Structural stability of C-60 films under the bombardment of 1.95 GeV Kr ions

The structural stability of C-60 films under the bombardment of 1.95 GeV Kr ions is investigated. The irradiated C-60 films were analyzed by Fourier Transform Infrared (FTIR) spectroscopy and Raman scattering technique. The analytical results indicate that the irradiation induced a decrease of icosahedral symmetry of C-60 molecule and damage of C-60 films; different vibration modes of C-60 molecule have different irradiation sensitivities; the mean efficient damage radius obtained from experimental data is about 1.47 nm, which is in good agreement with thermal spike model prediction.

Pion Production in Heavy-ion Collisions in the 1 A GeV region

Within the framework of the improved isospin dependent quantum molecular dynamics (ImIQMD) model, the pion emission in heavy-ion collisions in the region 1AGeV is investigated systematically, in which the pion is considered to be mainly produced by the decay of resonances ∆(1232) and N∗(1440). The in-medium dependence and Coulomb effects of the pion production are included in the calculation. Total pion multiplicity and π−/π+ yields are calculated for the reaction 197Au+197Au in central collisions for selected Skyrme parameters SkP, SLy6,Ska, SIII and compared them with the measured data by the FOPI collaboration.

Pion Production in Heavy-Ion Collisions in the 1 A GeV Region

Within the framework of the improved isospin dependent quantum molecular dynamics (ImIQMD) model, pion emission in heavy-ion collisions in the region 1 A GeV is investigated systematically, in which the pion is considered to be mainly produced by the decay of resonances Delta(1232) and N*(1440). The in-medium dependence and Coulomb effects of pion production are included in the calculation. Total pion multiplicity and pi(-)/pi(+) yields are calculated for the reaction Au-197+(197) Au in central collisions for selected Skyrme parameters SkP, SLy6, Ska, SIII and compared with the measured data of the FOPI collaboration.

Measurement of K*(892)(0) and K-0 mesons in Al plus Al collisions at 1.9A GeV

A new measurement of subthreshold K*(892)(0) and K-0 production is presented. The experimental data complete the measurement of strange particles produced in Al + Al collisions at 1.9A GeV measured with the FOPI detector at SIS at GSI (Darmstadt). The K*(892)(0)/K-0 yield ratio is found to be 0.0315 +/- 0.006(stat.) +/- 0.012(syst.) and is in good agreement with the transport model prediction. These measurements provide information on the in-medium cross section of K+-pi(-) fusion, which is the dominant process in subthreshold K*(892)(0) production.

25MeV/u Kr辐照下PET薄膜的损伤机制研究；Damage Mechanism of PET Irradiated by 25 MeV/u Kr Ions

通过25MeV/u86Kr离子辐照叠层结晶聚对苯二甲酸乙二醇酯膜(PET),在不同的电子能损(3.407.25keV/nm)和离子注量(5×10113×1012ions/cm2)辐照条件下,对Kr离子在PET中引起的辐照损伤效应进行了研究。借助傅里叶变换红外光谱分析,通过对样品的红外吸收峰进行扣除基底后的Lorentz拟合,分析了与主要官能团对应的吸收峰强度的变化趋势,研究了化学结构与组分在重离子辐照下的变化规律;利用X射线衍射光谱仪测量,研究了Kr离子在PET潜径迹中引起的非晶化过程,并通过对吸光度和非晶化强度随离子注量的指数衰减规律的分析,获得了不同电子能损离子辐照PET时主要官能团的损伤截面和非晶化截面及对应的潜径迹半径。

