Production of Superheavy Nuclei in Massive fusion reactions

A master equation is constructed to treat the nucleon transfer process in heavy ion fusion reactions to form superheavy nucleus. The relative motion concerning the energy, the angular momentum and the fragment deformation relaxations is explicitly treated to couple with the diffusion process. The nucleon transition probabilities, which are derived microscopically, are thus time dependent. The calculated evaporation residue cross-sections for both cold and hot fusion are in good agreement with the known experimental data.

Spectra of identified high-p(T) pi(+/-) and p((p)over-bar ) in Cu + Cu collisions at root s(NN)=200 GeV

We report new results on identified (anti) proton and charged pion spectra at large transverse momenta (3 < p(T) < 10 GeV/c) from Cu + Cu collisions at root s(NN) = 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider (RHIC). This study explores the system size dependence of two novel features observed at RHIC with heavy ions: the hadron suppression at high-p(T) and the anomalous baryon to meson enhancement at intermediate transverse momenta. Both phenomena could be attributed to the creation of a new form of QCD matter. The results presented here bridge the system size gap between the available pp and Au + Au data, and allow for a detailed exploration of the onset of the novel features. Comparative analysis of all available 200 GeV data indicates that the system size is a major factor determining both the magnitude of the hadron spectra suppression at large transverse momenta and the relative baryon to meson enhancement.

Identified particle production, azimuthal anisotropy, and interferometry measurements in Au plus Au collisions at root s(NN)=9.2 GeV

We present the first measurements of identified hadron production, azimuthal anisotropy, and pion interferometry from Au + Au collisions below the nominal injection energy at the BNL Relativistic Heavy-Ion Collider (RHIC) facility. The data were collected using the large acceptance solenoidal tracker at RHIC (STAR) detector at root s(NN) = 9.2 GeV from a test run of the collider in the year 2008. Midrapidity results on multiplicity density dN/dy in rapidity y, average transverse momentum < p(T)>, particle ratios, elliptic flow, and Hanbury-Brown-Twiss (HBT) radii are consistent with the corresponding results at similar root s(NN) from fixed-target experiments. Directed flow measurements are presented for both midrapidity and forward-rapidity regions. Furthermore the collision centrality dependence of identified particle dN/dy, < p(T)>, and particle ratios are discussed. These results also demonstrate that the capabilities of the STAR detector, although optimized for root s(NN) = 200 GeV, are suitable for the proposed QCD critical-point search and exploration of the QCD phase diagram at RHIC.

Experimental Study on the Exotic Structure of N-12 in RIBLL

We measured the total reaction cross sections of N-12 in Si at 36.2 MeV/u. using Radioactive Ion Beam Line in Lanzhou (RIBLL) with a new method. The reaction target was installed at the intermediate focusing point T1 at RIBLL. This scheme allows us to identify particles before and after the reaction target unambiguously. The total reaction cross section (1760 +/- 78mb) of N-12 in Si is obtained. Assuming that N-12 consists of a core C-11 plus one halo proton, the excitation function of N-12 on the Si and C targets is calculated with the Glauber model and the Fermi-Fermi density distributions. It can fit the experimental data very well. A large diffusion of the protons density distribution supports the halo structure for N-12.

Emittance estimation by an ion optical element with variable focusing strength and a viewing target

The emittance of an extracted ion beam can be estimated to first order by a series of three linear independent profile measurements. This estimation is restricted to the evaluation of an upper limit of the emittance value for a homogeneous, nonfilamented beam. The beam is assumed to be round, respectively elliptical, without any structure of the intensity distribution, no space charge has been assumed for the drifting beam, and the optics is assumed to be linear. Instead of using three different drift sections, a linear focusing element with three different focusing strengths can be used. Plotting the beam radius as function of focusing strength, three independent solutions can be used to calculate the Twiss parameters alpha, beta, and gamma and furthermore the emittance epsilon. Here we describe the measurements which have been performed with the SECRAL ion source at Institute of Modern Physics Lanzhou.

