The mechanism of direct knockout of a nucleon from heavy deformed nuclei with $A\gtrsim 100$ by photons in the $E_{\gamma }\lesssim 40$ MeV energy range is considered, and the interaction of the ejected nucleon with the rotational degrees of freedom of the final nucleus is taken into account. It is assumed that the rotation frequency of the nucleus is much less than the frequency of its surface vibrations and the Siegert's theorem is in effect. This model was applied to calculation of the total and differential cross sections of direct proton knockout reactions on ${}^{108}\mathrm{Pd}, {}^{160}\mathrm{Gd}$, and ${}^{184,186}\mathrm{W}$ and the bremsstrahlung-induced yield of photoprotons on ${}^{180}\mathrm{Hf}$. Comparison with the experimental data and with the results of a statistical model calculation indicates importance of the direct photoeffect for such nuclei in the considered energy range. Calculations show that for deformed nuclei the interaction of the ejected nucleon with the rotational excitations of the final nucleus results in a significant enhancement of the direct photoeffect cross section. Angular distribution of ejected protons reveals a large asymmetry in the forward direction at $E_{\gamma }>20$ MeV.

• Received 27 April 2023
• Revised 14 October 2023
• Accepted 24 October 2023

DOI:https://doi.org/10.1103/PhysRevC.108.054606