[Triumf-seminars] TRIUMF Seminar today at 11:00

[triumf-seminars at lists.triumf.ca]

Date/Time: Wed 2011-05-25 at 11:00

Location:  Auditorium          

Speaker:   Gregory Christian (NSCL, Michigan State University)

Title:     Spectroscopy of Neutron Unbound Fluorine

Abstract: Knockout reactions from a beam of Ne-29 at 62 MeV/u were used to populate the neutron-unbound ground state of F-28, as well as unbound excited states in F-27. These nuclei lie close to the traditional magic number N = 20, which has been shown to break down for neutron rich nuclei. Knowledge of the F-28 and F-27 level structure gives insight into the mechanisms which allow for bound F-29 and F-31, helping to explain why an abrupt shift in the neutron dripline--of six of more neutrons--is observed between Oxygen and Fluorine.  The neutron unbound states under investigation decay through the emission of one or more neutrons which were detected near zero degrees in the MoNA plastic scintillator array. The remaining charged fragments were deflected by the Sweeper dipole magnet, and their kinematic properties were measured in detectors behind the magnet. The decay energy was then calculated from the measured energies and angles of the neutrons and the fragments. In addition, coincident gamma-rays were measured at the target location using the recently commissioned CAESAR CsI(Na) array. The gamma-ray tagging was used to determine whether the neutron decayed to the ground state or an excited state of the daughter nucleus. In this talk, an overview of the motivation, experimental technique, data analysis, and preliminary results will be presented.

Stimulants available 15 minutes before the talk.

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