Study of the 22Mg Waiting Point Relevant for X-Ray Burst Nucleosynthesis via the 22Mg(,p)25Al Reaction

The 22Mg(alpha, p)25Al reaction rate has been identified as a major source of uncertainty for understanding the nucleosynthesis flow in Type-I x-ray bursts. We report a direct measurement of the energy-and angle-integrated cross sections of this reaction in a 3.3-6.9 MeV center-of-mass energy range using the MUlti-Sampling Ionization Chamber (MUSIC). The new 22Mg(alpha, p)25Al reaction rate is a factor of similar to 4 higher than the previous direct measurement of this reaction within temperatures relevant for x-ray bursts, resulting in the 22Mg waiting point of x-ray burst nucleosynthesis flow to be significantly bypassed via the (alpha, p) reaction.