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A Study of the Li⁷(He³,n)B⁹ Reaction by Time-of-Flight Techniques


Dietrich, Frank Sigel, III (1964) A Study of the Li⁷(He³,n)B⁹ Reaction by Time-of-Flight Techniques. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Q5EC-9W47.


NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The Li^7(He^3,n)B^9 reaction has been investigated at incident energies from 5.2 to 12.5 Mev, using a pulsed-beam time-of-flight spectrometer in conjunction with the ONR-CIT tandem accelerator. The spectrometer includes a pre-acceleration beam-bunching system, which increases the average target current by a factor of approximately 10 for protons and deuterons, and 4 for He^3 and alpha beams. Previously unreported B^9 levels were found at the energies listed below, together with their widths: [...] At 12.5-Mev bombarding energy, neutron groups corresponding to known B^9 states at 17.19 and 17.63 Mev were observed. No other B^9 states were resolved below 17.9-Mev excitation. The neutron groups were superimposed on an intense background continuum, attributable to processes leading to the final configuration 2[alpha] + p + n. An angular distribution at 8.7-Mev incident energy of neutrons leading to the 14.67-Mev state is roughly isotropic in the center-of-mass system, and the total cross section is 8 mb. A T=3/2 assignment for the 14.67-Mev state is suggested by its narrow width, and by recent studies of the Li^7(t,p)Li^9 and Li^7(He^3,p)Be^9 reactions. A comparison of the Li^7(He^3,p)Be^9 and Li^7(He^3,n)Be^9 reactions shows that the cross sections for formation of the 14.67-Mev B^9 state and the analogous Be^9 state are approximately equal, if barrier-penetration effects in the outgoing channels are removed.

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):
  • Barnes, Charles A. (advisor)
  • Kavanagh, Ralph William (advisor)
  • Lauritsen, Thomas (advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:19 May 1964
Record Number:CaltechETD:etd-09262002-161756
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3780
Deposited By: Imported from ETD-db
Deposited On:27 Sep 2002
Last Modified:19 Jan 2024 00:49

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PDF (Dietrich_fs_1964.pdf) - Final Version
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