Features of Magneto-Optical Resonances in an Elliptically Polarized Traveling Light Wave

The parameters of nonlinear absorption magneto-optical resonances in the Hanle configuration have been studied as functions of the ellipticity of a traveling light wave. It has been found that these parameters (amplitude, width, and amplitude-to-width ratio) depend strongly on the polarization of the light wave. In particular, the resonance amplitude can increase by more than an order of magnitude when the polarization changes from linear to optimal elliptic. It has been shown that this effect is associated with the Doppler frequency shift for atoms in a gas. The theoretical results have been corroborated in experiments in Rb vapor.Comment: 5 page

Paramagnetic and antiferromagnetic resonances in the diamagnetically diluted Haldane magnet PbNi2V2O8

The impurity-induced antiferromagnetic ordering of the doped Haldane magnet Pb(Ni{1-x}Mg{x})2V2O8 (0 < x <0.06) was studied by electron spin resonance (ESR) on ceramic samples in the frequency range 9-110 GHz. Below the N\'{e}el temperature a transformation of the ESR spectrum was found, indicating an antiferromagnetic resonance mode of spin precession. The excitation gap of the spin-wave spectrum increases with increasing Mg-concentration $x$ in the same manner as the N\'{e}el temperature, reaching its maximum value of 80 GHz at x > 0.04. At small concentrations x < 0.02 the signals of antiferromagnetic resonance were found to coexist with the signal of the paramagnetic resonance indicating a microscopic separation of the magnetic phases.Comment: 10 pages, 9 figure

The Minimum Stellar Mass in Early Galaxies

The conditions for the fragmentation of the baryonic component during merging of dark matter halos in the early Universe are studied. We assume that the baryonic component undergoes a shock compression. The characteristic masses of protostellar molecular clouds and the minimum masses of protostars formed in these clouds decrease with increasing halo mass. This may indicate that the initial stellar mass function in more massive galaxies was shifted towards lower masses during the initial stages of their formation. This would result in an increase of the number of stars per unit halo mass, i.e., the efficiency of star formation.Comment: 18 pages, 7 figure

RESULTS AND CHARACTERISTICS OF 5G HOLE DRILLING AND THE FIRST TAPPING OF LAKE VOSTOK

We present here a brief description of the drilling operations in the deep 5G hole at the Russian Vostok Station with more detailed account of the final stage of this long-term project successfully ended on February 5, 2012 with the first Lake Vostok unsealing. Relevant information on the borehole design and the technical characteristics of the downhole and surface drilling equipment is given. The peculiarities of the drilling process are discussed in connection with changing properties of the penetrated ice. The data analysis allows defining the main factors that influence the efficiency of the electromechanical drill system at great depths. It is shown that the elevated temperature of ice and its coarse-crystalline texture are mainly responsible for the significant for the showing-down of ice coring in the bottom sections of ice sheets observed at Vostok and at other drilling sites in Antarctica and Greenland as well. Based on the large amount of experimental data obtained in the course of the deep drilling at Vostok, we discuss the processes which occur in the borehole during the ice drilling and unsealing the sub-ice water bodies. In particular, we investigate the conditions for occurrence of hydraulic fracturing in the hole and the possible effect of the hydrofrac on the height of the water column that have risen in hole 5G after the Lake Vostok unsealing. Finally we formulate the drill equipment requirements and process specifications that would ensure the best performance of an electromechanical drill and trouble-free drilling operations at different depths in a borehole up to the bottom of ice sheet