Loss of collectivity in the transitionalEr156nucleus at high spin

Abstract

The 114 Cd( 48 Ca, 6nγ ) reaction at 215 MeV has been investigated using the Gammasphere spectrometer to study the high-spin structure of the nucleus 156 68 Er 88 . Many new transitions have been established along with definitive spin-parity level assignments from a high-fold angular-distribution analysis. In addition, absolute B(M1) and B(E1) strengths have been inferred from measured γ -ray branching ratios. Strong B(E1) strength (10 −3 W.u.) is discussed in terms of possible octupole collectivity at low spin. At high spin, this nucleus undergoes a Coriolis-induced shape transition from a prolate state of collective rotation to a noncollective, triaxial-oblate configuration. The yrast positive-parity structure ultimately terminates in an energetically favored oblate state at I π = 42 + . Several weak high-energy γ -ray transitions have been discovered that feed this favored state. State-of-the-art cranked Nilsson-Strutinsky calculations are used to interpret the high-spin behavior of 156 Er and comparisons are made with other N = 88 isotones.

Core excitations beyond maximally aligned configurations in123I

“…The first case was the I π = 40 + state in 158 Er [12], where a neutron of h 9/2 f 7/2 character is antialigned relative to the maximally aligned configuration with I π = 46 + . Similar states were found later also in 156 Er, 157 Er, and 159 Er [13][14][15]. In the mass-125 region, in addition to 125 I, such a state was reported only in 121 I [10].…”

“…Higher-spin states, beyond the full alignment of the valence particles, can only be created by energetically expensive particle-hole excitations from the core. This type of excitation was observed, e.g., in 155−158 Er [13,[16][17][18], where many weakly populated states, lying between 1.0 and 2.5 MeV above the terminating states, were delineated. Such excitations, feeding maximally aligned states, were also reported in 121 I [10].…”

Locally Rotationally Symmetric Vacuum Solutions in f(R) Gravity

“…Sharif and Shamir [34]- [35] investigated the solutions of Bianchi type I and V spacetimes in framework of f (R) gravity. Paul and collaborators [36] studied FRW cosmologies in f (R) gravity. Recently, Jamil and Saima [?]…”

Advanced Optical Metamaterials

“…However, it turned out that due to the mesoscopic nature of current metamaterials spatial dispersion prevents to meet this requirement, [6] rendering them far away from being applicable for the purpose of imaging. [7,8] A solution to this problem is not straightforwardly at hand, since metamaterials are usually designed in forward direction; implying that the optical properties are only evaluated for a specific metamaterial geometry. Here, we lift these limitations in a twofold way.…”

“…However, for all current metamaterials designed to operate at optical frequencies this requirement is not fulfilled; [7] thus, most metamaterials perform worse than an ordinary lens, since even in the long wavelength limit their refraction, diffraction, and absorption properties are anisotropic. [8] In this case, one appropriately has to resort to quantities to be derived from the isofrequency surface v ¼ vðk x ; k y ; k z Þ ¼ const: of the dispersion relation, such as refraction ($@k z =@k x;y ) and diffraction coefficients ($@ 2 k z =@k 2…”