We discuss two experimental techniques we are using to study fusion reactions, above and below the barrier, induced by weakly bound radioactive nuclei. In order to study fusion reactions induced by the halo nucleus He on Zn around and below the barrier, we detect off-line atomic X-rays following the electron capture decay of the evaporation residues. To investigate on the fusion process between weakly bound nuclei above barrier, we are studying the reaction N+ Be. To identify the evaporation residues we use an array of monolithic silicon telescopes. Such detectors, with their very thin ΔE stage of about 1 μm, allow a good charge identification down to about 350 keV/nucleon and appear to be very promising to study reactions induced by low energy RIBs.