Evidence for the coexistence of spherical and deformed states in38Ar

An unambiguous Jπ assignment from γ-rays produced in heavy-ion reactions; The lowest J=6+, 38Ar level

“…The upper limit of 3% for the 6.41 ~ 5.35 MeV, 6+-* 4 + branch corresponds to an E2 strength of less than 1.6 W.u., more than a factor 19 -+ 5 weaker than the 5.35 ~ 3.94 MeV, 4+~ 2 ÷ transition with a strength fo 30-+ 8 W.u. [13]. This situation is very similar to that in 42Ca where the 6 + ~ 4 + E2 transition is weaker than the 4 + ~ 2 + transition by a factor of 16 -+ 5 [9].…”

Density of high-spin states in38Ar and42Ca

“…Besides spherically symmetric states of simple shell model structure there exist well deformed rotational states at low excitation energies. This is for instance the case in the semi closed-shell nuclei 3SAr and 42Ca, where a K~=0 + rotational band is now known [6,7] up to the J~= 8 + member. In shell model language the coexistence phenomenon implies that multi-particle excitations from the s-d into the f-p shell must be included into the configuration space.…”

The gamma decay of high spin states of39K

“…Interest in this subject arose after the identification of a K=0 § prolate rotational band in 4~ which is thought to be connected with the excitation of 4 nucleons into the K = 1/2-[330] Nilsson orbit [21. A similar K=0 rotational band up to the 8 + state was recently found in 38At [3]. Strutinsky type calculations which reproduce the excitation energies and deformations of these bands also suggest low-lying deformed states in 39K [4] with K=7/2-(oblate) and K = 3/2-and 1/2 + (prolate), Recently, the J~= 1/2 + 4095 keV state in 39K was interpreted by Durell et al [5] to be the band head of the K = 1/2 + An extensive experimental study of the 39K(p,p '7) reaction [5] revealed a large number of states which were found to decay to the levels at 2 814 keV (J~ = 7/2-) and 3597 keV (J~=9/2) and thus presumably have spins J>5/2.…”