Study of Some F20 Excited States

J. G. Pronko
Phys. Rev. C 7, 127 – Published 1 January 1973
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Abstract

Excited states of F20 which deexcite via γ-ray cascades through the 823-keV state were studied using the O18(He3,p) reaction at a beam energy of EHe3=2.88 MeV. Particle γ-ray angular correlations in a standard collinear geometry were obtained using NaI detectors for observing those γ rays which were in coincidence with proton groups representing excited states up to 4.3 MeV excitation. The analysis of these data involved the simultaneous fitting of the correlations of all possible cascading γ rays from the state under study and resulted in the measurement of spins, branching, and multipole mixing ratios for some excited states and their subsequent electromagnetic deexcitations. Coincident γ-ray spectra were also obtained with a Ge(Li) detector which provided additional information regarding the more complex decay schemes. Previously unreported lifetime information for the 1824- and 1972-keV states was obtained using the Doppler-shift-attenuation method and the O18(t,nγ)F20 reaction at a beam energy of Et2.85 MeV. These mean lifetimes are ≤ 65 fsec and ≥ 1.1 psec, respectively. The combined data for the 1824-keV state, as well as recently reported two-particle transfer data, suggest that the 823- and 1824-keV states are the Jπ=4+ and 5+ members, respectively, of the ground-state rotational band. Data obtained regarding the 1972-keV state suggest that this state has a Jπ=3 assignment, while those for the 2195-keV state imply a Jπ=3+ assignment. The results of this experiment are compared with recently reported shell-model calculations.

  • Received 11 September 1972

DOI:https://doi.org/10.1103/PhysRevC.7.127

©1973 American Physical Society

Authors & Affiliations

J. G. Pronko

  • Lockheed Palo Alto Research Laboratory, Palo Alto, California 94304

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Vol. 7, Iss. 1 — January 1973

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