Photoproton cross section and isospin components of the giant resonance in 64Zn

The absolute cross section for the reaction ⁶⁴Zn(γ, p)⁶³Cu using a thin target of 99.6 % isotopically pure ⁶⁴Zn has been measured at four angles using bremsstrahlung from the Los Alamos Electron Prototype Accelerator. The results are compared with the previously measured ⁶⁴Zn(γ, n)⁶³Zn cross section to clearly show the two isospin components of the giant dipole resonance. The measured photoproton cross section is combined with previously measured (γ, n), (γ, 2n) and (γ, np) results to obtain a “total” photodisintegration cross section for ⁶⁴Zn.