0.4-1.2A GeV能区重离子碰撞中的直接流系统性研究

直接流是研究重离子碰撞动力学演变和压缩形成的高密核物质性质很好的探针，本论文系统地研究了0.4、0.8和1.16A GeV的Ni+Ni和Pb+Pb碰撞中的直接流。实验是在德国重离子研究中心(GSI)的FOPI探测装置上完成的。论文中，简单总结了中高能区重离子碰撞的现状和描述集体流的主要理论模型，介绍了FOPI探测系统，给出了详细的实验数据分析过程，对所得到的物理结果进行了讨论。本论文工作的重点如下：基于FOPI系统的实验数据，发展了一套质量相关(Z=1离子)的直接流的提取方法。提取了各碰撞系统出射P、D和T粒子在不同碰撞中心度下的微分直接流和积分直接流。研究了P、D和T的直接流对碰撞中心度、系统尺寸和碰撞能量的依赖性，以及对核物质状态方程的敏感性。结果表明：直接流敏感地依赖于碰撞中心度，近中心碰撞具有更强直接流信号；对于轻重两种系统，用常用的AP1/3+AT1/3系数对积分直接流进行了标度，观察到一定的标度性，但不能完全标度；通过研究直接流对碰撞能量的依赖性发现，在0.4－1.2A GeV能区内，随能量升高，直接流在已经达到了饱和，并开始下降，并且P、D和T的变化趋势相同。实验数据与输运模型IQMD计算比较发现，直接流的变化趋势和最大密度变化趋势相同，说明直接流是核物质压缩程度的一个良好探针。计算得到的P、D和T微分和积分的V1值表明，与质量相关的直接流，无论是微分值还是积分值都敏感依赖于模型中EoS参数。比较发现，不同碰撞能量下，重的Pb+Pb系统的数据和软的EoS符合很好，说明核物质不可压缩系数在210 MeV附近，这与文献中的结果相吻合，说明与质量相关的直接流是EoS的敏感探针。对于轻Ni＋Ni系统，目前的IQMD还不能重现数据，但其趋向于硬的EoS，需要发展描述碰撞过程更为精细的理论模型。数据整体趋势表明，随者系统变重，中子比例的增加，EoS变软，难以给出同一组IQMD参数来同时解释全部的实验数据。对于所研究的碰撞系统，比较中心快度区斜率行为时发现，P、D和T的直接流与出射粒子质量数呈线性关系，并且出射粒子的积分直接流可以很好的用常数(A+1)/2进行标度。如果出射粒子的直接流用IQMD计算的核阻止进行归一，归一后的直接流与碰撞能量成正比。这证明核阻止与直接流有线性关联，反映了核阻止对于碰撞中核物质达到的最高密度起决定性的作用。论文工作的另一部分是完成了FOPI探测装置中飞行时间探测器的升级工作。研制了新型的玻璃MMRPC，完成了性能的批量测试，并研究了该探测器的高计数率行为。测量结果显示，在实验计数率(0.1 kHz/cm2)条件下，MMRPC时间分辨达到75 ps，探测效率达到98％。当计数率达到3－5 kHz/cm2时，时间分辨和探测效率降至约110 ps和75％。高计数率探测效率变差的幅度可以用DC模型进行解释，然而时间分辨的变化幅度用DC模型难以解释

Y_(1.95-x)Gd_xSiO_5:Eu_(0.05)的真空紫外光谱

利用高温固相法合成了 Ｙ１．９５－ｘＧｄｘＳｉＯ５：Ｅｕ０．０５（ｘ＝０．６ｍｏｌ％）荧光体。结构测定表明所合成的荧光体为单斜晶系的Ｘ２型Ｙ２ＳｉＯ５相，空间群为Ｂ２／ｂ。真空紫外光谱表明：随着Ｇｄ３＋含量的增加，在１９２ｕｍ附近，出现了Ｇｄ＋的激发峰，且此峰的强度随着Ｇｄ３＋含量的增加而增大；同时位于１５０～１８５ｎｍ之间的基质吸收带的强度也增大；而位于２００～３００ｎｍ之间的Ｅｕ的电行迁移带的强度却随着Ｇｄ３＋含量的增加而降低。

