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A Study of the Decay Modes of the ⁹Li Nucleus


Chen, Yu-Ssu (1970) A Study of the Decay Modes of the ⁹Li Nucleus. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/G3CW-6R66.


The beta decay of the ^9Li nucleus and the subsequent particle decays of the unbound states of the ^9Be nucleus have been investigated with two complementary techniques - The recoil-particle method and the beta-neutron coincidence method. ^9Li nuclei were produced by the ^(18)O (^7Li, ^9Li)^(16)O reaction with a 20 MeV bombarding energy and by the t(^7Li, ^9Li)p reaction with a 14 MeV bombarding energy. The energy spectrum of the delayed alphas and the time-of-flight spectrum of the delayed neutrons were obtained. The half life was also measured and was found to be 177 ± 3 msec. Besides the known decay branches to the ground state and to the 2.43 MeV state in ^9Be, a new decay branch to an unbound state in ^9Be at an excitation energy of 2.78 ± 0.125 MeV was observed. The branching ratios and the log ft values were found to be:

(65.0^(+2.7)_(-2.4))%, (32.0^(+2.7)_(-3.7))%, (3.0^(+2.7)_(-0.3))% and

(5.12^(+0.01)_(-0.02)), (5.00^(+0.04)_(-0.05)), (5.97^(+0.05)_(-0.28)) to the ground state,

the 2.43 MeV and the 2.78 MeV states, respectively. The observed properties of the 2.78 MeV state favor an assignment of ½^-. It decays mainly by p-wave neutron emission to the ground state of ^8Be and has center-of-mass width of 1.1 ± 0.125 MeV.

The fraction of the decays of the 2.43 MeV state in ^9Be involving emission of an f-wave neutron to the ground state of ^8Be was found to be (6.4 ± 1.2)%.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Tombrello, Thomas A.
Thesis Committee:
  • Unknown, Unknown
Defense Date:15 September 1969
Record Number:CaltechTHESIS:04142011-082223479
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6326
Deposited By: Tony Diaz
Deposited On:20 Apr 2011 16:00
Last Modified:25 Jun 2021 21:06

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