High-spin states in neutron-rich 102Mo nucleus

High-spin states in neutron-rich 102Mo nucleus have been studied by measuring the prompt γ-rays in the spontaneous fission of 252Cf. The previous level scheme has been updated and some new levels and transitions are identified. The one-phonon γ-band is expanded and a band head level of the two-phonon γ-band is proposed. The systematic characteristics of yrast bands, one-phonon γ-bands, two-phonon γ-bands and quasi-particle bands in 102Mo, 104Mo and 106Mo are discussed.     

High spin states in neutron-rich 106Tc nucleus

The high spin states of the neutron-rich odd-odd 106Tc nucleus have been reinvestigated by observing prompt γ-rays from the spontaneous fission of 252Cf. A previously known collective band is confirmed and expanded, and a new collective band is newly identified. Several levels in previous report in 106Tc are reexamined and they belong to the members of a band in 107Tc. The total Routhian surface (TRS) calculations show that the 106Tc has triaxial shape. The spins and parities as well as the configurations for these bands have been tentatively assigned according to the analysis of the angular momentum alignments.     

基于平面超材料的Fano谐振可调谐研究

基于两段相同金属分裂环谐振器构成的单层结构, 从理论及实验方面研究了平面超材料的可调谐Fano谐振. 实验测量了平面超材料对TE和TM入射波的电磁响应, 利用电磁波的入射角度控制Fano谐振的强度, 实现了谐振的开关特性, 谐振频率红移可达到21%. 基于有限元法给出了平面超材料的场分布, 强的正常色散表明平面超材料的电磁响应可类比经典电磁诱导透明现象, 仿真与实验结果相符合. 对称结构超材料Fano谐振的开/关特性为超材料性能的可调谐控制提供了有效途径.     

High-spin states in neutron-rich ~(102)Mo nucleus

High-spin states in neutron-rich 102Mo nucleus have been studied by measuring the prompt γ-rays in the spontaneous fission of 252Cf. The previous level scheme has been updated and some new levels and transitions are identified. The one-phonon γ-band is expanded and a band head level of the two-phonon γ- band is proposed. The systematic characteristics of yrast bands, one-phonon γ-bands, two-phonon γ-bands and quasi-particle bands in 102Mo, 104Mo and 106Mo are discussed.     

High-spin states in neutron-rich 102Mo nucleus

High-spin states in neutron-rich ¹⁰²Mo nucleus have been studied by measuring the prompt γ-rays in the spontaneous fission of ²⁵²Cf. The previous level scheme has been updated and some new levels and transitions are identified. The one-phonon γ-band is expanded and a band head level of the two-phonon γ-band is proposed. The systematic characteristics of yrast bands, one-phonon γ-bands, two-phonon γ-bands and quasi-particle bands in ¹⁰²Mo, ¹⁰⁴Mo and ¹⁰⁶Mo are discussed.     

Fano resonances in semiconductor superlattices

We use semiconductor superlattices as a model system for the investigation of Fano resonances. In absorption the excitonic transitions of the Wannier–Stark ladder show the typical asymmetric line shape due to coupling to the continuum of lower-lying transitions. The unique feature of these Fano resonances is that they allow to continuously tune the key parameter – the coupling strength Γ between the discrete state and the degenerate continuum – by varying the bias voltage. Using this feature, we directly show that the Fano coupling leads to a fast polarization decay. We also investigate the dependence of the Fano parameters on the structure of the superlattice and compare with an extensive theoretical model of the resonances.     

High spin states in neutron-rich ~(106)Tc nucleus

The high spin states of the neutron-rich odd-odd 106Tc nucleus have been reinvestigated by observing prompt γ-rays from the spontaneous fission of 252Cf. A previously known collective band is confirmed and expanded, and a new collective band is newly identified. Several levels in previous report in 106Tc are reexamined and they belong to the members of a band in 107Tc. The total Routhian surface (TRS) calculations show that the 106Tc has triaxial shape. The spins and parities as well as the configurations f...     

High spin states in neutron-rich 106Tc nucleus

The high spin states of the neutron-rich odd-odd ¹⁰⁶Tc nucleus have been reinvestigated by observing prompt γ-rays from the spontaneous fission of ²⁵²Cf. A previously known collective band is confirmed and expanded, and a new collective band is newly identified. Several levels in previous report in ¹⁰⁶Tc are reexamined and they belong to the members of a band in ¹⁰⁷Tc. The total Routhian surface (TRS) calculations show that the ¹⁰⁶Tc has triaxial shape. The spins and parities as well as the configurations for these bands have been tentatively assigned according to the analysis of the angular momentum alignments.     

First observation of excited states in the neutron-rich nucleus 138Te

The very neutron-rich nucleus ¹³⁸Te produced in the spontaneous fission of ²⁴⁸Cm has been investigated using the EUROGAM II %-ray multidetector array. The excited states of ¹³⁸Te observed for the first time indicate that the region of ground state deformation beyond the doubly magic nucleus ¹³²Sn has yet not been reached.     

