Coulomb displacement energies and decay widths of isobaric analog states from Sm(3He, t) at [theta] = 0[deg]

Abstract

The 144,147,148,149,150,154Sm(3He, t)144,147,148,149,150,152,154Eu reactions leading to ground-state isobaric analog states (IAS) have been studied at [theta] = 0[deg] and E(3He) = 45.9 MeV. The Coulomb displacement energies decrease more rapidly than A-1/3. Approximately 110 keV of the total decrease of about 470 keV from A = 144 (spherical) to A = 154 (deformed) can be ascribed to deformation. No discontinuity is apparent at the transition from spherical to deformed shapes at N = 88-90. This is attributed to two effects: (i) rms radii increase with static deformations and with dynamical vibrations; (ii) Coulomb displacement energies depend on rms charge radii and on the rms radii of the neutron excess. The data suggest neutron deformations greater than proton deformations for A = 148 and 150 but smaller for A = 152 and 154. The IAS widths increase from ~30 keV to ~90 keV and can be attributed to mixing with the (T0-1) component of a proposed isovector giant monopole resonance.