CMOS器件60Co γ射线、电子和质子电离辐射损伤比较

利用TRIM95蒙特卡罗软件计算了质子在二氧化硅中的质量阻止本领和能量沉积，比较了质子在二氧化硅中的电离阻止本领与核阻止本领，分析了质子在材料的表面吸收剂量与灵敏区实际吸收剂量的关系.利用⁶⁰Co γ射线、1MeV电子和2—9 MeV质子对CC4007RH和CC4011器件进行辐照实验，比较⁶⁰Co γ射线和带电粒子的电离辐射损伤情况.实验结果表明，⁶⁰Co γ射线、1MeV 电子和2—7MeV质子辐照损伤效应中，在0V栅压下可以相互等效； 关键词： γ射线 电子 质子 辐射损伤     

不同粒子辐射条件下CC4013器件辐射损伤研究

本文采用60 MeV Br离子、5 MeV质子和1 MeV电子等三种辐射源, 针对CC4013型互补金属氧化物半导体器件(complementary metal oxide semiconductor, CMOS)进行辐射损伤研究. 通过Geant4程序计算了该器件电离辐射吸收剂量与芯片厚度的关系, 经过计算, 在相同注量下, 60 MeV Br离子的电离吸收剂量最大, 1 MeV电子产生的电离吸收剂量最小. 应用Keithley4200-SCS半导体特性分析仪在原位条件下研究了CC4013器件电性能参数随辐射吸收剂量的变化关系. 测试结果表明, 相同电离辐射吸收剂量下, 1 MeV电子对CC4013器件的阈值电压参数影响最大, 5 MeV质子其次, 60 MeV Br离子的影响最弱. 关键词： CMOS器件 高能带电粒子 电离辐射 辐射损伤     

LN晶体的激光损伤研究

测量了ＬＮ晶体的表面和体损伤阈值，以及重复频率脉冲的积累效应，研究了晶体中的非线性吸收过程。分析了损伤机理，发现在表面和体内都会发生多光子吸收，并且是引起晶体破坏的根源，造成宏观破坏的原因在体内是应力炸裂，在表面是热烧熔化和等离子体抛射。     

用散射光观察激光损伤的动态过程

本文利用散射光观察强激光对光学材料损伤的动态过程，详细说明了材料损伤时，散射光变化特点，以及损伤阈值的确定和散射光变化与损伤形貌的关系，并研究了激光损伤累积效应。     

Cryoradiolytic reduction of crystalline heme proteins: analysis by UV‐Vis spectroscopy and X‐ray crystallography

The X‐ray crystallographic analysis of redox‐active systems may be complicated by photoreduction. Although radiolytic reduction by the probing X‐ray beam may be exploited to generate otherwise short‐lived reaction intermediates of metalloproteins, it is generally an undesired feature. Here, the X‐ray‐induced reduction of the three heme proteins myoglobin, cytochrome P450cam and chloroperoxidase has been followed by on‐line UV‐Vis absorption spectroscopy. All three systems showed a very rapid reduction of the heme iron. In chloroperoxidase the change of the ionization state from ferric to ferrous heme is associated with a movement of the heme‐coordinating water molecule. The influence of the energy of the incident X‐ray photons and of the presence of scavengers on the apparent reduction rate of ferric myoglobin crystals was analyzed.     

XRD and AFM study of radiation damage induced by swift heavy ions in Y3Al5O12 single crystals

Defects induced in Y₃Al₅O₁₂ single crystals by swift heavy ions are investigated by X-ray diffraction (XRD) and atomic force microscopy. The irradiation was performed at GANIL with 561 MeV ⁵¹Cr, 466 MeV ¹²⁸Te, and 957 MeV ²⁰⁸Pb ions. The XRD data reveal that the lattice strain increases with increasing electronic stopping power, whereas the hillock parameters (height and diameter) are not influenced by the electronic stopping power. According to our experimental data, for the same mean electronic stopping power, the hillock parameters are more pronounced for the lower range in contrast to swelling measurements. The experimental data show a strong increase in the hillock parameter at higher fluence, indicating the amorphization of Y₃Al₅O₁₂ single crystals.     

A comparison between electron and ion damage in quartz

Abstract

The effects of in-situ electron and ion bombardment in quartz are compared. Both types of irradiation readily induce the metamict transformation and, furthermore, do so in linear proportion over the entire range of their combination. The results suggest that the creation of oxygen vacancies is responsible for the metamict transformation in both cases.     

