  We present a large multi-epoch high resolution spectroscopic investigation
for the search of binary candidates in the Galactic Globular Cluster (GGC) M4.
The aim of our work is the identification of the binary candidates, and the
determination of the binary fraction and of the binary radial distribution. We
present a large multi-epoch high resolution spectroscopic investigation for the
search of binary candidates in the Galactic Globular Cluster (GGC) M4. The aim
of our work is the identification of the binary candidates, and the
determination of the binary fraction and of the binary radial distribution. The
average radial velocity of the observed cluster members is
$70.29+/-0.07(+/-0.3)(+/-0.1)km/s. The search for variations in radial
velocities among the stars with multi-epoch observations yielded 57 binary star
candidates. Our radial velocity measurement accuracy allowed us to identify at
a 3sigma level binaries with radial velocity variations larger than ~0.3km/s
for the target stars with V<15, and larger than ~0.5km/s for the targets with
V>15. We identified 4 binary star candidates out of 97 observed targets inside
the core radius, and 53 candidates out of 2372 observed stars outside the core
radius. Accounting for the incompleteness affecting our survey, the lower limit
for the total binary fraction is f=3.0+/-0.3%. The lower limit for the binary
fraction in the cluster core is f=5.1+/-2.3%, while outside the core it
decreases to f=3.0+/-0.4%. Similarly, we found f=4.5+/-0.4% and f=1.8+/-0.6%
for the binary fraction inside and outside the half mass radius.
