MEASUREMENT OF MONOENERGETIC NEUTRONS FROM THE (P)OVER-BARD REACTION AT REST

To search for baryonium states. a highly sensitive experiment with goo d statistics has been carried out at KEK by using an antiproton beam, deuterium target, and time-of-flight counter together with a modulariz ed 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, howeve r, we have observed four narrow peaks with 3.7 sigma-3.5 sigma, and tw o at an even lower significance level, in different charge-multiplicit y final states. The recoil momentum distribution of the neutrons has b een extracted for the channel with zero charge prongs. The energy spec tra for gamma rays in coincidence with the neutron have been also obta ined.