2011年 第28卷 第3期
用各向同性的火球模型研究了能量为14.6 AGeV的16OEm碰撞中末态产物的发射角分布和能量为4.5 AGeV的28SiEm碰撞中靶核碎块中黑粒子的方位角分布。 在这个模型中增加横向流可以描述能量为3.7 AGeV的C-Ne和C-Cu碰撞中靶核碎块π介子和质子的方位角分布。 计算结果与实验数据符合得较好， 表明改进了的火球模型能够描述高能核核碰撞的角分布。
The emission angular distributions of finalstate particles produced in 16OEmulsion (Em) collisions at 14.6 AGeV, and the azimuthal angular distributions for the black particles produced in 28SiEm at 4.5 AGeV have been studied by an isotropic fireball model. The model including transverse flow is used to describe the azimuthal distributions of midrapidity π- mesons and protons produced in CNe and CCu collisions at 3.7 AGeV. The calculated results are in agreement with the experimental angular distributions. It shows that the improved fireball model gives a good description of nucleusnucleus collisions at high energies.
在相对论平均场理论框架内，利用Λ超子的结合能和中子星质量的观测数据得到超子标量介子耦合参数χσ的范围是0.33—0.77。在这个范围内， 研究了χσ取不同值时， 包含核子， Λ和Ξ超子的热前中子星（固定单个重子熵s=1）的性质。结果表明, 如果超子耦合参数变大， 前中子星核心温度变高， 中微子丰度变低， 前中子星的亚稳态质量范围变小。如果χσ超过了0.75， 前中子星不可能演变成黑洞。联系SN1987A讨论了这一结果的意义。In the framework of the relativistic mean field theory(RMFT), protoneutron stars with hyperons are studied. To be compatible with neutron star masses, the hyperon scalar coupling χσ should lie in the range of 0.33—0.77. As the hyperon scalar coupling increases, in protoneutron star matter, the core temperature increases whereas the abundance of neutrinos decreases. The metastable mass range of protoneutron stars narrows as the temperature increases. It is found that a protoneutron star cannot subside into a low mass black hole when χσ>0.75. Furthermore, the case of SN1987A is discussed.
对引力场的能量\|动量和角动量守恒定律研究进展进行了总结。依此探讨了一般五维时空膜宇宙模型中的能量\|动量张量、 角动量张量以及它们的守恒定律。通过计算一个膜宇宙模型中的能动张量， 论证了该模型中“可见膜”上的引力非常弱， 这可认为是从引力的角度反映了规范层次问题。结果与一般的结论， 即引力系统总能量为零是一致的。同时， 分析了这个膜宇宙模型中的角动量张量， 计算了该模型中的总角动量， 讨论了暴涨Randall\|Sundren(RS)模型中的总角动量的一些性质。说明了在这类模型中总角动量的类空分量均为零， 这与普通RS模型是一样的。同时， 分析了RS模型中背景以及膜上的宇宙学常数， 发现在RS模型中五维背景宇宙学常数和两个膜上的真空能都能取它们的自然值。最后通过修改RS模型， 得到了一种可以产生很小的有效宇宙学常数的机制。
We summarized both the general covariant energy\|momentum and angular momentum conservation law in the gravitational system and analyzed the general covariant energy\|momentum tensor of the gravitational system in general five\|dimensional cosmological in brane\|universe models. After calculating this energy\|momentum for the cosmological generalization of the Randall\|Sundrum(RS) model which includes the original RS model as the static limit, we are able to show that the weakness of the gravitation on the “visible” brane is a general feature of this model. This is the origin of the gauge hierarchy from a gravitational point of view. Our results are also consistent with the fact that a gravitational system has vanishing total energy. We also discussed the properties of the general covariant angular momentum in five\|dimensional brane-universe model. With calculation of the total angular momentum of this model, we analyzed the properties of the total angular momentum in the inflationary RS model. We pointed that the space-like components of the total angular momentum are zero while the others are non-zero, which agrees with the results from ordinary RS model. We also investigated the bulk cosmological constant and brane vacuum energies in RS model. We show that the five\|dimensional bulk cosmological constant and the vacuum energies of the two branes could take their natural values. Finally we argued how we can generate a small four-dimensional effective cosmological constant on the branes by modifying the original RS model.
