M1 {gamma} Strength for Zirconium Nuclei in the Photoneutron Channel

• Published in: Physical review letters Vol. 100; no. 16
• Main Authors: Utsunomiya, H., Kondo, T., Kaihori, T., Makinaga, A., Akimune, H., Yamagata, T., Goriely, S., Goko, S., Toyokawa, H., Matsumoto, T., Harano, H., Hohara, S., Lui, Y.-W., Hilaire, S., Peru, S., Koning, A. J.
• Format: Journal Article
• Language: English
• Published: United States 25-04-2008
• Subjects: CAPTURE; CROSS SECTIONS; GAMMA RADIATION; HARTREE-FOCK-BOGOLYUBOV THEORY; INELASTIC SCATTERING; MEV RANGE 01-10; NEUTRON REACTIONS; NEUTRON SEPARATION ENERGY; NUCLEAR PHYSICS AND RADIATION PHYSICS; PROTONS; RANDOM PHASE APPROXIMATION; RESONANCE; ZIRCONIUM 91; ZIRCONIUM 92; ZIRCONIUM 94
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PHYSREVLETT.100.162502

Photoneutron cross sections were measured for {sup 91}Zr, {sup 92}Zr, and {sup 94}Zr near the neutron separation energy with quasimonochromatic {gamma} rays. The data exhibit some extra components around the neutron threshold. A coherent analysis of the photoneutron data for {sup 92}Zr together with the neutron capture on {sup 91}Zr based on the microscopic Hartree-Fock-Bogoliubov plus quasiparticle random-phase approximation model for the E1 strength has revealed the presence of an M1 resonance at 9 MeV. The microscopic approach systematically shows the same M1 strength in the photoneutron cross section for {sup 91}Zr and {sup 94}Zr. The total M1 strength is about 75% larger than the strength predicted by the systematics, being qualitatively consistent with the giant M1 resonance observed in the inelastic proton scattering.