Radiostability of Allantoin by Using Electron Spin Resonance Spectroscopy

The radiosterilization potential and dosimetric feature of allantoin were investigated through the molecular degradations produced after ultraviolet and gamma irradiation using electron spin resonance, infrared, and ultraviolet spectroscopies and thermal measurement techniques (differential thermal analysis and the glass transition temperature). Although ultraviolet-irradiated allantoin presents no electron spin resonance signal, gamma irradiation exhibited an electron spin resonance signal of triplet appearance. Room temperature and high-temperature line intensity and spectrum area data and their variations with applied microwave power, storage time, annealing time, annealing temperature, and applied radiation dose were analyzed by assuming the production of two different types of radicals having different spectroscopic and decay characteristics. Based on its relatively stable nature toward gamma and ultraviolet radiations, it was concluded that allantoin itself and the products containing it can be sterilized by gamma and/or ultraviolet radiations without creating a great loss in its beneficial effects in the allowed radiosterilization dose limits.     

TL and PTTL in natural fluorite previously irradiated with gamma rays and heavy ions

The effect of annealing temperature on the phototransfer thermoluminescence (PTTL) signal was studied to determine the appropriate annealing temperature for treating the natural powder before irradiation. The temperatures used to anneal virgin natural fluorite samples (only natural dose without giving the samples any artificial doses) were 150, 250, 350, 450, 550, 650 and 750°C for a duration of 1 h in each case. The results show that the PTTL response did not change for anneal temperatures up to 450°C, but at higher temperatures the signal decreased rapidly. The height of the 90°C peak decreased by two orders of magnitude as the anneal temperature increased from 450 to 750°C, whilst the height of the 180°C peak decreased by three orders of magnitude between the same two annealing temperatures. In order to investigate the effect of previous gamma rays and heavy ion irradiation on thermoluminescence (TL) and PTTL signals, powdered samples of natural fluorite from Cornwall, England, were annealed at 500°C and then irradiated (at GSI, Darmstadt, Germany) with ¹⁶¹Dy ions of energy 13 Mev/n; the range of fluences used was from 10⁴ to 10¹² ion cm⁻². Identical samples were given gamma doses in the range 1 Gy to 2.6 × 10⁴ Gy in order to compare the effects of gamma rays and heavy ions. The sensitivities of TL and PTTL were studied by giving the samples a gamma test dose of 1 Gy after annealing the samples at 500°C for 30 min in order to eliminate the TL resulting from previous gamma or heavy ion irradiation.     

Influence of gamma irradiation on surface potential decay of corona charged polyethylene

In the present paper the surface potential decay after dc corona charging of gamma-irradiated low-density polyethylene (LDPE) has been studied. The irradiation was carried out in air, nitrogen gas and vacuum to investigate the effect of irradiation environment on the surface potential of LDPE. Samples with different absorbed doses were obtained by exposing samples to ⁶⁰Co for various times at room temperature. It has been found that there is a significant change in the surface potential decay characteristics after different irradiation dose and the surface potential decay pattern depends also on irradiation environment. The possible surface potential decay mechanisms responsible for the above were discussed. The results are useful in the context of long-term performance of electrets.     

典型模拟电路低剂量率辐照损伤增强效应的研究与评估

采用变剂量率和变温两种辐照方法,对4款典型模拟电路的低剂量率辐照损伤特性及变化规律进行了研究与评估,分析了两种辐照方法下其辐照敏感参数的变化,比较了不同辐照方式下器件的退化程度,讨论了这两种实验室加速评估低剂量率辐照损伤方法的机理.结果显示,变剂量率辐照可以较快地预测实际低剂量率下的辐照损伤趋势,且在较低的总剂量下能够给出不太保守的估计,但其预测的总剂量受到器件退化速度的影响;变温辐照加速评估方法能够保守地估计其低剂量率下的辐照损伤,其评估范围不仅可达1000 Gy(Si),且可将评估时间缩短为12 h左右.研究结果表明,双极电路的低剂量率辐照损伤增强效应与感生的界面态密度和氢化的氧空位缺陷有关,辐照时剂量率和温度的改变会促进界面态的生长,抑制界面态的钝化作用,从而激发器件的辐照损伤潜能.     

