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Cosmological equations and thermodynamics on apparent horizon in thick braneworld
No full textWe derive the generalized Friedmann equation governing the cosmological evolution inside the thick brane model in the presence of two curvature correction terms: a four-dimensional scalar curvature from induced gravity on the brane, and a five-dimensional Gauss-Bonnet curvature term. We find two effective four-dimensional reductions of the generalized Friedmann equation in some limits and demonstrate that the reductions but not the generalized Friedmann equation can be rewritten as the first law of equilibrium thermodynamics on the apparent horizon of thick braneworld
80keV N离子注入对ZnO薄膜结构的影响；Effects of 80 keV N-ion Implantation on Structures of ZnO Films
No full text室温下用80keVN离子注入ZnO薄膜样品,注量分别为5.01014,5.01015和5.01016ions/cm2,然后用X射线衍射和透射电镜技术对样品的结构特性进行了表征。实验结果表明,由高度(002)择优取向的致密柱状晶构成的薄膜中,注入5.0×1015ions/cm2时,观测到缺陷生成和局域无序化现象,但薄膜总体结构仍保持柱状晶和(002)择优取向;随着注量的增大,晶格常数c和压应力呈增大趋势。对注入N离子对ZnO薄膜结构特性的影响机理进行了简单的讨论
Neutron dose measurement in carbon ion radiation therapy at HIRFL (IMP)
No full textFor radiation protection purposes, the neutron dose in carbon ion radiation therapy at the HIRFL (Heavy Ion Research Facility in Lanzhou) was investigated. The neutron dose from primary C-12 ions with a specific energy of 100 MeV/u delivered from SSC was roughly measured with a standard Anderson-Broun rem-meter using a polyethylene target at various distances. The result shows that a maximum neutron dose contribution of 19 mSv in a typically surface tumor treatment was obtained, which is less than 1% of the planed heavy ion dose and is in reasonable agreement with other reports. Also the gamma-ray dose was measured in this experiment using a thermo luminescent detector
New development of advanced superconducting electron cyclotron resonance ion source SECRAL (invited)
No full textSuperconducting electron cyclotron resonance ion source with advance design in Lanzhou (SECRAL) is an 18-28 GHz fully superconducting electron cyclotron resonance (ECR) ion source dedicated for highly charged heavy ion beam production. SECRAL, with an innovative superconducting magnet structure of solenoid-inside-sextupole and at lower frequency and lower rf power operation, may open a new way for developing compact and reliable high performance superconducting ECR ion source. One of the recent highlights achieved at SECRAL is that some new record beam currents for very high charge states were produced by 18 GHz or 18+14.5 GHz double frequency heating, such as 1 e mu A of Xe-129(43+), 22 e mu A of Bi-209(41+), and 1.5 e mu A of Bi-209(50+). To further enhance the performance of SECRAL, a 24 GHz/7 kW gyrotron microwave generator was installed and SECRAL was tested at 24 GHz. Some promising and exciting results at 24 GHz with new record highly charged ion beam intensities were produced, such as 455 e mu A of Xe-129(27+) and 152 e mu A of Xe-129(30+), although the commissioning time was limited within 3-4 weeks and rf power only 3-4 kW. Bremsstrahlung measurements at 24 GHz show that x-ray is much stronger with higher rf frequency, higher rf power. and higher minimum mirror magnetic field (minimum B). Preliminary emittance measurements indicate that SECRAL emittance at 24 GHz is slightly higher that at 18 GHz. SECRAL has been put into routine operation at 18 GHz for heavy ion research facility in Lanzhou (HIRFL) accelerator complex since May 2007. The total operation beam time from SECRAL for HIRFL accelerator has been more than 2000 h, and Xe-129(27+), Kr-78(19+), Bi-209(31+), and Ni-58(19+) beams were delivered. All of these new developments, the latest results, and long-term operation for the accelerator have again demonstrated that SECRAL is one of the best in the performance of ECR ion source for highly charged heavy ion beam production. Finally the future development of SECRAL will be presented
The effect of human rhythm on packet delivery
