Sensitivity of tungsten neutron cross sections to target band mixing andβ6deformation

It is shown that insertion of a deformation parameter ${\beta }_6$ in coupled channels calculations may be necessary for proper predictions of the neutron total cross sections (${\sigma }_T$) at incident energies below ∼700 keV. This is illustrated in the present work with the ${\sigma }_T$ measurements of Whalen et al. on the ${}_{}{}^{182,184,186}{}_{}{}^{}\mathrm{W}$ isotopes. In a previous report it has been established that these data could not be well reproduced using coupled channel calculations involving only ${\beta }_2$ and ${\beta }_4$ deformations. It is shown presently that this discrepancy can be removed if, provided that self-shielding corrections to these measurements are made, a small deformation parameter ${\beta }_6$ is considered in coupled channel analyses. As the W isotopes are lying at the rotational edge of the $A=190-200\mathrm{}$ transitional mass region, it is also emphasized that band mixing effects on the model predictions might be of some importance. These effects have been investigated for ${}_{}{}^{182,184,186}{}_{}{}^{}\mathrm{W}$ as well as for ${}_{}{}^{183}{}_{}{}^{}\mathrm{W}$ using realistic collective wave functions.