Precision measurements of the 12C(αγ) reaction with gamma beams and TPC detector(s)

Abstract

The cross section of the 12C(α,γ)16O reaction, well-recognized as the most important nuclear input of stellar evolution theory, has eluded precise measurements over the last few decades, as evident in the lack of precise confirmation of an elementary prediction of quantum mechanics of the E1-E2 mixing phase angle (ϕ12). More troubling are modern data, measured with 4π array of HPGe detectors, that are in conflict with this prediction. A new method to measure this cross section with TPC detectors and gamma-beams, by measuring the time reverse 16O(γ,α)12C reaction discussed here, shows great promise, for example the measured data do not disagree with the predicted π12 and agree with the predicted trend.