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2009年  第26卷  第2期

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核物理
核物质对称能的高密行为研究
雍高产, 李宝安, 陈列文
2009, 26(2): 85-92. doi: 10.11804/NuclPhysRev.26.02.085
摘要:
同位旋物理的主要任务之一是通过放射性核束引起的核反应来探索介质中有效核子-核子相互作用的同位旋依赖性,尤其是同位旋相关的核物质状态方程, 即密度依赖的核物质对称能。由于对称能,尤其是其高密行为,对核物理学和天体物理学具有重要意义,密度依赖的对称能在过去10年一直是中能重离子物理研究领域的主要焦点之一。近年来,低密对称能的研究已经取得了重要进展, 而对称能的高密行为仍然很不确定。在理论方面,人们提出了许多对高密对称能敏感的观测量。 实验方面, 关于对称能高密行为研究的实验计划已经展开,世界各地正在建造的放射性核束装置为对称能的高密行为研究提供了新的机遇。基于IBUU输运模型综述了研究对称能高密行为的一些敏感观测量及其最新进展, 以及所面临的挑战与机遇。One of the major tasks of studying isospin physics via heavyion collisions with neutronrich nuclei, is to explore the isospin dependence of inmedium nuclear effective interactions and the equation of state of neutronrich nuclear matter, i.e., the density dependence of nuclear symmetry energy. Because of its great importance for understanding many phenomena in both nuclear physics and astrophysics, the study of the density dependence of nuclear symmetry energy has been the main focus of the intermediateenergy heavyion physics community during the last decade. Nowadays significant progress has been achieved in studying the low density behavior of nuclear symmetry energy, but the high density behavior of nuclear symmetry energy is still very uncertain. Theoretically, a number of observables have been proposed as sensitive probes to the high density behavior of nuclear symmetry energy. With new opportunities provided by the various radioactive beam facilities being constructed around the world, studies of the high density behavior of nuclear symmetry energy is expected to be one of the main forefront research areas in nuclear physics in the near future. In this report, based on the transport model IBUU we have reviewed the major progress achieved in studying the high density behavior of nuclear symmetry energy and discussed future challenges in this field.
核物质热力学性质的同位旋和动量相关性
徐骏, 陈列文, 李宝安 马红孺
2009, 26(2): 93-101. doi: 10.11804/NuclPhysRev.26.02.093
摘要:
利用3个具有不同的同位旋和动量相关性的热力学模型研究了非对称核物质的热力学性质, 它们是重离子碰撞中同位旋弥散数据约束下的、 同位旋和动量相关的MDI模型, 完全动量无关的MID模型, 以及同位旋标量动量相关的extended MDYI(eMDYI)模型。 主要研究了同位旋非对称热核物质的对称能和系统力、 化学不稳定性以及液气相变的温度效应。 MDI模型对称能的温度效应来源于动能和势能两部分贡献, 而MID和eMDYI模型只有势能部分对对称能的温度效应有贡献。 研究结果还表明, 力学不稳定性区域、 化学不稳定性区域和液气共存区都依赖于模型的同位旋和动量相关性, 以及对称能的密度依赖关系。In this article, three models with different isospin and momentum dependence are used to study the thermodynamical properties of asymmetric nuclear matter. They are isospin and momentumdependent MDI interaction constrained by the isospin diffusion data of heavy ion collision, the momentumindependent MID interaction and the isoscalar momentumdependent eMDYI interaction. Temperature effects of symmetry energy, mechanical and chemical instability and liquidgas phase transition are analyzed. It is found that for MDI model the temperature effects of the symmetry energy attribute from both the kinetic and potential energy, while only potential part contributes to the decreasing of the symmetry energy for MID and eMDYI models. We also find that the mechanical instability, chemical instability and liquidgas phase transition are all sensitive to the isospin and momentum dependence and the density dependence of the symmetry energy.
三体系统中的Efimov态(英文)
陈双, 任中洲, #, 许昌
2009, 26(2): 102-106. doi: 10.11804/NuclPhysRev.26.02.102
摘要:
通过求解Faddeev方程, 研究了量子三体系统中的Efimov效应。 改进了变分方法对于求解激发态的不足。 在不同的两体作用下得到了三体系统中的Efimov态。 讨论了在不同质量比的三体系统中出现Efimov态的条件。 并由三体计算的结果分析了具有两个价中子的核系统在两体存在束缚态时可能存在的Efimov效应。We studied the Efimov effect in a threebody system by solving the Faddeev equations. Different models and interactions were considered. The occurrence of Efimov states was discussed. The possible Efimov state was clearly presented and its properties were investigated.
