2013年 第30卷 第2期
对于近年来清华大学与美国合作研究组在原子核结构实验研究中有关奇A 核的多声子 振动带方面的进展进行了评述。研究人员通过有效的国际合作，识别了质量数A = 100 丰中子核区的奇A核103Nb，105Mo，107Tc 和109Tc中的两声子 振动带，这是迄今为止国际上在奇A 核的结构研究中发现的仅有的4 例这样的结构。对于实验方法、研究结果以及这些多声子 振动带的特性进行了评述，并对目前在多声子带其他方面的研究及今后进一步的工作进行了概述。The experimental research on multi-phonon γ-vibrational bands in odd-A nuclei by our international collaboration has been reviewed. The two phonon -vibrational bands in 103Nb, 105Mo, 107Tc and 109Tc in the A = 100 neutron-rich nuclear region were identified, which are the only four such bands discovered in nuclear structure studies until now. The experimental methods and results are summarized, and the characteristics for these band structures are discussed. The other aspects for our research on the multi-phonon vibrational bands as well as our future research work are also briefly reviewed.
通过CR-39 核径迹探测器对471 AMeV 56Fe 和400 AMeV 20Ne 诱发Al，C 和CH2 靶反应的弹核碎裂反应截面及出射角度进行了测量，并利用改进的量子分子动力学(ImQMD) 模型和描述统计衰变的GEMINI 模型对实验结果进行了分析和讨论。实验结果表明，总反应截面与弹核的能量无关，但随着靶核质量的增加而增加。这与其他的实验结果以及Bradt-Peters 的半经验理论公式所得结果一致。理论计算和实验测量结果中，分截面出现了明显的奇偶效应。理论计算结果表明，奇偶效应主要产生于受激碎块的衰变过程，其中对效应起着重要作用，而且，主要形成于擦边碰撞的反应中且多来自于同位旋为TZ = 0; ±0:5 的弹核碎块的贡献。产生碎块的同位素分布与弹核的种类有关，与入射能量和靶核的种类没有太大依赖性，其较小的偏转角大部分来自于擦边碰撞产生的较重的类弹碎块的贡献。We have measured the fragmentation cross sections and the emission angles for 471 AMeV 56Fe and 400AMeV 20Ne on Al, C and CH2 targets using CR-39 plastic nuclear track detector. The total charge changing cross sections agree well with other previous experimental results at different energies and the theoretical prediction of Bradt-Peters semiempirical formula, which are pproximately independent of the beam energy but increase with the increase of the target mass. The experimental results are compared with the prediction of the improved quantum molecular dynamical model (ImQMD) together with the GEMINI model. The odd-even effect of the partial cross sections observed in experiments is well produced. It is found that such effect is mainly formed in the grazing collisions and comes from the fragments with TZ = 0; ±0:5. The shape of the isotopic distribution is independent on the target mass and the incident energy but the projectile mass and charge, and the small angular distribution of all fragments comes from the heavier projectile-like fragments which produced in the peripheral collision.
实验测量了7Li+11B 体系的弹性散射角分布，其中弹核7Li 的入射能量分别为9.85，13.3，18.3，23.3 和28.3 MeV，测量的角度范围为θc:m: ≈ 15◦ ∼ 80◦。通过对本次实验数据以及文献中34 MeV 的数据拟合，抽取了该体系的唯象光学势参数。结果表明，在固定作用势形状因子下，势深度与能量具有线性相依的关系：实部深度随着弹核能量的增加而线性减小，而虚部深度则在平均值10.35 MeV 附近变化。Angular distributions of 7Li+11B elastic scattering were measured at Elab(7Li)=9.85, 13.3, 18.3, 23.3 and 28.3 MeV within the angular range of θc:m: ≈ 15◦ s 80◦. The analyse of these angular distributions together with the data taken from literatures at Elab(7Li) = 34 MeV have been performed to extract the parameters of optical model potential. With the fixed geometrical shapes, the potential strengths show a concise relation to the reaction energy: the depths of real potential decrease linearly with energy increasing, whereas the depths of imaginary part just slightly vary around the average value of 10.35 MeV.
