The (γ,p) reaction in 197Au

✍ Scribed by T. Tamae; T. Hino; H. Kawahara; M. Nomura; M. Sugawara; A. Tanaka; T. Tanaka; H. Tsubota; T. Yokokawa; T.K. Yoshida

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 152 KB
• Volume: 690
• Category: Article
• ISSN: 0375-9474
• DOI: 10.1016/s0375-9474(01)00365-7

✦ Synopsis

Proton energy spectra of the 197 Au(e, p) reaction were measured in the region between 17 and 30 MeV at three angles: 40 • , 90 • and 140 • . Two prominent bumps were observed in the (γ , p) spectra converted using virtual photon theory. The higher-energy bump shifts with photon energies and the lower-energy one stays at 10.5 MeV. The higher-energy bump is much larger at 40 • than at 140 • ; on the contrary the angular dependence of the lower-energy bump is small. Neither bump can be described by a statistical calculation. A calculation of a microscopic shell model shows that the lower-energy bump is attributed to the decay of proton-particle-neutron-hole pairs in the T > states, leaving a neutron hole around the Fermi surface. The higher-energy bump can be ascribed to the direct-semidirect mechanism. This paper gives the solution to a part of the long-standing question about the origin of photo-proton emission in heavy nuclei.