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HK: Fachverband Hadronen und Kerne

HK 13: Hadron Structure and Spectroscopy I

HK 13.2: Talk

Monday, March 16, 2009, 16:45–17:00, H-ZO 20

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, George Macharashvili, and Yury Uzikov — 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. This is equivalent 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 calculated 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 GeV, as well as upper limits for 0.318 and 0.800 GeV. The energy dependence obtained shows clear bump around T_p = 0.550 GeV, which may reflect the influence of the Δ(1232) excitation, even though this channel is suppressed compared to the similar np→γ d reaction. The results of the research might help to understand the underlying dynamics of the short range NN 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.