THE 24Mg(3He, t)24A1 REACTION AND L = 1 GIANT RESONANCE SYSTEMATICS USING AN EFFECTIVE 3He-n INTERACTION AT 27 MeV/NUCLEON

Differential cross sections from the 24Mg(3He, t)Z4Al reaction have been measured from 0 to 32” in the laboratory system. DWBA calculations using an effective projectile-nucleon interaction are compared with the data to verify the applicability of such an approach as well as to deduce spectroscopic information. By employing DWBA in conjunction with transition amplitudes obtained from realistic microscopic wave functions, J” assignments could be made. Strength normalizations for all observed transitions to positive-parity T = 1 final states of Z4Al are given. Localized AL = 1 strength around 10 MeV in excitation energy contains most of the expected isovector giant dipole resonance (GDR) and the magnetic quadrupole resonance (MQR) strengths with systematics that are consistent with those for most light, self-conjugate nuclei. A comparison with Coulomb-energy shifted (-y, n) data assists in locating the GDR analog. The isovector Ostrength is not directly observed, but the total expected AL = 1, AS = 1 cross section is found in the broad collective “bump” at about 10 MeV and in a number of lower-lying states of negative parity. NUCLEAR REACTIONS 24Mg(3He, t), E = 81 MeV; measured a(&, 8,). 24A1 deduced E levels, L, J, n. DWBA analysis, effective ‘He-n force, shell-model form factors. ‘*C, 160, =Mg> 28Si(3He, t), E = 81 MeV; ‘2S(3He, t), E = 73 MeV; 40Ca(3He, t), E = 75 MeV, measured a( E,, B, = 0”), ‘*N, r6F, 24AI, “P, ‘*Cl, “SC deduced isovector giant resonances. ’ Present address: International Christian University, Mitaka-shi, Tokyo, Japan. ’ Present address: PTT, Groningen, The Netherlands. 3 Present address: Gasunie, Groningen, The Netherlands. 0375-9474/91/$03.50