Level density and shape changes in excited sd shell nuclei

In the present calculation we have used the Monte Carlo method of generating collective spin and total energy of the nucleus for various configurations of the system with N ₀ single particle states available for n number of particles. The different configurations (arrangements of occupied single particle states) leading to a particular energy E and spin J are then collected to get the density of states for the given energy E and spin J. We find that if we use the cranked Nilsson model single particle states for the rotational frequency Ω = 0.0ħω, 0.05ħω and 0.1ħω there is a shift in the maximum density of states W _max with a tendency for the system to become more oblate or prolate depending on the shift in the maximum density of states as the angular momentum decreases or increases. The change in nuclear level density with collectivity, i.e. with the use of cranked Nilsson model single particle levels has been noticed.      

Microstructure of Mo – 47% Re – 0.4% Zr alloys after rolling at room temperature. I. Anisotropy of microband structure and peculiarities of internal structure of microbands

The results of an electron microscopy investigation of microstructure of a Mo – 47% Re – 0.4% Zr alloy after rolling deformation (ε ≈ 90%) at room temperature are presented. A special focus is made on investigation of anisotropy of microband nanostructured states and high-energy defect substructures with high values of the crystal lattice curvature, dislocation density and local internal stresses. A disclination mechanism of reorientation as a mechanism of fragmentation of the internal microband structure is proposed.     

Electron emission during pulsed polarization switching of ferroelectric ceramics

It is shown that in the pulsed polarization switching of polycrystalline ferroelectrics in high fields the external field is damped by the electronic subsystem associated with the crystallite boundaries. Therefore, the reorganization of a ferroelectric system with a high density of surface states at the crystallite boundaries is not irreversible, and the system returns to its former state after the polarization-switching voltage is removed. Because of this, electron emission from the surface of a ferroelectric ceramic can be brought about by unipolar pulses. Zh. Tekh. Fiz. 69, 49–52 (July 1999)     

Ks0 and Λ elliptic flow from 200 GeV Cu+Cu collisions

Elliptic flow allows us to probe early dynamics in high energy nuclear collisions. The υ ₂ result of charged hadrons and identified hadrons [1,2] from 200 GeV Au+Au collisions at RHIC suggest that the matter with partonic collectivity and thermalization has been formed in central collisions. In this analysis, we present preliminary results of υ ₂ for K _S ⁰ and Λ from 200 GeV Cu+Cu collisions. The partonic collectivity and thermalization assumption are tested in smaller Cu+Cu system comparing with those from Au+Au collisions.     

Suppression of the equilibrium tunneling current between slightly disordered two-dimensional electron systems with different electron concentrations in a high magnetic field

Tunneling between parallel two-dimensional electron gases (2DEG) in accumulation layers formed on both sides of the single doped AlGaAs barrier are examined in both zero and high magnetic field. Accumulation layers are separated from highly n-doped contact regions which freely supply electrons to the 2DEGs via 80 nm thick lightly n-doped spacer layers. Strongly oscillating current with magnetic field along the 2DEGs is absent in this arrangement. Without magnetic field resonant tunneling between 2DEGs with different as grown electron concentration could be settle by application of external voltage bias. High magnetic fields (ν<1) shift resonant tunneling to zero external bias and suppresses tunneling current, creating wide gap in the tunneling density of states at the Fermi level arisen from the in-plane Coulomb interaction in the 2DEGs. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 3, 236–241 (10 February 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Signal physics

A classical signal which agrees with the ideas of mathematical analysis on infinitesimal quantities possesses an infinite information capacity, which contradicts the concept of information that is finite by definition. A real signal should have some “threshold” for determining a finite step between its distinguishable states and the “limit” for the possible number of states. This paper considers the influence of the level of required energy, performance, and noise of the receiver on the capability of distinguishing the set of states in the signal. It is shown that the generalized threshold is the constraint on the spectral density of the signal energy and the limit is the constraint on the energy density with respect to time or spatial coordinate.     