CMOS有源像素图像传感器的电子辐照损伤效应研究

对某国产CMOS图像传感器进行了两种不同能量的电子辐照试验,在辐照前后及退火过程中采用离线测量方法,考察了暗信号、饱和电压、光谱响应特性等参数,分析了器件的电子辐照效应损伤机理。结果表明:暗信号和暗信号非均匀性都随着辐照剂量的增加及高温退火时间的延长而增大;饱和电压在两种能量电子辐照下均出现较大幅度的减小,并在高温退火过程中有所恢复;光谱响应特性无特别明显变化。经分析,暗电流、饱和电压的变化主要由辐照诱发的氧化物陷阱电荷导致的光敏二极管耗尽层展宽和界面陷阱电荷密度增大导致产生-复合中心的增加所引起。     

低温退火对HgCdTe中波光导器件γ辐照效应的影响

 研究了低温退火对HgCdTe中波光导探测器γ射线辐照效应的影响。经过剂量为1 Mrad的辐照后，器件的性能下降。对经过辐照的器件进行低温退火，退火温度范围为313～333 K，退火时间在5~16 h之间不等。在相同条件下测量了器件辐照前后及不同退火温度、不同退火时间下的体电阻、响应率、探测率和响应光谱。通过对比辐照前后及不同退火温度下性能参数的变化，分析了退火对器件的γ辐照效应的影响。实验表明：低温退火对辐照引起的性能的下降有一定的恢复作用。     

Synergistic effects of neutron and gamma ray irradiation of commercial CHMOS microcontroller

This paper presents the experimental results of a combined irradiation environment of neutron and gamma rays on 80C196KC20, which is a 16-bit high performance member of the MCS96 microcontroller family. The electrical and functional tests were made in three irradiation environments: neutron, gamma rays, combined irradiation of neutron and gamma rays. The experimental results show that the neutron irradiation can affect the total ionizing dose behaviour. Compared with the single radiation environment, the microcontroller exhibits considerably more severe degradation in neutron and gamma ray synergistic irradiation. This phenomenon may cause a significant hardness assurance problem.     

Total dose radiation response of modified commercial silicon-on-insulator materials with nitrogen implanted buried oxide

Nitrogen ions of various doses are implanted into the buried oxide(BOX) of commercial silicon-on-insulator(SOI) materials,and subsequent annealings are carried out at various temperatures.The total dose radiation responses of the nitrogen-implanted SOI wafers are characterized by the high frequency capacitance-voltage(C-V) technique after irradiation using a Co-60 source.It is found that there exist relatively complex relationships between the radiation hardness of the nitrogen implanted BOX and the nitrogen implantation dose at different irradiation doses.The experimental results also suggest that a lower dose nitrogen implantation and a higher post-implantation annealing temperature are suitable for improving the radiation hardness of SOI wafer.Based on the measured C-V data,secondary ion mass spectrometry(SIMS),and Fourier transform infrared(FTIR) spectroscopy,the total dose responses of the nitrogen-implanted SOI wafers are discussed.     

Total ionizing radiation-induced read bit-errors in toggle magnetoresistive random-access memory devices

The 1-Mb and 4-Mb commercial toggle magnetoresistive random-access memories(MRAMs) with 0.13 μm and 0.18-μm complementary metal–oxide–semiconductor(CMOS) process respectively and different magnetic tunneling junctions(MTJs) are irradiated with a Cobalt-60 gamma source. The electrical functions of devices during the irradiation and the room temperature annealing behavior are measured. Electrical failures are observed until the dose accumulates to 120-krad(Si) in 4-Mb MRAM while the 1-Mb MRAM keeps normal. Thus, the 0.13-μm process circuit exhibits better radiation tolerance than the 0.18-μm process circuit. However, a small quantity of read bit-errors randomly occurs only in 1-Mb MRAM during the irradiation while their electrical function is normal. It indicates that the store states of MTJ may be influenced by gamma radiation, although the electrical transport and magnetic properties are inherently immune to the radiation. We propose that the magnetic Compton scattering in the interaction of gamma ray with magnetic free layer may be the origin of the read bit-errors. Our results are useful for MRAM toward space application.     

Synergistic effects of neutron and gamma ray irradiation of a commercial CHMOS microcontroller

This paper presents the experimental results of a combined irradiation environment of neutron and gamma rays on 80C196KC20,which is a 16-bit high performance member of the MCS96 microcontroller family.The electrical and functional tests were made in three irradiation environments:neutron,gamma rays,combined irradiation of neutron and gamma rays.The experimental results show that the neutron irradiation can affect the total ionizing dose behaviour.Compared with the single radiation environment,the microcontroller exhibits considerably more severe degradation in neutron and gamma ray synergistic irradiation.This phenomenon may cause a significant hardness assurance problem.     

Changes in the electrical properties of pure and doped polymers under the influence of small doses of X-rays

Abstract

A study has been made of the temperature dependence of the d.c. conductivity of pure and borated low density polyethylene LDPE (4% and 8% borax). The above calculations were carried out before and after X-ray irradiation. The irradiation dose was varied from 0 to 1000 rad.

