A controlled experiment was done to study the response as well as the detection efficiency of CR-39 (DOP) detectors to very high energy neutrons originating from **9Be ( alpha , xn) reaction at E// alpha approx. 50 mev from the Variable Energy Cyclotron at Calcutta. A NE213 liquid scintillation neutron detector coupled to a photomultiplier having neutron-gamma phase discrimination property was used to record the neutron flux as well as the spectrum. The CR-39 result obtained are compared with the NE213 monitor data. The sensitivity of CR-39 for neutron detection comes out to be 5 tracks cm** minus **2 mrem** minus **1 for the high energy neutrons used.