Dissociative recombination of the acetaldehyde cation, CH3CHO+

The dissociative recombination of the acetaldehyde cation, CH3CHO+, has been investigated at the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory in Stockholm, Sweden. The dependence of the absolute cross section of the reaction on the relative kinetic energy has been determined and a thermal rate coefficient of k(T) = (1.5 +/- 0.2) x 10(-6) (T/300)(-0.70 +/- 0.02) cm(3) s(-1) has been deduced, which is valid for electron temperatures between similar to 10 and 1000 K. The branching fractions of the reaction were studied at similar to 0 eV relative kinetic energy and we found that breaking one of the bonds between two of the heavy atoms occurs in 72 +/- 2% of the reactions. In the remaining events the three heavy atoms stay in the same product fragment. While the branching fractions are fairly similar to the results from an earlier investigation into the dissociative recombination of the fully deuterated acetaldehyde cation, CD3CDO+, the thermal rate coefficient is somewhat larger for CH3CHO+. Astrochemical implications of the results are discussed.

Nuclear physics program at HIRFL

With the commissioning of HIRFL-CSR, HIRFL can provide heavy ion beams with energy covering the range of several MeV/u to 1 GeV/u. In this talk, the experiments on nuclear physics at different energies to be carried out with different experimental setups at HIRFL will be introduced.

Some Superconducting Magnets at IMP

Some superconducting magnets research at IMP (Institute of Modern Physics, CAS, Lanzhou) will be described in this paper. Firstly, a superconducting electron cyclotron resonance ion source (SECRAL) was successfully built to produce intense beams of highly charged heavy ions for Heavy Ion Research Facility in Lanzhou (HIRFL). An innovation design of SECRAL is that the three axial solenoid coils are located inside of a sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. Some excellent results of ion beam intensity have been produced and SECRAL has been put into operation to provide highly charged ion beams for HIRFL since May 2007. Secondly, a super-ferric dipole prototype of FAIR Super-FRS is being built by FCG (FAIR China Group) in cooperation with GSI. Its superconducting coils and cryostat is made and tested in the Institute of Plasma Physics (IPP, Hefei), and it more 50 tons laminated yoke was made in IMP. This super-ferric dipole static magnetic field was measured in IMP, it reach to the design requirement, ramping field and other tests will be done in the future. Thirdly, a 3 T superconducting homogenous magnetic field solenoid with a 70 mm warm bore has been developed to calibrate Hall sensor, some testing results is reported. And a penning trap system called LPT (Lanzhou Penning Trap) is now being developed for precise mass measurements.

DISSOCIATIVE RECOMBINATION OF PROTONATED PROPIONITRILE, CH3CH2CNH+: IMPLICATIONS FOR TITAN'S UPPER ATMOSPHERE

The dissociative recombination of protonated propionitrile, CH3CH2CNH+, has been investigated at the heavy ion storage ring, CRYRING, at the Manne Siegbahn Laboratory, Stockholm University, Sweden. The thermal rate coefficient has been deduced to follow k(T) = (1.5 +/- 0.2) x 10(-6) (T/300)(-0.76) (+/-) (0.02) cm(3) s(-1) for electron temperatures ranging from similar to 10 to similar to 1000 K. Measurements of the branching fractions were performed at similar to 0 eV relative kinetic energy. It has been found that in 43% +/- 2% of the reactions the four heavy atoms remain in the same product fragment. An equal portion of the reactions leads to products where one of the heavy atoms is split off from the other three and 14% +/- 1% result in a breakup into two heavy fragments containing two heavy atoms each. We discuss the significance of the data to Titan's upper atmosphere.

深层治癌束运线极高、超高真空系统

本论文根据已有的设计方案及图纸，验证设计方案的可行性。主要内容如下：第一，根据公式估算深层治癌束运线各段的真空度，并用VAKTRAK程序模拟出压力分布曲线；第二，运用ANSYS程序对烘烤段各真空管道，尤其是盒形真空室（二极铁真空室）进行力学分析，验证设计尺寸是否可行；第三，根据力学分析，确定超薄壁拱形真空管道的波宽和波高，能够满足使用要求。第四，参考德国GSI有关资料，对膜窗材料进行了计算和验证，并成功的运用到实际中去。 目前，深层治癌束运线真空系统已经安装完毕，经过抽空、检漏，各元件均已达到设计要求，非烘烤段的真空度已达标，烘烤段已达到烘烤前应有的真空度，现正在安装烘烤外套及烘烤控制装置

