Mass determination near N=20 for Al and Na isotopes

We report on the mass measurements of Na31,32 and Al29,34,35, performed with the TITAN Penning trap mass spectrometer at TRIUMF. The mass excesses were found to be 12246(14) and 18638(37) keV for Na31,32 and −18207.77(37),−3000.5(29), and −223.7(73) keV for Al29,34,35, respectively. Our measurements confirm the observation of a crossover in the two-neutron separation energies of Mg33 and Al34. We did not observe the recently reported, long-lived, isomeric state of Al34, but, based on the previously measured half-lives, the mass value of the ground state was determined.