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The β-delayed α spectrum of ^(16)N and the low-energy extrapolation of the ^(12)C(α, γ)^(16)O cross section

Buchmann, L. and Azuma, R. E. and Barnes, C. A. and Chen, A. and Chen, J. and D'Auria, J. M. and Dombsky, M. and Giesen, U. and Jackson, K. P. and King, J. D. and Korteling, R. and McNeely, P. and Powell, J. and Roy, G. and Trinczek, M. and Vincent, J. and Wrean, P. R. and Wong, S. S. M. (1993) The β-delayed α spectrum of ^(16)N and the low-energy extrapolation of the ^(12)C(α, γ)^(16)O cross section. In: Nuclei in the Cosmos. Institute of Physics , Philadelphia, pp. 275-286. ISBN 0-7503-0260-7. https://resolver.caltech.edu/CaltechAUTHORS:20150916-062850057

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Abstract

The low-energy part of the βα-decay spectrum of ^(16)N permits the determination of the reduced α-width θ^2_ɑ 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(α, γ)^(16)O. In a first run, a total of 7.1 x 10^3 a particles from the decay of ^(16)N nuclei, selected by the TRIUMF isotope separator TISOL, have been observed in a 10.6 μm detector in coincidence with the recoiling ^(12)C nuclei in a second detector, thus removing most sources of low-energy a background. These new data show a narrower width for the main a 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 parametrized in K- and R-matrix calculations, which also include the previously-measured ^(12)C(α, γ)^(16)O cross sections and elastic scattering phase shifts. Results of a data collection run in June with much higher α yields will be presented.


Item Type:Book Section
Additional Information:© 1993 IOP Publishing Ltd. Numerous people have contributed to this experiment. We want to thank in particular H. Biegenzein, D. Jones, P. Machule, H. Sprenger and A. Wilson for help in the mechanical set-up of the experiment, G. Sheffer and the electronics workshop for help in the requisition and setting up of the electronics components, and D. Diel and P. Green for help with the data acquisition system. The operators of the 500 MeV cyclotron are acknowledged for providing the essential proton beam. Our special thanks go to Teleglobe Canada for the donation of a 6 GHz amplifier without which the operation of the ECR source at TISOL and this experiment would have been impossible. One of the authors (REA) wishes to express his thanks to Caltech for the hospitality received during the early stages of the experiment. We are grateful to Triumf management for their vigorous support of the TISOL facility in general and timely assistance to this experiment in particular. Funding for the experiment was provided by the Natural Sciences and Engineering Research Council of Canada. The Caltech participation was supported in part by the U.S. National Science Foundation.
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Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150916-062850057
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ID Code:60269
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:16 Sep 2015 17:39
Last Modified:03 Oct 2019 08:55

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