Nuclear Seminar

"²⁴Mg(α,γ)²⁸Si Resonance Parameters at Low Alpha Energies”

Elizabeth K. Strandberg
University of Notre Dame

Monday, March 26, 2007   4:00 p.m.   NSH 124
(Refreshments served prior to seminar in NSH 124)

²⁸Si is formed by successive alpha captures on ¹²C during the AGB (asymptotic giant branch) stage of stellar burning.  The last reaction in this series, ²⁴Mg(α,γ)²⁸Si, has not been examined with sufficient sensitivity at alpha energies below 1.5 MeV.  Several ²⁸Si states appear favorable for formation by this reaction in the alpha energy range of 1.0 – 1.5 MeV, motivating a new study of this reaction at the University of Notre Dame.  To maximize experimental sensitivity, a high efficiency coincidence detection system was developed.  Several previously unknown resonances were observed between 1.1 and 1.5 MeV, and an upper limit for any lower energy resonances was obtained.  Newly calculated resonance parameters and reaction rates will be presented.