Institutional Repository of Institute of Modern Physics, CAS
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First recombination experiment of fluorine-like nickel ions at the main cooler storage ring
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Absolute non-resonant recombination (RR) rate coefficients of Ni19+ ions were measured by employing the electron-ion merged-beams technique at the main cooler storage ring in Lanzhou. Using the electron cooler and energy detuning system, we obtained a narrow momentum spread (Delta p/p similar to 2 x 10(-4))and tuned precisely relative energies (minimum electron energy detuning step voltage 1 V) between electrons and ions. In addition, we compared the RR rate coefficients with the theoretical ones calculated by the self-consistent-field Dirac-Slater method, and found that they are in good agreement.</span
Preparations for laser cooling of relativistic heavy-ion beams at the CSRe
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Laser cooling is one of the most promising techniques to reach high phase-space densities for relativistic heavy-ion beams. Preparations for laser cooling of relativistic lithium-like ions, such as C3+ and N4+, are being made at the experimental cooler storage ring (CSRe) in Lanzhou, China. In December 2011, a new buncher was installed and tested with a 70 MeVu(-1) Ne-22(10+) ion beam by electron cooling at the CSRe. The longitudinal momentum spread of the bunched ion beam was measured by the new resonant Schottky pick-up. As a result, Delta p/p approximate to 2 x 10(-5) has been reached at ion numbers less than 10(7). According to this test result, the RF-buncher is suitable for the upcoming experiment of laser cooling at the CSRe. Laser cooling of heavy-ion beams will also be applied at future storage ring facilities, e. g. FAIR in Darmstadt, and HIAF in Lanzhou.</span
The SHER-HIAF ring lattice design
No full text<span style="color: rgb(0, 0, 0); font-family: Arial, verdana, helvetica, sans-serif; line-height: 14px;">Super Heavy Experimental Ring (SHER) is one of the rings of the next accelerator complex High Intensity Heavy Ion Accelerator Facility (HIAF) at IMP[4]. Here, present ideas of the lattice design for the operation of the large acceptance ring are presented. The SHER ring has to be optimized for e-cooling and the lattice is designed for different modes. First of all, it is designed in the so called isochronous mode as time-of-flight mass spectrometer for short-lived secondary nuclei. Secondly, SHER can also be used to be a storage ring for collecting and cooling the secondary rare isotope beams from the transport line. In order to fulfill its purpose, the ion optics can be set to different ion optical modes. Copyright © 2013 by JACoW.(5 refs)</span>Asian Committee for Future Accelerators (ACFA); American Physical Society Division of Physics of Beams (APS-DPB); Chinese Academy of Sciences (CAS); European Physical Society Accelerator Group (EPS-AG)
螺线管透镜像差导致的束流发射度增长研究
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">螺线管透镜常作为低能束流的聚焦元件,不可避免地具有像差,导致束流发射度增长,降低束流传输效率。本文通过理论推导和计算机模拟,给出了不同束流包络、不同磁感应强度和不同磁场形状的情况下束流经过实际透镜后的发射度增长。结果表明,发射度增长主要与束流包络和磁感应强度有关。但在一定范围内,优化磁场形状也能起到控制发射度增长的作用。</span><span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">T he solenoid lens are effective for focusing the low energy beam, but the beam efficiency decreases with the beam emittance growth,which increases with the spherical aberration of solenoid lens.Emittance grow th due to spherical aberration of solenoid lens was studied in both theory and simulation in this paper.The results show that emittance grow th is mainly dominated by the beam envelope in lens and magnetic strength of lens. Optimizing the magnetic field uniformity of solenoid lens, which decides the aberration coefficient,can reduce the spherical aberration and enhance the quality of beam to an ex tent.</span
MASS MEASUREMENT OF Cr-45 AND ITS IMPACT ON THE Ca-Sc CYCLE IN X-RAY BURSTS
