Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session EM: Nuclear Structure A=6-20 Part II
7:00 PM–9:30 PM,
Thursday, October 25, 2018
Hilton
Room: Queen's 6
Chair: Frederic Sarazin, Colorado School of Mines
Abstract ID: BAPS.2018.HAW.EM.5
Abstract: EM.00005 : Study of neutron unbound states in 18O by β-delayed neutron decay of 18N
8:00 PM–8:15 PM
Presenter:
Hajime Umehara
(Department of Physics, Osaka University)
Authors:
Hajime Umehara
(Department of Physics, Osaka University)
Shun Iiumra
(Department of Physics, Osaka University)
Shinnosuke Kanaya
(Department of Physics, Osaka University)
Hiroki Nishibata
(RIKEN Nishina Center)
Atsuko Odahara
(Department of Physics, Osaka University)
Tadashi Shimoda
(Department of Physics, Osaka University)
Masaharu Kinoshita
(Department of Physics, Osaka University)
Rei Shudo
(Department of Physics, Osaka University)
Ryo Nakajima
(Department of Physics, Osaka University)
Takafumi Hara
(Department of Physics, Osaka University)
Ryo Wakabayashi
(Department of Physics, Osaka University)
The neutron-unbound states in 18O have been investigated in various types of experiments, however, the data are still in disagreement with each other. The latest β-delayed neutron data in 2005 showed a large missing neutron intensity. We have performed an experiment to measure the β-delayed neutron decay of 18N for the unbound states in 18O with a newly developed TOF detector system consisting of large and small plastic scintillators for a wide neutron energy range (100 keV- 4 MeV), which was designed for spectroscopy of very neutron-rich nuclei far from the stability.
The radioactive nucleus 18N was produced at RCNP, Osaka University by the direct reaction of 9Be(18O,18N)9B at 9.4 MeV/u. The secondary 18N beam was isotope-separated by the fragment separater and transported to a gold stopper foil. The 18N beam intensity of ~1300 pps with purity of ~98% was obtained with the primary beam intensity of 3.2 eμA. The β ray and the γ ray were detected by thin plastic scintillators and Ge detectors, respectively.
With such system we could find a new low-energy neutron peak (En~355 keV) with large intensity, which may solve the missing neutron intensity problem. Search for other small peaks is in progress. A revised decay scheme of 18N is presented based on β-n-γ coincidence relation.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.HAW.EM.5
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