掺锗石英光纤的稳态和瞬态γ辐射效应研究

开展了掺锗石英光纤在1.0×10~(-4)~0.5Gy(Si)/s剂量率下的稳态γ辐照实验和10~6~10~9 Gy(Si)/s剂量率下的瞬态γ辐照实验。结果表明:光纤辐射感生损耗与辐照总剂量呈饱和指数关系,与色心浓度微分方程推导出的结论相一致。在辐照总剂量相同的情况下,光纤辐射感生损耗随辐照剂量率的增大而增大。辐照期间有光注入较无光注入时的光纤辐射感生损耗低,证实了光褪色效应的存在。对实验用650、850和1 310nm 3个波长,光纤辐射感生损耗随波长的增大而减小。与光纤稳态辐射感生损耗相比,光纤瞬态辐射感生损耗要大得多;光纤瞬态辐射感生损耗峰值与脉冲总剂量呈线性关系,这与饱和指数关系在低剂量下的泰勒展开近似一致。     

职业受照人群死亡率、发病率及健康状况调查

为了解职业受照人群的健康状况,实现放射工作人员健康状况的宏观管理,对我国部分放射性作业人员的健康状况进行了全面调查和分析。职业受照人群死亡率调查,采用历史前瞻性队列研究方法;死因追踪调查,采用粗死亡率、标化死亡比;慢性病发病率调查指标为粗发病率、标化发病率;健康状况调查的指标主要包括眼晶体混浊,细胞遗传学指标微核率、染色体畸变率,肝脏损伤指标,免疫球蛋白,肾功能检测等。调查结果表明,职业受照人群死亡率低于全国或当地水平;慢性病发病率低于或与全国慢性病发病水平接近;个别职工染色体畸变率和微核率超出实验室正常值。初步认为,在目前的防护条件下的放射性作业是比较安全的。     

Investigation of the Surface Ionization Effect on Planar Silicon Bipolar Transistors and the Improvement of the Resistance to Radiation by an Irradiation-Annealing Treatment

By irradiation of the surface structure of silicon planar transistors with a narrow electron beam adjusted parallel to the pn-junctions of the devices it was possible to show in a very direct manner that the increase in base current occurs only if the beam is directed to the immediate vicinity of the emitter-base pn-junction. Subjecting the collector-base pn-junction and the remainder of the transistor surface to radiation has no effect on the current gain. A comparison of the radiation damage to bipolar silicon planar transistors in metal packages and plastic envelopes shows that the packaging method has a strong influence on the degradation in current gain if the pn-junctions are reverse-biased during the irradiation. The resistance of bipolar planar transistors to ionizing radiation can be improved considerably if the device is subjected to a high dose of ionizing radiation under conditions at which the damage anneals out immediately. The cause for this phenomenon mainly is a decrease of the concentration of interface states effected by this treatment. Reductions of the increase in base/collector current ratio of one order of magnitude have been obtained.     

释光断代技术研究

本文对释光断代中遇到的问题提出了一些看法,供同行们进一步研究和讨论.     

Effects of Pulsed Ionizing Radiation on Some Selected Quartz Oscillator Crystals

The effects of high-energy ionizing radiation on the behavior and output frequency of electronic oscillators, whose frequency-determining elements were quartz crystals operating in the vicinity of 5 Mc, have been studied. Both fundamental- and fifth-overtone crystals were studied over a dose range from 3,000 rads (Si) to 2 Mrads (Si). The crystals studied were of two types: (1) standard commercial precision crystals fabricated from natural quartz with Q's of approximately 2.5 × 106 for the fifth overtone and 4 × 105 for the fundamental, and (2) special fifth-overtone crystals fabricated from swept pure Z-growth synthetic quartz. The natural quartz showed much larger changes in frequency and transient loss of Q than the swept synthetic crystals. The crystals were incorporated into commercial precision oscillator circuits and maintained in a temperature-controlled oven. The radiation doses (both 25-MeV electrons and 10-MeV peak bremsstrahlung gamma rays) were provided by the General Atomic electron linear accelerator. The radiation was collimated to irradiate only the crystal. The oscillator output signal was monitored with an oscilloscope during and after the radiation burst, and the frequency was measured by cycle counting for 10-or 100-sec time intervals. The precision of the frequency measurements was ±2 parts in 108 for the 10-sec intervals and ±2 parts in 109 for the 100-sec intervals. Electrons and gamma rays were shown to have the same effect on the crystals; therefore, most of the work was done with electrons because of the convenience of accumulating large doses in 4.5-psec pulses.     