重离子辐照引起的金属/金属界面混合与相变研究

本论文用重离子在室温下辐照Fe/Cu(Si/Fe(10nm)/[Cu(2.5nm)/Fe(2.5nm)]8/Cu(5n m)、Si/Fe(10nm)/[Cu(4nm)/Fe(4nm)]5(8)/Cu(4nm)、Si/[Fe(10nm)/Cu(10nm)]5)和Fe/Nb(Si /[Fe(10nm)/Nb(4nm)/Fe(4nm)/Nb(4nm)]2/[Fe(4nm)/Nb(4nm)]4))金属多层膜样品，然后利用X射线衍射谱、俄歇电子元素深度剖析谱、透射电子显微镜和振动样品磁强计对样品进行分析。主要研究界面原子混合、相变现象及其与离子辐照参数之间的关系。 1. 室温下用400 keV Xe离子辐照Fe/Cu(Si/Fe(10nm)/[Cu(2.5nm)/Fe(2.5nm)]8/Cu (5nm)、Si/Fe(10nm)/[Cu(4nm)/Fe(4nm)]5/Cu(4nm))和Fe/Nb多层膜。结果显示：随着辐照量的增加，离子辐照引起了Fe/Cu多层膜中Fe与Cu原子的混合和Cu基fcc固溶体和Fe基bcc固溶体地出现；而在Fe/Nb多层膜中，离子辐照引起Fe与Nb原子的混合和FeNb固溶体和非晶态FeNb合金相的出现。随着样品的结构变化，样品的磁滞回线也发生了变化。 2. 室温下用2 MeV Xe离子辐照Fe/Cu和Fe/Nb多层膜。结果显示：随着辐照量的增加，首先发生Fe、Cu原子的偏析和界面锐化，接着发生混合，辐照量较大时形成Cu基fcc固溶体和Fe基bcc固溶体；而在Fe/Nb多层膜中，低辐照量辐照引起多层膜的界面锐化，高辐照量辐照引起Fe与Nb原子混合和FeNb固溶体和非晶态FeNb合金相的出现。随着样品的结构变化，样品的磁滞回线也发生了变化。 3. 室温下用2.03 GeV Kr离子辐照Fe/Cu和Fe/Nb多层膜。结果显示：对于Si/Fe(10nm)/[Cu(4nm)/Fe(4nm)]5/Cu(4nm)多层膜，辐照量为1.0×1013ions/cm2时，发生Fe、Cu原子的偏析和界面锐化；对于Si/[Fe(10nm)/Cu(10nm)]5多层膜，随着辐照量的增加，首先发生Fe、Cu原子的偏析和界面锐化，接着发生混合；对于Fe/Nb多层膜，低辐照量辐照引起多层膜的界面锐化，高辐照量辐照引起Fe与Nb原子混合。随着样品的结构变化，多层膜样品的磁滞回线也发生了变化。 4. 室温下用1.08 GeV Kr离子辐照Fe/Cu和Fe/Nb多层膜。结果显示：在Si/Fe(10nm)/[Cu(4nm)/Fe(4nm)]5/Cu(4nm)、Si/[Fe(10nm)/Cu(10nm)]5和Fe/Nb多层膜中，辐照引起Fe层与Cu（Nb）层混合。随着样品的结构变化，多层膜样品的磁滞回线也发生了变化。 最后，对重离子辐照引起多层膜界面原子混合及相变的机理进行了探讨

Raman spectroscopy of apatite irradiated with swift heavy ions with and without simultaneous exertion of high pressure

Durango apatite was irradiated with energetic U ions of 2.64 GeV and Kr ions of 2.1 GeV, with and without simultaneous exposure to a pressure of 10.5 GPa. Analysis by confocal Raman spectroscopy gives evidence of vibrational changes being marginal for fluences below 5x10(11) ions/cm(2) but becoming dominant when increasing the fluence to 8x10(12) ions/cm(2). Samples irradiated with U ions experience severe strain resulting in crystal cracking and finally breakage at high fluences. These radiation effects are directly linked to the formation of amorphous tracks and the fraction of amorphized material increasing with fluence. Raman spectroscopy of pressurized irradiated samples shows small shifts of the band positions with decreasing pressure but without a significant change of the Gruneisen parameter. Compared to irradiations at ambient conditions, the Raman spectra of apatite irradiated at 10.5 GPa exhibit fewer modifications, suggesting a higher radiation stability of the lattice by the pressure applied.

