Direct observation of the giant dipole resonance of sup 16 O via electromagnetic dissociation

• Published in: Physical review. C, Nuclear physics Nuclear physics, 1991-11, Vol.44:5
• Main Authors: Olson, D.L., Baumgartner, M., Greiner, D.E., Lindstrom, P.J., Symons, T.J.M., Wada, R., Webb, M.L., Berman, B.L., Crawford, H.J., Engelage, J.M.
• Format: Article
• Language: English
• Subjects: 651320 - Nuclear Properties & Reactions, A=6-19, Experimental; 651620 - Nuclear Properties & Reactions, A=59-89, Experimental; 652020 - Nuclear Properties & Reactions, A=220 & above, Experimental; ACTINIDES; ALKALINE EARTH METALS; BASIC INTERACTIONS; BERYLLIUM; CHARGED-PARTICLE REACTIONS; COINCIDENCE METHODS; COPPER; COULOMB FIELD; COUNTING TECHNIQUES; CROSS SECTIONS; DECAY; DIFFERENTIAL CROSS SECTIONS; DIFFRACTION MODELS; DIRECT REACTIONS; ELECTRIC FIELDS; ELECTROMAGNETIC INTERACTIONS; ELECTROMAGNETIC RADIATION; ELEMENTS; ENERGY RANGE; ENERGY SPECTRA; GAMMA RADIATION; GEV RANGE; GEV RANGE 100-1000; GIANT RESONANCE; HEAVY ION REACTIONS; INTERACTIONS; IONIZING RADIATIONS; ISOTOPES; LIGHT NUCLEI; MASS SPECTRA; MATHEMATICAL MODELS; METALS; NITROGEN 15; NITROGEN ISOTOPES; NUCLEAR PHYSICS AND RADIATION PHYSICS; NUCLEAR REACTIONS; NUCLEI; ODD-EVEN NUCLEI; OXYGEN 16 REACTIONS; PARTICLE MODELS; PROTON SPECTRA; QUASI-ELASTIC SCATTERING; QUASI-FREE REACTIONS; RADIATIONS; RELATIVISTIC RANGE; RESONANCE; SCATTERING; SPECTRA; STABLE ISOTOPES; TRANSITION ELEMENTS; URANIUM
• ISSN: 0556-2813; 1089-490X
• DOI: 10.1103/PhysRevC.44.1862

We have measured the invariant-mass spectrum of the final-state {sup 15}N+{ital p} system in the reaction {ital T}({sup 16}O,{sup 15}N+{ital p}){ital X} at 2.1{ital A} GeV with Be, Cu, and U targets ({ital T}). Electromagnetic dissociation of the {sup 16}O projectile nucleus in the Coulomb field of the target nucleus produces two prominent peaks in the proton-energy spectrum, one at 9 MeV, from transitions to the ground state of the residual {sup 15}N nucleus, and the other at 4 MeV, from transitions to excited states. This is corroborated by {gamma} rays corresponding to the deexcitation of the {sup 15}N nucleus which are in coincidence with the 4-MeV peak and are suppressed for the 9-MeV peak. Nucleon-nucleus diffractive dissociation makes a significant contribution to the cross section and results in a peak at 1.5 MeV. Nucleon-nucleon quasielastic scattering results in a featureless high-energy tail above 20 MeV.