The 7Be(p, γ) 8B Reaction and its Future

Abstract

The experimental landscape for the 7 Be+p radiative capture reaction is rapidly changing as new high precision data become available. We present an evaluation of existing data, detailing the treatment of systematic errors and discrepancies, and show how they constrain the astrophysical S factor ( S 17 ), independent of any nuclear structure model. With theoretical models robustly determining the behavior of the sub-threshold pole, the extrapolation error can be reduced and a constraint placed on the slope of S 17 . Usin only radiative capture data, we find S 17 ( 0 ) = 20.7 ± 0.6 ( stat ) ± 1.0 ( syst ) eV b if data sets are completely independent, while if data sets are completely correlated we find S 17 ( 0 ) = 21.4 ± 0.5 ( stat ) ± 1.4 ( syst ) eV b . The truth likely lies somewhere in between these two limits. Although we employ a formalism capable of treating discrepant data, we note that the central value of the S factor is dominated by the recent high precision data of Junghans et al., which imply a substantially higher value than other radiative capture and indirect measurements. Therefore we conclude that future progress will require new high precision data with a detailed error budget.