Deformation of aerogel strongly modifies the orientation of the order parameter of superfluid 3 He confined in aerogel. We used a radial squeezing of aerogel to keep the orbital angular momentum of the 3 He Cooper pairs in the plane perpendicular to the magnetic field. We did not find strong evidence for a "polar" phase, with a nodal line along the equator of the Fermi surface, predicted to occur at large radial squeezing. Instead we observed 3 He-A with a clear experimental evidence of the destruction of the long-range order by random anisotropy -the Larkin-Imry-Ma effect. In 3 He-B we observed and identified new modes of NMR, which are impossible to obtain in bulk 3 He-B. One of these modes is characterized by a repulsive interaction between magnons, which is suitable for the magnon Bose-Einstein condensation (BEC). The p-wave superfluid 3 He, which is characterized by an 18-dimensional order parameter, is an amazing test system for different aspects of quantum field theory [1]. Confined in a silica aerogel, superfluid 3 He becomes an ideal system for the investigation of the effect of impurities on a long-range order. In a first approximation the aerogel reduces the superfluid transition temperature [2,3]. Here we report the influence of the aerogel anisotropy on the 3 He order parameter orientation. It was demonstrated earlier that a uniaxial squeezing of a cylindrical aerogel sample leads to the orientation of the orbital momentuml along the cylinder axis [4]. Here we report the first results of experiments with superfluid 3 He whose order parameter is deformed by radially squeezing the aerogel, which is equivalent to uniaxially stretching along the axis of a cylindrical sample. The particular interest for this kind of deformation is due to the prediction of a new phase of superfluid 3 He -the "polar" phase, which has a nodal line in the quasiparticle energy gap in the plane perpendicular to the stretching direction [5]. In our experiments no strong evidence of a polar phase has been found. However, a precursor of a polar phase formation -orientation of the orbital vectorl in the plane of the aerogel squeezing in both 3 He-A and 3 He-B -has been observed.This orientational effect allows us to study the influence of the local random anisotropy of aerogel on the U (1)-field of the vectorl, which is kept in the plane of squeezing. We find that instead of a polar phase, the Imry-Ma state of superfluid 3 He-A is formed. The quenched random anisotropy of the aerogel strands destroys the long-range orientational order (LROO) according to the famous Imry-Ma scenario [6] (see [7,8] and references therein). This is the counterpart of the effect of collective pinning in superconductors predicted by Larkin [9], in which weak impurities destroy the longrange translational order of the Abrikosov vortex lattice.The Larkin-Imry-Ma (LIM) effect has been studied experimentally in 3 He-A confined in a non-deformed aerogel [4,10]. The aerogel diminishes the value of Leggett frequency, which leads to decrease of the frequency s...
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in late 2012. eROSITA is fully approved and funded by the German Space Agency DLR and the Max-Planck-Society.The design driving science is the detection of 50-100 thousands Clusters of Galaxies up to redshift z~1.3 in order to study the large scale structure in the Universe and test cosmological models, especially Dark Energy. This will be accomplished by an all-sky survey lasting for four years plus a phase of pointed observations. eROSITA consists of seven Wolter-I telescope modules, each equipped with 54 Wolter-I shells having an outer diameter of 360 mm. This would provide and effective area at 1.5 keV of ~1500 cm2 and an on axis PSF HEW of 15" which would provide an effective angular resolution of 25"-30". In the focus of each mirror module, a fast frame-store pn-CCD will provide a field of view of 1deg in diameter for an active FOV of ~0.83 deg2. At the time of writing the instrument development is currently in phase C/D.Comment: 6 Pages, 3 Figure, Proceedings of the conference "X-ray Astronomy 2009", Bologna, September 200
We report on the calibration of a superfluid 3 He bolometer developed for the search of non-baryonic Dark Matter. Precise thermometry is achieved by the direct measurement of thermal excitations using Vibrating Wire Resonators (VWRs). The heating pulses for calibration were produced by the direct quantum process of quasiparticle generation by other VWRs present. The bolometric calibration factor is analyzed as a function of temperature and excitation level of the sensing VWR. The calibration is compared to bolometric measurements of the nuclear neutron capture reaction and heat depositions by cosmic muons and low energy electrons. The comparison allows a quantitative estimation of the ultra-violet scintillation rate of irradiated helium, demonstrating the possibility of efficient electron recoil event rejection.
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