重离子核反应中的碎片发射机制是近年来人们十分关注的研究课题。利用ΔE-E 探测器，测量了~6 MeV/u 的19F+27Al 反应中核电荷数Z = 2 ~13 的出射碎片。对产物的能谱、角分布、激发函数及能量自关联函数的分析表明，出射产物主要来自弹靶核深部非弹性碰撞所形成的转动的双核系统。In recent years, extensive studies have been made to understand the fragment emission mechanisms in low energy light heavy-ion reactions. These fragments are found to be emitted from quasielastic/projectile breakup, deep-inelastic and fusion-fission processes. Fragments of Z = 2~13 induced by the collision of 19F+27Al have been measured by ΔE-E telescope. The analysis of the energy spectra, angular distributions, excitation functions and energy auto-correlation functions of these fragments shows that the emission of fragments is coming from a rotational dinuclear system formed in the dissipative collision of the projectile and target nuclei.
以双层系统的ZHK 模型为基础，研究了双层量子霍尔系统在朗道填充因子取υ = 1=2 这种状态的静态涡流解。ZHK模型是一种包含Chern-Simons 规范相互作用的有效理论。为了简便，假定涡流具有柱对称的结构，随后写出了无量纲的非线性运动方程组，并分析了解的渐进行为。另外，在自对偶条件下，确定了自耦合常数的形式，并写出了关于密度的自对偶方程。最后，使用数值方法找到了类型分别为(0,1)，(0, -1)，(1,-1) 和(-1,-1) 的涡流解。发现拓扑数为(1,-1) 的涡流是不稳定的,它会衰变为(1,0) 和(0,-1) 两种涡流。数值结果表明，拓扑数为(0,-1)和(-1,-1)的涡流确实是自对偶涡流解。We investigate the static vortex solutions of a bilayer quantum Hall state at the Landau-level filling factor υ = 1=2. This work is based on the ZHK model, which is an effective field theory including Chern-Simons gauge interactions. We deduce the dimensionless nonlinear equations of motion for vortices possessing cylindrically symmetry, and analyze the asymptotical behaviors of solutions. Additionally, we analyze the values of critical coupling constants under the self-dual condition, and obtain the self-dual equations. Finally, vortices of type (0,1)，(0, -1)，(1,-1) and (-1,-1) are solved with numerical methods. We reach the conclusion that vortex of type (11,-1) is unstable, which will decay to (1,0) and (0,-1). The vortices of type (0,-1) and (-1,-1) are self-dual solutions from numerical results.
由于束流的传输效率对射频四极场加速器(RFQ) 中射频场的分布极其敏感，所以在RFQ 的运行过程中不再采用传统的调谐器调谐RFQ。水冷调谐的方法基本上不影响RFQ 射频场的分布，所以适用于RFQ 的调谐。中国科学院高能物理研究所为C-ADS、CSNS 预研RFQ 项目开发建造了一套水冷调谐系统，使用RF 相位差作为控制量进行RFQ 水冷调谐，相位差的控制精度达到了1°运行结果显示该系统满足了RFQ 的调谐需求。介绍了该系统的水冷系统、调谐控制系统和一些运行经验。Since the beam transmission of a Radio Frequency Quadrupole(RFQ) Accelerator is very sensitive to the field profile, the ordinary frequency tuning method by the local movable tuner is no more adopted in an RFQ operation. The tuning method by controlling cooling water temperature is widely adopted to tune the RFQ due to the less affect on the RFQ field profile. A Resonance Control Cooling System (RCCS) is developed and commissioned for the 973 RFQ，which is a R&D project for C-ADS and CSNS RFQ at IHEP. This system adopts the RF phase difference as control variable to tune the RFQ. The control accuracy of the RF phase difference is about 1°. The running of the 973 RFQ shows that the RCCS works very well and fully satisfies the operation requirement of the RFQ. In this paper, the water skid, resonance control system of the RCCS and the operation experiences will be presented.