No full textIn communication networks such as the Internet, the relationship between packet generation rate and time is similar to a rectangle wavefunction due to the rhythm of humans. Thus, we investigate the traffic dynamics on a network with a rectangle wavepacket generation rate. It is found that the critical delivering capacity parameter beta(c) (which separates the congested phase and the free phase) decreases significantly with the duty cycle r of the rectangle wave for package generation. And, in the congested phase, more collective generation of packets (smaller r) is helpful for decreasing the packet aggregation rate. Moreover, it is found that the congested phase can be divided into two regions, i.e., region1 and region2, where the distributions of queue lengths are nonlinear and linear, respectively. Also, the linear expression for the distribution of queue lengths in region2 is obtained analytically. Our work reveals an obvious effect of the rectangle wave on the traffic dynamics and the queue length distribution in the system, which is of essential interest and may provide insights into the designing of work-rest schedules and routing strategies
PROPERTIES OF ALPHA DECAY TO ROTATIONAL BANDS OF HEAVY NUCLEI
No full textIn the framework of the generalized liquid drop model (GLDM) and improved Royer's formula, we investigate the branching ratios and half-lives of alpha-decay to the members of the ground-state rotational bands of heavy even-even Fm and No isotopes. The calculated results are in good agreement with the available experimental data and some useful predictions are provided for future experiments
TIME-DEPENDENT DENSITY FUNCTIONAL STUDY OF MULTIELECTRON TRANSFER IN Cq+-Na-4 COLLISIONS
No full textThe process of multielectron transfer from a Na-4 cluster induced by highly charged C6+, C4+, C2+ and C+ ions is studied using the method of time-dependent density functional theory within the local density approximation combined with the use of pseudopotential. The evolution of dipole moment changes and emitted electrons in Na-4 isobtained and the time-dependent probabilities with various charges are deduced. It is shown that the Na-4 cluster is strongly ionized by C6+ and that the number of emitted electrons per atom of Na-4 is larger than that of Na-2 under the same condition. One can find that the detailed information of the emitted electrons from Na-4 is different from the same from Na-2, which is possibly related to the difference in structure between the two clusters
Magnetic Field Design of the Dipole for Super-FRS at FAIR
No full textThe Super-FRS (Super FRagment Separator) is a part of FAIR (Facility for Antiproton and Ion Research), which will be constructed at GSI, Germany by 17 countries. The Super-FRS comprises 24 superferric dipole magnets. The 2D and 3D magnetic field simulations of the prototype magnet are described in this paper. A passive trim slot and four chamfered removable poles are used to satisfy the required field homogeneity which is better than +/-3 x 10(-4) at 1.6 T, 0.8 T and 0.16 T in a wide elliptical useable aperture of 380 mm x 140 mm. Measurement results at various field levels are shown in this paper as well. It can be seen from the comparison of calculation and measurement results that the magnetic designs of the magnet fulfils the requirements
The beam monitor system for heavy-ion therapy
No full text重离子束所具有的倒转深度剂量分布—Bragg 曲线，较小横向扩展和较高相对生物
学效应等优点，使得重离子辐照成为肿瘤治疗的最佳放射疗法。中国科学院近代物理研
究所基于兰州重离子研究装置(HIRFL-CSR)，实现了重离子束浅层和深层肿瘤治疗临床
试验。
在临床照射治疗中，为保证治疗方案的准确执行和患者照射治疗时的安全，必须实
现对照射束流的强度、位置及均匀性、照射剂量的实时监测。用于重离子治癌终端的束
流监测系统主要有：束流强度及剂量监测系统，实现在 0～109pps（particles per second）
大流强范围内对束流强度和照射剂量实时监测；具有 2mm 位置分辨的束流位置及均匀性
监测系统，实现对束照射野均匀性的实时监测，同时利用相关算法实现束流横向分布的
二维成像；利用不同厚度水等效材料与若干单元电离室组成快速 Bragg 曲线探测器，测
量实际分层照射条件下的 Bragg 曲线，实现对治疗计划中剂量分布的验证。论文的最后
还对临床照射条件下的束流纯度进行测量，结果表明在实际照射过程中可能出现一定数
量的轻粒子碎片，这些碎片会对临床照射剂量分布造成一定的影响。
本论文设计完成的束流监测系统工作稳定，运行良好，已经很好的应用到重离子治
癌的临床实验中
State-selective electron capture in collisions of slow highly charged Ar, Xe ions with He, Ne atoms
No full text本工作基于德国马普核物理研究所的EBIT与反应显微谱仪，对低能高电荷态Ar16+、
Xe42+离子与He、Ne原子碰撞反应进行了运动学完全测量，系统地研究了碰撞过程中的
态选择电子俘获，得到了与电子态布居信息相关的Q值谱、相对截面和角微分截面。对3.26 keV/u Xe42+He、Ne碰撞体系，本工作着重研究了态选择单电子俘获，分析了靶电子束缚能和碰撞参数对电子态布居的影响。研究结果表明：随着靶电子束缚能的减小，电子趋于布居在入射离子n较高的量子数态上，同时反应窗口变宽；n较高量子态的相对截面随着碰撞参数的增大而增大；入射离子散射角微分截面以半库仑角为中心呈对称分
布，但小于MCBM模型计算结果；同时，对于该碰撞体系，MCBM模型高估了电子态布
居有效主量子数。基于本工作和前人实验结果，本工作给出了适用于低能（<8 keV/u）
高电荷态离子与氦、氖原子碰撞电子态布居有效主量子数的经验公式。
本工作还对3.2 keV/u Ar16++He、Ne碰撞过程双电子俘获的态布居信息、稳定比系数
和角微分截面进行了深入的分析和讨论。可以认为，对于该碰撞体系，双电子俘获过程
中电子的布居机制主要是“两步”过程机制。其中，自电离双电子俘获（ADC）是主要的
反应道，电子布居在对称能级（n, n’，n≈n’）上，n和n’是双电子俘获中电子在入射离子
上布居的主量子数；真正的双电子俘获（TDC）过程电子布居在非对称能级上（n, n’，n>>n’）上。
在Ar16++Ne碰撞体系中，还观测到双电子俘获过程中伴随有靶激发现象，在
ADC过程中，实验观测到的俄歇电子与散射离子末态Ar15+（n，n=4）相关