  For a long time Gerry Brown and his collaborator Hans Bethe considered the
question of the final fate of a core collapse (Type II) supernova. Recalling
ideas from nuclear structure on Kaon condensate and a soft equation of state of
the dense nuclear matter they concluded that progenitor stars with mass as low
a 17-18M$_\odot$ (including supernova 1987A) could collapse to a small mass
black hole with a mass just beyond 1.5M$_\odot$, the upper bound they derive
for a neutron star. We discuss another nuclear structure effect that determines
the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also
determines the fate of a Type II supernova with a carbon rich progenitor star
producing a neutron star and oxygen rich collapsing to a black hole. While the
C/O ratio is one of the most important nuclear input to stellar evolution it is
still not known with sufficient accuracy. We discuss future efforts to measure
with gamma-beam and TPC detector the 12C(a,g)16O reaction that determines the
C/O ratio in stellar helium burning.
