A new study of Mg-25(alpha, n)Si-28 angular distributions at E-alpha=3-5MeV

The observation of Al-26 gives us the proof of active nucleosynthesis in the Milky Way. However the identification of the main producers of Al-26 is still a matter of debate. Many sites have been proposed, but our poor knowledge of the nuclear processes involved introduces high uncertainties. In particular, the limited accuracy on the Mg-25(alpha, n)Si-28 reaction cross section has been identified as the main source of nuclear uncertainty in the production of Al-26 in C/Ne explosive burning in massive stars, which has been suggested to be the main source of Al-26 in the Galaxy. We studied this reaction through neutron spectroscopy at the CN Van de Graaff accelerator of the Legnaro National Laboratories. Thanks to this technique we are able to discriminate the (alpha, n) events from possible contamination arising from parasitic reactions. In particular, we measured the neutron angular distributions at 5 different beam energies (between 3 and 5 MeV) in the 17.5 degrees-106 degrees laboratory system angular range. The presented results disagree with the assumptions introduced in the analysis of a previous experiment.