一种低噪声快电荷灵敏前置放大器的研制

简要介绍了新型低噪声快电荷灵敏前置放大器。这种电荷灵敏前置放大器采用新的设计方法案，该前放主要采用低噪声场效应晶体管和集成运算放大器构成，其等效输入噪声≤2．2keV。该前放具有电路结构简单、体积小、输出信号上升时间快、噪声低、稳定性好等特点。     

基于阻容低通反馈的电荷灵敏前置放大器的设计

传统电荷灵敏前置放大器以高阻值电阻作为低频反馈端,高阻值电阻所引入的热噪声为前置放大器噪声的主要来源。本文以N沟道结型场效应晶体管和阻容(Resistor-Capacitance,RC)电路构成低通网络代替传统高阻值反馈电阻完成了新型电荷灵敏前置放大器的研制。该电路以结型场效应晶体管和集成运算放大器构成放大电路,具有高输入阻抗及大开环增益的优点;以小容值电容构成高通回路,为电路提供高频反馈回路,同时实现核脉冲电流的积分;以RC低通网络构成直流反馈回路,为电路提供一个稳定的直流工作点,同时构成电压分压器使N沟道结型场效应管工作在正向偏置状态,实现对反馈电容中的电荷进行连续放电。相比于传统阻容反馈式电荷灵敏放大器,该电路能够有效克服大阻值反馈电阻引入的噪声,尤其适用于Si-PIN等半导体探测器。将该电荷灵敏前置放大器与BPX66型Si-PIN探测器连接,在室温下对241Am源进行测量,其能量分辨率可达到3.03%@59.5 keV。     

一种新型的8路电荷灵敏前置放大器

本文介绍了一种新型专用的多路电荷灵敏前置放大器,其路数最多为八路,这种电荷灵敏置放大器采用新的设计方案,该前放主要采用低噪声场效应晶体管和集成运算放大器构成,其等效输入噪声小于等于2．2 keV。该前放具有电路结构简单、体积小、输出信号上升时间快、噪声低、稳定性好等特点。并对它的设计以及特点作了较详细的阐述。     

空间X射线测量用电荷灵敏前置放大器和主放大器的研制

为配合我室与高能物理研究所合作的星载“多路Si—PIN探测器系统”地面原理样机项目的需要,开发研制空间X射线测量用多路电荷灵敏前置放大器和主放大器。把电荷灵敏前置放大器和主放大器共同安放在1个90mm×60mm的电路板上,有单独的3路输入和输出,相当于常规的3个电荷灵敏前置放大器和主放大器。整个电路采用低功耗的表面贴元器件,具有低噪声、低功耗、电路简单、体积小等特点,并可应用于多路探测器测量系统中。     

一种低噪声电荷灵敏前置放大器的研制

介绍了一款新型低噪声电荷灵敏前置放大器的研制。该电荷灵敏前置放大器采用新的自主设计方案,可利用计算机的USB接口直接供电,其电子学等效输入噪声约为0.08 f C,积分非线性为1.8%。该电荷灵敏前置放大器可用于小型半导体核探测谱仪的信号读出放大。集探测器偏置高压、低压电源、电荷灵敏前放、成形电路于一体,体积小、使用方便、噪声低。     

一种新型电荷灵敏前置放大器和成形峰保持混合电路

本文介绍一种我们研制的新型电荷灵敏前置放大器和成形放大与峰保持混合电路,该电路采用了新的设计方案,它采用电荷灵敏前置放大器将探测器信号预放大后,再经过放大成形和峰值保持,以便后继电路采样和进行数据的处理.放大器信号成形时间为0.5 μs;1μs;2μs三档可调,放大倍数为×10;×100两档选择,峰保持时间为6μs,它具有噪声低;体积小;电路结构简单;价格低等特点,并且对整个电路做了较详细的阐述.     

电子能量损失符合谱仪的一维位置灵敏探测器的读出系统

介绍了用于电子能量损失符合谱仪的一维位置灵敏探测器的读出系统。一维位置灵敏探测器可以大大提高谱仪的探测效率。其读出系统包括电荷灵敏前置放大器、主放大器、位置信号采集板和接口电路。使用自己设计的信号源对系统进行了测试,取得了较好结果。     

FH4-049型低输入阻抗电荷灵敏前置放大器

一、电路介绍 图1是FH4-049型低输入阻抗电荷灵敏前置放大器的电路图,它包括一个电荷灵敏放大级和一个电压放大级。     

便携式X荧光分析仪前置放大器的设计

介绍了一种新型高速低噪声器的电荷灵敏前置放大器,该放大器已应用于便携式X射线荧光分析仪中,它具有电路结构简单、性能可靠、线性度较好、输出信号上升时间快、噪声低等特点,有较好的性能价格比。     

一种用于测量气载放射性碘的模拟信号采样电路

介绍了一种为气载放射性碘探测器研制的模拟电路。在探测器设计方案中,打破了传统上将前置放大器与主放大器分离的思想,将电荷灵敏前置放大电路与主放大电路置于探头以内;为了实现信号脉冲的较长距离传输,在信号电缆前端设置了既有电流放大又具备阻抗匹配功能的驱动电路,该驱动电路实现了在信号电缆后端免接地匹配电阻的需求,增强了探头的电子学兼容性。该研究成果得到理论与试验的验证,对工程应用具有较大参考价值。     

一块罕见陨石的穆斯堡尔效应研究

用穆斯堡尔效应对一块罕见陨石进行了测定，结果表明此陨石的黑白部分均由橄榄石，辉石，陨硫铁和铁镍合金等主要成分组成，但其含量有明显差异，进一步证实此陨石属于平衡的橄榄石－古铜辉石球粒陨石。     

