Constraints on the low-energy [ital E]1 cross section of [sup 12]C([alpha],[gamma])[sup 16]O from the [beta]-delayed [alpha] spectrum of [sup 16]N

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.50.1194· OSTI ID:7015099

Azuma, R E; Buchmann, L; Barker, F C; Barnes, C A; D'Auria, J M; Dombsky, M; Giesen, U; Jackson, K P; King, J D; Korteling, R G; McNeely, P; Powell, J; Roy, G; Vincent, J; Wang, T R; Wong, S S.M.; Wrean, P R ^[1]

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1. Department of Physics; University of Toronto; Toronto; Ontario; M5S 1A7 (Canada) TRIUMF; 4004 Wesbrook Mall; Vancouver; British Columbia; V6T 2A3 (Canada) Department of Theoretical Physics; Research School of Physical Sciences Engineering; Australian National University; Canberra; Australian Capital Territory 0200 (Australia) W. K. Kellogg Laboratory; California Institute of Technology; Pasadena; California 91125 (United States) Department of Chemistry; Simon Fraser University; Burnaby; British Columbia; V5A 1S6 (Canada) Department of Physics; University of Alberta; Edmonton; Alberta; T6G 2J1 (Canada)

The shape of the low-energy part of the [beta]-delayed [alpha]-particle spectrum of [sup 16]N is very sensitive to the [alpha]+[sup 12]C reduced width of the 7.117 MeV subthreshold state of [sup 16]O. This state, in turn, dominates the low-energy [ital p]-wave capture amplitude of the astrophysically important [sup 12]C([alpha],[gamma])[sup 16]O reaction. The [alpha] spectrum following the decay of [sup 16]N has been measured by producing a low-energy [sup 16]N[sup 14]N[sup +] beam with the TRIUMF isotope separator TISOL, stopping the molecular ions in a foil, and counting the [alpha] particles and [sup 12]C recoil nuclei in coincidence, in thin surface-barrier detectors. In addition to obtaining the [alpha] spectrum, this procedure determines the complete detector response including the low-energy tail. The spectrum, which contains more than 10[sup 6] events, has been fitted by [ital R]- and [ital K]-matrix parametrizations which include the measured [sup 12]C([alpha],[gamma])[sup 16]O cross section and the measured [alpha]+[sup 12]C elastic scattering phase shifts. The model space appropriate for these parametrizations has been investigated. For [ital S][sub [ital E]1](300), the [ital E]1 part of the astrophysical [ital S] factor for the [sup 12]C([alpha],[gamma])[sup 16]O reaction at [ital E][sub c.m.]=300 keV, values of 79[plus minus]21 and 82[plus minus]26 keV b have been derived from the [ital R]- and [ital K]-matrix fits, respectively.

• OSTI ID: 7015099
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 50:2; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA DECAY
ALPHA REACTIONS
BETA DECAY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY
BETA-MINUS DECAY RADIOISOTOPES
CAPTURE
CARBON 12 TARGET
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DECAY
E1-TRANSITIONS
ELASTIC SCATTERING
ELECTROMAGNETIC RADIATION
ENERGY RANGE
ENERGY SPECTRA
ENERGY-LEVEL TRANSITIONS
EVEN-EVEN NUCLEI
GAMMA RADIATION
IONIZING RADIATIONS
ISOTOPES
LIGHT NUCLEI
MATRICES
MEV RANGE
MEV RANGE 100-1000
MULTIPOLE TRANSITIONS
NITROGEN 16
NITROGEN ISOTOPES
NUCLEAR DECAY
NUCLEAR REACTIONS
NUCLEI
ODD-ODD NUCLEI
OXYGEN 16
OXYGEN ISOTOPES
PHASE SHIFT
R MATRIX
RADIATIONS
RADIOISOTOPES
SCATTERING
SECONDS LIVING RADIOISOTOPES
SPECTRA
STABLE ISOTOPES
TARGETS