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Excited states of the mirror nuclei beryllium-7 and lithium 7


Brown, Alfred B. (1950) Excited states of the mirror nuclei beryllium-7 and lithium 7. Dissertation (Ph.D.), California Institute of Technology.


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A low energy group of alpha particles has been found to result from the reaction B[superscript 10](p [alpha])Be[superscript 7*], indicating the existence of an excited state of Be[superscript 7]. Observation of this group and separation of the group from protons elastically scattered by the thin B[superscript 10] targets was made possible through high resolution magnetic analysis supplemented by absorption techniques. The excitation of the state is 0.434 [...] .005 Mev, and the Q-value of the reaction to the ground state is 1.148 [...] .006 Mev. The Q-value of the reaction to the excited state is thus 0.714 [...].008 Mev. On the basis of approximately equal neutron-neutron and proton-proton forces, the energy difference between the ground states of Li[superscript 7] and Be[superscript 7] can be accounted for as electro-static eneray, using a reasonable value of average separation of protons in the two nuclei. The energy difference between the state in Be[superscript 7] at 0.434 Mev and the state in Li[superscript 7] at 0.478 Mev can be similarly accounted for, if a small increase in the size of the nuclei over their size in the ground state is assumed. These results indicate that the ground states of the two nuclei may be considered corresponding states, and that the excited states may also be so considered. In the reaction to the excited state in Be[superscript 7] a resonance of about 0.28 Mev width exists at 1.51 Mev proton energy, and is observed in the yield of both alpha particles and gamma rays. In the reaction to the ground state there is a resonance 0.55 Mev wide at 1.06 Mev proton energy, and there is some indication of another at about 1.5 Mev.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Lauritsen, Charles Christian (advisor)
  • Fowler, William A. (advisor)
Thesis Committee:
  • Lauritsen, Charles Christian (chair)
  • Chao, C. Y.
  • Fowler, William A.
Defense Date:1 January 1950
Record Number:CaltechETD:etd-08252008-142317
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3223
Deposited By: Imported from ETD-db
Deposited On:25 Aug 2008
Last Modified:26 Dec 2012 02:58

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