Strange-quark collectivity of the φ-meson at RHIC

Based on A Multi-Phase Transport (AMPT) model, the elliptic flow v₂ of φ-mesons which is reconstructed from K ⁺ K ^- at the Relativistic Heavy-Ion Collider (RHIC) energy has been studied. The results show that the reconstructed v₂ of the φ-meson can keep the earlier information before φ decays and it seems to obey the number of constituent-quark scaling as other mesons and baryons. This result indicates that the φ v₂ mostly reflects the parton level collectivity developed during the early stage of the collisions and the strange and light up/down quarks have similar collectivity properties before the hadronization.     

Stochastic Chaos and Markov Blankets

In this treatment of random dynamical systems, we consider the existence—and identification—of conditional independencies at nonequilibrium steady-state. These independencies underwrite a particular partition of states, in which internal states are statistically secluded from external states by blanket states. The existence of such partitions has interesting implications for the information geometry of internal states. In brief, this geometry can be read as a physics of sentience, where internal states look as if they are inferring external states. However, the existence of such partitions—and the functional form of the underlying densities—have yet to be established. Here, using the Lorenz system as the basis of stochastic chaos, we leverage the Helmholtz decomposition—and polynomial expansions—to parameterise the steady-state density in terms of surprisal or self-information. We then show how Markov blankets can be identified—using the accompanying Hessian—to characterise the coupling between internal and external states in terms of a generalised synchrony or synchronisation of chaos. We conclude by suggesting that this kind of synchronisation may provide a mathematical basis for an elemental form of (autonomous or active) sentience in biology.     

Molecular spectra, quantum chaos, and scars

Low resolution features in the spectra of classically chaotic atomic and molecular systems are known to be related to recurrences induced by classical periodic motions. In this paper we study how such characteristics reveal in the LiNC/LiCN isomerizing molecular system, and describe how the transition from regularity to classical chaos that takes place in this system shows up at quantum level in the structure of the corresponding wavefunctions in the form of “scars”. To this end we use some projection techniques, based on the propagation of wave packets, which have been developed in our laboratory. In this way some regions at the border of the chaotic region can be detected, in which the systematics of “scar” formation can be studied at a very elementary level, without complications due to the high level density which are customarily used in this type of studies in order to achieve the semiclassical limit. Received: 16 March 1998 / Revised: 23 April 1998 / Accepted: 4 May 1998     

Expanded fluid mercury in the metal-nonmetal transition range. An ab-initio MD study

Fluid Hg undergoes a metal-nonmetal (M-NM) transition when is expanded from the triple point towards a density of around 9 gr/cm³ at high temperature and high pressure. To investigate the related changes in the static and dynamic properties, we have performed ab-initio molecular dynamics simulations for some states close to the M-NM transition range. The calculated static and dynamic structure factors show a good agreement with the available experimental data. It is found that the volume expansion reduces the number of nearest neighbors at the expense of the inner ones. The dispersion relation exhibits a positive dispersion which is not so marked as that deduced from experimental data. The total electronic density of states shows the appearance of a band gap at a density somewhat smaller than 9 gr/cm³.     

A Geometrical Representation of Entanglement as Internal Constraint

We study a system of two entangled spin 1/2, were the spin's are represented by a sphere model developed within the hidden measurement approach which is a generalization of the Bloch sphere representation, such that also the measurements are represented. We show how an arbitrary tensor product state can be described in a complete way by a specific internal constraint between the ray or density states of the two spin 1/2. We derive a geometrical view of entanglement as a “rotation” and “stretching” of the sphere representing the states of the second particle as measurements are performed on the first particle. In the case of the singlet state entanglement can be represented by a real physical constraint, namely by means of a rigid rod.     

Decay of entanglement in coupled,driven systems with bipartite decoherence

We analyze a system of two qubits embedded in two different environments. The qubits are coupled to each other and driven on-resonance by two external classical sources. In the secular limit, we obtain exact analytical results for the evolution of the system for several classes of two-qubit mixed initial states. For Werner states we show that the decay of entanglement does not depend on coupling. For other initial states with “X"-type density matrices we find that the sudden death time displays a rich dependence on the coupling energy and state parameters due to the existence of processes of delayed sudden birth of entanglement.     