Gamma ray induced sensitization in CaSO4: Dy and competing trap model

Gamma ray induced sensitization in CaSO₄ :Dy has been compared for different temperatures during irradiation (25° 120° and 250°C). Enhanced sensitization at elevated temperatures seems to support the competing trap model for supralinearity and sensitization in CaSO₄ :Dy.     

Specific radiation damage to acidic residues and its relation to their chemical and structural environment

Intense synchrotron radiation produces specific structural and chemical damage to crystalline proteins even at 100 K. Carboxyl groups of acidic residues (Glu, Asp) losing their definition is one of the major effects observed. Here, the susceptibilities to X‐ray damage of acidic residues in tetrameric malate dehydrogenase from Haloarcula marismortui are investigated. The marked excess of acidic residues in this halophilic enzyme makes it an ideal target to determine how specific damage to acidic residues is related to their structural and chemical environment. Four conclusions are drawn. (i) Acidic residues interacting with the side‐chains of lysine and arginine residues are less affected by radiation damage than those interacting with serine, threonine and tyrosine side‐chains. This suggests that residues with higher pK_a values are more vulnerable to damage than those with a lower pK_a. However, such a correlation was not found when calculated pK_a values were inspected. (ii) Acidic side‐chains located in the enzymatic active site are the most radiation‐sensitive ones. (iii) Acidic residues in the internal cavity formed by the four monomers and those involved in crystal contacts appear to be particularly susceptible. (iv) No correlation was found between radiation susceptibility and solvent accessibility.     

The many faces of radiation‐induced changes

During diffraction experiments even cryo‐cooled protein crystals can be significantly damaged due to chemical and physical changes induced by absorbed X‐ray photons. The character and scale of the observed effects depend strongly on the temperature and the composition of crystals. The absorption of radiation energy results in incremental regular changes to the crystal structure, making its impact on the process of solving the structure strongly correlated with other experimental variables. An understanding of all the dependencies is still limited and does not allow for a precise prediction of the outcome of a particular diffraction experiment. Results are presented of diffraction experiments performed under different experimental conditions. The influence of temperature and crystal composition on different characteristics of radiation damage is analyzed. The observed effects are discussed in terms of their impact on data processing and phasing procedures.     

激光偏振取向与光栅能量吸收及破坏阈值的关系

本文从实验和理论方面研究了光栅吸收与入射激光的偏振取向和波长的关系.从计算模型得出的理论结果与观察值相符.     

表面Al膜污染物诱导熔石英表面损伤特性

在熔石英表面人工溅射一层Al膜污染物,分别测试污染前后熔石英基片在355 nm波长激光辐照下的损伤阈值,并采用透射式光热透镜技术、椭偏仪和光学显微镜研究了污染物Al膜的热吸收、厚度以及激光辐照前后熔石英的损伤形貌。用355 nm波长的脉冲激光分别辐照位于污染的熔石英和洁净的熔石英前后表面的损伤点,并用显微镜在线采集损伤增长图样,测试损伤点面积。实验表明:熔石英前表面的金属Al膜污染物导致基片损伤阈值的下降约30%,后表面的污染物导致基片下降约15%,位于熔石英样片后表面损伤点面积随激光辐照次数呈指数增长,而位于前表面的损伤点面积与激光脉冲辐照次数呈线性增长关系;带有污染的熔石英样片的增长因子比洁净的熔石英样片的增长因子高30%。     

Generation of paramagnetic centres in crystalline quartz by ultraviolet irradiation

Irradiation of α-quartz crystals with ultraviolet light (4.0–5.0 eV) results in ionization of alkali-compensated aluminum tetroxide impurity centres, as observed by electron paramagnetic resonance spectroscopy of the hole centres created or of the germanium tetroxide electron centres formed when Ge is present.     

