The fsub(7/2) isobaric analog resonance of 139La and 141Pr

The isobaric analog resonance of La-139 and Pr-141 in (e,e' p) experiment was studied. A proton group (proton group 2), which does not show a decay pattern of the isobaric analog state, was previously reported. In this paper, the purpose is the confirmation of the existence of resonance emitting this proton group by the isochromat analysis. The isochromat means the graphic representation of the number of the emitted protons in a specified energy range as a function of incident electron energy. The analysis of the isochromat gives the cross-section of (γ, p sub(o)) reaction. The results of analysis showed the isobaric analog resonance at 14.9 MeV incident electron energy in the cross section of Pr-141. The absolute value of the cross-section of La-139 was small, and the isobaric analog resonance at 16.15 MeV incident electron energy was not clear. The cross-section of Pr-141 (γ, p sub(o)) reaction obtained from the present Pr-141 (e,e' p) experiment was in good agreement with the result obtained from Ce-140 (p, γ0) experiment. The present method of analysis can be used for the case in which the residual state is not ground state. In case of La-139 and Pr-141, this method was applied. Resonance was seen near the f sub(7/2) isobaric analog state of Pr-141 and La-139. Then, it was concluded that the proton group 2 is emitted through the resonance near the isobaric analog state. (Kato, T.)