Context : 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 .

Aims : We present the first results of our HARPS long-term radial velocity ( RV ) survey which aims to discover exoplanets around intermediate-mass ( between \sim 2 and 6 M _ { \odot } ) evolved stars in open clusters .

Methods : 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 \Delta RV / 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 .

Results : 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 \Delta RV / 2 .
Ten of the candidates have less than 3 M _ { \odot } , 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 m \sin i = 6.3 M _ { J } and a semi-major axis a = 2.0 AU .
The binary companion is NGC 5822 201B , with a very low minimum mass of m \sin i = 0.11 M _ { \odot } and a semi-major axis a = 6.5 AU , which is comparable to the Jupiter distance to the Sun .

Conclusions :