Charge stripping accumulation of light heavy ions in HIRFL-CSR main ring

The charge stripping injection method has been adopted for the accumulation of light heavy ions in HIRFL-CSR.This method has some special requirements for the accelerating particles,and at the same time the structure of the injection orbit has to be changed.In this paper,the design of the orbit has been presented,as well as the calculation of the beam line matching.According to the result of commissioning,stripping injection can accumulate the beam to a higher current.     

HITFiL同步加速器剥离注入

一台新的治癌专用加速器HITFiL正在设计和建造中,其中一台同步加速器为其主加速器,以高紧凑性、高可靠性和低成本为设计目标。同步加速器的注入系统采用剥离注入方式,剥离注入与单圈注入方式相比能达到较高的注入效率,而其造价明显低于多圈注入加电子冷却的注入方式。治癌采用碳粒子束,从ECR离子源产生的C5+离子经过回旋加速器预加速后在同步加速器注入点处剥离成为C6+注入到环里。详细阐述了该注入系统的设计方案,并对整个注入过程进行了计算机模拟。在模拟过程中,对束流的注入效率、束流损失机制和粒子数增益进行了研究,得到了实空间和相空间的粒子分布和发射度增长趋势,得到了满足要求的束流流强。     

HIRFL-CSR主环慢引出设计

对HIRFL-CSR工程的主环（CSRm）的共振慢引出进行了设计,并采用Winagile程序对引出过程进行了初步的计算机模拟。主环慢引出采用幅度和动量选择引出机制,其引出通道和快引出通道相同。采用了1/3整数共振慢引出机制来获得约1 s的较均匀的引出束流,该引出束流的水平发射度小于1 πmm·mrad。     

HIRFL-CSR主环慢引出设计

对HIRFL-CSR工程的主环（CSRm）的共振慢引出进行了设计，并采用Winagile程序对引出过程进行了初步的计算机模拟。主环慢引出采用幅度和动量选择引出机制，其引出通道和快引出通道相同。采用了1/3整数共振慢引出机制来获得约1 s的较均匀的引出束流，该引出束流的水平发射度小于1 πmm·mrad。     

空间电荷阻抗和纵向束团定态解

回顾了加速器的阻抗模型,讨论了空间电荷阻抗和管道壁阻的高频衰减特性.从Vlasov?Maxwell方程出发提出了当存在类似空间电荷阻抗时,在任意外场、任意分布下,束团定态分布的一般解法,并以两种重要分布为例,给出重离子加速器强流参数下的定态分布.解得的定态分布可以进一步应用于稳定性分析和计算机模拟计算.由定态分布的求解得出了对束团中的朗道阻尼和稳定性研究非常重要的纵向“色散”函数.     

Inclusive meson production in peripheral collisions of ultrarelativistic heavy ions

There exist several proposals to use Weizsäcker-Williams photons generated by ultrarelativistic heavy ions to produce exotic particles in γγ fusion reactions. To estimate the background conditions for such reactions we analyze various mechanisms of meson production in very peripheral collisions of ultrarelativistic heavy ions at RHIC and LHC energies. Besides the γγ fusion they include also electromagnetic γA interactions and strong nucleon-nucleon interactions in grazing AA collisions. All these processes are characterised by low multiplicities of produced particles. The γA an d AA events are simulated by corresponding Monte Carlo codes, RELDIS and FRITIOF. In each of these processes a certain fraction of pions is produced close to the mid-rapidity regionthat gives a background for the γγ events. The possibility of selecting the mesons produced in the γγ fusion events via different p _t cut procedures is demonstrated.     

Experimental verification of therapeutic doses for the superficially-placed tumor radiotherapy with heavy ions at HIRFL

Up to now, clinical trials of heavy-ion radiotherapy for superficially placed tumors have been carried out for six times and over 60 selected patients have been treated with 80--100 MeV/u carbon ions supplied by the Heavy Ion Research Facility in Lanzhou (HIRFL) at the Institute of Modern Physics, Chinese Academy of Sciences since November, 2006. A passive irradiation system and a dose optimization method for radiotherapy with carbon-ion beams have been developed. Experimental verification of longitudinally therapeutic dose distributions was conducted under the condition of simulating patient treatment in the therapy terminal at HIRFL. The measured depth-dose distributions basically coincide with the expected ones. These results indicate that the irradiation system and the dose optimization method are effective in the ongoing carbon-ion radiotherapy for shallow-seated tumors at HIRFL.     

