Measurement of monoenergetic neutrons from the (p)over-bard reaction at rest

To search for baryonium states. a highly sensitive experiment with good statistics has been carried out at KEK by using an antiproton beam, deuterium target, and time-of-flight counter together with a modularized NaI(Tl) detector. At the 4 sigma level, no narrow peaks due to the production of baryonia in the (p) over bar d --> Bn reaction have been observed in the neutron spectra. At lower significance levels, however, we have observed four narrow peaks with 3.7 sigma-3.5 sigma, and two at an even lower significance level, in different charge-multiplicity final states. The recoil momentum distribution of the neutrons has been extracted for the channel with zero charge prongs. The energy spectra for gamma rays in coincidence with the neutron have been also obtained.