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Contribution from recoiling atoms in secondary electron emission induced by slow highly charged ions from tungsten surface
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The electron emission yield gamma induced by Ne2+ and O2+ impacting on a clean tungsten surface has been measured. The range of projectile energy is from 3 keV/u to 14 keV/u. The total electron yield gradually increases with the projectile velocity. It is found simultaneously that the total electron yield for O2+ is larger than the total electron yield for Ne2+, which is opposite to the results for higher projectile velocity. After considering the contribution from recoiling atoms to the energy distribution and electron emission yield, we find that recoiling atoms am of crucial importance in electron emission in our energy range. Thus, the unexpected results in our experiment can be explained successfully.</span
Multiple ionization effects in M X-ray emission induced by heavy ions
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">M-shell ionization of tungsten by Ar12+ ions were investigated in the energy range of 1.2-3.0 MeV. The measurements were also implemented for H, He and Xe ions as a comparative study. A significant shift of the M X-ray lines to the higher energy side caused by multiple ionizations, which was verified by the analysis of the intensity ratios of M-gamma and M-alpha beta, was observed. The total experimental cross sections of tungsten were compared with the PWBA and ECPSSR theoretical predictions, which are based on two extreme assumptions, namely, single ionization and full ionization. (C) 2012 Elsevier B.V. All rights reserved.</span
Test of IMME in fp shell via direct mass measurements of T-z =-3/2 nuclides
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Isochronous mass spectrometry has been applied to neutron-deficient Ni-58 projectile fragments at the HIRFL-CSR facility in Lanzhou, China. Masses of four short-lived T-z = -3/2 nuclides Ti-41, Cr-45, Fe-49, and Ni-53 have been measured with a precision of 20 - 40 keV. The new mass data enabled for the first time to test the isobaric multiplet mass equation (IMME) in fp-shell nuclei. We observed that the IMME is inconsistent with the generally accepted quadratic form for the A = 53, T = 3/2 quartet. We performed full space shell model calculations and compared them with the new experimental results. The main results were published in Y.H. Zhang et al., Physical Review Letters 109 (2012). Here we give details on the experiment and data analysis as well as summarize the main findings.</span
Design studies on the 4 pi gamma-ray calorimeter for the ETF experiment at HIRFL-CSR
No full textA high detection efficiency calorimeter which is used to detect gamma-rays with energies from 1 MeV up to 10 MeV as well as light charged particles has been proposed. Design of the geometry, results of the crystal tests and Monte Carlo simulations are presented in this paper. The simulation results confirm that the calorimeter can obtain high detection efficiency and good energy resolution with the current designed geometry. And the calorimeter is competent for the future External Target Facility (ETIF) experiments
高温-应力载能离子辐照装置
No full text<p><font face="宋体" size="3">发明涉及一种高温-应力载能离子辐照装置，其特征是在离子束传输真空管道的前端外围设有电磁扫描设备，后端连接真空腔室；半拦截式离子束流探测器和离子束斑探测器位于真空管道内部，拦截式离子束流绝对测量探测器置于真空腔室内，离子束斑探测器位于半拦截式束流探测器和拦截式束流探测器之间，与离子束线呈45°夹角，外侧设有CCD离子束斑监示探测器；内置腔室中有辐射加热源，外围设有辐射屏蔽层；拉/压施压传感系统竖直位于内置腔室的中心，温度测量与自动控制系统与拉/压样品夹上固定的样品直接相连；真空腔室的外侧及拉/压施压传感系统上部外侧均设有循环冷却水套。本发明的优点在于不仅适用于高温、应力等特殊环境下的载能离子辐照材料实验，同时可以作为常规载能离子辐照和相关材料力学性能测量的装置。</font></p
Characterization of the oxide particles in Al-added high-Cr ODS ferritic steels