Fano resonances and electron localization in heterobarriers

A study is made of electron tunneling in semiconductor heterostructures having a complex dispersion law. A generalized Fabry-Perot approach is used to describe tunneling across the barrier. Mixing of electron states at the heterojunctions is responsible for the asymmetric resonant structure of the transmission which is characterized by a resonance-antiresonance pair. The resonance corresponds to a pole while the antiresonance corresponds to a zero of the scattering amplitude in the complex energy plane, i.e., near the pole and the zero the transmission of the heterobarrier has a Fano resonance structure. It is shown that for certain barrier parameters the resonances may collapse and localized states may appear in the heterobarrier, which is observed on the current-voltage characteristics of the barriers. The two-valley model of a GaAs/Al_xGa_1?x As/GaAs heterostructure is considered as an example. An analysis is made of the resonance structure in the barrier as a function of the type of boundary conditions used for the heterojunctions. The low-temperature current-voltage characteristic of the barrier is calculated.     

Fano resonances in prism-coupled square micropillars

We report Fano resonances in the frustrated total internal reflection (TIR) spectra of a prism-coupled square micropillar. Our angle-selective frustrated TIR technique reveals characteristically asymmetric resonance line shapes, which evolve spectrally over approximately a 2pi phase in the far field within a subdegree range of reflection angles. We theoretically model the asymmetric line shapes by the interference between a high-Q resonance that is evanescently coupled and partially confined by TIR, and a coherent background that is total internally reflected at the prism surface without coupling to the micropillar.     

Universal dimer in a collisionally opaque medium: experimental observables and Efimov resonances

A universal dimer is subject to secondary collisions with atoms when formed in a cloud of ultracold atoms via three-body recombination. We show that in a collisionally opaque medium, the value of the scattering length that results in the maximum number of secondary collisions may not correspond to the Efimov resonance at the atom-dimer threshold and thus cannot be automatically associated with it. This result explains a number of controversies in recent experimental results on universal three-body states and supports the emerging evidence for the significant finite range corrections to the first excited Efimov energy level.     

Five- and six-body resonances tied to an Efimov trimer

We explore the properties of weakly bound bosonic states in the strongly interacting regime. Combining a correlated-Gaussian basis set expansion with a complex-scaling method, we extract the energies and structural properties of bosonic cluster states with N ≤ 6 for different two-body potentials. The identification of five- and six-body resonances attached to the first-excited-Efimov trimer provides strong support to the premise of Efimov universality in bosonic systems. Our study also reveals a rich structure of bosonic cluster states. Besides the lowest cluster states that behave as bosonic droplets, we identify cluster states weakly bound to one or two atoms forming effective cluster-atom dimers and cluster-atom-atom "trimers." The experimental signatures of these cluster states are discussed.     

Fano resonances in vertically and horizontally coupled micro-resonators

Fano resonances are desirable lineshapes for numerous applications in diverse fields, due to their small bandwidth and potentially high extinction ratio. In this paper we propose and analyze two configurations of optical add-drop filters exhibiting Fano resonances. The first approach is based on a planar structure add drop filter comprising concentric racetrack resonators. The second approach is based on a multi-layer structure comprising two micro-rings located in different layers which are coupled via I/O waveguides located in a middle layer. Analytic models for these structures are developed and studied and compared to three dimensional finite difference time domain simulations.     

Continuum resonances with shielded Coulomb-like potential and Efimov effect

Motivated by the possibility of the second energy level (0 ₂ ⁺ ) of ¹²C (in a three-alpha model) to turn into an Efimov state, we study a simple non-realistic toy model formed by three bosons interacting by the phenomenological s-wave Ali-Bodmer potential plus a Coulomb interaction. An artificial three-body potential was used to create a resonance with energy close to the energy of the 0 ₂ ⁺ of ¹²C, 0.38 MeV. The strength of the Coulomb potential is decreased until the energies of the two alpha pairs are zero. The system was placed inside a harmonic trap and a stabilization method has been used to calculate the energies of the resonances. We found that the shielded-Coulomb potential, which keeps the long tail, is not able to produce the Efimov effect. The energy of the three alphas decreases only to 0.19 MeV when the two-body energy crosses the threshold to become bound.     

Fano resonances in planar silver nanosphere clusters

The plasmonic properties of silver nanosphere clusters are investigated using the finite element and the plasmon hybridization methods. The nanoparticle clusters are found to exhibit multiple plasmon resonances with large induced electromagnetic field enhancements. For symmetric clusters, we show how group theory can be used to identify the microscopic nature of the plasmon resonances. For larger clusters, we show that narrow Fano resonances are frequently present in their optical spectra.     

Efimov states in a Bose-Einstein condensate near a Feshbach resonance

Recent experiments with Bose-Einstein condensates of 85Rb atoms near a Feshbach resonance have produced evidence for a condensate of diatomic molecules coexisting with the atom condensate. It should also be possible to create condensates of the triatomic molecules predicted by Efimov coexisting with the atom and dimer condensates. The smoking gun for the trimer condensate would be oscillatory dependence of observables on the binding energy of the trimer. It may also be possible to deduce the existence of the trimer condensate from the spectra of the bursts of atoms and dimers created in the disappearance of the trimers.