通过48Ca+249Bk 合成Z=117的可能性研究
张群武, 沈彩万, #, 赵恩广
2009, 26(2): 107-111. doi: 10.11804/NuclPhysRev.26.02.107
摘要:
利用两步模型对可能合成 Z=117 的核反应48Ca+249Bk 进行了研究。模型将熔合过程分为弹靶接触前的粘连过程和从弹靶接触到形成复合核的形成过程。结合统计蒸发模型,计算了297117 蒸发数个中子的剩余截面。结果表明,在激发能 E* = 31 MeV且复合核蒸发3中子时的剩余截面最大为 0.34 pb ,已经可以用实验方法进行探测。
在超重核区应用Viola Seaborg公式研究α衰变寿
彭金松
2009, 26(2): 112-116. doi: 10.11804/NuclPhysRev.26.02.112
摘要:
在超重核区(Z≥104)使用文献[7—9]给出的3组参数应用ViolaSeaborg公式计算了α衰变寿命, 所得结果与实验值进行比较, 发现其结果与实验值相差较大。 为此, 利用最小二乘法分别在重核区和超重核区重新对参数进行了拟合, 得到的计算结果与实验值相比符合得较理想, 尤其是由超重核得到的参数的结果非常理想。The α decay halflives of the superheavy nuclei in the mass region (Z≥104) were calculated by ViolaSeaborg formula with three sets of parameters. The calculated results show that all the three sets of parameters caused rather large deviations from the experimental data. To solve this problem, we have done a parameter fitting in the regions of heavy nuclei and superheavy nuclei respectively, with the least squares method. With the new sets of parameters, the calculated α decay halflives are in much better agreement with the experimental data. In particular, the results calculated with the new parameters in the region of superheavy nuclei are even better.
利用imaging方法提取高能重离子碰撞中Core-Halo模型发射源的信息
杨志韬, 吉日木图, 张卫宁
2009, 26(2): 117-122. doi: 10.11804/NuclPhysRev.26.02.117
摘要:
根据对高斯源的检验, 引入两个π介子相对距离的均方根半径Rrmst来表示高能重离子碰撞中π介子发射源的空间尺寸。 利用imaging计算方法可以不依赖于源模型计算出相对距离的均方根半径。 对Core-Halo模型进行计算并与高斯拟合结果比较, 结果显示, 由于长寿命共振态衰变产生的π介子的贡献, 半径Rrmst显示出较大的π介子发射空间。 另外,对于π介子为混沌发射的情况, 通过imaging方法计算得到的π介子发射源的混沌性参量明显大于高斯拟合所得到的结果。
加速器
SSC新高频腔设计与分析
张生虎, 许哲, #, 张秋余, 冯勇, 马云, 高宜海, 吴建强, 王贤武, 王皓宁
2009, 26(2): 123-126. doi: 10.11804/NuclPhysRev.26.02.123
摘要:
简要分析了HIRFL SFC与SSC之间的束流匹配关系, 给出了新高频腔的频率范围。 利用经典三维电磁场数值模拟软件MAFIA对SSC新高频腔体进行了模拟计算, 得出了SSC新高频腔体的相关物理参数, 并对频率范围、Q值、 并联阻抗和电压分布等参数进行了分析。 高频腔体的模拟计算结果完全符合SSC回旋加速器改造的物理设计及空间结构要求。
核技术
气体喷嘴反冲传输技术及在核科学中的应用
郭俊盛, 林茂盛, 秦芝, 甘再国, 吴晓蕾, 范芳丽, 孙锡军, 刘洪业, 罗亦孝
2009, 26(2): 127-135. doi: 10.11804/NuclPhysRev.26.02.127
摘要:
气体喷嘴反冲传输技术是继“跑兔”装置之后发展和完善起来的适合于短寿命核素研究的一种快速而有效的在线脱束方法。 它能够将短寿命核反应产物传输至远离高辐射区的低本底场所进行收集和测量。 该技术已在加速器和反应堆上得到了广泛的应用, 是一种研究核反应、 核谱学和合成与鉴别新元素、 新核素的一种不可缺少的基本实验技术和工具。 描述了气嘴系统的结构、 基本原理、 设计要求以及它的主要特性, 特别是对系统的气体动力学机制以及各种参数对系统特性的影响等进行了讨论。 最后, 综述了它在核物理、 核化学以及质谱学等领域的应用情况, 并且给出了几个应用的典型例子。 The gasjet recoil transport technique is developed and improved as a new rapid and effective online and off beam method following “rabbit” apparatus in the study of short lives nuclei. It can transport the short halflife nuclear reaction products far from high radioactive area for collection and measurement at low background area. This technique has been widely used in the researches with accelerator and reactor. It is indispensable basic experimental technology and tool applied to nuclear reaction, spectroscopy, as well as synthesis and identification of new elements and nuclei. The basic principle, structure, design requirement and main characteristics of gasjet system are described in this paper, especially the mechanism of gas dynamics and the effect of several parameters on the system properties are discussed. Finally, the applications of this technique in several fields such as nuclear physics, nuclear chemistry and massspectroscopy etc. are comprehensively represented. Several typical applications are also illustrated.