Experimental verification of therapeutic doses for the superficially-placed tumor radiotherapy with heavy ions at HIRFL

Up to now, clinical trials of heavy-ion radiotherapy for superficially placed tumors have been carried out for six times and over 60 selected patients have been treated with 80--100 MeV/u carbon ions supplied by the Heavy Ion Research Facility in Lanzhou （HIRFL） at the Institute of Modern Physics, Chinese Academy of Sciences since November, 2006. A passive irradiation system and a dose optimization method for radiotherapy with carbon-ion beams have been developed. Experimental verification of longitudinally therapeutic dose distributions was conducted under the condition of simulating patient treatment in the therapy terminal at HIRFL. The measured depth-dose distributions basically coincide with the expected ones. These results indicate that the irradiation system and the dose optimization method are effective in the ongoing carbon-ion radiotherapy for shallow-seated tumors at HIRFL.     

Folding interactions in the scattering of soft heavy ions by light nuclei

Scattering of polarized ⁷Li by ¹²C and polarized ⁶Li by ¹⁶O at E_lab～20 MeV is studied by both cluster folding interactions and double folding ones, where projectile virtual excitation effects are included by the coupled-channel method. The results strongly depend on the choices of interactions and reaction mechanisms reflecting low Coulomb barrier effects.     

Advantages of an InGaN-based light emitting diode with a p-InGaN/p-GaN superlattice hole accumulation layer

P-InGaN/p-GaN superlattices (SLs) are developed for a hole accumulation layer (HAL) of a blue light emitting diode (LED). Free hole concentration as high as 2.6×1018 cm-3 is achieved by adjusting the Cp2Mg flow rate during the growth of p-InGaN/p-GaN SLs. The p-InGaN/p-GaN SLs with appropriate Cp 2 Mg flow rates are then incorporated between the multi-quantum well and AlGaN electron blocking layer as an HAL, which leads to the enhancement of light output power by 29% at 200 mA, compared with the traditional LED without such SL HAL. Meanwhile, the efficiency droop is also effectively alleviated in the LED with the SL HAL. The improved performance is attributed to the increased hole injection efficiency, and the reduced electron leakage by inserting the p-type SL HAL.     

12 MeV直线感应加速器主开关的优化设计

 介绍了12MeV直线感应加速器主开关的一种优化设计。在保持原有主开关的设计风格和接口结构的条件下，通过优化设计局部结构和调整开关电极尺寸，把主开关的结构电感从63.7nH减小到35nH，使得加速腔的高压脉冲前沿从39.6ns减小到27ns，从而有利于提高12MeV直线感应加速器的性能，验证了优化设计的可行性。     

Switching the direction of spin accumulation in the spin Hall effect of light by adjusting the optical axis of an uniaxial crystal

We theoretically and experimentally investigate a switchable spin Hall effect (SHE) of light in reflection near the Brewster angle at an air-uniaxial crystal interface. We find a large transverse spin splitting near the Brewster angle, whose sign can be altered by rotating the optical axis. As an analogy of the SHE in an electronic system, a switchable spin accumulation in the SHE of light is detected. We are able to switch the direction of the spin accumulation by adjusting the optical axis angle of the uniaxial crystal. These findings may give opportunities for photon spin manipulating and developing a new generation of nano-photonic devices.     

