Study of electric monopole transitions between the ground state and the first excited 0 + state in 40, 42, 44, 48Ca with high resolution inelastic electron scattering

Abstract

Monopole transitions from the 0 1 + ground states to 0 2 + excited states at 3.353 MeV ( 40Ca), 1.837 MeV ( 42Ca), 1.884 MeV ( 44Ca) and 4.272 MeV ( 48Ca) have been investigated with high resolution inelastic electron scattering (FWHM ≈ 30 keV) at low momentum transfer (0.29 ≦ q ≦ 0.53 fm −1). The respective monopole matrix elements are 2.53 ± 0.41 fm 2, 5.24 ± 0.39 fm 2, 5.45 ± 0.41 fm 2 and 2.28 ± 0.49 fm 2. These results are used together with known ground state charge radii and the average number of holes in the sd shell in the ground state to estimate the number of particle-hole excitations in the wave functions of the excited 0 + states.