Abstract
The proton-removal mechanism of the 12C→11B reaction induced on a carbon target via elementary nucleon-nucleon scattering is investigated in exclusive triple-coincidence measurements. The observed two-nucleon angular correlations are found to be consistent with quasi-free scattering of a projectile-like proton off a target-like nucleon. Exclusive cross sections for one-step pp and pn interactions are determined as σpp=17.2(12) mb and σpn=18.2(18), respectively. The extracted quasi-free component amounts up to 58(4)% of the total proton-removal cross section. The results are compared to total proton-removal cross sections obtained from the experiment and eikonal reaction theory.
Highlights
In all simulations the Fermi momenta of both interacting nucleons were assumed to be equivalent to the measured recoil momentum of the outgoing 11B (Fig. 4), which can be reasonably well described by the quasi-free knockout of a proton from the p-shell in 12C [24]
The sum of σpp and σpn accounts for about 58% of the total p-removal cross section, and the remaining part is almost completely attributed to σres which can be related predominantly with the exceeding Nc =1 events in the Crystal Ball (CB)
Such a two-step mechanism is not taken into account in eikonal theories used to analyze nucleon-removal reactions, and it can result in additional reduction of the survival probability for ( A-1) fragments. Since this effect is expected to be larger for well-bound nucleons compared to loosely bound nucleons, it could possibly give a sizeable contribution to the reduction of cross sections for knockout of more deeply bound nucleons as found in intermediate-energy nucleon-removal reactions compared to theoretical cross sections [19]
Summary
In all simulations the Fermi momenta of both interacting nucleons were assumed to be equivalent to the measured recoil momentum of the outgoing 11B (Fig. 4), which can be reasonably well described by the quasi-free knockout of a proton from the p-shell in 12C [24]. Some evidence of the transfer processes was found in nucleon-removal reactions slightly below 100 MeV/u [17], their contribution to the total cross section was on the order of 10% so that one may expect practically negligible values at our beam energy.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
