一种新阈探测器的实验验证和重离子靶区中子测量

验证了用^2099Bi作为一种新的阈探测器测量高能中子的可能性，并利用^115In,^27Al,^19F,^12C和^209Bi组成的阈探测器组合测量了中能重离子反应实验靶区出射中子的注量率分布、能量分布和剂量当量率分布。     

Fluence and dose measurements for an accelerator neutron beam

The 3 MV Van de Graaff accelerator at McMaster University accelerator laboratory is extended to a neutron irradiation facility for low-dose bystander effects research. A long counter and an Anderson-Braun type neutron monitor have been used as monitors for the determination of the total fluence. Activation foils were used to determine the thermal neutron fluence rate (around 10⁶ neutrons s⁻¹). Meanwhile, the interactions of neutrons with the monitors have been simulated using a Monte Carlo N Particle (MCNP) code. Bystander effects, i.e. damage occurring in cells that were not traversed by radiation but were in the same radiation environment, have been well observed following both alpha and gamma irradiation of many cell lines. Since neutron radiation involves mixed field (including gamma and neutron radiations), we need to differentiate the doses for the bystander effects from the two radiations. A tissue equivalent proportional counter (TEPC) filled with propane based tissue equivalent gas simulating a 2 μm diameter tissue sphere has been investigated to estimate the neutron and gamma absorbed doses. A photon dose contamination of the neutron beam is less than 3%. The axial dose distribution follows the inverse square law and lateral and vertical dose distributions are relatively uniform over the irradiation area required by the biological study.     

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.     

一种高灵敏度环境中子剂量当量仪的能量响应计算与实验验证

利用MCNP4C程序计算了一种高灵敏度环境中子剂量当量仪的响应曲线.计算结果在感兴趣能量区间与ICRP建议书中的H*(10)曲线符合较好,通过实验验证,计算结果与实验数据相对偏差在-21.6%以内(对中子要求偏差在±50%以内),实验表明,用MCNP程序优化设计探测器可提高设计效率,并可同时为实验验证提供参考数据.     

低能离子探测器的设计及测试

自行设计制作并测试了用于电子-离子碰撞电离截面测量实验的低能离子探测器。该探测器由Al_2O_3转换板、加速电极、单通道电子倍增器三部分组成。离子沿70°方向轰击转换板,产生数目与离子能量成正比的二次电子,电子由单通道倍增器测量。采用合适的电子学线路和甄别阈,可以有效地把离子计数与本底分开。对10keV Ar~+在入射束流小于10~4s~(-1)时,探测效率接近100％。本探测器可用于低能重离子的计数测量。     

新型半导体探测器发展和应用

新型半导体探测器如硅微条、Pixel、CCD、硅漂移室等,近些年发展很快,在高能物理和天体物理实验中作为顶点及径迹探测器应用很广。主要是它们的位置分辨率非常高,像硅微条探测器．目前可做到好于1．4μm,这是任何气体探测器和闪烁探测器很难做到的。主要介绍这些新型半导体探测器的结构、原理、及其发展在高能物理、天体物理、核医学等领域应用。     

一种新型半导体探测器的应用

介绍了一种测量X射线的Si-PIN电制冷半导体探测器,以及它在X射线谱分析中的应用。由于该探测器采用了电制冷方法,从而摆脱了传统的Si(Li)探测器在使用和保存时必须定期向其添加液氮的麻烦。     

固体气泡损伤探测器阈起源的实验判别

用500MeV/u^56Fe,650MeV/u^40Ar,600MeV/u^28Si和180MeV/u^4He对固体气泡损伤探测器（T－12型）进行了实验研究，实验结果表明，固体气泡损伤探测器的阈特性可用临界能量损失率表征，在一般条件下，限定能量损失率在不同重离子产生径迹时不具有相同的临界值，因此，不能作为径迹形成的判据。     

Development of an high resolution neutron spectroscopy system using a diamond detector and a remote digital acquisition methodology

The need of performing high resolution fast neutron spectroscopy in a very harsh environment like that of the Radial Neutron Camera (RNC) of ITER, requires to develop new detectors and methodologies. Diamond detectors have been proved to be excellent candidates but the electronics needs a substantial improvement. Because of the high radiation level and the temperatures expected near the detector positions in the RNC, the electronics must be placed several meters away. A novel Fast Charge Amplifier (FCA) was developed that, connected to a diamond detector using several tens of meters of low capacitance coaxial cable, is able to produce fast output signals suitable to be processed by digital electronics. These fast output signals allow to operate at high count rates avoiding pile-up problems. This novel amplifier connected to a digitizer is here tested in the neutron energy range from 5 to 20.5 MeV using the mono-energetic neutrons produced by the Van de Graaff (VdG) accelerator of the EC-JRC-IRMM and by the PTB cyclotron. From the measurements the experimental response functions of the diamond detector at different neutron energies were obtained. The shape of the response functions have been compared with that predicted with a routine which was implemented for the Monte Carlo code MCNPX with the scope to validate the calculations versus the experimental data. The goal is to develop a tool which allows to calculate the diamond detector response functions also in term of absolute efficiency. This methodology along with the ability to measure at high reaction rates and the insensitivity to radiation damage launches the system described in this paper as a promising method for neutron spectrometry in the RNC of ITER.     

西安脉冲堆~3He快中子夹心谱仪的方案设计

本文介绍了3He快中子夹心谱仪的气体填充、探测器、三通道数字符合和数据分析处理系统,描述了探测器系统的理论分析及实验标定方法,提出了谱仪符合本底计数的来源,绐出了扣除几种符合本底的理论和实验方法,研究结果表明本工作可指导3He快中子夹心谱仪的深入研究.     

