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HK: Hadronen und Kerne

HK 57: Plenar

HK 57.2: Vortrag

Donnerstag, 19. März 1998, 09:45–10:30, P

Probing Few-Body Systems with Bremsstrahlung — •N. Kalantar-Nayestanaki¹, J.C.S. Bacelar¹, M.J. van Goethem^1,2, M.N. Harakeh¹, M. Hoefman^1,2, H. Huisman¹, A. Kugler^3,2, H. Löhner^1,2, J.G. Messchendorp¹, R.W. Ostendorf^1,2, S. Schadmand^1,4,2, M. Seip¹, R. Simon^5,2, R. Turrisi^1,2, M. Volkerts¹, V. Wagner^3,2, and H.W. Wilschut^1,2 — ¹KVI, Groningen — ²for the TAPS collaboration — ³NPI, Řež u Prahy — ⁴Univ. Gießen — ⁵GSI, Darmstadt

A series of bremsstrahlung measurements have been performed at KVI with the new superconducting cyclotron, AGOR, aiming to investigate the “off-shell” behavior of the nucleon-nucleon interaction at energies below particle-production threshold. Nucleon-nucleon bremsstrahlung is the most fundamental process used for such studies as it involves the strong interaction between two nucleons and the well-known electromagnetic interaction. In addition, the cross section for nucleon-nucleon bremsstrahlung is the basis of all calculations which deal with photon production in heavy-ion collisions.

At KVI, we have used the high-quality polarized beam of 190 MeV protons to perform the most complete experiment to date on proton-proton and proton-deuteron systems. The second system was chosen such that one is able to study all possible bremsstrahlung channels and infer the contribution from the neutron-proton system. High precision cross-section and analyzing-power data have been obtained enabling one to extract information on the structure of the nucleon, the role of virtual nucleon-resonance excitation at these energies, the “off-shell” properties of the T-matrix and the role of two-body effects such as MEC. The measurements were performed with the Small-Angle Large-Acceptance Detector (SALAD) and the Two-Arm Photon Spectrometer (TAPS). Some of the results will be presented along with the most modern calculations which still disagree with the data in specific regions of phase space.