Role of Bi3+ ions for Er3+ ions efficient 1.54 mu m light emission in Er/Bi codoped SiO2 thin film prepared by sol-gel method

Er/Bi codoped SiO2 thin films were prepared by sol-gel method and spin-on technology with subsequent annealing process. The bismuth silicate crystal phase appeared at low annealing temperature while vanished as annealing temperature exceeded 1000 degrees C, characterized by X-ray diffraction, and Rutherford backscattering measurements well explained the structure change of the films, which was due to the decrease of bismuth concentration. Fine structures of the Er3+-related 1.54 mu m light emission (line width less than 7 nm) at room temperature was observed by photoluminescence (PL) measurement. The PL intensity at 1.54 gm reached maximum at 800 degrees C and decreased dramatically at 1000 degrees C. The PL dependent annealing temperature was studied and suggested a clear link with bismuth silicate phase. Excitation spectrum measurements further reveal the role of Bi3+ ions for Er3+ ions near infrared light emission. Through sol-gel method and thermal treatment, Bi3+ ions can provide a perfect environment for Er3+ ion light emission by forming Er-Bi-Si-O complex. Furthermore, energy transfer from Bi3+ ions to Er3+ ions is evidenced and found to be a more efficient way for Er3+ ions near infrared emission. This makes the Bi3+ ions doped material a promising application for future erbium-doped waveguide amplifier and infrared LED

Melting of Au and Al in nanometer Fe/Au and Fe/Al multilayers under swift heavy ions: A thermal spike study

Knowing that Fe is sensitive to swift heavy ion irradiations whereas Au and Al are not, the behavior of nanometric metallic multilayer systems, like [Fe(3 nm)/Au(x)](y) and [Fe(3 nm)/Al(x)](y) with x ranging between 1 and 10 mn, were studied within the inelastic thermal spike model. In addition to the usual cylindrical geometry of energy dissipation perpendicular to the ion projectile direction, the heat transport along the ion path was implemented in the electronic and atomic sub-systems. The simulations were performed using three different values of linear energy transfer corresponding to 3 MeV/u of Pb-208, Xe-132 and Kr-84 ions. For the Fe/Au system, evidence of appearance of a molten phase was found in the entire Au layer, provided the Au thickness is less than 7 nm and 3 nm for Pb and Xe ions, respectively. For the Fe/Al(x) system irradiated with Pb ions, the Al layers with a thickness less than 4 nm melt along the entire ion track. Surprisingly, the Fe layer does not melt if the Al thickness is larger than 2 nm, although the deposited energy surpasses the electronic stopping power threshold of track formation in Fe. For Kr ions melting does not occur in any of the multilayer systems.

Multi-electron processes in C-13(6+) ions with neon collisions in energy region 4.15-11.08 keV/u

The cross-section ratios of double-, triple-, quadruple-, and the total multi-electron processes to the single electron capture process sigma(DE)/sigma(SC), sigma(TE)/sigma(SC), sigma(QE)/sigma(SC) and sigma(ME)/sigma(SC)) as well as the relative ratios among reaction channels in double-electron active, triple-electron active and quadruple- electron active are measured in C-13(6+) -Ne collision in the energy region of 4.15-11.08 keV/u by employing position-sensitive and time-of-flight coincident techniques. It is determined that the cross-section ratios sigma(DE)/sigma(SC), sigma(TE)/sigma(SC), sigma(QE)/sigma(SC) and sigma(ME)/sigma(SC) are approximately the constants of 0.20 +/- 0.03, 0.16 +/- 0.04, 0.06 +/- 0.02 and 0.42 +/- 0.05. These values are obviously smaller than the predictions of the molecular Coulomb over-the-barrier model (MCBM) [J. Phys. B 23 (1990) 4293], the extended classical over-the-barrier model (ECBM) [J. Phys. B 19 (1986) 2925] and the semiempirical scaling laws (SL) [Phys. Rev. A 54 (1996) 4127]. However, the relative ratios among partial processes of DE, TE and QE are found to depend on collision energy, which suggests that the collision dynamics depends on the collision velocity. The limitation of velocity-independent character of ECBM, MCBM and SL is undoubtedly shown.

