Astrophysical conditions for an r-process in the high-entropy wind scenario of type II supernovae

Within a full dynamical parameter study including freezeout effects, we have determined the astrophysical conditions for an r-process in the so-called 'neutrino-wind' scenario of core-collapse type II supernovae (SNII). We have started our calculations after the total photodisintegration of the matter above the nascent neutron star at 9-bar 109 Kelvin with protons and neutrons. We have used the charged-particle network of Thielemann and the r-process code of Freiburghaus, combined with the NON-SMOKER neutron-capture rates of Rauscher, nuclear masses from the ETFSI-Q mass model and recent experimental and theoretical gross β-decay properties. Using the three parameters Vexp (expansion speed of the shock wave), S (entropy of the bubble) and the neutron-to-proton ratio Ye, we show that the above quantities have to fulfill specific conditions in order to make a successful r-process. According to observations and hydrodynamical simulations, respectively, a realistic value for Vexp is 7500 km/s, and Ye<0.5