Isoscalar multipole strength decomposition in 40Ca with the (e,e′α0) reaction

A multipole decomposition of the angular correlation functions of the reaction 40Ca(e,e′, α)36Arg.s. in the excitation energy range Ex = 10 – 20 MeV is presented. The response in 40Ca is dominated by isoscalar E0 and E2 strength exhausting 12.8(2.6)% and 8.4(1.7)% of the respective energy-weighted sum rules. The deduced energy distributions are in qualitative agreement with results from α-induced coincidence experiments on 40Ca, but the transition strengths are about a factor of two smaller. Some possible origins of this discrepancy are discussed.