Lithium abundances as a tracer of AGB stars pollution in the globular
  cluster NGC 6752
  This paper presents the chemical abundance analysis of 217 stars in the
metal-poor globular cluster NGC 6752, distributed from the turn-off to the
lower red giant branch. Aluminium and Lithium abundances were derived through
spectral synthesis applied to spectra collected with FLAMES, both in GIRAFFE
and UVES modes. The work aims to gain insight into the nature of the
polluter(s) responsible for the abundance variations and C-N, Na-O, Al-Mg
anti-correlations associated with the multiple population phenomenon. We found
a plateau at A(Li)=2.33$\pm$0.06 dex in unevolved stars, with the average Li
content decreasing continuously down to $\sim$1.25 dex at the bottom of the red
giant branch. As expected in the classic anti-correlation scenario, we found
stars low in Al and high Li abundance and stars high in Al and low in Li.
However, in addition, we also found evidence of Al-rich, second-generation
stars with high Li content. This finding suggests the need for Li production,
known to happen in intermediate-mass ($\sim$4-8M$_{sun}$) AGB stars through the
Cameron-Fowler mechanism. It is worth noticing that the Li abundance observed
in Al-rich stars never exceeds that in Al-poor stars.