The d.c. electrical conductivity of Polyvinyl chloride (PVC) and perspex was measured as a function of temperature ranging from 20°C to 100°C. These samples were irradiated with X-rays of dose 200 rad. The variation of the d.c. conductivity of the treated samples versus temperature was investigated.

The results reveal that the d.c. conductivity of LDPE is highly affected by radiation and/or dopant. In addition, the sensitivity of the explored polymers to X-ray irradiation is strongly dependent on its chemical nature.     

Microwave annealing of defects in ferroelectric triglycine sulfate

The effect of microwave irradiation of ferroelectric triglycine sulfate (TGS) samples with different degrees of imperfection (determined by the annealing conditions) has been investigated. It is shown that the irradiation effect depends on both the degree of perfection of the samples and the irradiation time (dose). As for gamma irradiation, low doses of microwave radiation lead to partial annealing of defects and, therefore, should improve the parameters of TGS-based devices. High irradiation doses cause degradation of TGS properties, which is highest in perfect crystals.     

Effect of gamma ray irradiation on optical properties of Nd doped phosphate glass

The effect of gamma irradiation in the dose range of 5-500 kGy on the optical absorption and luminescence spectra of Nd doped phosphate glass is reported. The spectral absorption of this glass before and after gamma irradiation was measured in the spectral range 300-900 nm at room temperature using spectrophotometer and synchrotron beamline. Drastic increase in absorption was noted below 600 nm after gamma irradiation, which was dependent on the dose of irradiation. Additional absorption (AA) spectra of irradiated sample shows generation of two absorption bands below 600 nm, which finally became one very broad band peak with increased intensity at irradiation dose of 500 kGy. AA spectra also show the presence of negative peaks at the location of absorption peaks of Nd³⁺. Photoluminescence of Nd doped phosphate glass shows two strong bands which decreases to a very low intensity with a red shift after gamma irradiation. These results indicate that irradiation produces different kinds of defects in the glass material along with conversion of valence state of Nd³⁺ to Nd²⁺. This change was found irreversible at room temperature.     

Effect of gamma irradiation on chromate sorption over magnetite surface

Aqueous chromate sorption on suspended magnetite in the presence of gamma irradiation has been evaluated. Kinetics of chromate removal was evaluated using Lagergren's absorption model. Chromate removal with respect to the accumulated dose followed a Lagergren's pseudo-first-order kinetic model. A comparison of kinetics of chromate removal with respect to total accumulated dose for gamma irradiation experiment vis-à-vis with respect to time of treatment for different isothermal interactions has been undertaken. Rate constants indicate that the chromate removed per minute in isothermal equilibration at 80 °C is comparable to the chromate removed per kilogrey of gamma irradiation received. There is a redox interaction between the chromate and the ferrous of the suspended magnetite which was confirmed by X ray photo electron spectroscopy (XPS) analysis. This process reaches a saturation much before the consumption of entire ferrous ions of magnetite, indicating a passivating nature of the product. The effect of radiation on both chromate solution and dispersed magnetite to alter the redox process could be ascertained. Gaussian–Lorenzian peak fittings to the XPS data have been carried out to evaluate the chemical composition of the deposited chromium and the resultant change in the chemical composition of the iron in the oxide lattice. This indicated that the magnetite equilibrated with chromate under gamma irradiation resulted in a different surface composition as compared with the one obtained in absence of gamma irradiation. XPS data indicated the presence of hydroxyl group and oxide group attached to both iron and chromium moieties in case of irradiation, whereas only oxide group was seen with only temperature treatment.     

Influence of nitrogen implantation into the buried oxide on the radiation hardness of silicon-on-insulator wafers

In order to improve the total-dose radiation hardness of the buried oxide of separation by implanted oxygen silicon-on-insulator wafers, nitrogen ions were implanted into the buried oxide with a dose of 1016 cm-2 , and subsequent annealing was performed at 1100°C. The effect of annealing time on the radiation hardness of the nitrogen implanted wafers has been studied by the high frequency capacitance-voltage technique. The results suggest that the improvement of the radiation hardness of the wafers can be achieved through a shorter time annealing after nitrogen implantation. The nitrogen-implanted sample with the shortest annealing time 0.5 h shows the highest tolerance to total-dose radiation. In particular, for the 1.0 and 1.5 h annealing samples, both total dose responses were unusual. After 300-krad(Si) irradiation, both the shifts of capacitance-voltage curve reached a maximum, respectively, and then decreased with increasing total dose. In addition, the wafers were analysed by the Fourier transform infrared spectroscopy technique, and some useful results have been obtained.     