重离子治癌装置的束流位置控制系统

近代物理所依托兰州重离子冷却储存环（HIRFL-CSR）开展重离子治癌研究。在重离子治癌过程中，需要对束流位置十分精确的控制。本文实现了精确控制重离子束对肿瘤实现三维适形扫描。 对肿瘤切片方向定位采用主动磁扫描方式，通过控制X、Y 扫描铁电源实现束流对肿瘤一层切片中各点的扫描，在治疗过程中需要实现位置变化与辐照剂量的联动。为满足束流位置切换时扫描铁电源的阶跃响应过程，采用了一种新的加速器电源控制方式，通过控制频率变化实现扫描铁电源阶跃响应过程。该方法具有精度高、参数少、响应速度快和实时性好的特点。本文提出了扫描铁电源电压控制的数学模型和实现结构，通过FPGA+DSP+DDS的硬件平台实现该电源控制方法。最终完成了对扫描铁电源高精度的控制。 肿瘤深度方向定位实质上是重离子束流Bragg峰的定位。Bragg峰与束流能量的关系要求重离子束在不同能量间切换，因而需要加速器实现变能加速。本文设计完成了适应变能加速的高频控制器，介绍了高频控制器实现方法，从而满足不同深度肿瘤切片对束流能量的要求。 核心及创新点：(1)实现重离子治癌过程中束流位置和剂量的联动; (2)基于频率调节的扫描铁电源控制器; (3)满足变能加速的高频控制器 从现场的测试和应用结果表明位置控制系统达到了设计要求

GeV能区重离子碰撞中碎片的形成和核穿透效应

分析了从0.4至1.2GeV/u 的Ni+Ni和Pb+Pb重离子碰撞过程中的径向流，核穿透等动力学现象及其对碎片形成的影响，得出如下结果： 实验结果发现，从出射粒子的快度分布可以看出，越重的粒子产额越小，且较容易出现在弹靶核快度区域，并且系统越重越有利于碎片的形成。不同快度区间的出射粒子的平均质量数可以说明，碎片不仅来自于弹靶核的碎裂，同时“火球”区域的轻核子凝聚也是一重要来源，对于不同的系统和不同的入射能量，两者的贡献不同。在某一入射能量的某一碰撞系统，不同质量数的粒子的产额随质量数满足很好的指数下降的关系，其斜率随快度绝对值的变化与系统质量相关，……，说明重碎片可能来自弹靶核的碎裂，而随着系统质量的增加，“火球”区域的轻核子凝聚变得越来越重要。 根据冲击波模型假设的出射粒子的平均动能随粒子的质量数的线性变化关系，提取出径向流，发现径向流随入射能量的增高而增高，并且系统越重，径向流越明显。并且发现出射粒子的横向快度分布比纵向快度分布窄，说明碰撞过程中存在部分穿透，并且穿透对系统的大小和入射能量有很强的依赖关系，经“Vartl”定量的描述，发现随着入射能量升高系统的变轻，穿透现象越明显，并且发现径向流与核阻止有很明显的关联关系。 经过理论结果与实验结果的对比，可以发现例如径向流、核穿透等动力学因素对碎片的形成有很明显的影响。同时为提取核物质状态方程（EOS）提供了有用的数据