上海光源是我国刚刚建成的一台第三代中能同步辐射光源。为使得上海光源能够严格工作在设计状态下， 在调试过程中进行了一系列线性模型的校正， 主要包括闭轨校正、 基于束流准直（BBA）校正、 LOCO参数校正和线性耦合校正。经过反复的线性模型校正以后， 上海光源储存环的闭轨畸变均方根误差在水平和垂直两个方向可以分别控制到50和60 μm的水平， 包络函数畸变和色散函数畸变都可以控制到小于1%的状态， 工作点和束流发射度基本上校正到了设计值。线性耦合校正能够方便地将储存环的耦合度从0.02%调节到2%左右。调试结果表明， 上海光源采取的这一套线性模型校正方法， 能够有效地将上海光源的工作状态校正到设计状态， 并且为其他模式的调节奠定了基础。In the commissioning stage of Shanghai Synchrotron Radiation Facility(SSRF) storage ring, several methods were used to correct the linear optics. Beam Based Alignment(BBA) was used for BPM\|Quadrupole offsets measurement; Response matrix was used for orbit correction; LOCO was used for linear optics fitting, and quadrupoles strength were adjusted to correction the beta function; coupling was measured and corrected by skew quadrupoles. After correction， closed orbit are reduced to 50/60 μm in hortizontal and vertical plane; β beating and dispersion errors are less than 1%; betatron tune and emmittance are closed to the design value; betatron coupling also can be adjusted from 0.02% to 2%. These methods have been proved to be useful for storage ring calibrations, with the help of these methods, SSRF storage ring can be tuned to the design model and other model easily.
设计了一台用于兰州重离子加速器HIRFL-CSR的六极磁铁数字电源， 该电源以H桥变换器为主拓扑结构电路， 采用Cyclone II FPGA作为核心硬件， 以Verilog语言实现了全数字化的PI调节算法。 电源输出电流达到了340 A， 直流电流稳定度达到了3.14×10-5， 达到了1×10-4的设计指标。One digital power supply was designed for the sextupole magnets of CoolerStorageRing of the Heavy Ion Research Facility in Lanzhou (HIRFLCSR). It adopts HBridge convertor as the main topology circuit and Cyclone II FPGA as the main hardware, and has realized fully digitized PI regulation arithmetic by Verilog language. The peak current of the power supply reaches 340 A and the stability approaches 3.14×10-5. Finally the power supply has achieved the designed specification of 1×10-4.
在经典力学框架内和小振幅近似下， 把准等时同步加速器中的粒子纵向运动方程化为具有阻尼项、 受迫项的广义维尔斯特拉斯方程。在无扰动情况下， 用维尔斯特拉斯函数分析了系统的相平面特征； 在扰动情况下， 用多尺度法讨论了系统的稳定性。结果表明， 在相平面上， 分支轨道是一条过不稳定点的同宿轨道， 包围的区域呈“鱼形”或α形。系统的稳定性由“鱼形”区的面积决定， 面积越大系统越稳定； 结果还表明， 系统除了ωm=1的主共振外， 还存在ωm=2, 1/2的超次谐共振， 并找到了系统稳定性的临界条件。In the classical mechanics frame and with small amplitude approximation, the longutudial motion equation of particles in quasi\|isochronous syhchrotron is reduced to the general Weierstrass equation with a damping term and a forced term. In the non-perturbed case, the phase plane properties are analysed by using Weierstrass function; in the perturbed case, the stabilities are discussed in terms of the multi\|scalar techniques.The results show that the separatrix orbit is a homoclinic orbit through the instable point in the phase plane, the surrounding area is the fish form or α\|form.The stabilities are determined by the fish area, the large the area, the better the stability; also the results show that there are ωm=2, 1/2 super\| and sub\|harmonics resonance except the main resonance ωm=1, the critical condition of an instability is found.
