B(E2)Values inN150

Abstract

Lifetimes of states in 150Nd were measured using the recoil distance method following Coulomb excitation of 150Nd by a 132 MeV 32S beam. The experiment was performed at the Yale Tandem accelerator, employing the SPEEDY gamma-ray detector array and the New Yale Plunger Device. Reduced transition probabilities in 150Nd are compared to the predictions of the critical point symmetry X(5) of the phase/shape transition that occurs for the N = 90 rare earth isotones. Very good agreement was observed between the parameter-free (apart from scale) X(5) predictions and the low-spin level scheme of 150Nd, revealing this as the best case thus far for the realization of the X(5) symmetry.

Evolution of nuclear shapes in medium mass isotopes from a microscopic perspective

“…7 for the energy plotted as a function of γ for different choices of Q 0 . The plots presented for these two sets of isotopes are rather similar to the ones already discussed for the Pd case and from them we can conclude that the Xe and Ba isotopes studied can be Next, we consider several rare-earth isotopic chains (like Nd, Sm, Gd, and Dy) where candidates exhibiting X(5) behavior have been identified [11,12,[30][31][32][33]. The nuclei considered can always be grouped in isotones (same number of neutrons) and it turns out that the PECs for all the members of an isotonic chain are very similar.…”

“…Several candidates have already been proposed experimentally for both E(5) and X(5) symmetries. For example, the nuclei 134 Ba [7], 102 Pd [8], 108 Pd [9], and 128−130 Xe [10] have been identified as candidates for E(5), whereas 152 Sm [11], 150 Nd [12], 154 Gd [13], and 156 Dy [14] provide examples of X(5) symmetry.…”

Shape phase transitions in the interacting boson model: Phenomenological versus microscopic descriptions

“…As has been often noted so far, the nuclei with N ≈ 90 are known [44][45][46][47][48] to be examples of the X(5) critical point, and this special behavior can be seen in the evolution of S 2n with N as shown in Fig. 12 where the twoneutron separation energies show a pronounced plateau.…”

Absoluteβ-to-ground band transition strengths in154Sm

“…The applicability of this approach for the description of K π = 0 + excited bands has been shown in several nuclei considered to be near the phase shape transitional point, e.g. 152 Sm [7], 150 Nd [9], 154 Gd [10], 156 Dy [11], 178 Os [12].…”