为了提高强流ECR 离子源的引出束流品质，分别设计了1# 和2# 引出系统，利用束流引出模拟软件PBGUNS 对1# 和2# 引出系统进行了质子束流引出与传输的模拟计算，结合实际测得的发射度数据分析引出系统，发现2# 引出系统比1# 引出系统引出束流品质高。对ECR 离子源引出系统的电势等位线分布等参数引起的球差进行了简单数学推导及MATLAB 绘图，并结合1# 和2# 引出系统束流相图模拟结果证明了球差会使引出束流品质有效发射度增长，通过适当加大电极孔径可改善束流聚焦情况，得到了束流光学聚焦较好的束流引出系统设计。To improve the quality of extracted ion beam from a high current ECR ion source, 1# and 2# extraction systems were designed and tested. The PBGUNS code was used to simulate the 1# and 2# extraction systems of proton ion beam. The emittance measurement results with the two different extraction systems were compared and analyzed with the simulation, the conclusion that more high quality beam extracted from 2# system than 1# system was got. The formula derivation of ECR ion source extraction system spherical aberration and MATLAB drawing was done by the analyzing on the distribution of extraction field equipotentials, effective emittance increasing caused by spherical berration was proved by 1# and 2# extraction systems beam phase space simulation result, beam focusing would be improved if electrode hole size increasing appropriately and a general concept on good optics focusing of ion beam extraction system was proposed finally.
基于CST 微波工程软件对四杆型RFQ 的模拟运算，分析了在不同情况下不同的RFQ 结构参数σ/R与电极最大表面电场Emax 之间的关系，发现对应于不同RFQ 孔径下的最小的Emax，其结构参数σ/R 的值是不同的。同时发现改变σ/R，RFQ极间电场线性度始终保持在99.5% 以上，但σ/R 变大会微幅提升极间电场线性度。Based on the simulation on 4-rods RFQ by the CST MWS software, we analyzed the relationship between the RFQ’s structure parameter σ/R and the maximum electrode field Emax, and found that as the aperture R varies，the value of σ/R corresponding to the minimum Emax does not necessarily keep constant. We also found that the RFQ interelectrode field linearity maintains over 99.5% as σ/R veries, although it slightly increases as σ/R increases.
根据D-D 反应中子的能谱和角分布数据，建立了中子源模型；根据石灰岩地层标准刻度井群数据，建立了井模型。采用MCNP 程序模拟了井中中子和γ 射线的输运，得到了不同地层密度和不同源距处NaI 探测器中的混合γ 射线能谱和非弹γ 射线能谱。在混合γ 射线能谱2.5~5.0 MeV 能区开窗，研究了开窗区混合γ 射线相对计数随源距的变化关系，确定源距应选择在30~80 cm 范围，给出了密度与混合γ 射线计数之间的非线性关系。研究表明，可以利用D-D中子源的混合γ 射线能谱来实现n-γ 密度测井。A D-D neutron source model was developed according to the neutron spectrum and the neutron angular distribution of D-D reaction. A standard calibration well model was built. The transports of the D-D neutrons and γ-rays in the well were simulated using MCNP code. The mixed γ-spectra and inelastic γ-spectra in the NaI detector were obtained for both different distances from a neutron source and different densities. Mixed γ count in the energy range of 2.5 to 5.0 MeV as a function of distance shows that the NaI detector should be located at a distance of 3080 cm from the neutron source. The nonlinear relationships between the density and the mixed γ count were presented in this paper.
It was demonstrated that the energy spectrum of mixed γ rays can realize the n-γ density logging.
为了精确测量keV能区的中子俘获截面，中国原子能科学研究院正在建造一台4π 全吸收型γ 探测装置---GTAF，锂玻璃探测器将会作为中子束流监视器测量中子能谱。利用5SDH-2 加速器刻度了锂玻璃探测器在两个入射中子单能点(250 和565 keV) 的探测效率，并使用EANT4 和MCNP 程序模拟计算了锂玻璃探测器的相对探测效率。通过归一化实验数据和模拟结果，得到了锂玻璃探测器在10keV~1 MeV 能区的中子探测效率曲线。对于把锂玻璃探测器测量得到的飞行时间谱转化为中子束流能谱，是一项非常重要的工作，同时为探测器效率刻度提供了新方法。In order to accurately measure the neutron capture cross section in the energy range of keVMeV, 4 πgamma-ray total absorption facility (GTAF) is being constructed at China Institute of Atomic Energy (CIAE). The lithium glass detector will be used as a neutron beam monitor for GTAF. The detection efficiency of the lithium glass detector at two incident neutron energy points (250, 565 keV) was calibrated in 5SDH-2 accelerator, and the relative detection efficiency was simulated by GEANT4 and MCNP code. By the normalization of the experimental data and simulation result, the neutron detection efficiency curve of the lithium glass detector between 10 keV and 1 MeV was obtained. This work will be important to convert the Time-of-flight spectrum that be measured by Li-glass detector to the energy spectrum of neutron beam, and provide the new method for calibration of detection efficiency.
