Institutional Repository of Institute of Modern Physics, CAS
Not a member yet
5769 research outputs found
Sort by
Surface damage on 6H-SiC by highly-charged Xeq+ ions irradiation
No full textSurface damage on 6H-SiC irradiated by highly-charged Xeq+ (q = 18, 26) ions to different fiuences in two geometries was studied by means of AFM, Raman scattering spectroscopy and FTIR spectrometry. The FTIR spectra analysis shows that for Xe26+ ions irradiation at normal incidence, a deep reflection dip appears at about 930 cm(-1). Moreover, the reflectance on top of reststrahlen band decreases as the ion fluence increases, and the reflectance at tilted incidence is larger than that at normal incidence. The Raman scattering spectra reveal that for Xe26+ ions at normal incidence, surface reconstruction occurs and amorphous stoichiometric SiC and Si-Si and C-C bonds are generated and original Si-C vibrational mode disappears. And the intensity of scattering peaks decreases with increasing dose. The AFM measurement shows that the surface swells after irradiation. With increasing ion fluence, the step height between the irradiated and the unirradiated region increases for Xe18+ ions irradiation; while for Xe-26+ ions irradiation, the step height first increases and then decreases with increasing ion fluence. Moreover, the step height at normal incidence is higher than that at tilted incidence by the irradiation with Xe18+ to the same ion fluence. A good agreement between the results from the three methods is found. (C) 2014 Elsevier B.V. All rights reserved
The effects of high-energy uranium ion irradiation on Au/n-GaN Schottky diodes
No full textThe I-V and C-V characteristics of Au/n-GaN Schottky diodes irradiated with 290-MeV U-238(32+) ions are presented. The U ions can penetrate the n-type GaN epi-layer with a thickness about 3 mu m grown on the c-plane of a sapphire substrate using the MOCVD technique, leaving a purely electronic energy deposition. The Au/n-GaN Schottky diodes were irradiated to successively increasing fluences from 1 x 10(9) to 5 x 10(11) ions cm(-2). The measured I-V curves show that the height of the Schottky barrier decreases after irradiation and that the Schottky barrier almost disappears when the ion fluence reaches 5 x 10(9) ions cm(-2). Meanwhile, the irradiation increases the series resistance. The C-V curves show that the capacitance drops sharply when the ion fluence reaches 5 x 10(10) ions cm(-2). The dielectric constant also decreases following the irradiation. The changes of the electrical properties are ascribed to the neutralization of the donor-like surface state and the acceptor-like surface state due to the migration of Au atoms at the interface of Au/n-GaN under energetic U ions irradiations. (C) 2014 Elsevier B.V. All rights reserved
A timing detector with pulsed high-voltage power supply for mass measurements at 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);">Accuracy of nuclear mass measurements in storage rings depends critically on the accuracy with which the revolution times of stored ions can be obtained. In such experiments, micro-channel plates (MCP) are used as timing detectors. Due to large phase space of injected secondary beams, a large number of ions cannot be stored in the ring and is lost within the first few revolutions. However, these ions interact with the detector and can saturate the MCP and thus deteriorate its performance. In order to eliminate such effects, a fast, pulsed high-voltage power supply (PHVPS) has been employed which keeps the detector switched-off during the first few revolutions. The new detector setup was taken into operation at the Experimental Cooler-Storage-Ring CSRe in Lanzhou and resulted in a significant improvement of the detector amplitude and efficiency characteristics. (C) 2014 Elsevier B.V. All rights reserved.</span
Potential sputtering on SiO2 and Au induced by highly charged ions impact
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);">Potential sputtering was studied using highly charged ions impacting on SiO2 and Au surface. A threshold effect for potential sputtering was found for gold.</span
SHER-HIAF ring lattice design
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 Super Heavy Experimental Ring (SHER), which is one of the rings of the next accelerator complex High Intensity Heavy Ion Accelerator Facility (HIAF) at IMP, has to be optimized for e-cooling. Its lattice is designed for two modes: the first is the isochronous mode, which is a time-of-flight mass spectrometer for short-lived secondary nuclei, the second is the storage ring mode, which is used for collecting and cooling the secondary rare isotope beams from the transport line. In order to fulfil its purpose, the ion optics can be set to different ion optical modes.</span
Lattice considerations for the spectrometry ring (SRing) of the HIAF project
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 spectrometry ring (SRing) is one of the rings of the next generation accelerator complex High Intensity Heavy Ion Accelerator Facility (HIAF) of Institute of Modern Physics of the Chinese Academy of Sciences. The SRing will be in operation mode as a time-of-flight mass spectrometer for short-lived nuclei. The SRing's circumference is 188. 7 m, the maximum magnetic rigidity is 13 T. m. The SRing is consisted by magnet systems, injection/extraction storages, stochastic cooling systems and detectors. It aims at stochastic precooling of both rare isotope and measuring nuclear masses in an isochronous mode. In order to fulfill it's purpose, the ion optics can be set to different ion optical modes. This paper discusses the considerations of the injection/extraction storages of these two different modes.</span
