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No abstract available
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; 
; v. 17(8); p. 1410
; v. 17(8); p. 1410
No abstract available
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; v. 17(8); p. 1409-1410
; v. 17(8); p. 1409-1410
[en] The reaction γd→ppπ- has been studied in order to investigate whether dibaryon resonances contribute to the cross section in the invariant mass region from 2.16 to 2.32 GeV/c2. Using a bremsstrahlung photon beam we have determined the invariant mass Mppπ by detecting both outgoing protons in large solid angle TOF spectrometers, thus achieving a statistical accuracy of 1 to 2% per 2.5 MeV/c2 bin, a mean invariant mass resolution of 4.4 MeV/c2(σ) and a smooth Mppπ acceptance. Despite the resulting high resonance sensitivity no evidence for a dibaryon resonance in the Mppπ distribution was found. Assuming an isotropic phase space decay we estimate the upper limit for the dibaryon resonance cross section to be 1 μb for masses around 2.23 GeV/c2 and resonance widths between 5 and 40 MeV/c2. (orig.)
Journal
No abstract available
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; v. 19(3); p. 1015-1016
; v. 19(3); p. 1015-1016
[en] Studying the reaction γd→ppπ-, a narrow resonance structure in the pp invariant mass distribution has been observed at 2014±2 MeV/c2 with a statistical significance of 4.7 standard deviations. Using a bremsstrahlung photon beam (k0=520 MeV), the kinematics of the reaction were completely determined by detecting both outgoing protons in two large solid angle time-of-flight spectrometers. By accepting only proton momenta greater than ∝300 MeV/c, the predominant contribution from quasi-free pion production was suppressed. (orig.)
Journal
[en] At the Bonn 2.5 GeV electron synchrotron an angular distribution of the target asymmetry of the reaction γ+d↑→p+n has been measured at photon-lab-energies of 450 and 650 MeV and at proton-CM-angles between 250 and 1550. At 550 MeV the data of our previous run have been improved. Using deuterated ammonia as material for the polarized deuteron target a maximum vector polarization of 44% could be achieved. At 450 and 650 MeV the data are consistent with a smooth sin 2Θ-like distribution. The evidence for a structure around 900 at 550 MeV remains. This might be due to the influence of a higher momentum state (like a dibaryon). The feasibility of measuring the tensor asymmetry of the deuteron photodisintegration with a polarized target has been shown for the first time. Data were taken in a short run for one kinematical setting. (orig.)
Journal
No abstract available
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; v. 18(6); p. 1198
; v. 18(6); p. 1198
[en] The differential cross section of the reaction ß+p->π+-n was measured at pion CM-angles of 200 and 300 for photon energies between 500 MeV and 1,400 MeV. The pions were detected in a magnetic spectrometer. By measuring each pion trajectory and by offline calculation of the initial pion parameters an energy resolution of about 2.5% FWHM was achieved. The results complete a set of data which were measured in recent years at the Bonn 2.5 GeV synchrotron. In comparison to photoproduction analyses two effects were revealed: the eta cusp appears in the energy dependence of the cross section as a sharp drop at Ksub(ß)=710 MeV. In the region of the third resonance the data show a greater enhancement that predicted by most of the analyses. (orig.)
Journal
Zeitschrift fuer Physik. C, Particles and Fields; ISSN 0170-9739; ; v. 18(3); p. 199-205
; v. 18(3); p. 199-205
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