Experiments on JET with ICRH acceleration of neutral beam ions allows to create plasma condi-tions with a large population of energetic ions in the MeV range. The scope of these experiments is to study various aspects of fast particle physics relevant to burning plasmas. In addition, it is pos-sible to test new diagnostic techniques for fast particles. We report on measurements of escaping MeV ions losses performed during recent Helium plasma experiments with ICRH third harmonic acceleration of Helium beam ions. The measurements are based on activation technique. Samples made of suitable materials, inserted inside the vacuum vessel and located near the plasma edge, are used as flux monitors. Activation due to fast neutrons with En >2.5 MeV is observed. Activation caused by losses of alpha particles is found below detection limit. However, signi fi cant activation due to losses of protons and deuterons is observed. To enhance the sensitivity of the analysis, a dedicated technique was applied to obtain activation measurements with very low background. Exposed sample surfaces are contaminated with various materials sputtered from the sample holder or the machine walls. This effect is discussed and can in some cases make the interpretation of mea-surements more difficult. Combining activation data with additional surface analysis data (SIMS), it is possible to assess angular distribution of measured fast particles. Counter-going fast ions are recorded, mainly, and with a local pitch angle in the range of - 0 .6 < x < 0 in agreement with fast particles trajectory calculations.