Search results for "LEVEL"
showing 10 items of 3465 documents
Open questions about homogeneous fluid dynamos: The VKS experiment
2002
International audience; We consider several problems that arise in the context of homogeneous fluid dynamos such as the effect of turbulence on the dynamo threshold, the saturation level of the generated magnetic field above the threshold and its dynamics. We compare some of our predictions with the recent experimental results of the Karlsruhe and Riga experiments. Finally, we present the VKS experiment that we have designed to answer some of the remaining open questions. We study, in particular, the response of a turbulent flow to an external magnetic field.
Level structure of 99Nb
1998
The β decay of 97Sr to 97Y has been investigated using ion-guide on-line mass separation and a 10 Ge-detector array to record γ−γ coincidences to a detection limit well below that of former studies. Similarities are found in the β-decay patterns of 99Zr and of its isotone 97Sr and also in the γ-ray decay rates and branchings of the corresponding levels in their respective daughters 99Nb and 97Y. This indicates a persisting influence of the d5/2 neutron shell closure for 99Nb. The level structure of 99Nb and the β-feeding pattern are discussed in the frame of the interacting boson-fermion plus broken pair model and the microscopic quasiparticle phonon model.
Operation conditions and stability of a degenerate two-photon laser
1993
Abstract The presence of a far off-resonant intermediate level in a degenerate three-level two-photon laser model manifests through a steady pump-dependent and a dynamic frequency shift on the laser equations. The steady shift strongly affects the pump threshold necessary for emission, preventing it in certain cases. The dynamic shift makes the frequency pulling/pushing to be intensity-dependent and substantially modify the domains of existence and stability of the lasing solution permitting stable operation for large cavity losses in certain cases.
Nonlinear Current Generation in Degenerate Semiconductors Embedded in Constant and Low-Frequency Electric Fields
2006
The explicit analytical forms of nonlinear currents in degenerate semiconductors serving as sources of coherent radiation in the wavelength millimetric and submillimetric ranges are established.
Su(4) approach to fourfold degenerate electronic states of some hexafluoride molecules
2003
Abstract We show that two appropriate realizations of the su (4) algebra allow the construction of all electronic operators needed for the study of vibronic and rovibronic interactions in a G ′ electronic state. In each case a full bosonic realization is made and all matrix elements are calculated. Illustrations of our formalism and comparisons with previous approaches are made in the case of ν 5 ( F 2 g ) and ν 3 ( F 1 u ) modes.
Nonlinear effects in optical pumping of a cold and slow atomic beam
2015
By photoionizing hyperfine (HF) levels of the Cs state $6{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{3/2}$ in a slow and cold atom beam, we find how their population depends on the excitation laser power. The long time (around $180\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{s})$ spent by the slow atoms inside the resonant laser beam is large enough to enable exploration of a unique atom-light interaction regime heavily affected by time-dependent optical pumping. We demonstrate that, under such conditions, the onset of nonlinear effects in the population dynamics and optical pumping occurs at excitation laser intensities much smaller than the conventional respective saturation values. The ev…
Evidence of chiral bands in even-even nuclei
2018
Evidence for chiral doublet bands has been observed for the first time in the even-even nucleus 136 Nd . One chiral band was firmly established. Four other candidates for chiral bands were also identified, which can contribute to the realization of the multiple pairs of chiral doublet bands ( M χ D ) phenomenon. The observed bands are investigated by the constrained and tilted axis cranking covariant density functional theory (TAC-CDFT). Possible configurations have been explored. The experimental energy spectra, angular momenta, and B ( M 1 ) / B ( E 2 ) values for the assigned configurations are globally reproduced by TAC-CDFT. Calculated results support the chiral interpretation of the o…
Collective rotation of an oblate nucleus at very high spin
2019
International audience; A sequence of nine almost equidistant quadrupole transitions is observed in Nd137. The sequence represents an extremely regular rotational band that extends to a spin of about 75/2 and an excitation energy of ≈4.5MeV above yrast. Cranked mean-field calculations of the Nilsson-Strutinsky type suggest an oblate shape for the band. They reproduce the observed I(I+1) dependence of the rotational energy whereas predicting a pronounced decrease in the deformation, which is the hallmark of antimagnetic rotation.
Level structure of ^100Nb
2000
Levels in the odd-odd nucleus ${}^{100}\mathrm{Nb}$ situated at the edge of a region of especially fast shape transitions have been calculated in the framework of the interacting boson fermion fermion model. Levels observed in decay studies can be interpreted in a spherical basis. Low-lying ${I}^{\ensuremath{\pi}}{=8}^{+}$ and ${10}^{\ensuremath{-}}$ states are predicted. Their relationship with the unplaced levels populated with a $12 \ensuremath{\mu}\mathrm{s}$ delay after fission is discussed.
Quantum Criticality of Spin Liquids in Novel Insulators and Magnets
2014
Strongly correlated Fermi systems are among the most intriguing and fundamental systems in physics, whose realization in some compounds is still under consideration. Quantum spin liquids are a promising new phases, where exotic quantum states of matter could be realized. Exotic quantum spin liquid (QSL) made of such hypothetic particles as fermionic spinons which carry spin \(1/2\) and no charge are considered in this chapter. Magnetic insulators with geometrical frustration produce important experimental facts shedding light on the nature of quantum spin liquid composed of spinons. We present a theory of the thermodynamic properties of quantum spin liquids, elucidating how their properties…