J. Fernández-Vázquez

Structure of neutron-rich oxygen isotopes

One-nucleon removal reactions at relativistic energies have been used as a spectroscopic tool for obtaining information about the ground state of neutron-rich oxygen isotopes. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after breakup were measured along with the one-nucleon removal cross-sections. The relative contributions of the remaining fragments in their ground and excited states have been determined for a few cases from measurements of γ rays in coincidence with the longitudinal momentum distribution. The controversial case of 23O has been directly addressed. Comparison of our exclusive momentum distributions for the one-neutron removal channel to theoretical momentum distributions calculated with an Eikonal model for the knockout process rendered a spin and parity of Iπ = 1/2+ for the 23O ground state. This result resolves the existent experimental discrepancy and supports sub-shell closure at N = 14 with a fairly pure 2s1/2 neutron in 23O.

Spectroscopy of light exotic nuclei using nuclear break‐up

One‐nucleon removal reactions at relativistic energies have been used as spectroscopic tool to obtain information about the ground state properties of several neutron‐rich isotopes in the sd‐shell. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after one‐nucleon removal cross‐sections were measured. The relative contributions of the remaining fragments in their ground and excited states have been determined from measurements of γ rays in coincidence with the longitudinal momentum distributions. The interesting case of 23O will be directly address. The interpretation of our experimental results in the framework of a simple theoretical model will favours a spin and parity assignment of 1/2+ for the 23O ground state in agreement with shell model predictions.

New Results On 8B And 23O Ground State Properties

One‐nucleon removal reactions at relativistic energies have been used as spectroscopic tool to obtain information about the ground state properties of 8B and 23O. Using the FRS at GSI, the longitudinal momentum distributions of the emerging fragments after breakup and the one‐nucleon removal cross‐sections were measured. The relative contributions of the remaining fragments (7Be and 22O) in their ground and excited states have been determined from measurements of γ rays in coincidence with the longitudinal momentum distributions. In the 8B case, the experimental breakup data on two different targets (C and Pb) allow a determination of the weight of the 7Be* component in the 8B ground state wave function as (13.3±2.2) %. These results are discussed in the context of a theoretical three‐body model. Preliminary results on 23O indicate a spin and parity assignment of 1/2+ in agreement with shell model predictions.