title: (22)Ne(alpha,n)(25)Mg: the key neutron source in massive stars.
abstract: The excitation function of the reaction (22)Ne(alpha,n)(25)Mg, the key neutron source in the astrophysical s process in massive stars, has been determined from threshold at E(alpha) = 570 up to 1450 keV with an experimental sensitivity of 10(-11) b. For all resonances in this energy range new resonance parameters have been measured. For a possible resonance at about 635 keV a new upper limit omega gamma < 60 neV for the strength was obtained. Based on the new data, improved reaction rates were calculated as a function of temperature. The new uncertainty limits are considerably smaller than in previous determinations, ruling out the large enhancement factors, up to 500, assumed in some stellar model calculations.
authors.affiliation: Institut für Strahlenphysik, Universität Stuttgart, D-70550 Stuttgart, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Jaeger
authors.forename: R
authors.initials: R
authors.lastname: Kunz
authors.forename: A
authors.initials: A
authors.lastname: Mayer
authors.forename: J W
authors.initials: JW
authors.lastname: Hammer
authors.forename: G
authors.initials: G
authors.lastname: Staudt
authors.forename: K L
authors.initials: KL
authors.lastname: Kratz
authors.forename: B
authors.initials: B
authors.lastname: Pfeiffer