Bonn 2010 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 25: Hadronenstruktur und -spektroskopie V

HK 25.9: Talk

Tuesday, March 16, 2010, 18:30–18:45, HG III

Energy dependence of the cross section for pp→{pp}_sγ at intermediate energies — •Dmitry Tsirkov, Tatyana Azaryan, Sergey Dymov, Vladimir Komarov, Anatoly Kulikov, Vladimir Kurbatov, and George Macharashvili — Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia

The fundamental reaction pp→{pp}_sγ, where {pp}_s is a proton pair with excitation energy of E_pp < 3 MeV, has been observed with the ANKE spectrometer at COSY-Jülich. The reaction is a time reverse to photodisintegration of a free ¹S₀ diproton for photon energies E_γ≈ T_p/2. Previously only photodisintegration of a diproton bound within a nucleus has been observed. The integral cross section of the reaction was measured in the range of c. m. angles 0^∘< θ_pp < 20^∘ for proton beam energies of T_p = 0.353, 0.500, 0.550, 0.625, 0.700 GeV, as well as upper limit for 0.800 GeV. The energy dependence obtained shows clear bump around T_p = 0.625 GeV, which may reflect the influence of the Δ(1232) excitation, even though this mechanism is suppressed compared to that in a similar np→γ d reaction. The results of the research might help to understand the underlying dynamics of the short range NN and NΔ interaction, since quantum numbers for the pp→{pp}_sγ reaction differ from those of the extensively studied deuteron photodisintegration.

Supported by the COSY-FFE program.