液体闪烁体探测器γ射线测量研究
王琦, 阮锡超, 王松林, 黄翰雄, 聂阳波, 周祖英, 孔祥忠
2009, 26(2): 136-139. doi: 10.11804/NuclPhysRev.26.02.136
摘要:
利用几种单能γ源对BC501A型液体闪烁体探测器进行能量刻度, 以得到探测器对电子的光输出响应函数。 介绍了用蒙特卡罗模拟法确定康普顿边缘所对应的电子能量的方法, 得到的结果与用半高点确定康普顿边缘方法所得的结果做了比较。 利用德国PTB开发的PHRESP蒙特卡罗程序计算出液体闪烁体探测器对各种单能γ射线的光响应矩阵, 阐述了利用γ射线响应函数矩阵和γ射线的反冲电子谱求解待测γ能谱的原理, 对解谱的误差来源也进行了简要的分析。
The light output of the BC501A liquid scintillation detector for
γrays was calibrated by serial monoenergetic γray sources. The Monte Carlo simulation method to confirm Compton edge was described briefly. The result was compared with that obtained by the semiheight method. The γray response matrix of BC501A liquid scintillation detector was calculated by the Monte Carlo code PHRESP from PTB. The method of using response function matrix and recoil electron spectrum to unfold γray energy spectrum was introduced and the error of unfolding spectrum was also briefly discussed.

SPEES针尖参数对样品表面电子出射影响的模拟研究
李继伟, 徐春凯, # 刘文杰, 方可, 陈向军, 徐克尊
2009, 26(2): 140-145. doi: 10.11804/NuclPhysRev.26.02.140
摘要:
报道了对扫描探针电子能谱仪(SPEES)中俄歇电子出射的理论模拟研究。 通过对俄歇电子在针尖电场作用下运动轨迹的模拟以及综合考虑从针尖场发射电子到俄歇电子出射全过程中各种因素的影响, 系统研究了针尖形状、 针尖偏压和针尖样品距离对俄歇电子出射效率的影响, 以及出射俄歇电子束流密度在针尖电场区边缘处的分布。 研究结果为提高SPEES的收集效率、 空间分辨以及能量分辨提供了重要的参考数据。 The simulation of the Auger electron emissions in scanning probe electron energy spectrometer (SPEES) is reported. By simulating the trajectory of Auger electrons, we systematically investigate the dependence of the emission efficiency of Auger electrons on the shape of tip, the biasing voltage, and the distance between the tip and sample surface, as well as the intensity distributions of Auger electrons at the edge of tipsample region. The results will be the significant reference for improving the sensitivity, spatial and energy resolutions of SPEEs.