新型高灵敏度XRF分析仪的研制与应用

新型高灵敏度便携式X射线荧光(XRF)分析仪基于电致冷Si-PIN半导体X射线探测器和微机多道(2048道)谱仪系统,整机重3.8kg(探头重0.6kg),对铜、锌、砷等元素的分析检出限为10μg·g-1,适用于野外现场的天然岩石、土壤和水系沉积物的多元素含量的定量测定,以及工业原料、半成品、产品快速分析。     

用放射性示踪技术和中子活化法研究一种新型钙剂在兔子体内的分布和吸收

用４７Ｃａ放射性示踪剂和中子活化分析技术研究了一种由等离子体法制备的新型钙剂在兔子体内的药代动力学、分布、吸收及生物利用度。实验结果表明，这种新型营养品中的钙在口服６至７天后主要沉积在骨骼中，其吸收率约为３０％—４０％。     

CTOF measurements and Monte Carlo analyses of neutron spectra for the backward direction from a lead target irradiated with 200-1000 MeV protons

A calorimetric-time-of-flight technique was used for real-time, high-precision measurement of neutron spectra at an angle of 175^o from the initial proton beam direction, which hits a face plane of a cylindrical lead target of 20 cm in diameter and 25 cm thick. A comparison was performed between the neutron spectra predicted by the MARS, RTS&T, MCNP6, and the MCNPX 2.6.0 transport codes and that measured for 200, 400, 600, 800, and 1000 MeV protons. Neutron spectra were measured within the energy range from 0.7 to 250 MeV almost continuously. The transport codes tested here describe with different success the measured spectra, depending on the energy of the detected neutrons and on the incident proton energy, but all the models agree reasonably well with our data.     

核动力堆安全壳内外中子能谱和剂量测量

利用自制的多球谱仪测量了某核动力反应堆安全壳内外的中子能谱和剂量当量率。对安全壳外测量，中心探测器为球形^3He正比计数管；对安全壳内测量，中心探测器为球形金箔。系统的响应函数用MCNP程序计算，解谱程序为MIEKEB。为验证系统响应函数计算的准确性，进行了一些实验测量，并与理论计算结果进行了比较。结果表明，测量结果与计算结果在不确定度范围内相吻合。     

Transformation of a system consisting of plane isotropic source and unit sphere detector into a system consisting of point isotropic source and plane detector in Monte Carlo radiation transport calculation

In a nuclear power plant accident, radioactive nuclides may be released which are distributed uniformly on the ground. If estimation of dose rate from such a source by a Monte Carlo calculation is attempted, some difficulty is encountered because the calculation efficiency is very low. To solve this low efficiency problem, we show that a plane isotropic source can be transformed into a point isotropic source by changing the detector shape from a unit sphere to a plane. We verified the validity of this transformation by the numerical comparison of unscattered photon fluence. As an example of this transformation, the ambient dose rate D _i was calculated from the uniform radioactive nuclide distribution on the ground using the EGS5 Monte Carlo code. We also measured the radioactivity and ambient dose rate (M) on the KEK campus within a month after the releases from the Fukushima No. 1 Nuclear Power Plant accident. Using radioactivity data and D _i, we calculated the ambient dose rate (C). The calculated and measured ambient dose rates agreed reasonably well; their ratio (C/M) was 0.62 to 1.28.     

Initial dissolution rate of a Japanese simulated high-level waste glass P0798 as a function of pH and temperature measured by using micro-channel flow-through test method

Aqueous dissolution tests were performed for a Japanese type of simulated high-level waste (HLW) glass P0798 by using a newly developed test method of micro-channel flow-through (MCFT) method, and the initial dissolution rate of glass matrix, r ₀, was measured as a function of solution pH (3–11) and temperature (25–90°C) precisely and consistently for systematic evaluation of the dissolution kinetics. The MCFT method using a micro-channel reactor with a coupon shaped glass specimen has the following features to provide precise and consistent data on the glass dissolution rate: (1) any controlled constant solution condition can be provided over the test duration; (2) the glass surface area actually reacting with solution can be determined accurately; and (3) direct and totally quantitative analyses of the reacted glass surface can be performed for confirming consistency of the test results. The present test results indicated that the r ₀ shows a “V-shaped” pH dependence with a minimum at around pH 6 at 25°C, but it changes to a “U-shaped” one with a flat bottom at neutral pH at elevated temperatures of up to 90°C. The present results also indicated that the r ₀ increases with temperature according to an Arrhenius law at any pH, and the apparent activation energy evaluated from Arrhenius relation increases with pH from 54 kJ/mol at pH 3 to 76 kJ/mol at pH 10, which suggests that the dissolution mechanism changes depending on pH.     

An integral effect test of a complete loss of reactor coolant system flow rate for the SMART design using the VISTA-ITL facility and its simulation with the MARS-KS code

An integral effect test was successfully performed to provide data to assess the capability of the system analysis code to simulate a complete loss of reactor coolant system (RCS) flow rate (CLOF) scenario for the SMART (System-integrated Modular Advanced ReacTor) design. The steady-state conditions were achieved to satisfy initial test conditions presented in the test requirement, its boundary conditions were accurately simulated, and the CLOF scenario in the SMART design was reproduced properly using the VISTA-ITL facility. The natural circulation flow rate in the RCS was about 12.0% of the rated RCS flow rate and the flow rate in the passive residual heat removal system (PRHRS) loop was about 10.6% of its rated value in the early stage of the PRHRS operation. In this paper, the major experimental results of the CLOF test are discussed. The test results were analyzed using the best-estimate system analysis code, MARS-KS, to assess its capability to simulate a CLOF scenario for the SMART design.