Unperturbed inverse kinematics nucleon knockout measurements with a carbon beam

• Published in: Nature physics Vol. 17; no. 6; pp. 693 - 699
• Main Authors: Patsyuk, M., Kahlbow, J., Laskaris, G., Duer, M., Lenivenko, V., Segarra, E. P., Atovullaev, T., Johansson, G., Aumann, T., Corsi, A., Hen, O., Kapishin, M., Panin, V., Piasetzky, E.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.06.2021; Nature Publishing Group; Nature Publishing Group (NPG)
• Subjects: 639/766/387/1126; 639/766/387/1129; Antiparticles; Antiprotons; Atomic; Atomic structure; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Inverse kinematics; Ion beams; Ions; Isotopes; Kinematics; Letter; Mathematical and Computational Physics; Molecular; Nuclei; Nucleons; Optical and Plasma Physics; Physics; Physics and Astronomy; Protons; Scattering; Theoretical; Wave functions
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/s41567-021-01193-4

Particle knockout scattering experiments 1 , 2 are fundamental for mapping the structure of atomic nuclei 2 – 6 , but their interpretation is often complicated by initial- and final-state interactions of the incoming and scattered particles 1 , 2 , 7 – 9 . Such interactions lead to reduction in the scattered particle flux and distort their kinematics. Here we overcome this limitation by measuring the quasi-free scattering of 48 GeV  c –1 12 C ions from hydrogen. The distribution of single protons is studied by detecting two protons at large angles in coincidence with an intact 11 B nucleus. The 11 B detection suppresses the otherwise large distortions of reconstructed single-proton distributions induced by initial- and final-state interactions. By further detecting residual 10 B and 10 Be nuclei, we also identified short-range correlated nucleon–nucleon pairs 9 – 13 and provide direct experimental evidence for separation of the pair wavefunction from that of the residual many-body nuclear system 9 , 14 . All measured reactions are well described by theoretical calculations that include no distortions from the initial- and final-state interactions. Our results showcase the ability to study the short-distance structure of short-lived radioactive nuclei at the forthcoming Facility for Antiproton and Ion Research (FAIR) 15 and Facility for Rare Isotope Beams (FRIB) 16 facilities, which is relevant for understanding the structure and properties of nuclei far from stability and the formation of visible matter in the Universe. Initial- and final-state interactions distort the kinematics in particle knockout scattering experiments, complicating their interpretation. These effects are suppressed by detecting 11 B nuclei in quasi-free scattering of 12 C ions from hydrogen.