  We used deep observations collected with ACS@HST to derive the fraction of
binary systems in a sample of thirteen low-density Galactic globular clusters.
By analysing the color distribution of Main Sequence stars we derived the
minimum fraction of binary systems required to reproduce the observed
color-magnitude diagram morphologies. We found that all the analysed globular
clusters contain a minimum binary fraction larger than 6% within the core
radius. The estimated global fractions of binary systems range from 10% to 50%
depending on the cluster. A dependence of the relative fraction of binary
systems on the cluster age has been detected, suggesting that the binary
disruption process within the cluster core is active and can significantly
reduce the binary content in time.
