Eur. Phys. J. A 11, 357-370 (2001)

The E1 capture amplitude in

L. Gialanella¹, D. Rogalla¹, F. Strieder¹, S. Theis¹, G. Gyürki², C. Agodi³, R. Alba³, M. Aliotta¹, L. Campajola⁴, A. Del Zoppo³, A. D'Onofrio⁵, P. Figuera³, U. Greife¹, G. Imbriani⁴, A. Ordine⁴, V. Roca⁴, C. Rolfs¹, M. Romano⁴, C. Sabbarese⁵, P. Sapienza³, F. Schümann¹, E. Somorjai³, F. Terrasi⁵ and H.P. Trautvetter<sup>1

1</sup>  Institut für Physik mit Ionenstrahlen, Ruhr-Universität Bochum, Bochum, Germany
²  Atomki, Debrecen, Hungary
³  Laboratori Nazionali del Sud, INFN, Catania, Italy
⁴  Dipartimento di Scienze Fisiche, Università Federico II, Napoli and INFN, Napoli, Italy
⁵  Dipartimento di Scienze Ambientali, Seconda Università di Napoli, Caserta and INFN, Napoli, Italy

rolfs@ep3.ruhr-uni-bochum.de

(Received: 6 June 2001 / Revised version: 9 July 2001 Communicated by Th. Walcher)

Abstract
An excitation function of the ground-state -ray capture transition in ¹²C O at was obtained in far geometry using six Ge detectors, where the study of the reaction was initiated in inverse kinematics involving a windowless gas target. The detectors observed predominantly the E1 capture amplitude. The data at E = 1.32 to 2.99 MeV lead to an extrapolated astrophysical S factor keV b at E₀ = 0.3 MeV (for the case of constructive interference between the two lowest E1 sources), in good agreement with previous works. However, a novel Monte Carlo approach in the data extrapolation reveals systematic differences between the various data sets such that a combined analysis of all available data sets could produce a biased estimate of the S_E1(E₀) value. As a consequence, the case of destructive interference between the two lowest E1 sources with keV b cannot be ruled out rigorously.

PACS
24.10.-i - Nuclear-reaction models and methods.
25.40.-h - Nucleon-induced reactions.

© Società Italiana di Fisica, Springer-Verlag 2001