加速器质谱(AMS) 由于其极高的测量灵敏度而广泛应用于核科学、生命科学、地球科学、环境科学和考古学等研究领域，同时，AMS还可以用来分析样品中的微量核素，是核科学领域的重要研究工具。目前，AMS研究的最新领域是U和Pu 等锕系元素的测量，在核保障、核监测及核试验沉降物示踪大气输运和表面沉积物的迁移等研究中也显示出了较大潜力。综述了AMS在核科学研究中的应用及研究现状，主要包括AMS在放射性核素半衰期的测定、核反应截面的测量等方面的研究进展。Accelerator mass spectrometry (AMS) is a promising method to provide extreme sensitivity measurements of the production yields of long-lived radioisotopes, which cannot be detected by other methods. AMS technique plays an important role in the research of nuclear physics, as well as the application field of AMS covered nuclear science and technology, life science, earth science, environmental science, archaeology etc. The newest AMS field is that of actinide, particularly U and Pu, isotopic assay with expanding applications in nuclear safeguards and monitoring, and as a modern bomb-fallout tracer for atmospheric transport and surface sediment movement. This paper reviews the applications of AMS in the research of nuclear energy and nuclear security including the research of half life of radionuclides, cross section of nuclear reaction.
文章综述了重离子束在物理学、生物学、临床治疗等方面的优势，以及在放射生物学方面的基础实验研究内容。分析总结了国内外重离子束辐照治疗肿瘤的临床研究结果。其中，日本已接受治疗了约6 000 名不同类型的肿瘤患者，并取得较高的局部控制率和生存率；德国在头颈部肿瘤临床治疗方面取得了巨大的成功；在兰州重离子研究装置(HIRFL) 肿瘤治疗终端上，中国科学院近代物理研究所联合甘肃省肿瘤医院及兰州军区总医院对肿瘤患者的重离子治疗已进入临床试验阶段。甘肃省肿瘤医院治疗结果显示：43 例患者通过影像学检查评价疗效，客观有效率(CR+PR)为71.4%,主要急性放射损伤为1-2 级皮肤反应(红斑形成和脱皮)，发生率为61.9%，治疗1 个月后随访结果显示重离子束(12C6+)对深部肿瘤具有较好的局部控制作用，且无严重不良反应发生。This article reviews the advantages of heavy ion in physical, biological and clinical aspects, discusses the radio-biological basis of experiment research, and summarizes clinical results of heavy ion beam treatment on tumor at home and abroad. Japan has accepted and treated about 6000 cancer patients of different types with high local control rates and survival ones. Germany has achieved great success in head and neck tumor clinical treatment. Institute of Modern Physics, Chinese Academy of Sciences (IMP-CAS), Tumor Hospital of Gansu Province and Lanzhou General Hospital of PLA have begun clinical trial on heavy ion treatment of deep-seated tumors after the shallow-seated tumor therapy has been done at HIRFL (Heavy Ion Research Facility in Lanzhou). The treatment results of Tumor Hospital of Gansu Province show that the objective response rate (CR+PR) is 71.4% and the rate of 1-2 levels radiation injury to skin reactions (erythema and desquamation) is 61.9% when we evaluate the 43 patients by means of maging. The results of case follow-up after treatment in 1 month indicate that the deep-seated tumor therapy with heavy ion beam has high local control rates without severe adverse effect.
