Comment on E2 Contribution to the 8B ---> p + 7Be Coulomb Dissociation   Cross Section [K. Langanke and T.D. Shoppa, Phys. Rev. C49(1994)R1771,   ER(1994)]
  The E2 cross section calculated by Langanke and Shoppa for the Riken experiment on the Coulomb Dissociation of 8B uses E2 nuclear matrix elements from one specific model. Other nuclear models predict a considerably smaller E2 cross section (by a pproximately a factor of 3 to 4), and Langanke and Shoppa appear to assume the most optimistic scenario predicting large E2 cross section. We also note that Barker has already criticised the nuclear model used by Langanke and Shoppa. A MODEL INDEPENDENT Chi-Square analysis of the Riken data, suggest the best fit for the current Riken data is obtained with E1 amplitudes only. The upper limit (90% confidence) on the E2 component derived from our Chi-Square analysis is considerably smaller than used by Langanke and Shoppa. The MODEL DEPENDENT analysis of Langanke-Shoppa should not be considered as a correction to the Riken result, as claimed, and their quoted S17(0) is not substantiated. 
Moshe Gai (Yale University) and Carlos Bertulani