1993•Journal of Physics G Nuclear and Particle PhysicsOpen access
The beta -delayed alpha spectrum of16N and the low-energy extrapolation of the12C( alpha , gamma )16O cross section
L. Buchmann, R.E. Azuma, C. A. Barnes, A Chen, J Chen, J.M. D’Auria, Marik Dombsky, U. Giesen, K. P. Jackson, J. Derwin King, R. G. Korteling, P. McNeely, J Powell, G Roy, M. Trinczek, J. Vincent, P. R. Wrean, S.S.M. Wong
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Abstract
The low-energy part of the beta alpha -decay spectrum of 16 N permits the determination of the reduced alpha -width theta alpha 2 of the 7.12 MeV subthreshold state of 16 O, which dominates the low-energy p-wave capture amplitude of the astrophysically important reaction 12 C( alpha , gamma ) 16 O. In a first run, a total of 7.1*10 3 alpha particles from the decay of 16 N nuclei, selected by the TRIUMF isotope separator. TISOL, have been observed in a 10.6 mu m detector in coincidence with the recoiling 12 C nuclei in a second detector, thus removing most sources of low-energy alpha background. These new data show a narrower width for the main alpha peak than previously determined. In addition, there is an indication of the low-energy interference anomaly predicted by several authors. The spectrum obtained can be parameterized in K- and R-matrix calculations, which also include the previously-measured 12 C( alpha , gamma ) 16 O cross sections and elastic scattering phase shifts. Results of a data collection run in June with much higher alpha yields will be presented.
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