The Coulomb Dissociation of 8B and a Critical Assessment of the Seattle S17(0) Result

Moshe Gai

Submitted on 17 April 2004


The Coulomb dissociation of 8B, measured with high precision by the GSI group, is in excellent agreement with the astrophysical cross section factor (S17) measured by the Weizmann group with a 7Be target. The GSI and Weizmann data are in good agreement with the Seattle data at high energies, but at low energies we observe a slight systematic (up to 2sigma) deviation, yet the Seattle group repeatedly rejects the CD method. We show that when plotting the slopes, they mis plotted one CD data point and exclude measured slopes that contradict their claim. Indeed the measured slope is essential to elucidate the d-wave correction to S17(0) that could be as large as 15%, and is the last open question that needs to be resolved before S17(0) can be quoted with an accuracy of 5% or better. We show that this goal has not been achieved (in spite of the strong claim of the Seattle group), since currently there is no agreement among experiments as well as among theoretical models on the value of the slope. In addition, currently there is no theoretical framework within which (for example the Seattle) data can be analyzed and S17(0) extrapolated with the claimed high precision of 2.5%. This (last) issue of the slope and the d-wave correction must be resolved (by future measurements) so as to allow quoting S17(0) with an accuracy of 5% or better.


Comment: Invited Talk, 20th Winter Workshop on Nuclear Dynamics, Jamaica, March 15-20, 2004. Work Supported by USDOE Grant No. DE-FG02-94ER40870

Subjects: Nuclear Experiment; Astrophysics; Nuclear Theory