  Detecting exoplanets in clusters of different ages is a powerful tool for
understanding a number of open questions, such as how the occurrence rate of
planets depends on stellar metallicity, on mass, or on stellar environment. We
present the first results of our HARPS long-term radial velocity (RV) survey
which aims to discover exoplanets around intermediate-mass (between ~ 2 and 6
Msun) evolved stars in open clusters. We selected 826 bona fide HARPS
observations of 114 giants from an initial list of 29 open clusters and
computed the half peak-to-peak variability of the HARPS RV measurements, namely
DeltaRV/2, for each target, to search for the best planet-host candidates. We
also performed time series analysis for a few targets with enough observations
to search for orbital solutions. Although we attempted to rule out the presence
of binaries on the basis of previous surveys, we detected 14 new binary
candidates in our sample, most of them identified from a comparison between
HARPS and CORAVEL data. We also suggest 11 new planet-host candidates based on
a relation between the stellar surface gravity and DeltaRV/2. Ten of the
candidates have less than 3 Msun, showing evidence of a low planet occurrence
rate for massive stars. One of the planet-host candidates and one of the binary
candidates show very clear RV periodic variations, allowing us to confirm the
discovery of a new planet and to compute the orbital solution for the binary.
The planet is IC 4651 9122b, with a minimum mass of msini = 6.3 MJ and a
semi-major axis a = 2.0 AU. The binary companion is NGC 5822 201B, with a very
low minimum mass of msini = 0.11 Msun and a semi-major axis a = 6.5 AU, which
is comparable to the Jupiter distance to the Sun.