介绍了由中国科学院近代物理研究所和北京大学微电子研究院联合研制的双面硅多条探测器的初步测试过程及测试结果。测试内容包括： 探测器的电特性、 能量分辨率、 二维能谱、 条间串扰（crosstalk）。在-25 V全耗尽偏压下， 各条的反向漏电流均小于10 nA， 对于5.486 MeV的α粒子， 正面各条的能力分辨率在1.5%左右， 条间串扰在6%左右； 背面各条能量分辨率稍差， 在3%左右， 其条间串扰在1%左右。同时对进口的Micron BB1直流耦合单边读出的双面硅条探测器做了相同测试， 并进行了性能对比。The testing of a doubled-sided multi-strip silicon detector manufactured by Institute of Modern Physics of CAS and Peking University were introduced. The electrical characteristics and energy resolution, twodimensional spectrum, crosstalk were presented. The reverse leak current of each strip is smaller than 10 nA under bias voltage of 25 V. The energy resolution of strips on the front side is about 1.5%, but a little worse for the backside strips, about 3%. The level of crosstalk is about 6% for the front side, 1% for the backside. Same tests were carried out on the commercial Micron BB1 detector and a comparison was presented.
利用新型的MICROMEGAS探测器测量了6种不同比例的Ar+CO2 混合气体中第一汤逊系数α的两个实验参数A和B。实验结果分析表明， 电子在栅极的透过率在75%时， α的测量误差小于13%， 而探测器增益的涨落造成的α的测量误差小于8%。
In this paper， the MICROMEGAS detector was employed to measure the experimental parameters A and B of the first Townsend coefficient α in 6 different ratio of Ar+CO2 gas mixtures. The results indicate that the error of α is less than 13% in the condition of electron transmission rate of the mesh up to 75% and is less than 8% due to gain fluctuation of the detector.
在保留正电子寿命谱分析程序PATFIT和连续谱分析程序MELT主要优点的基础上研究开发了一个新的正电子湮没谱分析软件PASA。主要的改进包括：将PATFIT、MELT和多普勒展宽谱3种正电子湮没分析方法集成在Windows界面程序中, MELT程序脱离MATLAB环境独立运行; 编写了完整的多普勒展宽谱分析程序, 谱文件的读取、输入参数的调节和拟合结果的输出更加方便快捷, 重点加强了正电子湮没实验谱和拟合结果的图形显示、介绍PASA软件的使用经验。Based on the commonly used PATFIT and MELT program, a new program package — Positron Annihilation Spectrum Analysis(PASA) with many user\|friendly applications was developed. The main modifications are: three kinds of positron analysis methods (PATFIT, MELT, Doppler) were incorporated into PASA; MELT could run independently without being in MATLAB environment; Detailed Doppler analysis program were programmed into PASA. Experiences of using the PASA program were also introduced.
