质子辐照不锈钢中氢气泡产生和演化研究

采用质子辐照模拟方法和正电子湮没寿命测量方法研究了质子辐照在国产改进型316L不锈钢中产生的氢气泡及其随辐照质子注量的演化过程。5×10^12，5×10^13，5×10^14／cm^2质子辐照的实验结果表明，辐照在不锈钢中产生氢气泡的尺度随辐照质子注量增加而增大，在质子注量为5×10^14／cm^2时氢气泡尺寸达到0．62nm，气泡的浓度随质子注量增加而减小。The bubble production and evolution in the home-made modified 316L stainless steel have been investigated by the proton irradiation simulation technique and the positron annihilation lifetime measurement. The experimental results of 5 × 10^12, 5 × 10^13 and 5 × 10^14/cm^2 proton irradiations show that the produced bubble size increases, while the bubble concentration decreases, with the increasing of the irradiation proton flueence. At the proton irradiation fluence of 5 × 10^14/cm^2 the bubble size reaches 0.62 nm.     

不锈钢辐射损伤随温度和剂量的变化(英文)

用重离子辐照模拟和正电子湮没寿命技术研究了改进型316L不锈钢在21 和33 dpa辐照剂量下的辐照损伤在室温到802 °C温度范围随辐照温度变化和室温下0—100 dpa剂量范围随辐照剂量变化. 在580 °C左右实验观察到辐照肿胀峰， 在21 和33 dpa辐照剂量下相应的空位团分别由14和19个空位组成， 尺度分别为0.68 和0.82 nm. 空位团尺寸随辐照剂量增加， 在100 dpa时空位团由8个空位组成， 尺度为0.55 nm. 实验结果表明， 在改进型316L不锈钢中辐照损伤随辐照温度变化更灵敏.     

钨辐射损伤随辐照剂量变化的重离子辐照模拟研究

采用重离子辐照模拟方法和正电子湮没寿命测量技术研究了钨辐射损伤随辐照剂量的变化。20，60和90dpa（每个原子的位移次数）辐照损伤水平的实验结果表明，辐照在钨中产生单空位、双空位、位错和空位团等缺陷；随辐照剂量的增大，单空位、双空位和位错浓度增加，空位团的尺度和浓度都随之增大。Radiation damage in W has been studied as a function of irradiation dose by heavy ion simulation and positron annihilation lifetime measurement. The experimental results of 20, 60 and 90 dpa irradiations illustrate that the mono-and di-vacancies, dislocations and vacancy clusters are produced by the irradiation. The concentrations of the mono-and di-vacancies and dislocations and both the concentration and size of the vacancy clusters or voids all increase with the increasing of the irradiation dose.     

LaFeO3纳米材料电四极超精细相互作用TDPAC测量

用时间微分扰动角关联方法测量了LaFeO3纳米中的电四极超精细相互作用. 扰动角关联探针核14057La 14058Ce由139La(n,γ)140La反应产生, 实验只观察到一个La晶位的四极相互作用. 在室温下， 20和40 nm 以及晶体LaFeO3的四极相互作用频率ω0分别为 687.4 , 698.3 和742.9 Mrad/s , 频率分布宽度系数σ分别为 0.014, 0.009和0.001, 电场梯度不对称系数η=0. 实验数据表明, 电场梯度主轴与晶轴方向一致; 样品具有菱方结构, 晶体到纳米发生菱方向正交结构转变, 纳米尺度越小, 越趋于正交结构; 由于邻近核的扰动, 随纳米颗粒增大, 四极相互作用频率分布宽度系数σ变小, 晶体时最小. The quadrupole interactions in the nano and crystalline LaFeO3 perovskites have been investigated by TDPAC. The TDPAC probing nuclei 14057La 14058Ce were produced through the nuclear reaction 139La(n.γ)140La at the CIAE heavy water experimental reactor. One electric quadrupole interaction was detected for each material, which is assigned to the La site. The quadrupole interaction frequencies of 687.4, 698.3 and 742.9 Mrad/s with a distribution coefficient of 0.014, 0.009 and 0.001 were observed at room temperature for the 20 and 40 nm nano LaFeO3 and crystalline LaFeO3, respectively. The fitting yielded the EFG asymmetry parameter η=0, which indicates that the principal axes of the EFG is aligned with the crystallographic axes. The experimental results show that the structure of crystalline LaFeO3 is rhombohedral, the changing of the structure towards the orthorhombic structure takes place from the crystalline LaFeO3 to the nano LaFeO3, and the smaller the nano grain size, the larger the change. The frequency distribution is caused by the perturbation of the neighboring atoms, and thus, the distribution coefficient increases with decreasing the nano grain size and the crystalline LaFeO3 arrives at its maximum.     

PdAgHx金属氢化物正电子湮没研究

在77—295 K温区和氢浓度0—0.35范围采用正电子湮没寿命测量方法研究了Pd0.75Ag0.25H_x氢化物合金. 充氢后正电子湮没寿命谱可以用两个寿命成分表征. 短寿命成分τ1不随温度和氢浓度变化, 是自由正电子湮没寿命; 长寿命成分τ2及其相对强度I2不随温度变化, 但随氢浓度的增加分别增大和减小, τ2是氢气泡捕获的正电子湮没寿命, τ2增大和I2减小说明随氢浓度增大氢聚集成的气泡的尺度增大, 而浓度减小. 实验结果表明, 氢脆的微观机理是氢气泡致脆. The metal hydride PdAgHx with a hydrogen concentration x ranging from 0 to 0.35 has been investigated by positron annihilation lifetime method in the temperature region between 77 K and 295 K. The measured lifetime spectra in metal hydride PdAgHx are characterized by two lifetimes τ1 and τ2. The short lifetime τ1 is independent of both hydrogen concentration and temperature, which is ascribed to the annihilation lifetime of free positrons. The long lifetime τ2 and its intensity I2 do not change with temperature, while τ2 increases and I2 decreases with increasing of hydrogen concentration. τ2 is attributed to the lifetime of positrons trapped at the hydrogen bubble. The increase of τ2 indicates the growth of the hydrogen bubble, and the decrease of I2 shows the reduction of the hydrogen bubble concentration. The experimental result shows a microscopic mechanism that the hydrogen bubble produced causes hydrogen embrittlement.     

β–NMR和β–NQR谱仪的建立

介绍了在中国原子能科学研究院建成的我国第一台βNMR及βNQR谱仪.进行了¹²B的寿命、磁矩和极化度的测量,实验结果表明谱仪工作可靠     

Measurements of g-Factor of Rotational Levels in ^83Y

The g-factors of the positive parity rotational levels up to spin Ⅰ= 41/2 in ^83Y have been measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The experimentally measured g-factors show the g9/2 proton alignment followed by the g9/2 neutron alignment. The measured g-factors are in good agreement with the results calculated by an empirical formula based on the cranking shell model.     

Development of β-NMR and β-NQR

The β-NMR (nuclear magnetic resonance) and β-NQR (nuclear quadrupole resonance) technique and its ex-perimental set-up have been developed for the first time in China. The lifetime, magnetic moment and spin polarization of ^12B were determ/ned. The experimental results show the reliability of this newly developed β-NMR and β-NQR set-up.