ANGULAR AND ENERGY-DEPENDENCE OF (E,E') CROSS-SECTIONS FOR ORBITAL 1(-EXCITATIONS())

The main features of the (e, e') cross sections of low-lying orbital e xcitations with K-pi = 1(+) in heavy deformed nuclei are studied in RP A on the example of Gd-156. The dependence of the DWBA E2 and M1 cross sections on the scattering angle 0 degrees < theta < 180 degrees and incident electron energy E(i) < 210 MeV is analyzed in PWBA. The cross section is larger for M1 than for E2 transitions at any angle if E(i) < 30 MeV. The longitudinal (Coulomb) C2 excitation dominates the E2 r esponse for 5 degrees < theta < 170 degrees. Only transverse M1 and E2 excitations compete for theta > 175 degrees and the former one is dom inant for q < 1.2 fm(-1). The M1 response is almost purely orbital up to q = 1.4 fm(-1) even in backward scattering. Qualitative PWBA estima tes based on the q-dependence of the form factors alone are not able t o predict some important features of the (e.e') cross sections stemmin g from the strong magnetic and orbital character of the studied 1(+) e xcitations. The expectation for M1 over E2 dominance in backward scatt ering should not be extended to higher momentum transfers and incident energies.