Measurement of the helicity-dependent response in quasi-elastic proton knockout from $^{40}$Ca

Kolar, Tim (author), Mihovilovič, Miha (author), Požun, Matej (author), Širca, Simon (author)

The 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.

• Language: English
• Keywords: nuclear physics, nuclear structure, electron scattering, final-state interactions, nuclear optical potential, polarized electron scattering, beam helicity asymmetry
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 7 str.
• Numbering: Vol. 871, art. no. 139977
• PID: 20.500.12556/RUL-175984
• UDC: 539.1
• ISSN on article: 1873-2445
• DOI: 10.1016/j.physletb.2025.139977
• COBISS.SI-ID: 257424131
• Publication date in RUL: 17.11.2025

Record is a part of a journal

• Title: Physics letters
• Shortened title: Phys. lett., B
• Publisher: Elsevier Science
• ISSN: 1873-2445
• COBISS.SI-ID: 524694809

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: jedrska fizika