Stretched configuration of states as inferred from $\gamma$ -ray angular distributions in ⁴⁰Ar + ²⁰⁸Pb neutron transfer reactions

Abstract.

Angular distributions of $\gamma$ -rays for selected transitions in ^{40, 41, 42}Ar isotopes have been studied with the PRISMA magnetic spectrometer coupled to the CLARA $\gamma$ array. These transitions were populated in Ar isotopes reached via neutron transfer in the ⁴⁰Ar + ²⁰⁸Pb reaction. By comparison with the shape of the experimental angular distribution of the known E2 transitions we established more firmly the spin and parity of excited states. In particular, in ⁴¹Ar for the $(11/2^-)$ state through the $(11/2^-) \rightarrow 7/2^-$ transition whose structure was discussed in terms of a phonon-fermion coupled state. The comparison with the expected fully aligned spin indicated that a high level of spin alignment has been reached.