低剂量12C6+辐射对小鼠免疫系统损伤和抗氧化剂氮乙酰半胱氨酸的保护作用研究

实验目的：随着科技的发展，人类活动范围已经逐渐向外太空扩展，对于人类太空探索的最大威胁是太空中的各种粒子辐射。这些辐射包括太阳辐射（质子和电子）和银河辐射（质子占85%，氦离子占14%，重离子占1%）。众所周知，重离子与常规X和γ射线相比有较高的传能线密度（linear energy transfer, LET）和相对生物学效应（relative biological effectiveness, RBE），对机体组织和器官有较强的影响。放射治疗是肿瘤治疗的重要手段之一，由于肿瘤细胞的异质性，其对放、化疗的反应相差悬殊。本研究的目的是： 1评估辐射对健康机体产生的生物学风险； 2研究抗氧化剂氮乙酰半胱氨酸（NAC）对机体辐射损伤的保护作用 3不同肿瘤细胞辐射敏感性的差异。实验方法： 1 X射线或12C6+离子对小鼠进行不同剂量的全身辐射。NAC处理组小鼠在照射前1小时腹腔注射200mg/kg的NAC，对照组注射等体积的生理盐水。照射后不同时间点取样，利用流式细胞仪检测小鼠免疫细胞周期和凋亡情况，单细胞电泳检测淋巴细胞DNA损伤，MTT法（3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide）检测脾脏NK（natural killer，NK）细胞活性，微核法检测淋巴细胞染色体损伤情况，小鼠体内干扰素－γ（Interferon-γ，IFN-γ）由ELISA方法得到，小鼠血清中超氧化物岐化酶(Surperoxide dismutase SOD）由分光光度法测定，并观察胸腺和脾脏指数变化。 2 不同剂量X射线和12C6+离子辐射人肺腺癌细胞H1299和A549，用细胞克隆法检测照射后细胞存活曲线，流式细胞仪检测细胞周期和凋亡，Western-blot 检测A549 细胞P53蛋白表达。 结果： 1小鼠外周血淋巴细胞、胸腺细胞和脾脏淋巴细胞周期随着X射线照射剂量的增大而被阻滞在了G0/G1期，相同剂量的12C6+离子辐射时外周血淋巴细胞周期被阻滞在S期，分次连续X射线照射时，外周血淋巴细胞周期随着累积剂量的增加被阻滞在G2/M期；细胞凋亡比例随着照射剂量的增加而增加。小鼠血清中IFN-γ水平和脾脏中NK细胞活性在重离子照射剂量为0.05Gy时有显著增加，脾脏NK细胞活性随着照射剂量的增加而减弱。 2重离子照射后，小鼠淋巴细胞DNA和染色体的损伤随辐射剂量和照射后时间的延长而加剧。脾脏NK细胞活性在照射后各个时间点减弱，血清中IFN-γ水平和SOD酶活性随着重离子照射剂量的增加而降低。预防性给予NAC，12C6+离子辐射对淋巴细胞DNA和染色体所致损伤，胸腺细胞周期和凋亡，脾脏NK细胞活性，血清中IFN-γ的水平和SOD酶的活性的损伤与盐水组比较均有显著改善。 3 X射线照射对肺腺癌H1299细胞周期和凋亡率未产生明显影响，重离子照射后随着照射剂量的增加细胞周期被阻滞在G2/M期，细胞凋亡率也呈剂量依赖性；X射线和12C6+离子照射A549细胞后，细胞周期均被阻滞在G2/M期，凋亡率剂量依赖性增加。A549细胞P53蛋白的表达水平随着重离子照射剂量的增加而增加。结论： 1重离子辐射造成细胞DNA和染色体损伤随着照射剂量的增加和照射后时间的延长而增加，比X射线辐射损伤复杂和难以修复，产生这种现象的机理为辐射导致活性氧分子簇的产生，细胞因子和与细胞氧化反应有关的酶活性的变化，同时这种损伤对胸腺细胞周期、凋亡和胸腺、脾脏指数以及机体免疫系统都有影响；低剂量重离子辐射（0.05Gy）对小鼠机体的免疫力有刺激作用，机体免疫能力随着照射剂量增加和照射后时间的推移而减弱，不同的免疫器官对辐射的敏感性也不同； 2 200mg/kg 的NAC对辐射所致小鼠免疫系统损伤有很好的保护作用； 3 肺腺癌细胞H1299比同系A549具有较强的辐射敏感性，A549细胞凋亡的增加与P53蛋白表达水平升高有关

