The Dissociation of 8B in the Coulomb Field and the Validity of the CD Method - Nuclear ExperimentReport as inadecuate

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Abstract: The GSI1, GSI2 as well as the RIKEN2 and the corrected GSI2 measurements ofthe Coulomb Dissociation CD of 8B are in good agreement with the most recentDirect Capture DC 7Bep,g8B reaction measurement performed at Weizmann andin agreement with the Seattle result. Yet it was claimed that the CD and DCresults are sufficiently different and need to be reconciled. We show thatthese statements arise from a misunderstanding as well as misrepresentationof CD experiments. We recall a similar strong statement questioning thevalidity of the CD method due to an invoked large E2 component that was alsoshown to arise from a misunderstanding of the CD method. In spite of the goodagreement between DC and CD data the slope of the astrophysical cross sectionfactor S17 can not be extracted with high accuracy due to a discrepancybetween the recent DC data as well as a discrepancy of the three reports of theGSI CD data. The slope is directly related to the d-wave component thatdominates at higher energies and must be subtracted from measured data toextrapolate to zero energy. Hence the uncertainty of the measured slope leadsto an additional uncertainty of the extrapolated zero energy cross sectionfactor, S170. This uncertainty must be alleviated by future experiments toallow a precise determination of S170, a goal that so far has not be achievedin spite of strong statements that appeared in the literature.

Author: Moshe Gai Yale and UConn-LNS at Avery Point


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