The lowest T = 2 states have been identified and studied in the nuclei 12C, 12B, 20F and and 28Al. The first two of these wereproduced in the reactions 14C(p,t)12C and 14C (p,3He)12B, at 50.5 and63.4 MeV incident proton energy respectively, at the Oak RidgeNational Laboratory. The T = 2 states in 20F and 28Al were observedin (3He,p) reactions at 12-MeV incident energy, with the CaltechTandem accelerator.
The results for the four nuclei studied are summarized below:
(1) 12C: the lowest T = 2 state was located at an excitationenergy of 27595 ± 20 keV, and has a width less than 35 keV.
(2) 12B: the lowest T = 2 state was found at an excitationenergy of 12710 ± 20 keV. The width was determined to be less than54 keV and the spin and parity were confirmed to be 0+. A second12B state (or doublet) was observed at an excitation energy of14860 ± 30 keV with a width (if the group corresponds to a singlestate) of 226 ± 30 keV.
(3) 20F: the lowest T = 2 state was observed at an excitationof 6513 ± 5 keV; the spin and parity were confirmed to be 0+. A secondstate, tentatively identified as T = 2 from the level spacing, waslocated at 8210 ± 6 keV.
(4) 28Al: the lowest T = 2 state was identified at an excitationof 5997 ± 6 keV; the spin and parity were confirmed to be 0+. A secondstate at an excitation energy of 7491 ± 11 keV is tentatively identifiedas T = 2, with a corresponding (tentative) spin and parity assignmentJπ = 2+.
The results of the present work and the other known masses ofT = 2 states and nuclei for 8 ≤ A ≤ 28 are summarized, and massequationcoefficients have been extracted for these multiplets.These coefficients were compared with those from T = 1 multiplets,and then used to predict the mass and stability of each of the unobservedmembers of the T = 2 multiplets.
