First measurement on the anti-p p -> anti-n n depolarization parameter D0n0n at 546 and 875 MeV/c

The depolarization parameter Donon of the charge exchange reaction has been measured for the first time at the CERN Low Energy Antiproton Ring (LEAR) at two antiproton momenta, 546 and 875 MeV/c. The transverse polarization of the recoil neutron was analyzed using a large-acceptance neutron polarimeter made up of two parallel plastic scintillator planes. D0n0n is usually less than 0.35 which suggests that the spin-spin amplitudes dominate in the scattering matrix. Results are compared with the predictions of various potential models. The agreement is in general satisfactory