相对于被动式束流配送系统，由患者呼吸因素而引起的肿瘤靶区运动会对主动式束流配送系统下的离子束放射治疗带来非常严重的影响，造成离子束辐射场剂量分布的严重畸变，甚至对肿瘤靶区周围的健康组织造成严重损伤，很大程度上影响离子束治疗的疗效。因此，在主动式束流配送系统下，建立针对由呼吸因素引起的运动肿瘤靶区的适形调强照射方法就显得必要，且具有重要意义。系统介绍了呼吸运动探测、4D-CT 以及目前主要的3 种运动补偿方法(多次扫描、呼吸门控和主动跟踪技术)，并对这3 种方法在靶区适形度、稳健性以及技术复杂度等方面进行了比较。在靶区适形度方面主动跟踪技术优于门控技术，而门控技术又优于多次扫描技术；在稳健性方面多次扫描技术优于门控技术，而门控技术优于主动跟踪技术；在技术复杂度方面，多次扫描技术最简单，其次是门控技术，而主动跟踪技术最复杂。Active beam scanning results in serious distortion of ion-beam irradiation field in the presence of target motion and causes damage to healthy tissues round tumor target compared to passive beam shaping techniques. Therefore,it is necessary to establish suitable conformal irradiation methods for moving targets caused by the factor such as respiration in active ion beam scanning system. In this paper, motion detection, 4D-CT and three main ion beam specific mitigation techniques, namely rescanning, gating and beam tracking, are introduced. In addition, three motion mitigation techniques are compared comprehensively in terms of target conformation, robustness and mplementation complexity,respectively. For target conformation, the beam tracking is superior to gating, and gating is better than beam rescanning;the robustness decreases in the order rescanning-gating-beam tracking; for implementation complexity, beam rescanning is the most simple technology, followed by gating, while beam tracking is the most complex technique.
利用兰州重离子研究装置(HIRFL) 提供的高能12C6+离子束(能量为300 MeV/u，剂量率为0.5 Gy/min) 辐照大鼠离体胸主动脉环，考察了12C6+离子束辐照对主动脉环内皮依赖性舒张功能的影响，并采用NBT 还原法测定血管环生成超氧阴离子(O2􀀀) 水平，加入外源性超氧化物歧化酶(SOD) 干预探讨了O2􀀀在内皮功能损伤中的作用。研究结果表明，2.0，4.0 和6.0 Gy 的12C6+离子束辐照大鼠胸主动脉环后，可致血管内皮依赖性舒张功能的剂量依赖性明显受损(P <0.01 vs control group)，并可致血管环NBT 还原能力剂量依赖性增加(4.0 Gy 时，P <0.05；6.0 Gy 时，P <0.01 vs control group)。辐照前加入外源性SOD 对6.0 Gy 12C6+离子束辐照所致血管环NBT 还原能力升高有明显抑制作用(P <0.01)，对血管环内皮依赖性舒张功能也有明显的保护作用(P<0.01)，但辐照后10 min 加入外源性SOD，其保护作用明显不及前者。结论显示，12C6+ 离子束辐照大鼠胸主动脉环可致血管内皮功能受损，O2 清除剂SOD 对内皮功能受损有保护作用，说明O2􀀀介导了辐照所致内皮功能损伤。Heavy ion beam has many characteristics，and it is expected to be the most suitable radiation therapy technique for malignant tumor. It is lack of depth-understanding on the potential adverse reactions caused by using this technique, because heavy ion radiotherapy is applied to clinical for a short time. Studies have shown that the vascular injury plays a pivotal role in normal tissue damage induced in the conventional radiation therapy, but there was no research report on heavy ion beam irradiation-induced vascular injury. In the present study, the isolated aortic rings of rats were irradiated by 12C6+ ion beam (300 MeV/u, 0.5 Gy/min) delivered by HIRFL(Heavy Ion Research Facility in Lanzhou), the effects of 12C6+ ion beam irradiation on aortic rings with endothelium dependent diastolic function have been investigated.NBT reduction method was used for assaying the vascular ring formation of superoxide anion (O2􀀀) level, and the involvement of superoxide anion in endothelial function injury in rats was investigated through the intervention test of exogenous superoxide dismutase (SOD) on O2. The results showed that, the vascular endothelial dependent vasodilation was impaired significantly (P < 0:01 vs control group) by irradiation with 2.0, 4.0 and 6.0 Gy 12C6+ ion beam in a dosedependent manner, and the NBT reduction of vascular rings increased dose-dependently (P <0.05 at 4.0 Gy, P <0.01 at 6.0 Gy vs control group). Adding exogenous SOD before irradiation could significantly inhibit the increasing of NBT reduction (P<0.01), and also had protective effect on vascular endothelium dependent diastolic function (P<0.01), but 10 min after irradiation with exogenous SOD, its protective function was significantly less than before. Conclusion indicated that 12C6+ ion beam irradiation could cause endothelial function impaired, O2􀀀 scavenger SOD has a protective effect on endothelial dysfunction, suggesting that O2􀀀 mediates endothelial injury induced by heavy ion irradiation.