交叉学科
低速Ar q+(q=7—14)离子入射Au表面激发的X射线谱
任惠娟, 张小安, #, 肖国青
2009, 26(2): 146-149. doi: 10.11804/NuclPhysRev.26.02.146
摘要:
研究了高电荷态离子40Arq+(q=7—14)轰击金属Au表面产生的特征X射线谱。 实验结果表明, 在弱束流(nA量级)的情况下, 对于动能相同的入射离子, 当电荷态比较高(q=11)时, 便能有效地激发靶原子的特征X射线, 单离子的X射线产额高达10-8量级。 分析结果显示, 入射离子的势能、 动能和这种相互作用特有的镜像相互作用势能沉积在靶表面, 使靶原子内壳层电子激发和电离, 形成空穴和产生外壳层电子填充空穴辐射特征X射线,特征X射线的产额随入射离子的势能(电荷态)的增加而增加。 The Au atomic Mα characteristic Xray spectrum has been measured for the slow highly charged ions Arq+ (q= 7—14) impacting on Au surface. The result shows that as long as the charge state of projectile is higher(q=11), the characteristic Xrays of heavy atomic can be effectively excited even though the ionic beam is very weak(nA magnitude), and the single ionic Xray yield is in the order of 10-8 and increases with potential energies of projectiles.
基于核运动效应下的H同位素双原子分子的解析势能函
王蓉, 张莉, 蒋刚, 朱正和#
2009, 26(2): 150-153. doi: 10.11804/NuclPhysRev.26.02.150
摘要:
在加入核运动效应修正下的Born-Oppenheimer近似电子能量的基础上, 采用QCISD(T)/ aug-cc-pvqz方法计算出H同位素双原子分子(H2, HD, HT, D2, DT,T2)的势能函数参数, 获得体现H同位素分子质量差异下的势能函数。 并在此基础上导出H同位素分子的力常数和光谱数据。 同时对于OH, OD和OT分子采用QCISD/aug-cc-pvtz方法计算, 同样获得了这些分子对应的势能函数、 力常数和光谱数据。Based on the correction of the electron energy under BornOppenheimer approximation using nuclear motion effect, the parameters of potential energy functions for hydrogen isotopic diatomic molecules (H2, HD,HT,D2, DT,T2) are calculated with QCISD (T) method and aug-cc-pvqz basis set,and those potential energy functions that indicate the differences from the masses of hydrogen isotopic atoms are obtained. The force constants and spectroscopic data of those molecules are calculated as well. The potential energy functions, force constants, and spectroscopic data of the isotopic diatomic molecules OH, OD,and OT are also derived using QCISD method and aug-cc-pvtz basis set.
改进的SILAR法制备ZnO薄膜及其表征
张苓, 刘杰, 侯明东, 孙友梅, 段敬来, 姚会军, 莫丹, 陈艳峰
2009, 26(2): 154-157. doi: 10.11804/NuclPhysRev.26.02.154
摘要:
采用一种改进的液相成膜技术——连续离子层吸附与反应(SILAR)法, 用锌氨络离子\[Zn(NH3)4\]2+ 溶液作为独立的前驱体溶液, 以载玻片为衬底, 在(125±5) ℃的温度下沉积出致密、 透明的ZnO薄膜。 分别用冷场发射型扫描电镜(FESEM)和X射线衍射(XRD)分析了薄膜样品的表面形貌和结晶状态, 用紫外可见分光光度计(UV-Vis spectroscopy)研究了薄膜样品的发光性能。 结果表明: 获得样品为六角纤锌矿结构的多晶薄膜材料沿\[002\]方向择优生长; 样品表面均匀、 致密, 厚度约为550 nm;在可见光波段具有高的透射率(>80%)。 A modified solution method,successive ionic layer adsorption and reaction(SILAR),was applied to prepare transparent zinc oxide(ZnO) film on glass substrate at (125±5) ℃ in mixed ion precursor solution. The surface morphology and crystallizations of films were analyzed by field emission scanning microscopy(FESEM) and Xray diffraction(XRD), respectively. The optical properties of the films were studied by ultraviolet visible(UVVis)spectroscopy. The results show that the obtained samples are polycrystalline films of hexagonal wurtzite structure,with the preference of [002\] orientation. The asdeposited films exhibit uniform and compact surface morphology, with the film thickness of 550 nm, and have high transmittance in the visible band(>80%).
