Electron Cooling Experiments in CSR

The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou(HIRFL-CSR), the ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400MeV/u 12C6+ and 200MeV/u 129Xe54+ was stored and cooled in the experimental ring CSRe, the cooling force was measured in different condition.Comment: 5 pages 11 figure

Paleozoic late collisional strike-slip deformations in Tianshan and Altay, Eastern Xinjiang, NW China.

In Central Asia, thrusts and shear zones resulting from Palaeozoic accretional events were reworked by E–W-trending ductile strike-slip faults during late Palaeozoic–early Mesozoic time. In the Tianshan range, microstructures and quartz C-axis fabrics show a main dextral shearing associated with sinistral localized shear zones. The relationship between these conjugate structures indicates a NNW–SSE-trending bulk shortening. In the Chinese Altay mountains, the existence of δ-type microstructures in an important sinistral mylonitic zone infers high rates of deformation. This shear zone is bordered by a late dextral ductile fault synchronous with a granite emplacement. Field evidence and datings from the literature provide chronological constraints. In the late Carboniferous, the sinistral mylonitic deformation took place in the Erqishi–Irtysh shear zone in the northeastern part of Xinjiang and in Kazakhstan. During the Early Permian, a regional dextral event occurred in the Tianshan range and under the whole of northern Xinjiang

Femtosecond Laser-Induced Phase Transformation on Single-Crystal 6H-SiC

Silicon carbide (SiC) is widely used in many research fields because of its excellent properties. The femtosecond laser has been proven to be an effective method for achieving high-quality and high-efficiency SiC micromachining. In this article, the ablation mechanism irradiated on different surfaces of 6H-SiC by a single pulse under different energies was investigated. The changes in material elements and the geometric spatial distribution of the ablation pit were analyzed using micro-Raman spectroscopy, Energy Dispersive Spectrum (EDS), and an optical microscope, respectively. Moreover, the thresholds for structural transformation and modification zones of 6H-SiC on different surfaces were calculated based on the diameter of the ablation pits created by a femtosecond laser at different single-pulse energies. Experimental results show that the transformation thresholds of the Si surface and the C surface are 5.60 J/cm2 and 6.40 J/cm2, corresponding to the modification thresholds of 2.26 J/cm2 and 2.42 J/cm2, respectively. The Raman and EDS results reveal that there are no phase transformations or material changes on different surfaces of 6H-SiC at low energy, however, decomposition and oxidation occur and then accumulate into dense new phase material under high-energy laser irradiation. We found that the distribution of structural phase transformation is uneven from the center of the spot to the edge. The content of this research reveals the internal evolution mechanism of high-quality laser processing of hard material 6H-SiC. We expect that this research will contribute to the further development of SiC-based MEMS devices

BEAM-PHASE MEASUREMENT SYSTEM FOR HIRFL

The beam phase measurement system in HIRFL is<br />introduced. The system had been improved using RFsignal<br />mixing and filtering techniques and noise<br />cancellation method. Therefore, the influence of strongly<br />RF disturbing was eliminated and the signal to noise rate<br />was increased, and a stable and sensitive phase<br />measurement system was developed. The phase history of<br />the ion beam was detected by using 15 sets of capacitive<br />pick-up probes installed in the SSC cyclotron. The beam<br />phase information was necessary for tuning purposes to<br />obtain an optimized isochronous magnetic field, where<br />the beam intensity was increased and the beam quality<br />was optimized. The measurement results before and after<br />optimized isochronous magnetic field for 40Ar15+ ion and<br />12C6+ ion in SSC were given. The phase measurement<br />system was reliable by optimizing isochronous magnetic<br />field test, and the precision reached &plusmn;0.5o, the sensitivity<br />of beam signal measurement was about 10nA as well

Preparations for laser cooling of relativistic heavy-ion beams at the CSRe

<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