Experiments and modification on electron cyclotron resonance ion sources at the Institute of Modern Physics

Uranium ion beams were produced from electron cyclotron resonance (ECR) ion sources by sputtering method this year at the Institute of Modern Physics. At first, we chose the Lanzhou ECR No. 3 ion source to implement the production experiment of U ion beams. Finally, 11 e mu A of U28+, 5 e mu A of U32+, and 1.5 e mu A of U35+ were obtained. A U26+ ion beam produced by the LECR2 ion source was accelerated successfully by the cyclotron. This means that the Heavy Ion Research Facility in Lanzhou (HIRFL) has accomplished the acceleration of the ion beam of the heaviest element according to the designed parameters. The Lanzhou ECR ion source No. 2 (LECR2), which was built in 1997, has served the HIRFL for eight years and needed to be upgraded to provide more intense high charge state ion beams for HIRFL cooling storage ring. We started the upgrading project of LECR2 last year, and the modified design just has been finished. (c) 2006 American Institute of Physics.

Four-dimensional Newton's constant in brane world with a sloping extra dimension

We show the four-dimensional Newton's constant obtained naturally from five-dimensional brane world with a tinily sloping extra dimension, which is independent of the bulk Weyl tensor. The corresponding universe is stiff fluid dominated when the slope of extra dimension is very small. Otherwise, the universe may be undergoing a self-acceleration at present epoch and have a decelerated phase in very recent past.

Biomedical research with heavy ions at the IMP accelerators

The main ion-beam acceleration facilities and research activities at the Institute of Modern Physics (IMP), Chinese Academy of Sciences are briefly introduced. Some of the biomedical research with heavy ions such as heavy-ion biological effect, basic research related to heavy-ion cancer therapy and radiation breeding at the IMP accelerators are presented.

Crossing the phantom divide in brane cosmology with curvature corrections and brane-bulk energy transfer

We consider the Randall-Sundrum brane-world model with bulk-brane energy transfer where the Einstein-Hilbert action is modified by curvature correction terms: a four-dimensional scalar curvature from induced gravity on the brane, and a five-dimensional Gauss-Bonnet curvature term. It is remarkable that these curvature terms will not change the dynamics of the brane universe at low energy. Parameterizing the energy transfer and taking the dark radiation term into account, we find that the phantom divide of the equation of state of effective dark energy could be crossed, without the need of any new dark energy components. Fitting the two most reliable and robust SNIa datasets, the 182 Gold dataset and the Supernova Legacy Survey (SNLS), our model indeed has a small tendency of phantom divide crossing for the Gold dataset, but not for the SNLS dataset. Furthermore, combining the recent detection of the SDSS baryon acoustic oscillations peak (BAO) with lower matter density parameter prior, we find that the SNLS dataset also mildly favors phantom divide crossing.

Design of synchrotron for hadron therapy

According to the operation and development of radiation therapy in the world, in order to further promote the radiation therapy of tumour in China, a design of a special synchrotron with two super-periodicity for hadron therapy is presented, including lattice, injection system, RF acceleration and slow extraction of the third order resonance. The synchrotron accelerates the proton beam to 250MeV and the carbon beam to 4000MeV/u.

Materials research with swift heavy ions at the IMP accelerators

The main ion beams acceleration facilities and research fields of the Institute of Modern Physics (IMP) are briefly introduced. Some of the experimental instruments, typical works and the obtained results on the materials research with swift heavy ions at the IMP-accelerators are presented.

Development of the lanzhou heavy ion linac

The heavy ion linac in Lanzhou is designed as a future injector for the Cooling Storage Ring (CSR). In order to keep the total machine within 40 meters, the IH (Interdigital H-type) structure is adopted for its higher acceleration gradient compared with the traditional DTL structure. The designed minimum charge over mass ratio is 1/6, the output energy is 16MeV/u and the beam current is 1A.mu A. The RFQ and the first DTL tank will work at 100MHz, and the other DTL tanks will work at the double frequency. The design criteria, main parameters and the detailed beam dynamic design are introduced in this paper.

OVERVIEW ON THE HIRFL-CSR FACILITY

The status of the HIRFL (Heavy Ion Facility in Lanzhou) - Cooler Storage Ring (CSR) at the IMP is reported. The main physics goals at the HIRFL-CSR are the researches on nuclear structure and decay property, EOS of nuclear matter, hadron physics, highly charged atomic physics, high energy density physics, nuclear astrophysics, and applications for cancer therapy, space industries, materials and biology sciences. The HIRFL-CSR is the first ion cooler-storage-ring system in China, which consists of a main ring (CSRm), an experimental ring (CSRe) and a radioactive beamline (RIBLL2). The two existing cyclotrons SFC (K=70) and SSC (K=450) are used as its injectors. The 7MeV/u12C6+ ions were stored successfully in CSRm with the stripping injection in January 2006. After that, realized were the accelerations of C-12(6+), Ar-36(18+), Kr-78(28+) and Xe-129(27+) ions with energies of 1GeV/u, 1GeV/u, 450 MeV/u and 235 MeV/u, respectively, including accumulation, electron cooling and acceleration. In 2008, the first two isochronous mass measurement experiments with the primary beams of Ar-36(18+) and Kr-78(28+) were performed at CSRe with the Delta p/p similar to 10(-5).

Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators, due to their compactness and their convenient shape for tuning and coupling, are very attractive for low-beta beam acceleration. In this paper, two types of cavities with different geometry have been numerically simulated: the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz, beta=0.06 beams; then the relative electromagnetic parameters and geometric sizes have been compared. It is found that the second type, whose structural design is optimized with the conical stem and shaping drift-tube, can support the better accelerating performance. At the end of the paper, some structural deformation effects on frequency shifts and appropriate solutions have been discussed.

Ultrahigh compression of water using intense heavy ion beams: laboratory planetary physics

Intense heavy ion beams offer a unique tool for generating samples of high energy density matter with extreme conditions of density and pressure that are believed to exist in the interiors of giant planets. An international accelerator facility named FAIR (Facility for Antiprotons and Ion Research) is being constructed at Darmstadt, which will be completed around the year 2015. It is expected that this accelerator facility will deliver a bunched uranium beam with an intensity of 5x10(11) ions per spill with a bunch length of 50-100 ns. An experiment named LAPLAS (Laboratory Planetary Sciences) has been proposed to achieve a low-entropy compression of a sample material like hydrogen or water (which are believed to be abundant in giant planets) that is imploded in a multi-layered target by the ion beam. Detailed numerical simulations have shown that using parameters of the heavy ion beam that will be available at FAIR, one can generate physical conditions that have been predicted to exist in the interior of giant planets. In the present paper, we report simulations of compression of water that show that one can generate a plasma phase as well as a superionic phase of water in the LAPLAS experiments.

Drift distance survey in direct plasma injection scheme for high current beam production

In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between a laser target and beam extraction position. In direct plasma injection scheme, which uses a laser ion source and a radio frequency quadrupole linac, we can apply relatively higher electric field at beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration such as several tens of milliamperes, we observed mismatched beam extraction conditions. We tested three different ion current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C6+ beam was accelerated. We confirmed that matching condition can be improved by controlling plasma drift distance.

HIRFL-CSR主环中束流加速过程的研究及束流反馈环路分析

本文的第一部分对设计中的兰州重离子加速器冷却储存环(HIRFL-CSR)的主环(CSRm)中束流的加速运动进行了较为详细的研究和计算机模拟。首先，作为加速运动的理论基础，推导出同步加速器中束流纵向相运动方程，并对纵向运动作了全面的描述。接着分析了加速运动的过程，同时介绍了绝热捕获和绝热同步振荡运动的概念，在此基础上根据两种不同的加速模式分别对主环中束流加速过程进行了计算机模拟，给出了主环在加速期间的高频运行参数，并得到了引出束流在动量散度和相位方向上的分布。最后比较了绝热捕获和非绝热捕获下的加速效率。本文的第二部分，从理论上仔细分析了高频控制系统中的束流反馈环路。在CSR预研阶段，高频控制系统的主振荡器为压控振荡器(Voltage Controlled Oscillator)，由于其频率稳定度一般在1.0%附近，无法达到系统要求在0.1%左右的精度，故采取了束流反馈机制。首先，本文在频率失谐下的相运动方程基础上建立了数学模型，接着推导出系统的传递函数。然后在计算机模拟中，通过数值计算，得到了系统传递函数的仿真结果，并给出了在闭环控制下束流平均闭轨偏移以及频率稳定度随时间变化的曲线。通过模拟结果表明，束流反馈环路能保证高频系统所要求的频率稳定精度，这为CSR高频控制系统的设计提供了理论依据。

新疆水土保持与可持续发展研究

新疆维吾尔族自治区作为我国最大及地理位置重要的西北边陲省份 ,随着人口的增长和区域开发进程的进一步加快 ,水土流失问题日趋严重 ,水土保持和可持续发展已成为其生态环境建设的重要课题。分析了新疆水土流失的现状、特点和成因以及存在的问题 ,从可持续发展角度提出了新疆水土保持的对策和建议

Synthesis and characterization of spherical Sr2CeO4 phosphors by spray pyrolysis for field emission displays

A blue emitting Sr2CeO4 phosphor with a one-dimensional structure has been prepared by a two-step spray pyrolysis (SP) method, starting from the aqueous solutions of metal nitrates with citric acid and polyethylene glycol (PEG) as additives. The material is ultimately designed for field emission displays (FEDs). X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), field emission scanning electron microscope pictures (FE-SEM) as well as photoluminescence (PL) and cathodoluminescence (CL) spectroscopy and lifetime measurements have been employed to characterize the samples. The morphology, PL and low voltage CL properties of Sr2CeO4 phosphors as-prepared using the SP method have been investigated by changing the concentration of the precursor solution, concentration of PEG, annealing temperature, acceleration voltage and filament current. The obtained Sr2CeO4 phosphor particles are spherical and of submicron size, 0.5-2 mu m. The emission spectrum of the phosphors shows a broad band with maximum at 467 nm (lifetime = 37.4 mu s; CIE chromaticity coordinates: x = 0.15 and y = 0.21), presumably due to a ligand-to-metal charge-transfer transition.

Role of electron transfer of quinones in hydroxylation of phenol

It was found that at neutral pH the hydroxylation reaction rate of phenol was accelerated with an increase of the amounts of 1,4-quinone (1,4-BQ), This acceleration was ascribed to the formation of semiquinone from 1,4-BQ. The semiquinone and 1,4-BQ were suggested to play a role of actual oxidant (electron transfer) in the catalytic cycle. With further reaction, most 1,4-BQ was converted into 1,4-hydroquinone (HQ) and the corresponding mechanism was proposed.