早幼粒细胞白血病(PML) 蛋白通过异构体聚合形成核体(PML-NBs)，在自然免疫、血管生成和转录调节等过程中发挥作用，并参与细胞凋亡和辐射应激响应。实验结果表明，在受到电离辐照等外界刺激后，PML蛋白的表达随着照射剂量的增加而增加，随着照射后的时间延长而上调；PML-NBs 的数量与照射剂量呈正相关，但PML-NBs 的荧光强度却与照射剂量呈负相关。同时还发现，PML的表达水平呈细胞周期依赖性，在G1 期和S 期细胞中的表达高，在G2 期和M期细胞中的表达相对低。鉴于PML 功能的重要性和多样性，结合PML 在电离辐照后的显著变化，推测PML 在细胞辐射应激过程中发挥重要的调节作用，深入研究PML功能有助于揭示细胞辐射生物效应的分子机理。Promyelocytic leukemia (PML) plays an important role in natural immune, angiogenesis, and transcriptional regulation. It also participates in apoptosis and other radiobiological effects. We confirm that the PML expression in G1 and S phase cells is relatively higher than that in M and G2 phase cells. We also demonstrate that the expression of PML protein is up-regulated in both dose- and time-dependent manner after cells are exposed to ionizing radiation. The size and amount of PML-nuclear bodies (PML-NBs) increase in a dose-dependent manner whereas the fluorescence intensity of PML-NBs decreases. Taken together, PML is sensitive to ionizing radiation and its functional studies are facilitated to reveal the mechanisms underlying radiobiological effects.
对12C6+ 离子辐照诱变高产阿维链霉菌株ZJAV-Y1-203 和原始菌株ZJAV-A-1 的摇瓶发酵pH 值、菌体浓度、碳源和氮源代谢进行了测定，研究了12C6+ 辐照对阿维链霉菌的代谢效应。在发酵前期(48h)，原始菌株发酵液pH 值低于突变菌株；在发酵96~196 h，诱变高产菌株ZJAV-Y1-203 繁殖快，生长旺盛，N的利用率高；菌体浓度大于原始菌株的浓度，且发酵液的pH 稳定，菌体处于代谢相对更稳定期；在发酵144~240 h，诱变高产菌株ZJAV-Y1-203 对糖源消耗低于原始菌株ZJAV-A-1。这些结果表明，12C6+ 离子辐照对阿维链霉菌代谢影响有利于阿维菌素合成。pH value, mycelium concentration, carbon source and nitrogen metabolism in flask fermentation of the mutant high-producing strain ZJAV-Y1-203 and the original strain ZJAV-A1 have been investigated, in order to show the metabolic effect of avermitilis irradiated by ion beam of 12C6. In early stage (48 h) of the fermentation, pH value of the original fermentation was lower than that of the mutant strains. In 96~196 h of fermentation, the nitrogen utilization in the strains ZJAV-Y1-203 was higher than that in the original strains, its reproductive was fast, and its growing was vigorous. The mycelium concentration of ZJAV-Y1-203 was greater than the original strain, and the pH value of fermentation were stable, so its metabolism was relatively more stable. In 144240 h of fermentation, the strain ZJAV-Y1-203 on sugar consumption was less than the original strains. The effect of 12C6 ion irradiation on metabolism of Streptomyces avermitilis is conducive to the synthesis of avermectin.
利用12C6+离子诱变技术对面包酵母菌种进行诱变，得到一株粗蛋白含量达到55% 以上的菌株，借助Minitab16.0，采用Plackett-Burman 实验设计法及响应面分析法，对诱变后面包酵母菌发酵培养基的成分进行了优化，得到3 个最为显著的主要影响因子：葡萄糖、酵母抽提物和硫酸镁。利用最陡爬坡实验逼近最大响应区域后，利用Box-Behnken 实验设计及响应面分析法进行回归分析。通过求解回归方程，得到优化发酵的条件为，葡萄糖：11.03 g/L、酵母抽提物：6.53 g/L、硫酸镁：5.59 g/L。面包酵母生物量为4.84 g/L，相比未进行优化时的生物量提高了15%。A mutant bread yeast strain with high protein content of 55% was gained by use of 12C6+ ions. The MINITAB 16.0 software, Plackett-Burman experimental design and response surface methodology were applied to optimize the culture medium for the irradiated yeast. The most important three factors which influenced the culture results were identified as glucose, magnesium sulphate and yeast extract. The path of the steepest ascent was undertaken to approach the optimal region of the three significant factors. Box-Behnken design and response surface methodology were used for the regression analysis. Finally, the optimal fermentation conditions were identified as glucose 11.03 g/L, yeast extract 6.53 g/L and magnesium sulphate 5.59 g/L by the regression analysis. It was found that the biomass of the bread yeasts reached 4.84 g/L and increased by 15% compared to original conditions.
