Abstract
Background: For many years, quasifree scattering reactions in direct
kinematics have been extensively used to study the structure of stable
nuclei, demonstrating the potential of this approach. The (RB)-B-3
collaboration has performed a pilot experiment to study quasifree
scattering reactions in inverse kinematics for a stable C-12 beam. The
results from that experiment constitute the first quasifree scattering
results in inverse and complete kinematics. This technique has lately
been extended to exotic beams to investigate the evolution of shell
structure, which has attracted much interest due to changes in shell
structure if the number of protons or neutrons is varied.
Purpose: In this work we investigate for the first time the quasifree
scattering reactions (p, pn) and (p, 2p) simultaneously for the same
projectile in inverse and complete kinematics for radioactive beams with
the aim to study the evolution of single-particle properties from N = 14
to N = 15.
Method: The structure of the projectiles O-23, O-22, and N-21 has been
studied simultaneously via (p, pn) and (p, 2p) quasifree knockout
reactions in complete inverse kinematics, allowing the investigation of
proton and neutron structure at the same time. The experimental data
were collected at the (RB)-B-3-LAND setup at GSI at beam energies of
around 400 MeV/u. Two key observables have been studied to shed light on
the structure of those nuclei: the inclusive cross sections and the
corresponding momentum distributions.
Conclusions: The knockout reactions (p, pn) and (p, 2p) with radioactive
beams in inverse kinematics have provided important and complementary
information for the study of shell evolution and structure. For the (p,
pn) channels, indications of a change in the structure of these nuclei
moving from N = 14 to N = 15 have been observed, i.e., from the 0d(5/2)
shell to the 1s(1/2). This supports previous observations of a subshell
closure at N = 14 for neutron-rich oxygen isotopes and its weakening for
the nitrogen isotopes.
Users
Please
log in to take part in the discussion (add own reviews or comments).