在液氮低温下用400 keV的Ne2+离子束对Gd2Ti2O7多晶烧绿石进行了辐照实验研究， 离子束辐照量范围为5×1014—1×1016ions/cm2。利用掠X射线衍射技术对样品辐照层的结构变化进行了分析表征， X射线的掠射角分别为γ=0.25°, 0.5°, 1°和3°。结果表明: 在该实验条件的离子束辐照下， Gd2Ti2O7辐照层会发生明显的体积肿胀效应， 体积肿胀程度随入射离子束辐照量的增大而增大； 在同一辐照量下， 辐照层的体积肿胀程度也随X射线入射角的增大而增大。当辐照量达到1×1016ions/cm2时， 辐照层发生非晶化相变。Polycrystalline pyrochlore Gd2Ti2O7 compounds were irradiated with 400 keV Ne2+ ions at cryogenic temperature (~77 K). The irradiation fluences was ranging from 5×1014 to 1×1016 ions/cm2, corresponding to a peak ballistic damage dose of ~0.16 to 3.3 displacements per atom
二氧化钛（Titatium Dioxide,简称TiO2）晶体在中能重离子辐照时表面会出现肿胀效应， 肿胀高度与入射离子的电子能损和辐照注量有关。 辐照后的TiO2在一定条件下能够被氢氟酸溶液化学蚀刻，化学蚀刻的电子能损阈值为8.2keV/nm，未辐照TiO2呈现几乎零蚀刻率。要达到饱和蚀刻深度，辐照离子的注量必须大于或等于1×1013ions/cm2。采用离子辐照的潜径迹理论分析研究了辐照损伤及对化学蚀刻的影响, 快重离子辐照结合化学蚀刻是制备TiO2微结构的有效方法。 There appears volume swelling on the surface of the irradiated rutile TiO2 crystal and the volume swelling is affected by the ion fluence and the electronic stopping power. To induce adequate irradiation damage for the chemical etching, the irradiation parameters must fulfill some requirement. There is minimum electronic stopping power for the chemical etching of the irradiated region in TiO2 crystal， which is about 8. 2 keV/nm. If the ion fluence is below 1×1013ions/cm2, the saturated etching depth of the irradiated region in TiO2crystal cannot be reached. The irradiation damage based on latent track formation frame and the theoretical linkage to the etching technique is investigated. It is hopeful to fabricate microand nanoscale structurce in rutile TiO2 crystal by using the ion irradiation and chemical etching technique.
分别进行了2.3 MeV20 Ne8+ 离子和5.0 MeV84 Kr19+ 离子辐照GaN样品的实验， 并对实验样品进行了HRXRD的分析。结果发现， 随着这两种离子辐照剂量的增大， GaN的HRXRD谱（0002）衍射峰的峰位出现了向小角侧有规律的移动， 并在较高剂量时衍射峰发生分裂。同时， 对衍射峰的峰位的移动和峰形的变化等现象反映的辐照损伤机制进行了研究， 并探讨了电子能损与核能损各自在晶格损伤中的作用。
Irradiation experiments of gallium nitride (GaN) with 2.3 MeV20 Ne8+ and 5.0 MeV84 Kr19+ respectively were performed. The irradiated samples were analyzed using the high\|resolution X\|ray diffraction (HRXRD) spectrometry. It was found that the diffraction peak of GaN (0001) exhibited regular shift to smaller diffraction angles with the increase of ion fluence for the both ions， and the diffraction peak split into a few sub\|peaks at higher irradiation dose. Underlying mechanisms of the observed peak shift and split were investigated, the contributions of different energy losses to the damage accumulation in the irradiated GaN were discussed.
探究模拟微重力条件下不同剂量C离子辐射对雄性动物生殖器官的急性影响, 以期了解空间环境辐射所致机体生殖系统的损伤。采用小鼠尾部悬吊模型地面模拟微重力状态1周后, 利用重离子加速器提供的C离子辐照处理, 检测了生殖器官脏器系数及精子密度、组织形态变化、DNA损伤以及细胞凋亡各项指标。结果表明, 微重力和C离子辐射均能引起睾丸损伤, 且1 Gy单纯辐照组中损伤最为严重。此外发现, 模拟微重力能够在一定程度上降低辐射诱导的损伤, 其内在机制有待于进一步的研究。In this paper it was investigated that the effect of modeled microgravity on the acute injury induced by low doses of carbon ions in the male reproductive organs of mice, assessing the risk associated with the space environments. In our study, outbred Kunming mice were stimulated in microgravity by tail suspension, and then were irradiated with the low doses of carbon ions diliuered by HIRFL, and measured the testis and epididymis coefficient, sperm number of epididymis, histological alterations, DNA strand breaks and cell apoptosis. The results demonstrated that carbon ions and stimulated microgravity could induce the damage in the present study. Moreover, most serious injury all occurred in the irradiation group. In addition, it was also found that the damage of the carbon ion irradiation combined microgravity group were lower than those of the irradiation group, while the related mechanism needs the further investigation.
