The structure of ³⁶Ar and ³⁸Ar via the (³He, d) reaction on ³⁵Cl and ³⁷Cl

The level structures of ³⁶Ar and ³⁸Ar have been investigated with the ^35,37Cl(³He, d) ^36,38Ar reactions at a bombarding energy of 12 MeV. Deuteron angular distributions were measured for 31 levels in ³⁶Ar up to 8.5 MeV excitation and 29 levels in ³⁸Ar up to 6.9 MeV excitation. The l_p values and transition strengths were determined from a distorted wave Born analysis of the angular distributions. The results for the positive parity states of ³⁶Ar and ³⁸Ar are in reasonable agreement with a shell-model calculation which considers only Id _{3 2} and 2s _{1 2} nucleons outside a closed ²⁸Si core. The major components of the (f _{7 2}d _{3 2}⁵)_T = 1 configuration in ³⁸Ar for J^π = (3, 4, 5)^- and of the (f _{7 2}d _{3 2}³)_T = 0 configuration in ³⁶Ar for J^π = (3, 5)^- were identified. For the f _{7 2} transitions in ³⁸Ar, and to a lesser extent in ³⁶Ar, the observed severe fragmentation of strength shows that a model involving core polarization rather than a simple weak coupling model is applicable in describing the structure of these nuclei. All the p _{3 2}. transition strength to T_< states was accounted for in ³⁶Ar but only 12 % in ³⁸Ar. It appears that the P _{3 2}-f _{7 2} single-particle energy splitting is significantly smaller in ³⁶Ar than in ³⁸Ar. The angular distributions of all known 3^- states are consistent with mixed l = 1+3 transitions, showing that configuration admixtures between the (p _{3 2}dⁿ _{3 2}) and (f _{7 2}dⁿ _{3 2}) configurations are important.