Populating states in ^ { 22 } Mg via the ( p,t ) reaction in inverse kinematics with a 55 MeV/nucleon ^ { 24 } Mg beam , we have measured the proton-decay branching ratios of the levels at 5.96 MeV and 6.05 MeV and obtained an experimental upper limit on the branching ratio of the 5.71 MeV state .
On the basis of the present and previous measurements , we assign spins and parities to the 5.96 MeV and 6.05 MeV states .
We combine our branching ratios with independent measurements of the lifetimes of these states or their ^ { 22 } Ne analogs to compute the resonance strengths and thereby the astrophysical rate of the ^ { 21 } Na ( p, \gamma ) ^ { 22 } Mg reaction .
We perform hydrodynamic calculations of nova outbursts with this new rate and analyze its impact on ^ { 22 } Na yields .