12C6+离子预辐射对小鼠胸腺脾脏细胞周期进程的影响
赵卫平, 张红, #, 王燕玲, 李宁, 刘斌, 武振华, 谢漪, 郝冀方, 刘阳
2009, 26(2): 158-162. doi: 10.11804/NuclPhysRev.26.02.158
摘要:
以0, 0.05, 0.1, 0.25, 0.5 Gy 12C6+ 离子全身预辐照昆明小鼠, 间隔4 h后再对小鼠进行4 Gy全身辐射。 辐照后12 h用流式细胞仪检测小鼠胸腺脾脏细胞在各细胞周期时相的百分率, 同时用单细胞电泳检测受辐射小鼠胸腺脾脏细胞DNA损伤程度。 结果显示, 相对于大剂量预照射组, 各低剂量预照射组胸腺细胞S期细胞百分率显著减少; 脾脏细胞G0/G1期细胞百分率明显减少; 同时胸腺脾脏细胞的拖尾率及拖尾长度明显减少, 以0.1 Gy预辐照效果最为明显。 这些结果表明, 低剂量预辐射处理可以减弱胸腺细胞的S期阻滞及脾脏细胞的G1期阻滞, 并明显减轻胸腺脾脏细胞的DNA损伤程度。
医用质子和12C离子束的物理性质研究
徐俊奎, 党秉荣, 陈熙萌, #, 李文建, 刘全婷
2009, 26(2): 163-167. doi: 10.11804/NuclPhysRev.26.02.163
摘要:
质子和重离子在现代放射治疗手段中已起着不可替代的作用, 这主要取决于其独特的物理性质。 利用一步过程和两步过程的物理模型解释了离子能量损失的机制, 同时结合Geant4软件包模拟质子和12C在水中的运输过程, 研究了离子束的物理性质, 并讨论了计算的结果, 说明了质子和12C在医学中应用的优缺点。
Depending on their unique physical properties, proton and heavy ions have taken an irreplaceable role in modern means of tumor treatment. Onestep process and twostep process physical models were employed to explain the mechanism of ion energy loss. The transport process of proton and 12C in water was simulated by Geant4 toolkit to study the physical properties of ion beam. The calculation results were discussed, which showed the advantages and disadvantages of proton and 12C in the medical application.
不同LET 12C6+离子对生防菌BJ1的辐射诱变效应
马爽, 李文建, #, 王菊芳, 周利斌, 余丽霞, 董喜存, 陆栋, 刘敬
2009, 26(2): 168-171. doi: 10.11804/NuclPhysRev.26.02.168
摘要:
选取高低两个LET点(40和60 keV/??m), 剂量点分别为50, 100, 200, 400, 600 Gy进行辐照处理, 研究了生防菌的存活率与突变率的关系, 抑菌谱以及活性等。 结果表明, 在高LET条件下, 低剂量辐照就可以得到较多的突变体, 并且BJ1有较高的存活率和突变谱, 有利于筛选优良的正突变体。 因此高LET较低LET有更为明显的辐射诱变效应。
To explore the effects of different linear energy transfer(LET)of 12C6+ ion Beam irradiation on BJ1, survivals and biocontrol effects were cultured and treated with LET=40 and 60 keV/μm at the doses of 50, 100, 200, 400 and 600 Gy, respectively. The results showed more mutations and biocontrol charts and higher survivals were obtained with high LET(60 keV/μm) irradiations at lower dose, which was useful to screen good positive mutations. Based on the results above, it could be concluded that the condition of high LET(60 keV/μm) had obvious mutagenic effects than that of low LET(40 keV/μm).
MicroRNA发现的研究现状及重离子辐照相关应用前景
丁楠, 周光明#
2009, 26(2): 172-176. doi: 10.11804/NuclPhysRev.26.02.172
摘要:
MicroRNA(miRNA)是一类大小为19—24个核苷酸的非编码RNA, 它们通过与靶基因的信使RNA(mRNA)结合在转录后水平调节靶基因的表达, 因而在广泛的生物学过程中发挥重要作用。 首先从miRNA的获得和鉴定两方面对目前miRNA发现工作进行了概括, 然后分析和总结了近年来人源miRNA发现工作的现状, 最后提出有关新miRNA发现工作的新想法。 MicroRNAs(miRNAs) are one kind of small noncoding RNAs of 19—24 nucleotides that transcriptionally regulate the expression of target genes by binding to their mRNA and thus play a central role in gene regulation in a wide arrange of biological processes. In this paper, we reviewed the clone and identification of novel miRNAs, summarized recent work on novel human miRNA recognization, and proposed a potentially feasible way to discover more human miRNAs.