Design Concepts of a Transient Signal Recorder for Operation in Pulsed Ionizing Radiation

The feasibility of a recorder for measuring transient radiation effects, and which is radiation hardened so that it minimizes ionizing effects on the instrumentation itself, has been investigated by designing, fabricating, and testing a 10 channel analog sampling recorder which samples an input signal of ± 6 mA at 100 MHz sampling rate for 100 ns period. The instantaneous sample values are stored as magnetic flux in successive thin magnetic films of a channel. Upon non-destructive readout of the thin films, a time amplitude reconstruction of the input signal is made to within ± 15% of full scale. The system shows radiation hardness in excess of 1010 r/sec, except for the interface amplifier which is hard to 5 × 109 r/sec.     

Development of Fiber Optic Radiation Monitor using Plastic Scintillation Fibers

We have developed a radiation monitor by using plastic scintillation fibers (PSF), which we call the fiber optic radiation monitor. For wide-area radiation monitoring, the detection part needs to be longer, therefore we have produced a prototype monitor by combining the PSF and the silica fiber for optical propagation.

In this paper we first explain the characteristics when silica fiber of 100 m long is connected to the PSF. We found that in this case, the position resolution would drop. In order to determine the cause, we observed the aspects of optical pulse propagation. It was found that the light is transmitted through the silica fiber and is detected at fiber end as single photons, and the resolution deteriorated due to the difference in the propagation path of each of photons.

We next explain the prototype fiber optic radiation monitor with a detection length of 20 m and a total length of 60 m, and its performance.     

Effects of Simulated Nuclear Thermal Pulses on Fiber Optic Cables

The effects of pulsed thermal radiation on fiber optic cables with a variety of jackets (polyurethane, PVC, fluorocarbon) are presented. Exposure between 27 and 85 cal/cm2 did not sever the optical fibers, but the radiation did cause disintegration of the jackets and the Kevlar strength members, which resulted in a significant reduction of the cable's ability to survive mechanical stress. Hardening techniques are discussed. The addition of low absorptance materials (white Teflon tape and aluminum foil) under clear or white Teflon jackets prevented some types of cables from being affected at fluences up to 110 cal/cm2.     

Ionizing Radiation Effects in SOS Structures

The total ionizing radiation effects of n-channel enhancement mode silicon on sapphire MISFET's have been characterized up to a total dose of 107 rads (Si). The drain current versus drain voltage characteristics of the n-channel devices showing the "kink" effect were measured over a range of gate voltages and as a function of ionizing radiation. The effect of the ionizing radiation on the "kink" phenomenon was determined and the implications of this effect on the radiation hardness of n-channel MISFET's is discussed. The results show that the equivalent threshold voltage at the operating drain voltage must be defined and used in determining the radiation hardness of the n-channel device. The radiation induced back channel leakage currents of n-channel MISFET's are characterized in terms of device geometry and the amount of radiation induced trapped charge in the sapphire substrate. Results showing the leakage current plotted as a function of drain voltage suggest that the "kink" effect and related phenomena also enhance the radiation induced leakage current effects and lead to substantially increased values of leakage current.     

Radiation Response of Fiber Optic Waveguides in the 0.4 to 1.7? Region

The response of fiber optic waveguides to ionizing radiation has been studied. Measurements of the growth and decay of the radiation-induced loss at 0.82? have revealed that fibers with low OH are more susceptible to damage than those with high OH. The addition of P to Ge-doped silica core fibers has been found to suppress an intense transient absorption. Spectral measurements of the radiation-induced absorption between 0.4 - 1.7? have shown an increase in the OH overtone and combination band intensity with irradiation so that the induced loss at 1.3? is actually less in the low OH content silica core fibers than in the high OH content fibers. Real time spectral measurements of the damage following a pulsed irradiation have lead to an identification of the absorption bands and damage mechanisms responsible for the radiation-induced absorption.     

分布式感温光纤探测系统在AP1000核电厂中的应用

AP1000核电厂首次将分布式感温光纤探测系统应用于1E级与非1E级电缆桥架火灾探测。文章介绍了分布式感温光纤探测系统技术原理,分析了感温光纤探测系统的结构及其特点,并根据核电厂的特殊环境,研究了对感温光纤的影响以及提出了相关建议,最后介绍了AP1000分布式感温光纤探测系统设计、光纤布置方案。     

