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HK: Hadronen und Kerne
HK 43: Nuclear Forces III, Reactions, Resonances
HK 43.5: Vortrag
Dienstag, 17. März 1998, 18:30–18:45, J
The search for the Isovector Giant Monopole Resonance. — •R.G.T Zegers1, G.P.A. Berg2, S Brandenburg1, J.A. Brown3, C. Foster2, M.N. Harakeh1, J. Jänecke4, A. Nadasen4, T. O’Donnell4, K. Pham4, T. Rinckel2, D.A. Roberts4, S. Shaheen4, E.J. Stephenson2, and S.Y. van der Werf1 — 1Kernfysisch Versneller Instituut Groningen — 2Indiana University Cyclotron Facility — 3National Superconducting Cyclotron Laboratory — 4University of Michigan
The isovector giant monopole resonance (IVGMR) represents a fundamental collective motion of the nucleus. It is described in a hydrodynamical model as a breathing mode in which neutrons and protons oscillate out of phase. The higher isospin component of the IVGMR has been observed using the pion charge exchange reaction (π+,π−).
In the E394 experiment, done at IUCF in Autumn 1996, it was attempted to find the lower isospin component of the IVGMR in the (3He,t+n) reaction. It is thought that the backgroung from quasifree and break-up/pick-up reactions can be removed for a large part by requiring a coincidence between the triton and neutrons coming from the excited target nucleus. Because of the monopole character of the IVGMR the measurement was done at zero degrees and using the difference of spectra technique between excitation spectra at different angles the monopole signature can be even more enhanced. In the contribution results from the experiment will be discussed.