冷轧和退火对V-5Cr-5Ti合金组织结构和抗辐照硬化性能的影响

钒合金(V-5Cr-5Ti)是聚变堆第一壁以及包层的重要候选结构材料。不同加工工艺会对钒合金在聚变堆中的服役性能产生影响。本文利用兰州重离子研究装置(HIRFL)提供的337 MeV的高能Fe离子对不同程度冷轧(冷变形量分别为40%、60%和80%)以及冷轧后退火(1 273 K退火1 h)的V-5Cr-5Ti合金样品进行了辐照,研究了不同的冷轧和退火处理过程对材料抗辐照硬化性能的影响。电子背散射衍射技术(EBSD)测试结果显示,随着冷变形量的增加,样品中细小破碎晶粒比例增大,晶粒平均尺寸减小。退火处理后,细小破碎晶粒出现一定程度的长大,大晶粒几乎全部消失,晶粒尺寸分布更加均匀。维氏硬度结果表明随着冷变形量的增加,硬度随之增加,退火后硬度降低。辐照之后,材料硬度升高,出现了辐照硬化效应。在冷轧样品和退火样品中都观察到了辐照硬化效应随冷变形量的增加显著减弱的现象,这表明冷变形可以显著提高材料的抗辐照硬化能力。结合EBSD和硬度数据,对冷变形和退火处理引起钒合金抗辐照硬化性能变化的机理进行了讨论。讨论结果显示,冷轧使材料总的吸收尾闾增大,引起辐照硬化程度降低,退火处理使材料中晶界密度和位错密度降低,材料的总吸收尾闾降低,辐照硬化效应增加。     

Structural,dielectric and ac conductivity properties of Ni-doped HoFeO3 before and after gamma irradiation

A series of samples of HoFe_1?x Ni _x O₃ (x = 0.0, 0.1, 0.3) were prepared using the solid-state reaction technique to understand the structural, dielectric and conductivity properties before and after gamma irradiation of accumulated dose of 625 KGy. The X-ray diffraction confirms that all the samples exist in single-phase orthorhombic structure having space group Pbnm. With increasing dopant Ni, the unit cell volume and lattice parameters undergo small change. X-ray analysis show change in the interplanar spacing and full width at half maximum values after gamma irradiation. The Raman spectra of the samples show modifications after gamma irradiation. It can be easily seen that after gamma irradiation intensity, peak width are completely altered by gamma-absorbed dose. Measurement of dielectric loss and dielectric constant at room temperature was performed before and after gamma irradiation in the frequency range of 20 Hz–1 MHz. It is observed that the value of dielectric constant decreases after irradiation. The ac conductivity is estimated from the dielectric constant and loss tangent. Exposure to gamma radiation results in substantial modification in the physical properties of the Ni-doped Ho-based orthoferrites.     

Total ionizing dose effects of domestic Si Ge HBTs under different dose rates

The total ionizing radiation(TID) response of commercial NPN silicon germanium hetero-junction bipolar transistors(Si Ge HBTs) produced domestically are investigated under dose rates of 800 m Gy(Si)/s and 1.3 m Gy(Si)/s with a Co-60 gamma irradiation source. The changes of transistor parameters such as Gummel characteristics, and excess base current before and after irradiation, are examined. The results of the experiments show that for the KT1151, the radiation damage is slightly different under the different dose rates after prolonged annealing, and shows a time dependent effect(TDE). For the KT9041, however, the degradations of low dose rate irradiation is higher than for the high dose rate, demonstrating that there is a potential enhanced low dose rate sensitivity(ELDRS) effect for the KT9041. The possible underlying physical mechanisms of the different dose rates responses induced by the gamma rays are discussed.     

Ar离子辐照导致微球玻璃机械性能的变化

为研究离子辐照导致空心玻璃微球机械性能的变化,利用Ar离子辐照与空心玻璃微球组分相同的微球玻璃薄片,结合不同温度下的等时退火处理,采用纳米压痕测试方法研究了辐照前后玻璃机械性能的变化。测试结果表明:辐照后玻璃的硬度和模量均呈下降趋势,恢复阻力明显升高;退火后的未辐照样品硬度和模量呈上升趋势,恢复阻力在误差范围内没有发生变化; 退火后的模量呈下降趋势,恢复阻力呈下降趋势;在退火温度约为300 ℃时,辐照样品退火后的恢复阻力与未辐照样品基本相同。     

Temperature effect on the gamma dose response of glycine (spectrophotometric read-out) system

The glycine (spectrophotometric read-out) dosemeter has a useful dose range of 15–4000 Gy with good reproducibility and post-irradiation stability. It is a potential dosemeter for radiation processing applications, but the dose response of the system may vary with irradiation and measurement temperature. The effect of irradiation and variation in measurement temperature on the gamma dose response of this system was investigated. The gamma dose response was found to be constant for both irradiation and measurement temperatures ranging from 10 to 50 °C, and the maximum variation in response is within ±1%.