Flood frequency and routing processes at a confluence of the middle Yellow River in China

IEECAS SKLLQG

Multi-electron processes in 4.15-11.08 keV/u(13)C(6+) on argon collisions

The relative partial cross sections for C-13(6+)-Ar collisions at 4.15-11.08 keV/u incident energy are measured. The cross-section ratios sigma(2E)/sigma(SC), sigma(3E)/sigma(SC), sigma(4E)/sigma(SC) and sigma(5E)/sigma(SC) are approximately the constants of 0.51 +/- 0.05, 0.20 +/- 0.03, 0.06 +/- 0.03 and 0.02 +/- 0.01 in this region. The significance of the multi-electron process in highly charged ions (HCIs) with argon collisions is demonstrated (sigma(ME)/sigma(SC) as high as 0.79 +/- 0.06). In multi-electron processes, it is shown that transfer ionization is dominant while pure electron capture is weak and negligible. For all reaction channels, the cross-sections are independent of the incident energy in the present energy region, which is in agreement with the static characteristic of classic models, i.e. the molecular Coulomb over-the-barrier model (MCBM), the extended classical over-the-barrier (ECBM) and the semiempirical scaling laws (SL). The result is compared with these classical models and with our previous work of C-13(6+)-Ne collisions

Double electron processes in collisions of partially stripped ions Cq+ (q=1-4) with helium

The multi-electron processes are investigated for 17.9-120keV/u C1+, 30-323 keV/u C2+, 120-438 keV/u C3+, 287-480keV/u C4+ incident on a helium target. The cross-section ratios of double electron (DE) process to the total of the single electron (SE) and the double electron process (i.e. SE+DE), the direct double electron (DDI) to the direct single ionization (DSI) as well as the contributions of DDI to DE and of TI to DE are measured using coincidence techniques. The energy and charge state dependences of the measured cross-section ratios are studied and discussed.

Multi-electron processes in C-13(6+) ions with neon collisions in energy region 4.15-11.08 keV/u

The cross-section ratios of double-, triple-, quadruple-, and the total multi-electron processes to the single electron capture process sigma(DE)/sigma(SC), sigma(TE)/sigma(SC), sigma(QE)/sigma(SC) and sigma(ME)/sigma(SC)) as well as the relative ratios among reaction channels in double-electron active, triple-electron active and quadruple- electron active are measured in C-13(6+) -Ne collision in the energy region of 4.15-11.08 keV/u by employing position-sensitive and time-of-flight coincident techniques. It is determined that the cross-section ratios sigma(DE)/sigma(SC), sigma(TE)/sigma(SC), sigma(QE)/sigma(SC) and sigma(ME)/sigma(SC) are approximately the constants of 0.20 +/- 0.03, 0.16 +/- 0.04, 0.06 +/- 0.02 and 0.42 +/- 0.05. These values are obviously smaller than the predictions of the molecular Coulomb over-the-barrier model (MCBM) [J. Phys. B 23 (1990) 4293], the extended classical over-the-barrier model (ECBM) [J. Phys. B 19 (1986) 2925] and the semiempirical scaling laws (SL) [Phys. Rev. A 54 (1996) 4127]. However, the relative ratios among partial processes of DE, TE and QE are found to depend on collision energy, which suggests that the collision dynamics depends on the collision velocity. The limitation of velocity-independent character of ECBM, MCBM and SL is undoubtedly shown.