Measurement of the helicity-dependent response in quasi-elastic proton knockout from $^{40}$CaKolar, Tim (Avtor) Mihovilovič, Miha (Avtor) Požun, Matej (Avtor) Širca, Simon (Avtor) nuclear physicsnuclear structureelectron scatteringfinal-state interactionsnuclear optical potentialpolarized electron scatteringbeam helicity asymmetryThe role of the electron-helicity-dependent cross-section term and the structure function $f'_{01}$ in the quasi-elastic $A(\overrightarrow{e}, e' p)$ process was studied. The $f'_{01}$ was measured for proton knockout from the $1\mathrm{d}_{3/2}$ shell in $^{40}$Ca via the $^{40}$Ca$(\overrightarrow{e}, e' p)^{39} K_{g. s.}$ reaction, leaving the residual nucleus in a well-defined state. It requires a longitudinally polarized electron beam and out-of-plane proton detection. This structure function vanishes in the absence of final-state interactions (FSI) involving the ejected proton. Presented are the dependencies of $f'_{01}$ on the missing momentum (closely related to the initial proton’s Fermi momentum) and the angle between the knocked-out proton and the virtual photon momenta. The role of the spin-orbit interaction in FSI through the $\overrightarrow{L}\cdot \overrightarrow{S}$ term in a nuclear optical potential is discussed.20252025-11-17 11:27:26Članek v reviji175984sl