Study of two photon production process in proton-proton collisions at 216 MeV

摘要

The energy spectrum for high energy γ-rays (E{sub}γ ≥ 10 MeV) from the process pp→γγX emitted at 90° in the laboratory frame has been measured at 216 MeV. The resulting photon energy spectrum extracted from γ-γ coincidence events consists of a narrow peak (5.3σ) at a photon energy of about 24 MeV and a relatively broad peak (3.5σ) in the energy range of (50 - 70) MeV. This behavior of the photon energy spectrum is interpreted as a signature of the exotic dibaryon resonance d{sub}1{sup}* with a mass of about 1956 MeV which is assumed to be formed in the radiative process pp→γd{sub}1{sup}* followed by its electromagnetic decay via the d{sub}1{sup}*→ppγ mode. The experimental spectrum is compared with those obtained by means of Monte Carlo simulations.