a Co60 source, the best time resolutions achieved over a period of two hours being 164 psec at f.w.h.m. A hydrogen discharge lamp has been built which produced short light pulses whose shape is determinated by a sampling method. Several light intensities were used to simulate different energy losses in plastic scintillators and time resolution measurements were performed for different threshold settings of the discriminator. The results of these measurements were compared to theoretical data calculated by means of a statistical model of the photomultiplier. Good agreement was found assuming a photoelectronic yield of one photoelectron per 2.5 KeV in Naton 136 plastic scintillator and a single electron response (SER) variance of 500 psec. The necessity of having more accurate data on photomultiplier parameters, mainly concerning the transit time jitter, was pointed out in order to have a better understanding of the photomultiplier's behaviour.     

Measuring H with High Resolution ERDA

Elasticrecoildetectionanalysis(ERDA)isanimportantionbeamanalysistechnique.Ithasgreatadvantagesindepthprofilingoflowatomicnumberelements.Variouselementsfromlighttomediumcouldbemeasuredsimultaneouslyanddistinguisheddirectlywithoutdestroythesamples.Becauseof…     

16通道高分辨CAMAC时间数字转换器

介绍一种１６通道高分辨ＣＡＭＡＣ时间数字转换器组件,具有１２位动态范围,其最小时间分辨达２６ｐｓ,１６个通道的总变换时间仅１５μｓ。该组件采用ＣＯＭＭＯＮＳＴＡＲＴ模式,１６个独立的ＳＴＯＰ。该且件有两种读出方式;随机读出和稀疏扫描读出方式。     

针对薄层结构物质的微焦点摆动式分层成像方法研究

对薄层结构的复合材料及多层电路板进行密度分布情况及分层成像的研究，是无损检测技术的一个重要应用领域，提出了一种新的成像方法，在现有微焦点X辐射成像系统的基础上，采用一种特殊的摆动式扫描方式，基于非线性的重建成像算法，具有扫描速度快，算法简单，实时性高等特点，适合于多层大面积复合材料以及多层电路板的快速成像检测。