Magnetization reversal and spin accumulation in nonmagnetic metals by spin injection from lateral Co/Cu,Co/Al heterojunctions

We have fabricated ferromagnetic/nonmagnetic (FM/NM) metal heterojunctions for the detection of the spin accumulation effect in different nonmagnetic metals. To understand the effect of spin accumulation in more detail, the switching behavior of the ferromagnetic wires was studied by means of magnetoresistance (MR) measurements and Monte Carlo simulations (MC). The polycrystalline heterojunctions were prepared by high-resolution electron beam lithography (HR-EBL) and a special oblique evaporation technique. The ferromagnetic (FM) and the nonmagnetic (NM) metal were evaporated on top of each other in a single-evaporation step to achieve an interface between the two metals of high quality. To verify the quality of the interface, we measured the spin accumulation effect in nonmagnetic copper (Cu) and aluminum (Al) and determined the spin polarization of the current at the interface between the ferromagnetic and nonmagnetic metals.     

Amplification of near-infrared light in a photorefractive ring resonator

We have demonstrated efficient amplification of near-infrared, 0.83-μm and 1.06-μm light, in a photorefractive ring resonator using Rh:BaTiO₃. The optical power oscillating inside the ring exceeded the pump power by a factor of up to 2.34. The sensitivity of a ring resonator to nanometer changes in its length was characterised using a piezo-mirror. Received: 30 November 2000 / Revised version: 24 January 2001 / Published online: 20 April 2001     

Energy loss of light ions in polypropylene absorber foils

The energy loss of Li, C and O ions in polypropylene absorber foils has been measured using 15 UD Pelletron Accelerator facility at Inter University Accelerator Centre (IUAC), New Delhi, India. The actual experiment has been performed in low flux chamber attached to the General Purpose Scattering Chamber (GPSC). These experimental energy loss values have been compared with the computed values based on various empirical/semi-empirical formulations. Some interesting trends have been observed.      

Bunch compression at the SPring-8 linac and successive generation of THz pulse train in the isochronous ring

We have demonstrated the idea of circulating a short, intense linac bunch for some tens of turns in an isochronous ring. We compressed a bunch from the SPring-8 linac to a few picoseconds rms by means of an energy compression system and a beam transport line from the linac to NewSUBARU. The NewSUBARU storage ring was set to a quasi-isochronous condition and the bunch circulated for about 50 turns after injection while maintaining the short bunch length. At the same time, a pulse train of strong coherent synchrotron oscillation from the short bunch was observed.     

衍射极限储存环物理设计研究进展

总结了国内外在衍射极限储存环（DLSR）物理设计方面的研究进展。为了在合理的周长范围内实现超低束流发射度,DLSR线性束流光学设计普遍采用紧凑型多二极铁消色散结构。在非线性动力学优化中,通常采用相移控制技术、解析和数值优化技术减小由色品六极铁导致的强非线性效应。DLSR束流接受度较小,主要考虑脉冲多极铁偏轴注入和快速冲击磁铁在轴注入两种注入方案。束流集体效应（尤其是束流内部散射和托歇克散射效应）随发射度降低而增强,需要采用束长拉伸、横向反馈等方法提高DLSR中束流的稳定性。     

Poloidal rotation of main ions in the CT-6B tokamak

The poloidal rotation velocity of neutral hydrogen atoms is measured using the Doppler shift of the Hα spectral line emitted in the CT-6B tokamak. The poloidal rotation of hydrogen atoms is generated through the collisions and charge-exchanges with main ions (protons). Therefore, the rotation direction of main ions can be deduced from that of neutral hydrogen atoms. The experimental results show that the main ions rotate in the electron diamagnetic drift direction, the same as the impurity ions, in the plasma core. The neutral hydrogen atoms rotate also in the electron diamagnetic drift direction in the edge region of the plasma. However, the rotation direction of main ions in the edge region cannot be judged from the experimental result due to the long mean free path of hydrogen atoms in the edge region. An inward diffusion flux of hydrogen atoms toward the torus inside with a velocity of the same order of magnitude as their poloidal rotation is also observed.     

Calculation of the binding energy in negative ions of heavy elements

A calculation is made of the binding energy of an electron in negative ions of complex heavy Ga, In, Tl atoms in terms of the polarization potential formalism and the relativistic perturbation theory with a model potential of the zeroth-order approximation. The results obtained refine the literature data on the negative ions investigated. Odessa Hydrometereological Institute, 15, L'vovskaya St., Odessa, 270016, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 116–119, January–February, 1999.