定向诱导基因组局部突变技术(Targeting Induced Local Lesions IN Genomes, 简称TILLINC)是一种全新的、高通量和低成本反向遗传学研究方法。近年来, 随着突变筛选技术的革新, TILLING技术平台日趋多元化, 使得TILLING技术的操作更为简单﹑快速, 并广泛应用于作物育种研究领域。简要介绍了TILLING技术平台的最新发展动态, 并初步探讨了将辐射诱变处理与TILLING高通量筛选相结合在诱变育种中的应用前景。To investigate the M1 biological effects of heavy ions irradiation on Lycopersicon esculentum Mill., its seeds were irradiated by 12C6+heavy ions (80 MeV/u) with the dosages of 30, 60, 90, 120 and 160 Gy respectively . The results showed that with doses increased gradually, germination rate and seedling rate of Lycopersicon esculentum Mill. were decreased, and the latter was lower than the former, mainly due to the inhibition of root growth. The irradiation increased the content of MDA and proline evidently, showing irradiation could damage biomembrane, and also decreased the activities of POD and SOD with distinct inhibition pattern. However, the low dose and high dose irradiation promoted APX activity, illustrating APX was induced to protect irradiation injury. In brief, exposure to 12C6+ heavy ions had obvious injury effects on the seeds of Lycopersicon esculentum Mill.. Heavy ions irradiation damaged biomembrane, inhibited activities of enzymes, and finally inhibited the growth of the first generation of these seeds.
利用辐射能量为80 MeV/u 的12C6+重离子束辐照番茄种子, 辐照剂量分别为30, 60, 90, 120和160 Gy研究其对番茄M1代的生物学效应。结果表明, 随着辐照剂量的增大, 番茄的发芽率和成苗率降低, 且成苗率明显低于发芽率, 发现辐照损伤主要抑制了根的生长; MDA和脯氨酸含量变化的总体趋势为随着辐照剂量的增大先升后降再升高, 说明高剂量C离子辐照对生物膜造成更严重的损伤; APX活性随着辐照剂量的增大呈先升后降再升高的趋势, 表明APX在清除活性氧中起主要作用; POD和SOD活性的总体趋势是随着辐照剂量的增大而降低, 且明显低于对照组。综合分析表明, 12C6+重离子束辐照番茄种子, 对M1代具有明显的损伤效应, 高剂量辐照对番茄种子造成的损伤更大, 使酶的活性降低, 抑制植株生长。 To investigate the M1 biological effects of heavy ions irradiation on Lycopersicon esculentum Mill., its seeds were irradiated by 12C6+heavy ions (80 MeV/u) with the dosages of 30, 60, 90, 120 and 160 Gy respectively . The results showed that with doses increased gradually, germination rate and seedling rate of Lycopersicon esculentum Mill. were decreased, and the latter was lower than the former, mainly due to the inhibition of root growth. The irradiation increased the content of MDA and proline evidently, showing irradiation could damage biomembrane, and also decreased the activities of POD and SOD with distinct inhibition pattern. However, the low dose and high dose irradiation promoted APX activity, illustrating APX was induced to protect irradiation injury. In brief, exposure to 12C6+ heavy ions had obvious injury effects on the seeds of Lycopersicon esculentum Mill.. Heavy ions irradiation damaged biomembrane, inhibited activities of enzymes, and finally inhibited the growth of the first generation of these seeds.