表面n沟CCD的电离辐射损伤

本文报道了150光敏元表面n沟CCD(电荷耦合器件)在不同能量电子和γ射线辐照后的电离辐射效应。试验结果表明,转移失效率在≤10Gy时已明显增大。但大多数器件在累积剂量≤50Gy时,通过调整“胖零”注入仍可工作。在高剂量辐照期间,不同栅偏压器件的转移效率退化存在较大差异。应用高频和准静态C-V技术分析了参数退化的原因。     

医用电离辐射中的防护与安全

IRPA-1 0大会就医用电离辐射中的防护与安全领域提供了 4次特别讲座、2次专题会议和 70余篇壁报展示。本文对这个领域的论文进行评论 ,共由两部分组成 :第 1部分叙述特别讲座中 4个报告的内容 ;第 2部分叙述专题会议和壁报的内容 ,其中又分为 3个方面 ,即放射诊断学 (包括介入放射学 )、核医学和放射治疗。     

Origin of Interface States and Oxide Charges Generated by Ionizing Radiation

The randomly located trivalent silicon atoms are shown to account for the thermally generated interface states at the SiO2-Si interface. The interface state density is greatly reduced in water containing ambients at low temperatures (450°C) by forming trivalent silicon hydroxide bonds. Interface states are regenerated when the ?Si-OH bonds are broken by ionizing radiation and the OH ions are drifted away. In the bulk of the oxide film, the trivalent silicon and the interstitial oxygen donor centers are shown to be responsible for the heat and radiation generated positive space charge build-up (oxide charge) in thermally grown silicon oxide.     

Ionizing Radiation Effects in Inversion Layer Silicon Solar Cells

Ionizing irradiation experiments on a new inversion layer solar cell have been carried out to determine its potential for space applications. A scanning electron microscope was used as a source of low energy (2-12 keV) electrons in doses up to 1014 e/cm2. Phototopographic scanning and C-V analysis were used to determine the effects of the radiation on the Si02-Si system. The electron irradiation results are validated by comparison with those of a conventional X-ray experiment. The operation, fabrication and electrical characteristics of the cell are also discussed. Large increases in both the oxide charge and surface state density were observed, but little change occurred in the cells' output characteristics below 105 rads (Si). A drop-off in power at higher doses is explained in terms of surface recombination and series resistance increases. The results of isochronal and UV annealing experiments on these effects are also presented. The cells are concluded to have potential for use in space.     

热休克蛋白对电离辐射损伤的保护效应

近年来,热休克蛋白（HSPs）对电离辐射损伤的保护效应成为一个关注的热点。本文综述了热休克蛋白家族及其对电离辐射损伤的保护效应,包括HSPs对细胞凋亡的抑制作用和DNA损伤的保护作用两方面,对热休克蛋白与电离辐射损伤的关系进行了探讨。     

An Analysis of Ionizing Radiation Effects in Four-Layer Semiconductor Devices

The switching of a four-layer semiconductor device in an ionizing radiation environment is calculated by solving the charge transport equations to determine the motion of the electron and hole distributions and the changes in the electric field distribution throughout a one-dimensional device as a function of time. A discussion of the characteristic device turn-on as a function of the ionizing radiation exposure and external circuit and device parameters is presented. In addition to showing the detailed calculated device behavior, the theoretical and experimental results are compared.     

SEM Analysis of Ionizing Radiation Effects in Linear Integrated Circuits

A successful diagnostic technique was developed using a scanning electron microscope (SEM) as a precision tool to determine ionization effects in integrated circuits. Previous SEM methods radiated the entire semiconductor chip or major areas. The large area exposure methods do not reveal the exact components which are sensitive to radiation. To locate these sensitive components a new method was developed, which consisted in successively irradiating selected components on the device chip with equal doses of electrons [(10 rad (Si)], while the whole device was subjected to representative bias conditions. A suitable device parameter was measured in situ after each successive irradiation with the beam off.     

Generalized Model Analysis of Ionizing Radiation Effects in Semiconductor Devices

The necessity of analyzing complex semiconductor device behavior in the radiation environment requires improved analytical methods for accurate representation. The purpose of this discussion is to present work done on the applicability of the Linvill lumped model in a generalized model analysis. The advantages of the lumped model technique include flexibility in detail of device representation (i.e., accuracy), an intimate coupling to the well known radiation effects in bulk semiconductor material, and a unified analytical technique for a wide range of devices. It is shown that the lumped model analysis provides an effective technique for analyzing simple as well as complex devices in a pulsed ionizing radiation environment. Included is the representation of a simple p-n junction diode, a grown-junction transistor; and a planar-diffused transistor with its monolithic-chip substrate and isolation junction. The lumped-model behavior of the diode and grown junction transistor is compared to previously available analytical results. Using measured parameter values, the quantitative lumped-model predictions are compared to experimentally observed transient radiation response. The transistor response is investigated as a function of quiescent emitter current and external base resistance. The effect of the substrate junction in the monolithic-chip transistor is qualitatively presented as a function of the transistor parameters and the substrate proximity.     

