  By examining the diffusion of young white dwarfs through the core of the
globular cluster 47 Tucanae, we estimate the time when the progenitor star lost
the bulk of its mass to become a white dwarf. According to stellar evolution
models of the white-dwarf progenitors in 47 Tucanae, we find this epoch to
coincide approximately with the star ascending the asymptotic giant branch
($3.0 \pm 8.1$ Myr before the tip of the AGB) and more than ninety million
years after the helium flash (with ninety-percent confidence). From the
diffusion of the young white dwarfs we can exclude the hypothesis that the bulk
of the mass loss occurs on the red-giant branch at the four-sigma level.
Furthermore, we find that the radial distribution of horizontal branch stars is
consistent with that of the red-giant stars and upper-main-sequence stars and
inconsistent with the loss of more than 0.2 solar masses on the red-giant
branch at the six-sigma level.
