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Mass Measurements of Some Proton-Rich Nuclei


Miller, Richard Graham (1966) Mass Measurements of Some Proton-Rich Nuclei. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/YTVX-HS04.


The Q values and 0o cross sections of (He3, n) reactions forming seven proton-rich nuclei have been measured with accuracies varying from 6 to 18 keV. The Q values (in keV) are: Si26 (85), S30 (-573), Ar34 (-759), Ti42 (-2865), Cr48 (5550), Ni56 (4513) and Zn60 (818). At least one excited state was found for all but Ti42. The first four nuclei complete isotopic spin triplets; the results obtained agree well with charge-symmetry predictions. The last three, all multiples of the α particle, are important in the α and e-process theories of nucleo-synthesis in stars. The energy available for β decay of these three was found by magnetic spectrometer measurements of the (He3, p) Q values of reactions leading to V48, Co56, and Cu60. Many excited states were seen: V48 (3), Co56 (15), Cu60 (23). The first two states of S30 are probably 0+ and 2+ from (He3, n) angular distribution measurements. Two NaI γ-ray measurements are described: the decay of Ar34 (measured Ƭ1/2 = 1.2 ± 0.3s) and the prompt γ-ray spectrum from Fe54(He3, nγ)Ni56. Possible collective structure in Ni56 and Ca40, both doubly magic, is discussed.

The (He3, n) neutron energy and yield measurements utilized neutron-induced nuclear reactions in a silicon semiconductor detector. Cross sections for the most important detection processes, Si28 (n, α) Mg25 and Si28 (n, p) Al28, are presented for reactions leading to the first four states of both residual nuclei for neutron energies from 7.3 to 16.4 MeV. Resolution and pulse-height anomalies associated with recoil Mg25 and Al28 ions are discussed. The 0o cross section for Be9 (α, n) C12, used to provide calibration neutrons, has been measured with a stilbene spectrometer for no (5.0 ≤ Eα ≤ 12 MeV), n1 (4.3 ≤ Eα ≤ 12.0 MeV) and n2 (6.0 ≤ Eα ≤ 10.1 MeV). Resonances seen in the no yield may correspond to nine new levels in C13.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Physics and Biophysics)
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Minor Option:Biology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Kavanagh, Ralph William
Thesis Committee:
  • Unknown, Unknown
Defense Date:14 March 1966
Funding AgencyGrant Number
Office of Naval ResearchNonr-220(47)
Record Number:CaltechTHESIS:10122015-082232803
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9210
Deposited On:13 Oct 2015 20:28
Last Modified:05 Mar 2024 22:31

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