Sensitivity of the plasma electric potential to the transport barriers formation

Heavy Ion Beam Probe diagnostics was used to study plasma potential and density in the regimes with improvement in confinement on the T-10 tokamak. Time-spatial potential distribution was analyzed during the formation of transport barriers. The time evolution of the potential profile shows simultaneous formation of the internal negative potential well and external layer with strong Er, during the simultaneous formation of the internal and external transport barriers. The time history of the plasma potential in the inner region (0.6<ρ<1) shows its clear correlation with theD _α intensity. Presented at the Workshop on the Role of Electric Fields in Plasma Confinement and Exhaust, Budapest, 18–19 June, 2000. This work was supported by Russian Basic Research Foundation, Grant No. 99-02-18457.     

Splitting of atomic wave packets under multizone Raman excitation

A multizone excitation of a double Λ-system with three lower and two excited states (the so-called M-atom) by an optical radiation field is presented. It is shown that the Raman excitation of such a system can be used to implement an effective atomic beam splitter in one of the lower states. The advantage of the scheme under consideration is that the formation of a space lattice of the atomic density takes place when the atomic system interacts only with the optical radiation field and does not require any additional efforts to select the internal states in which such spatial structures are formed.     

Two-dimensional Anderson-Hubbard model in the DMFT + Σ approximation

The density of states, the dynamic (optical) conductivity, and the phase diagram of the paramagnetic two-dimensional Anderson-Hubbard model with strong correlations and disorder are analyzed within the generalized dynamical mean field theory (DMFT + Σ approximation). Strong correlations are accounted by the DMFT, while disorder is taken into account via the appropriate generalization of the self-consistent theory of localization. We consider the two-dimensional system with the rectangular “bare” density of states (DOS). The DMFT effective single-impurity problem is solved by numerical renormalization group (NRG). The “correlated metal,” Mott insulator, and correlated Anderson insulator phases are identified from the evolution of the density of states, optical conductivity, and localization length, demonstrating both Mott-Hubbard and Anderson metal-insulator transitions in two-dimensional systems of finite size, allowing us to construct the complete zero-temperature phase diagram of the paramagnetic Anderson-Hubbard model. The localization length in our approximation is practically independent of the strength of Hubbard correlations. But the divergence of the localization length in a finite-size two-dimensional system at small disorder signifies the existence of an effective Anderson transition.     

The tensor force in heavy nuclei: High momentum collectivity of unnatural parity excitations

The possibility of collectivity at high momentum transfer in unnatural parity states in finite nuclei, is outlined. This phenomenon is produced by the strong tensor force in the one pion exchange interaction operating coherently in a large oscillator space. The collectivity is observed at momentaq～(2-3)m _π corresponding to the critical momentum of pion condensation. If existent, such collective behaviour is expected to be seen in differential cross sections, e.g. for proton inelastic scattering, leading to unnatural parity states.     

Kinetics of nonequilibrium processes excited in broad-band dielectrics by synchrotron radiation

Luminescence spectroscopy with subnanosecond time resolution is used to study features of nonequilibrium processes excited in several broad-zone dielectrics (mainly inorganic scintillators) by pulses of synchrotron radiation (SR). When excitation density exceeds a certain level, which is different for each material, there is an abrupt change in the kinetics of relaxation of the nonequilibrium states. This change is accompanied by nonuniform broadening or shortwave shifting of the luminescence spectrum and a drop in quantum light yield. The decay time for natural luminescence decreases by 1–3 orders, to nanoseconds, and is independent of temperature within the range 80–450 K. The build-up stage disappears in the kinetics of luminescence of Ce³⁺-centers and decay time is reduced by a factor of 2–4. Density effects are found to be independent of the conditions under which the material is exposed to SR. A model is proposed in which density effects are related to nonradiative energy transfer from the upper excited states of the luminescence centers to external quenching centers. The contribution of the space charge induced by SR is also examined. Ural State Technical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 120–135, November, 1996.