表面Al膜污染物诱导熔石英表面损伤特性

在熔石英表面人工溅射一层Al膜污染物,分别测试污染前后熔石英基片在355 nm波长激光辐照下的损伤阈值,并采用透射式光热透镜技术、椭偏仪和光学显微镜研究了污染物Al膜的热吸收、厚度以及激光辐照前后熔石英的损伤形貌。用355 nm波长的脉冲激光分别辐照位于污染的熔石英和洁净的熔石英前后表面的损伤点,并用显微镜在线采集损伤增长图样,测试损伤点面积。实验表明：熔石英前表面的金属Al膜污染物导致基片损伤阈值的下降约30%,后表面的污染物导致基片下降约15%,位于熔石英样片后表面损伤点面积随激光辐照次数呈指数增长,而位于前表面的损伤点面积与激光脉冲辐照次数呈线性增长关系;带有污染的熔石英样片的增长因子比洁净的熔石英样片的增长因子高30%。     

Incident particle range dependence of radiation damage in a power bipolar junction transistor

The characteristic degradations in silicon NPN bipolar junction transistors(BJTs) of type 3DD155 are examined under the irradiations of 25-MeV carbon(C),40-MeV silicon(Si),and 40-MeV chlorine(Cl) ions respectively.Different electrical parameters are measured in-situ during the exposure of heavy ions.The experimental data shows that the changes in the reciprocal of the gain variation((1/β)) of 3DD155 transistors irradiated respectively by 25-MeV C,40-MeV Si,and 40-MeV Cl ions each present a nonlinear behaviour at a low fluence and a linear response at a high fluence.The(1/β) of 3DD155 BJT irradiated by 25-MeV C ions is greatest at a given fluence,a little smaller when the device is irradiated by 40-MeV Si ions,and smallest in the case of the 40-MeV Cl ions irradiation.The measured and calculated results clearly show that the range of heavy ions in the base region of BJT affects the level of radiation damage.     

单元素靶粒子位移损伤计算方法及有效模式分析

通过SRIM程序的快速损伤计算与全级联计算两种常用模式,对单元素靶材料进行粒子辐照模拟计算,分别利用基于损伤能量间接计算移位数的NRT位移模型方法和直接通过输出文件读取的方法获得移位数,并对数据进行相应的处理及分析对比,结果表明：对于单元素靶来说,在SRIM快速损伤和全级联两种计算模式下,利用NRT位移模型数值计算得到的移位数基本一致,都可以用于进一步计算得到可靠的位移损伤剂量（dpa）;而通过SRIM两种模式下的输出文件数据直接获得的移位数则有两倍左右的差异,要想得到相对可靠的dpa相关参数,需要根据不同辐照情况选取合适的计算模式。     

光学材料的激光损伤形态研究

 提出了破坏形态因子的概念并以高功率连续激光作用下的光学材料的热力学响应为例，通过积分变换的方法给出激光作用期间温度场和应力场的解析形式，继而得到破坏形态因子的表达式及其简化形式，研究破坏形态因子与材料性质、激光参数的关系，从而预言特定的材料在特定的激光作用下的破坏形态。     

Hard X‐ray‐induced damage on carbon–binder matrix for in situ synchrotron transmission X‐ray microscopy tomography of Li‐ion batteries

The electrode of Li‐ion batteries is required to be chemically and mechanically stable in the electrolyte environment for in situ monitoring by transmission X‐ray microscopy (TXM). Evidence has shown that continuous irradiation has an impact on the microstructure and the electrochemical performance of the electrode. To identify the root cause of the radiation damage, a wire‐shaped electrode is soaked in an electrolyte in a quartz capillary and monitored using TXM under hard X‐ray illumination. The results show that expansion of the carbon–binder matrix by the accumulated X‐ray dose is the key factor of radiation damage. For in situ TXM tomography, intermittent X‐ray exposure during image capturing can be used to avoid the morphology change caused by radiation damage on the carbon–binder matrix.     

Femtosecond laser-induced damage morphologies of crystalline silicon by sub-threshold pulses

The effect of sub-threshold pulses of circularly polarized Ti:sapphire femtosecond laser system on crystalline (1 0 0) silicon wafer was investigated. Surface damage morphologies were studied by irradiating the test silicon surface with pulses (peak fluence of 0.25 J/cm²) in succession. These pulses were below the single-pulse surface damage threshold. After the few initial pulses, the observed surface damage morphologies were found to be characterized by a minor phase change region and a major surface damage area at the center, corresponding to the well-known laser-induced periodic surface structure (LIPSS). Further increase in the number of pulses resulted in the formation of new surface morphologies with different features such as ablation, modification, and re-deposited materials. These features were reproducible and more distinguishable at higher number of pulses.