Orbital response to backward (e, e′) scattering at low and high excitation energies

Abstract

Abstract The response of orbital excitations with K π = 1 + in heavy deformed nuclei to backward ( e , e ′) scattering is studied in RPA on the example of 154 Sm. The summed M1 and E2 cross sections are of comparable magnitude over wide ranges of transferred momenta: 0.9 q −1 for low excitation energies E x q −1 in the high-energy region 17 E x q , where the M1 response dominates at low energy and the E2 response in the high-energy region. The transition densities of the single strongest RPA states from the two energy regions are similar to that of the scissors state, apart from their smaller amplitudes. The spin M1 responses are similar at low and high energy and dominant for high q . The orbital M1 response is dominant up to high q -values at low energy and only for small q at high energy. The electric response of the low RPA state (mainly C2) is suppressed at a full backward angle, while it persists at high energy for θ ⩾ 165° due to its dominant transverse E2 component. The E2 strength below 9 MeV and between 13 and 17 MeV belongs neither to the isoscalar nor to the isovector giant resonances.