基于球型光学模型、 预平衡发射和HauserFeshbach统计等理论， 编制了MEND程序（Medium Energy Nuclear Data）， 该程序适用于中重原子核在入射粒子能量低于250 MeV的中低能区的全套核数据计算。对于中子和质子在250 MeV以下诱发的核反应， 其全截面、 反应截面、 弹性散射微分截面、 双微分截面和能谱等理论计算值与相应的实验值基本一致。MEND是计算中低能核反应的基础程序， 在我国已被广泛用于核数据计算及建立中能核数据库Based on the spherical optical model, preequilibrium statistical theory, and HauserFeshbach theory, etc., the code MEND (Medium Energy Nuclear Data) is written for calculating the complete set of nuclear data of mediumheavy nuclei in mediumlow energy region (≤250 MeV). For the reactions induced by neutron and proton below 250 MeV, the total cross sections, reaction cross sections, elastic scattering differential cross sections, double differential cross sections and energy spectra, etc. calculated by the code MEND, generally agree with those corresponding experimental data. MEND is a foundational program for nuclear reaction in mediumlow energy region and is wildely used for nuclear data calculation and establishing ENDF/B6 format files of mediumlow energy region in China.
用中国原子能科学研究院HI13串列加速器上的多探测器快中子飞行时间谱仪， 测量了8.19 MeV中子与9Be作用时, 从20°到160°区间26个角度的次级中子双微分截面。测量截面以np散射截面作为标准进行归一。实验结果用Monte Carlo方法进行了中子注量率衰减、多次散射和有限几何修正， 并用MCNP4C程序对所用的Monte Carlo程序进行了验证。测量结果与评价数据以及其它实验室的数据进行了比较。The secondary neutron emission doubledifferential cross section of 9Be induced by 8.19 MeV neutron was measured at 26 different angles from 20°to 150°by using the multidetector fast neutron TOF spectrometer at the HI 13 Tandem Accelerator at China Institute of Atomic Energy(CIAE). The results were normalized to np scattering measurement. A special MonteCarlo code which was validated with the MCNP 4C code was employed to analyze the measured data for the corrections of neutron flux attenuation, multiple scattering and finite geometry. The measured results were compared with the evaluated data and the other measurements.
由于锂铅合金因具有高增殖比、低活泼性和可能作为冷却剂的特点，被认为是最有潜力的能源堆包层氚增殖材料。在理论模型描述熔融锂铅合金氚释放行为的基础上，开展了中子辐照后Li17Pb83合金的离线氚释放实验。结果表明： 释放氚的化学形式99％以上为难溶于水的成分（HT或T2）； 氚滞留时间随载气中氢分压的增加而减小，氢分压达到1000 Pa后变为常数，且与实体积无关；氚释放速率对温度的依赖性符合Arrhenius定律。以此为基础得到的氚在熔融锂铅中的动力学参数结果，虽与文献值有差异，但同样证明了在633—973 K的范围内， 氚从液态锂铅到气相的整个释放过程中起决定作用的是氚在合金内的扩散和气\|液界面的多相反应重组。Lithium\|lead alloy is considered to be one of the most prominent tritium breeding materials for the fusion reactor blanket because of its high breeding ratio, and low reactivity and possible use as coolant. An out\|of\|pile experiment of tritium release from Li17Pb83 alloy was performed after neutron irradiation on the base of mathematical model to describe tritium release behavior from an eutectic lithium\|lead alloy. The results suggest that the dominant chemical form of the released tritium (>99%) was the water\| insoluble component (HT or T2). Tritium residence time decreased with increasing H2pressure in carrier gas up to 1000 Pa, and above this concentration limit it became constant and not influenced by the plenum volume. The temperature dependence of the tritium release rate can be described by an Arrhenius law. Consequently, the present results on the kinetic parameters of tritium in molten Li17Pb83alloy are considered to be different from the values in literature, but it is the same that the overall release process is governed by the diffusion of tritium atoms in the Li17Pb83and by the heterogeneous reaction at the gas\|eutectic interface of the tritium atom recombination at temperatures from 633 to 973 K.