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Masses of neutron-deficient Ni-58 projectile fragments have been measured at the HIRFL-CSR facility in Lanzhou, China employing the isochronous mass spectrometry technique. Masses of a series of short-lived T-z = -3/2 nuclides including the Cr-45 nucleus have been measured with a relative uncertainty of about 10(-6)-10(-7). The new Cr-45 mass turned out to be essential for modeling the astrophysical rp-process. In particular, we find that the formation of the predicted Ca-Sc cycle in X-ray bursts can be excluded.</span
Al K-shell x-ray production cross section induced by proton and highly charged heavy ions
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Al K-shell x-ray production cross sections induced by 50-250 keV protons and 1-3 MeVAr11+ ions were measured. It was found that 3-4 L-shell electrons of the Al atom were multiply ionized by Ar11+ ion impact. The x-ray production cross sections were deduced from the experimental yield data and compared with binary encounter approximation (BEA), plane wave Born approximation and energy-loss Coulomb-repulsion perturbed-stationary-state relativistic (ECPSSR) theoretical predictions. For proton impact, the ECPSSR theory gave an accurate prediction of the experimental result. However, taking into account the multiple-ionization effect on fluorescence yield, the BEA model presented better agreement with the cross section data produced by Ar11+ ions.</span
X-ray spectrum emitted by the impact of ~(152)Eu~(20+) of near Bohn velocity on Au surface
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The characteristic X-ray spectra produced by the impact of highly charged ions of Eu-152(20+) with energies from 2.0 to 6.0 MeV on Au surface are measured. It is found that highly charged ions could excite both the characteristic X-ray spectra of M-zeta, M-alpha and M-delta of Au and the characteristic X-ray spectra of M-alpha of Eu. The total X-ray yield increases with the ion kinetic energy increasing. The total production cross section of Au induced by Eu20+ is measured and compared with those obtained from the binary encounter approximation, plane-wave-Born approximation, and the energy-loss Coulomb deflection perturbed stationary state relativistic theoretical models.</span
A new digital pulse power supply in heavy ion research facility in Lanzhou
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">To meet the increasing requirements of the Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR), a new digital pulse power supply, which employs multi-level converter, was designed. This power supply was applied with a multi H-bridge converters series-parallel connection topology. A new control model named digital power supply regulator system (DPSRS) was proposed, and a pulse power supply prototype based on DPSRS has been built and tested. The experimental results indicate that tracking error and ripple current meet the requirements of this design. The achievement of prototype provides a perfect model for HIRFL-CSR power supply system. (C) 2013 Elsevier B.V. All rights reserved.</span
重离子同步加速器中剥离累积时碳膜对束流的影响研究
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">治癌专用重离子加速器HITFiL中同步加速器的注入系统采用了剥离注入方式。剥离膜的存在使束流克服了刘维定理的限制从而累积达到较高流强,但粒子多次穿越剥离膜也会造成束流损失并使得束流品质变坏,其中包括:1)粒子从膜原子中俘获电子使粒子电荷态发生改变而导致束流损失;2)剥离膜对束流的多重库仑散射导致束流发射度增长;3)束流在剥离膜中的能损及能量岐离导致束流中心动量减少并使得动量分散增长。本文通过研究剥离注入过程中粒子与物质的相互作用规律,用蒙特卡罗方法建立了剥离膜与粒子的作用模型,在对ACCSIM程序改进的基础上研究了剥离膜对束流的影响。</span><span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Stripping-injection scheme is adopted in the synchrotron of an accelerator complex named as HITFiL.HITFIL is dedicated to cancer therapy.High intensity can be reached by using the stripping-injection as the limit of Liouville's theorem is broken due to charge-exchange.But unavoidable traversals of the circulating beams through the foil may cause beam-losses and deteriorations of beam quality,including:1)beam-losses caused by an alteration of the particles'charge state;2)emittance growth caused by Multiple Coulomb Scattering;and 3)decrease of mean-momentum and growth of momentum spread induced by energy loss and energy loss straggling.In this paper,the model of particle-foil interaction is established by Monte Carlo processes.The effects of the stripping foil on beams are studied based on an improvement of the ACCSIM code.</span