Color center formation in silica glass induced by high energy Fe and Xe ions

Silica glass samples were implanted with 1.157 GeV Fe-56 and 1.755 GeV Xe-136 ions to fluences range from 1 x 10(11) to 3.8 x 10(12) ions/cm(2). Virgin and irradiated samples were investigated by ultraviolet (UV) absorption from 3 to 6.4 eV and photoluminescence (PL) spectroscopy. The UV absorption investigation reveals the presence of various color centers (E' center, non-bridging oxygen hole center (NBOHC) and ODC(II)) appearing in the irradiated samples. It is found that the concentration of all color centers increase with the increase of fluence and tend to saturation at high fluence. Furthermore the concentration of E' center and that of NBOHC is approximately equal and both scale better with the energy deposition through processes of electronic stopping, indicating that E' center and NBOHC are mainly produced simultaneously from the scission of strained Si-O-Si bond by electronic excitation effects in heavy ion irradiated silica glass. The PL measurement shows three emissions peaked at about 4.28 eV (alpha band), 3.2 eV (beta band) and 2.67 eV (gamma band) when excited at 5 eV. The intensities of alpha and gamma bands increase with the increase of fluence and tend to saturation at high fluence. The intensity of beta band is at its maximum in virgin silica glass and it is reduced on increasing the ions fluence. It is further confirmed that nuclear energy loss processes determine the production of alpha and gamma bands and electronic energy loss processes determine the bleaching of beta band in heavy ion irradiated silica glass. (c) 2009 Elsevier B.V. All rights reserved.

高能kr离子辐照聚合物膜的潜径迹及其辐照降解特性的研究

本文简要叙述了快重离子在固体材料，特别是聚合物材料中引起的强电子激发效应研究的基本理论、发展历史和研究现状。描述了在兰州重离子加速器上完成的25 MeV/u 86Kr离子辐照叠层聚对苯二甲酸乙二醇酯膜（PET）和聚碳酸酯（PC）膜的实验及结果分析。应用傅立叶红外变换光谱（FT-IR）及X-射线衍射分析（XRD）方法研究了在不同电子能损及不同注量辐照条件下，高能Kr离子在聚合物PET和PC潜径迹中引起的的损伤效应。结果表明：高能Kr离子在聚合物PET、PC膜引起的损伤主要是由于辐照引起的断键及键的重组产生的官能团的降解及非晶化过程，损伤截面存在电子能损阈值，且与官能团的结构有关。 对PET的傅立叶红外变换光谱分析结果给出，电子能损为7.25 keV/nm时，对应官能团吸收峰794 cm-1, 849 cm-1, 1021 cm-1, 1341 cm-1, 1410 cm-1, 1505 cm-1,的损伤截面半径分别为：3.63 nm, 4.70 nm, 4.58 nm, 3.54 nm, 5.17 nm, 5.32 nm。X-射线衍射分析结果表明，PET的非晶化转变截面随离子注量和电子能损的增大而增加，（100）衍射峰的相对强度I/I0随离子注量的增加而指数衰减，对应电子能损为6.62, 6.93, 7.25 keV/nm，其相应的非晶化半径分别为4.86, 5.64, 6.77 nm。 对PC的傅立叶红外变换光谱分析表明，当电子能损比较小，大多数官能团的红外吸收无明显变化，直到当辐照注量为2×1012 ions/cm2 且电子能损比较大时，其绝对吸收强度才发生明显的改变。电子能损为6.37 keV/nm 时，对应官能团吸收峰为519 cm-1, 605 cm-1, 724 cm-1, 1014 cm-1，其损伤截面分别为：13.12, 45.40, 50.21, 56.28 nm2