Measurement of Mg-25(p,gamma)Al-26 resonance strengths via gamma spectrometry

The COMPTEL instrument performed the first mapping of the 1.809 MeV photons in the Galaxy, triggering considerable interest in determining the sources of interstellar Al-26. The predicted Al-26 is too low compared to the observation; for a better understanding more accurate rates for the Mg-25(p,gamma)Al-26 reaction are required. The Mg-25(p,gamma)Al-26 reaction has been investigated at the resonances at(11) E-r = 745, 418, 374, and 304 keV at Ruhr-Universitat-Bochum using a Tandem accelerator and a 4 pi NaI detector. In addition, the resonance at E-r = 189 keV has been measured deep underground at Laboratori Nazionali del Gran Sasso, exploiting the strong suppression of a cosmic background. This low resonance has been studied with the 400 kV LUNA accelerator and an HPGe detector. The preliminary results of the resonance strengths will be reported.