No full textIn the present work, microstructures of dispersoids in two Al-added high-Cr ODS ferritic steels (including the commercial MA956, and another ODS steel with a similar composition recently developed in Kyoto University) were studied. The study with transmission electron microscopy (TEM) of both the thin-foil specimens and the extraction replica specimens showed that the nano-sized oxides in the two ODS steels consist mainly of a complex Y-Al-O compound (YAlO(3)) in a perovskite structure (i.e. YAP), while other oxide particles with different chemical composition or crystalline structures are in significantly lower number density. The comparison between the two kinds of ODS steels shows that the size distribution and the number density of the oxide particles significantly depends on the conditions of fabrication. Mechanisms underlying the processes were discussed. (C) 2010 Elsevier B.V. All rights reserved
Spectrum study of damage accumulation in GaN irradiated by MeV-energy heavy ions
No full text<span style="font-family: 'Microsoft Yahei', 宋体, Arial, ' Helvetica', ' sans-serif'; font-size: 13px; line-height: 22px;">本学位论文的工作，利用所在单位中、高能离子加速器条件，分别开展了辐照剂量为1&times;1013ions/cm2、3&times;1013ions/cm2、1&times;1014ions/cm2的308MeV的129Xe35+离子，辐照剂量为1&times;1011ions/cm2、1&times;1012ions/cm2、1&times;1013ions/cm2、1&times;1014ions/cm2和1&times;1015ions/cm2的2.3MeV的 20Ne8+离子，以及辐照剂量为1&times;1011ions/cm2、1&times;1012ions/cm2、1&times;1013ions/cm2的5.0MeV的84Kr19+离子辐照GaN晶体膜的实验。对辐照后的样品进行了高分辨XRD、拉曼光谱、UV-Vis透射谱的研究。 研究发现，在2.3MeV 20Ne8+与5.0MeV 84Kr19+这两个中能离子的辐照实验中，GaN晶格的膨胀率随辐照剂量的增加而增大，且在离子射程范围，存在不同晶格膨胀率的区域。晶格膨胀的大小是晶格损伤大小的直接体现，实验发现在这个能区核能损是造成晶格损伤和应力的决定因素，其中3 keV/nm/ion的电子能损不能对GaN晶格造成有效的损伤。 实验结果进一步说明，在核能损作为晶格损伤的决定因素的情况下，晶格损伤的大小由核能损的沉积密度决定。当描述晶体原子离位损伤的dpa值小于0.032时，离子辐照在GaN晶体中引入的缺陷以点缺陷为主，晶格常数c随dpa的增加是线性增加的, 当dpa大于0.032时，晶格随dpa的增加而膨胀的趋势开始明显放缓；0.032附近是GaN晶体中辐照损伤形式由简单缺陷向缺陷复合体转变的dpa阈值，此时GaN晶格中的点缺陷密度达饱和，若辐照剂量进一步增大，将会出现点缺陷在动态退火作用下向复杂的缺陷集团的演化，这种聚集行为会延缓GaN晶格在辐照情况下随dpa的膨胀率。 而对于高能（308MeV）的129Xe35+离子辐照的样品，在相同的能量沉积密度下，高达28 keV/nm/ion的电子能损造成的损伤要比相同能量沉积密度下的中能离子核能损沉积造成的损伤程度要更加明显，说明GaN晶体对于高能快重离子的电子能损要比中低能辐照时的核能损要敏感的多。</span><div id="abstract_en_long" style="margin: 0px; padding: 0px; font-family: 'Microsoft Yahei', 宋体, Arial, ' Helvetica', ' sans-serif'; font-size: 13px; line-height: 22px; overflow: hidden;">
In the present work irradiation experiments of gallium nitride (GaN) with 308MeV 129Xe35+2.3MeV 20Ne8+ and 5.0MeV 84Kr19+ respectively were performed. The irradiation dose was 5&times;1012ions/cm2,1&times;1013ions/cm2,3&times;1013ions/cm2 to 308MeV 129Xe35+ , 1&times;1011ions/cm2, 1&times;1012ions/cm2,1&times;1013ions/cm2,1&times;1014ions/cm2,1&times;1015ions/cm2 to 2.3MeV 20Ne8+,and 1&times;1011ions/cm2,1&times;1012ions/cm2,1&times;1013ions/cm2 to 5.0MeV 84Kr19+. And the irradiated samples were investigated with the high-resolution X-ray diffraction spectrometry (HRXRD),Raman spectrometry and UV-Vis spectrometry. It was found that in the experiments of GaN irradiated with 2.3MeV 20Ne8+ and 5.0MeV 84Kr19+,GaN lattice swelled with the irradiation increasing. In the whole range of irradiation, there were swelling areas with different . The swelling degree answered the damage degree, It was the nuclear energy loss which caused the crystal damage and was the main reason of the stress introduced in GaN, GaN seemed to be non-sensitive to electrical energy loss less than 3keV/nm/ion. As the lattice damage was mainly caused by nuclear energy loss, the accumulation density of nuclear energy loss decided the damage degree.While the dpa is below 0.032, defects in GaN was mainly point defects, lattice constant c increased linearly with the dpa increasing, but it showed a slower trend when the dpa become greater than 0.032; dpa=0.032 seemed to be the threshold value that point defects defect type began to transform from simple type to complicated type, if the irradiation dose increased from that dpa, point defects caused by irradiation would migrate and cluster together in GaN under the driving force of dynamic annealing, which would slow the trend of the swelling of GaN irradiated by ions. For the 308MeV 129Xe35+ irradiation, under the same energy accumulation density, it was found that the accumulation of 28keV/nm/ion electrical energy loss caused much greater damage than the accumulation of nuclear energy loss, which meaned that GaN was much more sensitive to electrical energy loss of high-energy heavy ions than to nuclear energy loss of low-energy ions.</div>
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