Nowacki F, Poves A, Caurier E, Bounthong B
Université de Strasbourg, IPHC, 23 rue du Loess 67037 Strasbourg, France.
CNRS, UMR7178, 67037 Strasbourg, France.
Phys Rev Lett. 2016 Dec 30;117(27):272501. doi: 10.1103/PhysRevLett.117.272501. Epub 2016 Dec 27.
Large-scale shell-model calculations predict that the region of deformation which comprises the heaviest chromium and iron isotopes at and beyond N=40 will merge with a new one at N=50 in an astonishing parallel to the N=20 and N=28 case in the neon and magnesium isotopes. We propose a valence space including the full pf shell for the protons and the full sdg shell for the neutrons, which represents a comeback of the the harmonic oscillator shells in the very neutron- rich regime. The onset of deformation is understood in the framework of the algebraic SU(3)-like structures linked to quadrupole dominance. Our calculations preserve the doubly magic nature of the ground state of ^{78}Ni, which, however, exhibits a well-deformed prolate band at low excitation energy, providing a striking example of shape coexistence far from stability. This new IOI adds to the four well-documented ones at N=8, 20, 28, and 40.
大规模壳模型计算预测，包含N = 40及以上最重铬和铁同位素的形变区域，将与N = 50处的一个新区域合并，这与氖和镁同位素中N = 20和N = 28的情况惊人地相似。我们提出一个价空间，其中质子包含完整的pf壳层，中子包含完整的sdg壳层，这代表了在非常富中子区域中谐振子壳层的回归。形变的起始在与四极矩主导相关的代数SU(3) 类结构框架内得到理解。我们的计算保留了(^{78}Ni)基态的双幻性质，然而，它在低激发能下展现出一个明显形变的长椭球带，提供了一个远离稳定态的形状共存的显著例子。这个新的形变岛增加到了N = 8、20、28和40处已充分记录的四个形变岛之中。