大体积氟化钡探测器的性能测试

中国原子能科学研究院正在研制建立的γ全吸收型探测装置（GTAF）由40个氟化钡（BaF₂）探测器单元组成。对单个大体积氟化钡晶体探测器单元的主要相关性能,诸如单个探测器的组装、晶体封装条件和探测器能量分辨、时间分辨及其长期稳定性等进行测试。测试结果表明,40个氟化钡（BaF₂）探测器单元的能量分辨和时间分辨符合基于γ全吸收型探测装置的中子辐射俘获核反应截面测量需求。     

Radioactive Rare Gas Separation Using a Separation Cell with Two Kinds of Membrane Differing in Gas Permeability Tendency

A separation cell embodying two kinds of membrane—porous and nonporous, i.e. differing in gas permeability—has a separation factor higher than possible with a conventional separation cell with a single kind of membrane. The performance of such separation cells and of cascades constituted thereof are analyzed theoretically and measured experimentally for different conditions of operation, to determine the applicability of the concept to the separation of rare gases from gaseous waste out of nuclear plants.

Theoretical considerations indicate that, in a cascade composed of symmetric separation cells, the separation performance can be improved by recycling part of the effluent from a cell back through the same cell (recycling cascade). It is shown that its performance is better than with the arrangement of diverting another effluent several stages upstream. With the recycling cascade, the symmetric separation recycling rate is determined by the depletion separation and enrichment separation factors relevant to the respective membranes.

The separation performance of a 9-stage recycling cascade composed of separation cells with silicone rubber tubular membranes and cellulose acetate tubular membranes is derived for a case of Kr separation from N₂-Kr mixture. The experimental data coincide well with the analytical results.

From both the experimental and the analytical results, it is found that the attainable separation coefficient per stage of the cascade comes to average approximately 0.97.     

Study on three-dimensional heterogeneous calculation of ITER test blanket module with deterministic method

The neutronics analysis on the test blanket module (TBM) has important significance for the ITER device and its related experiment design. Quantities of scoping-type studies and conceptual designs were published by using the Monte Carlo method. However, disadvantages like time consuming make it necessary to develop a new highly efficient method. Hence, a new two-step approach method based on the 3D deterministic method for analyzing the TBM is proposed in this paper. A code package 3DMOC-NSPn was developed. It is mainly composed of three modules, the 3DMOC for generating the homogenization cross section; the LINK code for cross section condensation and the NSPn code for blanket calculation. The detailed flux distribution throughout the whole TBM and the mainly neutronics features, such as TBR, displacement per atom (DPA), helium and hydrogen production rate can be obtained. To validate the numerical approach and the code package, the calculations on China dual functional lithium lead-test blanket module (DFLL-TBM) was performed. The reference results were obtained by using the MCNP code. The numerical results from 3DMOC-NSPn are in good agreement with the references. It indicates that the whole code package is a reliable neutronics analysis tool for the TBM design and evaluation.     

双参数获取多功能控制器

双参数获取多功能控制器是一个单宽度NIM插件,与三个ADC,IBM微机及接口连接组成双参数获取多功能微机多道。它的功能分三部分:(1)双参数获取 全谱为256×256,利用开窗技术分区域获取可达512×512,1024×1024。(2)单谱 两个单路可同时获取。(3)谱定标(又称多谱获取)可用范围:单向 1024道×8,0048道×4;双向2×1024道×4,2×512道×8。     

人工合成超重元素的稳定性分析

本文通过对核的稳定性分析图对人工合成超重元素的稳定性进行了理论分析。分析表明：任何已知的两种原子核合成的超重核都是欠质量超重核,不稳定的主要因素就是质子间的排斥性库仑力的强烈作用,抵消这种作用的有效方法是采用中子渗入技术;超重元素的质子数最多不大于1002,质子数在362至1002之间的“极端”超重核估计是中子星;预计具有稳定性的质子数等于114的超重元素的质量数在299至315之间。     

Nuclear track formation and skewness of particle trajectories in the target: A new perspective

It is discussed why track detectors such as CR-39 and CN-85, which are only composed of light elements, are highly sensitive and efficient compared with detectors such as glass and mica, which are partly or fully composed of heavier elements. Weak scattering of incident particles by light target atoms does not significantly deviate incident particles from their straight trajectories while the target atoms recoil considerably, damaging the detector. Heavier atoms scatter incident particles through wide angles, significantly deviating them from their straight paths while the target atoms recoil weakly, producing less damage. Simulations are presented to demonstrate these concepts about nuclear track formation.     

Characterization of ancient Chinese pottery decorated with a black pigment

The Yangshao type pottery, made about 6000 yrs ago, was investigated by X-ray diffraction (XRD), and confirmed to be composed of quartz, feldspar, muscovite and calcite. A black pigment on it was assumed to be (Mn, Fe)₃O₄ from Particle Induced X-ray Emission (PIXE) and XRD experiments. Firing temperature of the pottery was assumed to be less than 600°C from a heating experiment of the fragment of the pottery.     

ITER校正场线圈等效材料属性有限元分析

校正场线圈是ITER大型超导磁体系统的重要组成部分,其线圈体由多种材料组成且周期性排列,对其等效材料属性预测很重要。目前主要采用基于均匀化理论的有限元方法,但其处理过程复杂。本文提出了基于广义虎克定律的有限元方法,使求解过程更简便。分析对比两种方法,后一种方法处理过程更简单,结果更精确,所得结果为校正场线圈的结构分析和热分析提供了必要的参数。