完成了不同注量或温度下100 keV 的He 离子注入高纯钨的实验，并利用纳米压痕技术测量了材料的微观力学性能。所有注入样品的纳米硬度值都高于未注入样品的纳米硬度值。对于室温注入样品，随着注量的增加，样品抗弹性变形能力下降；当注量不高于5x1017 ions/cm2 时，钨的纳米硬度峰值随着注量的增加而增加；注量为1x1018 ions/cm2 的钨样品的纳米硬度峰值反而降低。高温注入样品的抗弹性变形能力优于室温注入样品的抗弹性变形能力；随着注入温度的增加，样品的平均纳米硬度值和弹性模量略有下降。分析讨论了He 注入钨硬化和抗弹性形变能力降低的可能原因。Tungsten has been selected as divertor materials in fusion reactors because of its high thermal conductivity,high melting point, low expansion coefficient and high threshold energy for sputtering etc. The paper presents the hardening behaviour of high pure tungsten by 100 keV He+ with different fluences from 5x1016 ions/cm2 to 1x1018ions/cm2 at room temperature, and with fluence of 1x1018 ions/cm2 at higher temperatures (400, 600 and 800 °C). The microscopic mechanical properties of these samples were investigated by nano-indentation technology. The results show that all of the implanted samples harden obviously. The reason for hardening may be that defects of interstitial dislocation loops or dense helium bubbles etc induced by helium implantation obstacle the movement of dislocation. The peak nanohardness of the samples increased with the fluences increasing when the fluence is not more than 5x1017 ions/cm2, while the nano-hardness value of the implanted sample with the fluence of 1x1018 ions/cm2 decreases and the nano-hardness changes little in the region of 50 nm to 200 nm from surface. For all the implanted samples with 1x1018 ions/cm2 at higher temperatures, their nano-hardness values are similar, but show a trend of decrease with increasing temperature.The reason may be the decrease of the defects’ density during implantation at higher temperatures. In addition, the capability of resisting deformation for the implanted tungsten reduces with increasing fluence and increases a little at higher temperatures.
利用全相对论组态相互作用方法，详细研究了W44+ 离子从基组态3s23p63d104s2俘获一个电子形成双激发态(3s23p63d104s2)nln′l′(n = 4 ~ 6，n′= 4 ~7) 的双电子复合(DR) 过程。通过比较不同壳层电子激发的DR 速率系数，得知4s 电子激发和3d 电子激发的DR 速率系数分别在低温和中高温度时给出了主要贡献，得到了主要的电子激发DR通道。在1 eV~50 keV 温度范围内，计算了n = 4~18 的DR速率系数，并外推到了n= 100，得到总DR 速率系数。比较总DR 速率系数、三体复合(TBR) 以及辐射复合(RR) 速率系数，结果表明DR 速率系数在研究的温度范围内远大于TBR 和RR 速率系数，其将明显地影响ITER 等离子体的电离平衡和离化态布居。Based on the fully relativistic configuration interaction method, theoretical calculations are carried out to research the dielectronic recombination (DR) processes, in which W44+ ions in the ground state 3s23p63d104s2 trap an electron to form doubly excited states (3s23p63d104s2)nln’l’(n =4~6，n′= 4~7). The comparison of the DR rate coefficients of different shells shows that DR approach is as follow: the 4s subshell excitation dominates to DR at low temperature, but 3d subshell excitation attributes to DR at high temperature. Total DR rate coefficients from n=4~18 are evaluated directly, and the results are extrapolated up to n = 100 in the temperature range from 1 to 5×104 eV, and thus get the total DR rate coefficients. Compared total DR rate coefficients to three-body recombination (TBR) rate coefficients and radiative recombination (RR) rate coefficients, it showed that the total DR rate coefficients obviously significantly greater than other two recombination rate coefficients, and thus it obviously influence ionization equilibrium and ionization state population of ITER plasma.