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Proposal for precision determination of 7.8eV isomeric state in Th-229 at heavy ion 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);">The ultraviolet optical transition of the isomeric state in Th-229 has attracted much attention recently due to its potential application to building an atomic/nuclear clock with ultra-high precision. However, the lowest nuclear excitation energy and the lifetime of the first excited state of Th-229 were not measured directly and precisely until now, and how to precisely determine this isomer state of the Th-229 is an urgent requirement. Here an experimental approach of using a technique similar to that of dielectronic recombination to measure the transition energy of the isomer state of Th-229 at heavy ion storage rings is described. It is expected that the resonant transition can be found and determined with a precision better than several milli-eV.</span
Symmetry energy extraction from primary fragments in intermediate heavy-ion collisions
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);">An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature, a(sym)/T, for the heavy-ion reactions near the Fermi energy region, based on the modified Fisher Model (MFM). This method is applied to the primary fragments of the Anti-symmetrized Molecular Dynamics (AMD) simulations for the reactions of Ca-40 + Ca-40 at 35 MeV/nucleon. The density and the temperature at the fragment formation stage are extracted using a self-consistent method.</span
Charge-state dependence of inner-shell processes in collisions between highly charged Xe ions and solids at intermediate energies
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 x-ray emission during the penetration of 2-6 MeV Xeq+ (q = 20,22,26,30) ions into thick solid targets of iron and nickel has been measured. An obvious charge-state and incident-energy dependence of the target-to-projectile vacancy-production cross-section ratios was found for the iron target but not for the nickel target. The results are supported by the vacancy-sharing model and direct ionization theory and imply the great importance of level matching for the inner-shell process. The charge equilibration time of Xe30+ in solid iron was derived to be around 9 fs from the measured x-ray yields.</span
53.667MHz重离子RFQ的不稳定性研究
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);">采用多粒子跟踪程序BEAMPATH对53.667 MHz RFQ进行模拟计算,基于RFQ腔体冷测、机械测量的结果,在考虑其入口束流不稳定性、电压不平整度、高频系统稳定度、加工误差、安装误差等因素的情况下,对RFQ的出口束流品质和不稳定性进行了系统分析。结果表明,在现有的加工、安装水平下,提高RFQ入口束流稳定度和高频系统稳定度对束流在RFQ中的传输十分必要。</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);">Based on the database from RFQ cavity cold model test and tip-pole geometry measurement,53.667 MHz RFQ was simulated by BEAMPATH code.The RFQ output beam quality and instability were analyzed as functions of input beam instability, voltage roughness,stability of RF control system,RFQ manufacturing error,and misalignment. According to these results,it shows that it is essential for beam transmission in RFQ to improve input beam stability and RF control system stability at the pre-sent level of machining and alignment.</span
Development of intense proton source and LEBT system in compact pulsed hadron source
No full text<span style="color: rgb(0, 0, 0); font-family: Arial, verdana, helvetica, sans-serif; line-height: 14px;">A 2.45 GHz intense pulsed ECR proton source and low energy beam transport (LEBT) system was developed by Tsinghua University for the compact pulsed hadron source (CPHS). The proton injector provides proton beam into a 3.2 MeV RFQ accelerator. The 50 keV/75 mA hybrid beam extracted by a 4-electrode extraction system from the ion source passes through the LEBT to the RFQ entrance and the root-mean-square (RMS) normalized emittance is less than 0.2 πmm·mrad. The commissioning results of the intense proton source and low energy beam transport system were described in this paper. The beam quality was also studied. ©, 2015, Atomic Energy Press. All right reserved.(9 refs)</span
Incomplete guiding of 90 keV Oq+ ions through a straight macrocapillary: Experiments and simulations
No full textInfluence of the interface on the magnetic properties of NiZn ferrite thin films treated by proton irradiation
No full textIn order to systematically investigate the influence of the interface on the magnetic properties, polycrystalline NiZn ferrite thin films were irradiated with 60 keV proton in the dose range from 5 x 10(12) to 5 x 10(16) ions/cm(2). A non-destructive approach by proton irradiation was found to finely adjust the magnetic properties of polycrystalline NiZn ferrite thin films such as coercivity, perpendicular magnetic anisotropy as well as the effective g value. The coercivity is about 725 Oe for high proton dose ferrite, which is twice larger than the unirradiated one. The ferromagnetic resonance measurements indicated that perpendicular magnetic anisotropy and the effective g value increase with the irradiation dose. Our finding indicates that all modifications of these magnetic properties were associated with the change of interface due to the diffusion and the stress induced by proton irradiation. The change of the effective g value is a result of lattice expansion and the decrease of the magnetic dipole interaction between the columnar grains. This work provides a feasible way to tailor the magnetic properties of thin films by ion irradiation and promotes investigations for the stability of magnetic thin film devices in space or unclear radiation environments. (C) 2015 Elsevier B.V. All rights reserved