一氧化氮介导的神经胶质瘤细胞对重离子辐射抗性及动物实验降能装置设计

目的：１、研究一氧化氮(NO)介导的神经胶质瘤细胞对重离子辐射抗性；２、研究小鼠大脑受重离子辐照后的损伤修复；３、为了更好的研究小鼠大脑受重离子布拉格（Bragg）峰区辐照后的损伤修复，设计并制造了旋转轮状降能装置。材料与方法：１、采用兰州重离子研究装置（HIRFL）加速的碳离子束辐照人类神经胶质瘤三种基因型细胞株：野生型神经胶质瘤细胞（A172），带绿色荧光蛋白基因的神经胶质瘤细胞（EA172）和带诱导型一氧化氮合酶基因（iNOS）的神经胶质瘤细胞（iA172），以及一种加了一氧化氮合酶抑制剂（L-NAME）的A172细胞（L-NAME-A172）。分别利用化学法、流式细胞术和MTT法检测三种神经胶质瘤细胞中NO、谷胱甘肽（GSH）的含量，以及它们的细胞周期变化和辐照后存活状况。２、利用不同剂量的碳离子束辐照昆明小鼠全脑，采用八臂迷宫检测随时间推移及训练次数的增加小鼠记忆损伤恢复情况。３、采用蒙特卡罗法和模拟退火法设计制造了一个有机玻璃材料的旋转降能装置。结果：1、NO和GSH在iA172细胞中的含量比A172和EA172中显著要高；辐照后24小时，观察到A172和EA172细胞发生周期阻滞即细胞阻滞于G2／M期，而这种现象没有在iA172细胞中观察到，并且iA172在接受同样辐射刺激后，细胞存活率显著高于其它三个细胞株。2、动物实验表明，在0－2Gy的碳离子辐照在短期内影响小鼠的记忆，经过一定时间后，这种影响得到恢复。3、物理实验显示，降能装置的实验数据与理论计算相符。结论：在低剂量的重离子坪区辐射条件下，一定浓度的NO可以使神经胶质瘤细胞产生辐射抗性。低剂量的重离子辐射致脑损伤可以得到很快的修复

中能重离子碰撞中的同位旋效应及非对称核物质的状态方程研究

本论文介绍了放射性核束物理研究的现状以及当前常用的几种同位旋相关的重离子微观输运理论，系统描述了非对称核物质的状态方程、中能重离子碰撞中的同位旋效应以及中子星的性质。基于 Hartree-Fock 理论和扩展的 Skyrme 相互作用，在核物质近似下得到了一个非相对论性的密度、温度和同位旋相关的核物质状态方程 (IEOS)。系统研究了核物质状态方程的同位旋效应。讨论了核子的平均场、核物质的不可压缩系数、核子的有效质量以及核物质临界温度的同位旋相关性，并且给出了核物质饱笔点处的饱和密度、不可压缩系数以及单核子结合能的抛物线规律。同时，探讨了对称能的温度和密度相关性，给出了零温度时对称能的解析表达式，并提出了对称能温度相关性的抛物线规律，发现对称能随着温度的升高而减小。另外，基于以上的同位旋相关的核物质状态方程，对 ALADIN's Caloric Curve 给出了一种静态解释。在传统量子分子动力学 (QMD) 模型的基础上，通过在相互作用平均场、两体碰撞、泡利阻塞、初始化以及碎片构造过程中适当地考虑同位旋自由度，得到了一个同位旋相关的 QMD 模型 (IQMD 模型)。利用IQMD模型系统研究了中能重离子碰撞中的同位旋效应。例如，中能重离子碰撞中同位旋自由度的弛豫、重离子碰撞中核子前平衡发射的同位旋效应、重离子碰撞中的集体流（包括直接流、转动流、挤出流和径向流）及其同位旋相关性、原子核多重碎裂的同位旋效应及其消失、重离子碰撞中的化学不稳定性以及中能重离子碰撞中如何选取事件的碰撞参数及其同位旋效应等。同样，在传统的 Boltzmann-Langevin 方程中适当地考虑同位旋自由度，得到了同位旋相关的Boltzmann-Langevin方程 (IBLE)，利用IBLE研究了 ~(19)Na的产生截面。另外，利用IQMD模型探讨了多重碎裂的"neck" 机制以及重离子碰撞中局域势的有限程效应。基于前面给出的非相对论的核物质状态方程，系统研究了中子星的性质，如中子星的化学组份、质量、结合能、半径、密度剖面、转动惯量及表面红移等。结果表明，使用一些常用的 Skyrme 势参数能够给出与天文学观测相一致的结果。