辐射防护玻璃照射量累积因子的计算及分析

为研究γ放射源操作热室观察窗辐射防护玻璃的累积因子,开展高活度γ放射源热室观察窗的设计,本研究根据五种常用辐射防护玻璃的成分以及ANSI/ANS-6.4.3的数据,得到五种常用辐射防护玻璃的照射量累积因子G-P插值法参数,并利用这些参数计算五种辐射防护玻璃在60 Co、75 Se、137 Cs、192 Ir核素γ射线照...     

Effect of Irradiation on Crystal Defects in Quartz

X-and ?-irradiation characteristics of optically non-clear natural quartz and electronic grade synthetic crystals have been investigated. In particular, it has been shown how, due to relatively large concentration of crystal imperfections in non-clear natural quartz, a positive frequency shift of crystal resonator on extended irradiation, increased smoky coloration, broad and sharp ESR signals observable at room temperature and increased intensity of thermoluminescence are produced compared to the corresponding characteristics of optically clear quartz crystals. It has been shown, how by increasing the imperfections in non-clear natural quartz still further by neutron irradiation, the frequency characteristics of natural quartz crystals would simulate those of the electronic grade synthetic crystals, and viceversa, by thermal annealing of the latter. Based on the appropriate thermal annealing of electronic grade synthetic crystals, the investigations yield a new way of achieving the much desired radiation hardening of quartz resonators used in satellite-borne frequency standards for space communication.     

营养干预在急性放射损伤病人救治中的应用

营养干预能有效改善患者营养状态及预后,减轻放射损伤。本文主要介绍营养干预在急性放射损伤病人救治中的治疗原则,营养干预的种类及应用。     

射频辐射对健康影响的流行病学调查

从人体心血管系统、生殖系统、免疫系统以及主观症状、激素产生、听觉和前庭系统方面,介绍了射频电磁辐射对健康影响的流行病学调查现状,并对今后的研究工作提出建议。     

Effect of Condition of Recrystallization Heat Treatment on High-Temperature Mechanical Properties of an Irradiated AISI 316 Austenitic Steel

A study was made of the effects brought upon the radiation-induced high-temperature embrittlement of AISI 316 austenitic steel by different conditions to the specimens to produce recrystallization.

Cold worked specimens were recrystallized at temperatures 950°–1,100°C held for periods ranging 2~60 min. The specimens were then irradiated to 1.7×10²¹nvt(< MeV) at 55°C after which they were subjected to tensile testing at 650°C.

In the specimens recrystallized at 950°C, carbide precipitation was observed to have occurred, and these specimens were found less liable to show radiation-induced embrittlement. On the other hand, specimens recrystallized at 1,025° and 1,100°C became completely solution treated, and exhibited severe radiation-induced embrittlement. It is surmisted that the carbides precipitated on the grain-boundaries tend to inhibit propagation of grain-boundary cracks, and hence contribute to lessing radiation-induced embrittlement.     

