  Proton Induced X-ray Emission (PIXE) using high energy protons is a non
destructive multi elemental technique that can analyze medium and heavy trace
elements on thick samples. A new experimental setup is being built at the
ARRONAX facility (Nantes, France) for such purpose. Tests have been made in
order to quantify the background induced by a 68 MeV proton beam on a 250\mu m
copper target. Our measurement has been compared with expected theoretical
value including the various components of the bremsstrahlung and the Compton
induced by gamma rays. This study has allowed us to determine a detection limit
of the order of tens of ppm and has shown also the different ways to improve
it. Amongst them are a better shielding of the detector and the use of lower
beam intensity. Another ways consist to use the prompt gamma rays emitted by
the interaction of the beam with the target nucleus as well as the registration
of the decay of the activation product after the end of the bombardment. This
activation and especially the production of long lived radionuclide can be
controlled by tuning the proton energy and intensity resulting in a low
activation which is not prejudicial to most of the samples and with almost no
effect on the PIXE performances.