细胞遗传学技术在辐射生物剂量估算中的应用

细胞遗传学技术作为生物剂量测定方法,已在生物剂量估算特别是急性照射剂量估算方面得到广泛应用和验证。本文重点综述染色体畸变、微核、早熟染色体凝集作为生物剂量测定方法在剂量估算应用中的优缺点,扼要介绍近年来发展起来的一些分子生物学指标用作生物计量估算的进展。     

各相关领域实用的六类电离辐射量

为适应核科学和电离辐射技术的日益广泛应用,电离辐射量体系一直在不断演进。本文根据各种电离辐射量的实际应用场合和主要特性,归纳整合为六大类各相关领域实用的电离辐射量(包括有关衍生量)加以评述,旨在从方便实用出发,有助于各相关领域人员更好理解和正确应用有关的电离辐射量及单位。     

对医用电离辐射职业人员防护知识学习与培训的思考

医用电离辐射是最大的人工辐射应用领域。XCT、OSA、SPECT、PET、电子直线加速器等高新医用电离辐射设备的广泛应用和二手设备的转手使用,带来了医用电离辐射职业人员面临新的辐射防护问题;国家相关法规标准的修订颁布,进一步提高了对辐射防护的重视程度。本文就解决方法进行了探讨,提出有关设想,期望通过医学教育、在职培训及远程网络教学等方式,使医用电离辐射职业人员增加辐射防护知识,提高防护意识,以达到降低辐射危害的目的。     

Generation of Oxide Charge and Interface States by Ionizing Radiation and by Tunnel Injection Experiments

Results of irradiation and high field tunnel injection experiments on MOS capacitors are discussed. The midgap voltage shift as a function of dose is caused by hole trapping only. In the case of tunnel injection, the generation of electron-hole pairs by impact ionization requires a much larger electron density and high fields. Thus a model of charge build-up is established which takes into account the hole trapping in neutral oxide states, the subsequent electron trapping in now positively charged states and detrapping of captured electrons. By means of this model, the prediction of the radiation hardness of MOS devices is feasible, provided that the impact ionization coefficient a is known accurately. If this is not the case, the combined techniques of ionizing irradiation and tunnel injection can be utilized to determine ? = ?o exp(-H?/F) as a function of the electrical field F. Electron capture and detrapping crosssections ?n and ?n, resp., can be deduced by fitting the model to the experimental results. An F-3 dependency for ?n and an exp(-H?/F) dependency for ?n are found. Only a weak dependence on different processing parameters is observed. The proposed model is verified by a sequence of irradiation and injection steps. The generation of oxide charge is accompanied by an increase in interface state density Dit with a distribution, which peaks at about 0.15 eV above midgap, in both experiments. The results indicate that the generation of interface states is proportional to the amount of trapped holes.     

Study of Ionizing Radiation Damage in MOS Structures Using Internal Photoemission

The effects of ionizing radiation in large-geometry MOS structures were studied by use of internal photoemission techniques. Barrier heights at both the silicon-silicon dioxide and the silicon dioxide-metal (chromium and aluminum) interfaces were measured before and after irradiation in a Co60 gamma cell. It was determined that the measured barrier energy heights may be considerably reduced by radiation-induced oxide charge. The internal photoemission technique also provided significant information concerning the effects of impurities in the oxide and the related radiation hardness of the oxide layer. Oxide layers doped with chromium ions showed significant electron trapping at two discrete energy levels (3.4 and 3.8 eV). Samples exhibiting the 3.4 eV level showed great radiation hardness, while those with only the 3.8 eV peak were very radiation soft. The information obtained, using the internal photoemission technique, has provided considerable insight into the mechanisms and fabrication processes associated with radiation-hardened MOS devices.     

双极型运算放大器瞬时电离辐射效应实验研究

建立了运算放大器瞬时电离辐射效应在线测试系统,选取不同带宽、不同压摆率的3种双极型运算放大器,在西北核技术研究所的“强光一号”加速器上进行了实验。结果显示,在相同剂量率下,双极运算放大器的带宽越大、压摆率越高,其输出端口瞬时电离辐射恢复时间越短。分析表明,对于具有内补偿电容的双极运算放大器,其压摆率与补偿电容有关;补偿电容越小,压摆率越大,运算放大器输出端口瞬时电离辐射扰动的恢复时间越短。