Permanent Radiation Effects in Swept and Unswept Optical Grade Synthetic Quartz at Resonators

Permanent changes in the frequency versus temperature characteristics of unswept and swept optical grade synthetic quartz AT resonators which are caused by fast neutron and Co60 irradiations have been investigated. Neutron damage shifts the frequency versus temperature characteristics of the unswept resonators upwards in frequency across the entire zero to + 120°C temperature range at a rate of 0.56 × 10-15 ppm per N/cm2, which is the smallest value yet reported in the literature. The observed erratic results for swept resonators were attributed to effects of ionizing radiation accompanying the neutron fluence and led to the Co60> investigation. The unswept optical grade quartz was found to provide AT resonators which are more resistant to ionizing radiation than any other unswept material yet investigated in the literature. Appreciable amounts of acoustically active defects attributed to Na inpurities which were apparently gaded during sweeping were indicated by the Co results for the swept devices and made the swept devices useless as radiation resistant resonators.     

Investigation of 85Kr Emission and Its Effect on the Radiation Conditions during the Preparation of BOR-60 Fuel for Recovery

The main stages of the BOR-60 closed fuel cycle, implemented on the experimental base at the Scientific-Research Institute of Nuclear Reactors, are examined. The ⁸⁵Kr emission at the stages of preparation of the spent BOR-60 fuel assemblies for recovery is determined experimentally. It is shown that the maximum ⁸⁵Kr emission as a result of destruction of fuel element cladding with oxide uranium fuel is 68%; its contribution to the irradiation dose to the public as a result of mechanical disassembly of the fuel elements in a single BOR-60 fuel assembly with 10% burnup and a 10-yr holding time does not exceed 1·10^–4% of the dose limit (1 mSv/yr).     

High-Temperature Thermodynamic Investigation of Nano-Dispersed Nitrides Obtained in Thermal Plasma

The nitrides of transient metals have a high hardness, thermal stability, remarkable wear resistance in aggressive chemical mediums, melted metals and alloys, high corrosion resistance, and low coefficient of electric resistance. Under the conditions of low-temperature argon plasma （LTP）, thermodynamic investigations were conducted in the process of obtaining of A1N, TiN and Si3N4 in a temperature range of 1000 K to 6000 K. To investigate the thermodynamic possibility of obtaining nitrides, a computer model was used which provided the equilibrium composition of gaseous and solid phases at different temperatures. The conditions for chemical equilibrium of the system were based on the minimization of Gibbs＇ energy.     

Development and Investigation of a Dipole Magnet with a High-Temperature Superconductor Winding

The structure of a dipole magnet with an iron yoke, where the winding is made of a Bi-2223 high-temperature superconductor, has been developed and the magnet has been built at the Institute of High-Energy Physics. The magnet has also been tested. A magnetic field 0.9 T has been attained in the aperture at temperature 65 K and 1.9 T at 4.2 K. The special features of the magnet structure are described and the results of testing of the magnet in a submerged cryostat at different temperatures are presented.     

自显色个人剂量计研究

采用聚合变色体系,以类丁二炔单体PCDA为变色染料,制备了一种用于辐照剂量预警的自显色个人剂量计。对基体材料、稀释剂种类、变色染料、溶解温度、成膜厚度以及膜制备工艺进行了研究,建立了自显色个人剂量计制备方法。剂量计接受0.1～2.5 Gy辐照后,颜色从白色变为蓝色,在681.5 nm处测得剂量响应曲线线性相关系数为0.999 8,照后两周内稳定性良好,可作为预警式个人剂量计使用。     

聚醚聚氨酯泡沫塑料的辐射老化研究

研究了经电子束作用后聚醚聚氨酯(ETPU)泡沫塑料的辐射老化规律。采用气相色谱(GC)、热分析(TG)、扫描电镜(SEM)和透射电镜(TEM)技术，研究了材料经辐照后其辐解气体产物的种类和生成量以及材料的热性能、微观相分离和表观形貌的变化。     

Development of Free-Electron x-Ray Lasers on the TESLA Test Accelerator (DESY, Germany)

The program for developing free-electron x-ray lasers at TESLA started in 1994. The plan is to use the TESLA test accelerator to develop an x-ray laser with minimum wavelength 0.1–6 nm. The first phase of the project was successfully completed in 2001. At saturation, the laser produces ultrashort 30–100 fsec, gigawatt, radiation pulses. The wavelength can be tuned smoothly over the range 80–120 nm.