Fast Neutron Inelastic Scattering Cross Sections of²³⁸U for States between 680 and 1530 keV

Excitation of octupole, beta- and gamma-vibration band levels of 238U by inelastic neutron scattering

“…The latter level calculated cross section is shown in Fig. 15; it is in agreement with the time-of-flight (TOF) measured data by Shao et al [12]. In a calculation by Young et al [30] there is an appreciable direct excitation cross section of second octupole band-head 0.9308 MeV (K π = 1 − ), the same happens in case of 0.9502 MeV (J π = 2 − ) level.…”

“…5. In most cases calculated cross sections for excitation of discrete levels of first octupole K π = 0 − band levels are in nice agreement with time-of-flight (TOF) measured data by Shao et al [12], which are supported by data by Smith et al [33], Vorotnikov et al [34] and data by Kazjula et al [35] for E n 1 MeV. Measured data derived by the (n, n γ ) method [13] in most cases are higher than the calculated inelastic scattering cross section above E n ∼ 1.5 MeV and lower for E n 1.5 MeV, or in the whole energy range.…”

“…Differential scattering data (see Figs. 6, 7, 8, 9 and 10), relevant for the excitation of collective levels lying in the range of E exc ∼ 0.63-0.89 MeV for incident neutron energies E n = 2.047, 2.19, 2,51, 3.007, 3.51 MeV, as well as data by Allyar et al [10] and Shao et al [12], predict forward peaking of inelastic scattered neutrons; however, it might be due to unsubtracted elastic scattering background. The variation of β 3 octupole deformation parameter produces only 'parallel' shifts of angular distributions, i.e., we cannot reproduce forward peaking of angular distribution for E n = 2.047, 2.19 with the present model.…”

“…3, 4 and 5 show that the estimates for the levels J π = 1 − , 3 − and 5 − in [30,31] are too low, as compared with the present estimate and that by Lopez Jimenez et al [32]. The latter two estimates are supported by measured data from Shao et al [12].…”

“…A number of measured data is available for the K π = 0 + 2 , 0 + 3 and K π = 2 + band levels. Comparison of combined angle-integrated excitation cross section of γ -vibration band-head 0.9257 MeV (K π = 0 + 2 ) and second octupole band-head 0.9308 MeV (K π = 1 − ) with measured data [12,33,35] is shown in Fig. 14.…”