![]() It is stressed that in the case of two-electron processes the independent-electron model breaks down and the possible role of correlations between K-electrons is discussed. The CDW-EIS calculations along with the IEA model grossly underestimate the double ionization cross sections. The K-shell ionization cross sections are found to deviate strongly from the calculations based on the continuum distorted wave eikonal initial state (CDW-EIS) and ECPSSR models. The measured single K-K transfer cross sections are reproduced very well by the two-centre close-coupling calculations whereas the double K-K transfer data are underestimated by the theory based on the independent-electron approximation (IEA). The ratio of double to single K-K transfer cross sections is found to be quite large for this nearly symmetric collision system, whereas the ratio of double to single ionization cross sections is quite small. The enhancement in the fluorescence yields due to multiple vacancies was measured from the energy shifts and intensity ratios of the characteristic x-ray lines to derive K-shell vacancy production cross sections from x-ray production cross sections. The charge-state dependence of the normal and hypersatellite x-rays was used to derive the cross sections for the one- and two-electron processes, respectively. MC simulation was used by Lam and Singh13,14 for similar work, where the transitions between the confined states are treated according to quantum mechanics, as. Because the collapsing core is far from equilibrium, the effects of general relativity are small.We present a combined study of single and double K-K electron transfer cross sections along with the single and double K-shell ionization of Ar induced by Si projectiles in the energy range 0.9-4.0 MeV u-1. The mass of inner core is given, to about 20% by the formula of Goldreich and Weber. The entropy change during the infall is small: Vertical Bar. Greater lepton loss during collapse leads to larger pressure deficits, more rapid collapse, and smaller inner homologous cores. The effects of more ยป changes in the neutrino trapping density and of qualitative changes in the electron capture reactions on the evolution are explored. We treat neutrino transport by a leakage scheme. The electron capture rates on nuclei proceed rapidly for densities less than 10/sup 11/ g cm/sup -3/, but are suppressed at higher densities where the neutron number of the nucleus, N, exceeds 40 (Fuller, Fowler, and Newman). The models use the recent equation of state of Lamb, Lattimer, Pethick, and Ravenhall and general-relativistic hydrodynamics. In this paper we consider the infall epoch, between the onset of collapse and core bounce. ![]() We report on simulations of the collapse of the central iron core of 15 M/sub sun/ spherically symmetric star. For this reason, experimental and theoretical efforts should focus on this region of the nuclear chart. If more accurate estimates confirm this, results from this study indicate that significant changes to the core-collapse trajectory are expected. As measurements for medium-heavy (A>65) and neutron-rich nuclei are sparse, and because accurate theoretical models that account for nuclear structure considerations of individual nuclei are not readily available, rates for these nuclei may be overestimated. Additionally, the simulations are found to be more sensitive to a reduction in electron-capture rates than an enhancement, and specifically to the reduction in rates for neutron-rich nuclei near the N = 50 closed neutron shell. ![]() ![]() These ranges are five times as large as those seen from a separate progenitor study, where we evaluate the sensitivity of these parameters to 32 presupernova models. = luminosity during the deleptonization burst. ![]()
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