[en] The longitudinal Schottky spectrum of an ultra-cold ion beam in a storage ring is calculated in the frame of harmonic oscillations of a 1d Coulomb lattice. It is assumed that the extremely high cooling rate required to bring the beam into a one-dimensional ordered chain can be provided by electron or laser cooling. The anharmonic transversal oscillations with temperature much higher then the longitudinal one are taken into account within the self-consistent phonon approximation. The Schottky spectrum measured by the pick-up system consists of bands located near the harmonics of the revolution frequency of the beam. The total intensity of each band characterizes the temperature distribution of the phonons in an ionic chain. The amplitude and the width of the peaks in the spectrum are a function of the strength of relaxation processes (cooling and heating) as well as the Coulomb correlations, rsp. ordering. It is suggested that a careful analysis of these spectra could be a signature of the presence of 1d ordering in the beam. (orig.)

[en] For a unidimensional system in the Anderson dielectric state the distribution of the Knight shift is calculated. In the process of cooling the distribution broadens and becomes asymmetric. The NMR line at low temperatures acquires a similar form

No abstract available

[en] The longitudinal Schottky spectrum of an ultracold ion beam in a storage ring is calculated in the frame of harmonic oscillations of a one-dimensional (1D) Coulomb lattice. It is assumed that the extremely high cooling rate required to bring the beam into a one-dimensional ordered chain can be provided by electron or laser cooling. The anharmonic transversal oscillations with temperature much higher than the longitudinal one are taken into account within the self-consistent phonon approximation. The Schottky spectrum measured by the pickup system consists of bands located near the harmonics of the revolution frequency of the beam. The total intensity of each band characterizes the temperature distribution of the phonons in an ionic chain. The amplitude and the width of the peaks in the spectrum are a function of the strength of relaxation processes (cooling and heating) and the Coulomb correlations, respectively. It is suggested that a careful analysis of these spectra could be a signature of the presence of 1D ordering in the beam

No abstract available

[en] The most striking quantum property of a quantum crystal is the possibility of tunneling atoms located near various sites of a crystal lattice. In the paper it has been shown nearly-how such effects may be treated for a hypothetical classical crystal with small anharmonicities. The potential energy of a classical crystal in the configurational space has, apart from a minimum corresponding to the location of all atoms in lattice sited, exactly the same minima corresponding to redistributions of atoms over the sites. In a classical crystal these minima are separated from one another by a barrier, which is supposed to be impenetrable. The purpose of the paper is to find corrections associated with a finite penetrability of the barrier; the main contribution will give near redistributions. For a classical crystal with small anharmonicities an asymptotical expression has been derived to describe the wave function near the tunneling path. A general expression for the exchange integral, including the preexponential, has been obtained. The phonon-spin Hamiltonian for a crystal consisting of Fermi atoms has been found; the spin-phonon vertex established is large in comparison with usual magnet materials

[en] The nonlinear, stationary solution of the kinetic equations for a one-dimensional plasma with a small collision term is presented; we analyze the problem of the plasma interaction with a negative ion moving with small constant velocity through a one-component (electronic) plasma. A self-consistent two-scale analysis is performed. The solution is compared with the results of the corresponding linearized equations that are commonly used. It is shown that the theory based on the linearized Vlasov equation without collision term cannot give an adequate description of either potential profile or stopping power, at least in the regime of small projectile velocities

[en] We discuss the configurations in which singly and doubly quantized vortex lines coexist in a rotating superfluid. General principles of energy minimization lead to the conclusion that in equilibrium the two vortex species segregate within a cylindrical vortex cluster in two coaxial domains where the singly quantized lines are in the outer annular region. This is confirmed with simulation calculations on discrete vortex lines. Experimentally the coexistence can be studied in rotating superfluid ³He-A. With cw NMR techniques we find the radial distribution of the two vortex species to depend on how the cluster is prepared: (i) By cooling through T_c in rotation, coexistence in the minimum energy configuration is confirmed. (ii) A disordered agglomerate is formed if one starts with an equilibrium cluster of single quantum vortex lines and adds to it sequentially double quantum lines, by increasing the rotation velocity in the superfluid state. This proves that the energy barriers, which separate different cluster configurations, are too high for metastabilities to anneal