Energy dependence of hard bremsstrahlung production in proton–proton collisions in the Δ(1232) region

Abstract

Abstract. Hard bremsstrahlung production in proton-proton collisions has been studied with the ANKE spectrometer at COSY-Jülich in the energy range of 353-800 MeV by detecting the final proton pair {pp} s from the pp → {pp} s γ reaction with very low excitation energy. Differential cross sections were measured at small diproton c.m. angles from 0• to 20 • and the average over this angular interval reveals a broad peak at a beam energy around 650 MeV with a FWHM ≈ 220 MeV, suggesting the influence of ∆(1232)N intermediate states. Comparison with deuteron photodisintegration shows that the cross section for diproton production is up to two orders of magnitude smaller, due largely to differences in the selection rules.PACS numbers: 25.40. Ep, 25.20.Dc

Resonance-like coherent production of a pion pair in the reaction $pd \rightarrow pd \pi\pi$pd→pdππ in the GeV region

“…The deuteron momenta P d are also higher than this value, which corresponds to significant invariant momentum transfers between the initial and the final deuteron: |t dd | > 0. 35…”

“…The experimental setup, technique, and conditions in this work are similar to those used in several experiments performed at ANKE and described in detail before [30][31][32][33][34][35]. So sect.…”

The legacy of the experimental hadron physics programme at COSY

“…This means that the acceptance for two protons from a pp → ppX reaction is maximal when these have similar momentum vectors, i.e., the excitation energy E pp in the final pp rest frame is small. In such cases the Pauli principle requires the diproton to be in the 1 111,112]. The expected π 0 position is indicated by the arrow.…”

“…at six energies between 353 MeV and 800 MeV [111,112]. Such small angle studies were possible at ANKE because of the absence of a beam-pipe hole.…”

“…Angular dependence of the differential cross section for the pp → {pp}sγ reaction at four beam energies measured at ANKE[111,112]. Experimental results are shown at 353 MeV by (black) circles, at 500 MeV by (red) squares, at 550 MeV by (blue) triangles, and at 700 MeV by (magenta) stars.…”