NEW STELLAR REACTION-RATES FOR MG-25(P,GAMMA)AL-26 AND AL-25(P,GAMMA)SI-26

Existing experimental proton stripping reaction data on Mg-25 leading to threshold states in Al-26 are reinvestigated and reanalyzed in a co nsistent and improved manner. We use unbound state form factors in the DWBA analysis of the measured deuteron angular distributions to deduc e absolute rather than relative proton partial widths. For higher-lyin g resonances these values are compared to widths obtained from (p, gam ma) work. It is also shown that several of the unique J(pi) values ass igned previously to Al-26 states are erroneous. This paper reports on a reanalysis of spins, parities, and isospins for Al-26 states located at E(x)<8.00 MeV. We deduce new stellar rates for the reaction Mg-25( p,gamma)Al-26 and compare our results with previous values. Furthermor e, shell-model calculations for the mass A = 26 system are performed. Theoretical excitation energies, J(pi) values, gamma-ray transition st rengths, spectroscopic factors, and proton partial widths are compared to experimental data and new shell-model assignments of experimental states in Al-26 are derived. We estimate Coulomb displacement energies of excited Mg-26 and Si-26 mirror states and present new analog assig nments for T = 1 triplet states in A = 26 nuclei. Based on shell-model results and analog state information we present updated stellar rates for the Al-25(p, gamma)Si-26 reaction.