Measurement of the Shadowing of High-Energy Cosmic Rays by the Moon: A   Search for TeV-Energy Antiprotons
  The shadowing of high-energy cosmic rays by the Moon has been observed with a significance of 9.4 standard deviations with the L3+C muon spectrometer at CERN. A significant effect of the Earth magnetic field is observed. Since no event deficit on the east side of the Moon has been observed, an upper limit at 90% confidence level on the antiproton to proton ratio of 0.11 is obtained for primary energies around 1 TeV. 
L3 Collaboration, P. Achard, et al