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A study of the ^9 Be nucleus

Citation

Cocke, Charles Lewis (1967) A study of the ^9 Be nucleus. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2DBM-0G92. https://resolver.caltech.edu/CaltechTHESIS:11022015-145724587

Abstract

The reaction 7Li(3He, p)9Be has been used to measure excitations and intrinsic widths of levels in 9Be below the 7Li + d threshold. Previously unreported levels have been found at excitations of (13.78 ± .03) MeV and (16.671 ± .008) MeV with widths of (590 ± 60) keV and (41 ± 4) keV respectively. Two overlapping levels have been found at (11.81 ± .02) MeV and (11.29 ± .03) MeV with widths of (400 ± 30) keV and (620 ± 70) keV respectively. Branching ratios from 9Be levels populated in this reaction to the ground and first excited states of 8Be have been measured by observing the associated protons in coincidence with the decay neutrons. Branching ratios were found to be:

Excitation in 9Be .... Branching Ratio.......... Final Nucleus.........

(MeV) .......................... (percent) .....................................

.. 2.43 ........................... 7.5 ± 1.5 .............. 8Be(g.s.)

.. 3.03 ........................... 87 ± 13......................................

.. 4.65 ........................... 13 ± 4.......................................

.. 6.76 .............................. ≤ 2 ......................................

.. 11.29 ...............................≤ 2 ......................................

.. 11.81 ...............................≤ 3 ......................................

.. 6.76 ........................... .41 ≤ B.R. ≤ .69 ....... 8Be(2+)

.. 11.29 ........................... 14 ± 4 .......................................

.. 11.81 ........................... 12 ± 4 .......................................

Corresponding reduced widths for neutron emission are calculated and a comparison of the results with the expectations of current nuclear models is made. In particular the measured branching ratio to 8Be(g.s.) from 9Be(2.43 MeV) corresponds to an f-wave reduced with θ2f = 2.1 x 10-2, in units of ħ2/mR2, with R = 4.35 fm. A comparison of this value with that predicted by a Nilsson model calculation, in which 9Be is taken to be a deformed nucleus, is discussed. The measured value for θ2f is found to be consistent with that expected on the basis of measured E2-transition rates between rotational levels in 9Be.

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):
  • Lauritsen, Thomas
Thesis Committee:
  • Unknown, Unknown
Defense Date:5 May 1967
Record Number:CaltechTHESIS:11022015-145724587
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:11022015-145724587
DOI:10.7907/2DBM-0G92
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9268
Collection:CaltechTHESIS
Deposited By: Leslie Granillo
Deposited On:04 Nov 2015 22:07
Last Modified:20 Dec 2019 19:39

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