A study of T = 2 states in ^(12)B, ^(12)C, ^(20)F and ^(28)Al

The lowest T = 2 states have been identified and studied in the nuclei <sup>12sup>C, <sup>12sup>B, <sup>20sup>F and and <sup>28sup>Al. The first two of these were produced in the reactions <sup>14sup>C(p,t)<sup>12sup>C and <sup>14sup>C (p,<sup>3sup>He)<sup>12sup>B, at 50.5 and 63.4 MeV incident proton energy respectively, at the Oak Ridge National Laboratory. The T = 2 states in <sup>20sup>F and <sup>28sup>Al were observed in (<sup>3sup>He,p) reactions at 12-MeV incident energy, with the Caltech Tandem accelerator.

The results for the four nuclei studied are summarized below:

(1) <sup>12sup>C: the lowest T = 2 state was located at an excitation energy of 27595 ± 20 keV, and has a width less than 35 keV.

(2) <sup>12sup>B: the lowest T = 2 state was found at an excitation energy of 12710 ± 20 keV. The width was determined to be less than 54 keV and the spin and parity were confirmed to be 0<sup>+sup>. A second <sup>12sup>B state (or doublet) was observed at an excitation energy of 14860 ± 30 keV with a width (if the group corresponds to a single state) of 226 ± 30 keV.

(3) <sup>20sup>F: the lowest T = 2 state was observed at an excitation of 6513 ± 5 keV; the spin and parity were confirmed to be 0<sup>+sup>. A second state, tentatively identified as T = 2 from the level spacing, was located at 8210 ± 6 keV.

(4) <sup>28sup>Al: the lowest T = 2 state was identified at an excitation of 5997 ± 6 keV; the spin and parity were confirmed to be 0<sup>+sup>. A second state at an excitation energy of 7491 ± 11 keV is tentatively identified as T = 2, with a corresponding (tentative) spin and parity assignment J<sup>πsup> = 2<sup>+sup>.

The results of the present work and the other known masses of T = 2 states and nuclei for 8 ≤ A ≤ 28 are summarized, and massequation coefficients 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 unobserved members of the T = 2 multiplets.