Signatures of Central Collisions in Inelastic Nucleon–Nucleon Scattering

Physics of Particles and Nuclei Letters - Nucleon–nucleon collisions with impact-parameter values below the nucleon quark-core radius are considered and experimental signatures for selecting...     

Differential cross section and vector analysing power of the p pol p → {pp} s π0 reaction at 353–700 MeV

The reaction p _pol p → {pp} _s π⁰ was studied with the ANKE spectrometer at COSY-Jülich using a polarized beam with energies 353, 500, 550 and 700 MeV. The proton pairs {pp} _s were detected at low excitation energy E _pp < 3 MeV, where S-wave dominates. The angular dependences of vector analysing power A _y and differential cross section dσ/dΩ of the reaction have been obtained for the most of the angular range at 353 MeV and forward angles at the higher beam energies. The partial wave amplitude analysis, done with the 353 MeV results, is important for Chiral Perturbation Theory tests at this energy. The data at higher energies detalize the energy dependence of dσ/dΩ(0°) obtained earlier. It allows to learn about the dynamics of the Δ(1232) resonance excitation in two-nucleon systems.     

Observation of inverse diproton photodisintegration at intermediate energies

The fundamental reaction pp-->{pp}_{s}gamma, where {pp}_{s} is a proton pair with low excitation energy, has been observed with the ANKE spectrometer at COSY-Jülich for proton beam energies of T_{p}=0.353, 0.500, and 0.550 GeV. This is equivalent to photodisintegration of a free 1S0 diproton for photon energies E_{gamma} approximately T_{p}/2. The differential cross sections measured for c.m. angles 0 degrees gammad is on the 10;{-3}-10;{-2} level. The increase of the pp-->{pp}_{s}gamma cross section with T_{p} might reflect the influence of the Delta(1232) excitation.