Model independent Jπ assignments in 38Ar from γ-ray experiments in heavy-ion induced reactions

High-spin states of ³⁸Ar and ³⁵Cl have been investigated with the ²⁴Mg(¹⁶O, 2pγ)³⁸Ar and ²⁴Mg(¹⁶O, pαγ)³⁵Cl reactions at beam energies of 38 and 45 MeV. The experiments consisted of γ-γ coincidence, angular distribution and linear polarization measurements. A high-resolution large volume Ge(Li)-NaI(Tl) Compton-suppression spectrometer and a three-Ge(Li) Compton polarimeter were used. The analysis of the data, without assumptions about the reaction mechanism for the formation of the levels under study, is discussed. Unambiguous spin-parity assignments of J^π = 6⁺, 8⁺, and limitations of (5, 6, 7) and (7, 8⁺, 9) for the ³⁸Ar levels at E_x = 6408.3±0.2, 7609.3±0.3, 8012.9±0.3 and 10173.8±0.4 keV, respectively, are obtained. They are compared with results of shell-model calculations. Mixing ratios and spin-alignment attenuation factors for several transitions and levels in ³⁸Ar and ³⁵Cl are reported.