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Saint Petersburg, Russia

Korzinin E.Y.,Mendeleev Institute for Metrology | Ivanov V.G.,Pulkovo Observatory | Karshenboim S.G.,Max Planck Institute of Quantum Optics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Corrections to energy levels in light muonic atoms are investigated in order α2(Zα)4m. We pay attention to corrections which are specific for muonic atoms and include the electron vacuum polarization loop. In particular, we calculate relativistic and relativistic-recoil two-loop electron vacuum polarization contributions. The results are obtained for the levels with n=1, 2 and in particular for the Lamb shift (2p1/2-2s1/2) and fine-structure intervals (2p3/2-2p1/2) in muonic hydrogen, deuterium, and muonic helium ions. © 2013 American Physical Society. Source

Malkin Z.,Pulkovo Observatory
Journal of Geodesy | Year: 2011

Very Long Baseline Interferometry (VLBI) Intensive sessions are scheduled to provide operational Universal Time (UT1) determinations with low latency. UT1 estimates obtained from these observations heavily depend on the model of the celestial pole motion used during data processing. However, even the most accurate precession-nutation model, IAU 2000/2006, is not accurate enough to realize the full potential of VLBI observations. To achieve the highest possible accuracy in UT1 estimates, a celestial pole offset (CPO), which is the difference between the actual and modelled precession-nutation angles, should be applied. Three CPO models are currently available for users. In this paper, these models have been tested and the differences between UT1 estimates obtained with those models are investigated. It has been shown that neglecting CPO modelling during VLBI UT1 Intensive processing causes systematic errors in UT1 series of up to 20 μas. It has been also found that using different CPO models causes the differences in UT1 estimates reaching 10 μas. Obtained results are applicable to the satellite data processing as well. © 2011 Springer-Verlag. Source

Zaitsev V.V.,Institute of Applied Physics | Stepanov A.V.,Pulkovo Observatory
Solar Physics | Year: 2014

We propose a model to explain fast pulsations in sub-THz emission from solar flares. The model is based on the approach of a flaring loop as an equivalent electric circuit and explains the pulse-repetition rate, the high-quality factor, Q≥103, low modulation depth, pulse synchronism at different frequencies, and the dependence of the pulse-repetition rate on the emission flux, observed by Kaufmann et al. (Astrophys. J. 697, 420, 2009). We solved the nonlinear equation for electric current oscillations using a Van der Pol method and found the steady-state value for the amplitude of the current oscillations. Using the pulse rate variation during the flare on 4 November 2003, we found a decrease of the electric current from 1.7×1012 A in the flare maximum to 4×1010 A just after the burst. Our model is consistent with the plasma mechanism of sub-THz emission suggested recently by Zaitsev, Stepanov, and Melnikov (Astron. Lett. 39, 650, 2013). © 2014 Springer Science+Business Media Dordrecht. Source

Volobuev D.M.,Pulkovo Observatory
Climate Dynamics | Year: 2014

Antarctic "Vostok" station works most closely to the center of the ice cap among permanent year-around stations. Climate conditions are exclusively stable: low precipitation level, cloudiness and wind velocity. These conditions can be considered as an ideal model laboratory to study the surface temperature response on solar irradiance variability during 11-year cycle of solar activity. Here we solve an inverse heat conductivity problem: calculate the boundary heat flux density (HFD) from known evolution of temperature. Using meteorological temperature record during (1958-2011) we calculated the HFD variation about 0.2-0.3 W/m2 in phase with solar activity cycle. This HFD variation is derived from 0.5 to 1 °C temperature variation and shows relatively high climate sensitivity per 0.1 % of solar radiation change. This effect can be due to the polar amplification phenomenon, which predicts a similar response 0.3-0.8 °C/0.1 % (Gal-Chen and Schneider in Tellus 28:108-121, 1975). The solar forcing (TSI) is disturbed by volcanic forcing (VF), so that their linear combination TSI + 0.5VF empirically provides higher correlation with HFD (r = 0.63 ± 0.22) than TSI (r = 0.50 ± 0.24) and VF (r = 0.41 ± 0.25) separately. TSI shows higher wavelet coherence and phase agreement with HFD than VF. © 2013 Springer-Verlag Berlin Heidelberg. Source

Karshenboim S.G.,Max Planck Institute of Quantum Optics | Ivanov V.G.,Pulkovo Observatory | Korzinin E.Y.,Mendeleev Institute for Metrology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

The relativistic recoil contributions to the Uehling corrections are revisited. A controversy in recent calculations is considered, which is based on different approaches including Breit-type and Grotch-type calculations. It is found that calculations in those works were in fact done in different gauges and in some of those gauges contributions to retardation and two-photon-exchange effects were missed. Such effects are evaluated and a consistent result is obtained. A correct expression for the Grotch-type approach is presented, which produces a correct gauge-invariant result. A finite-nuclear-size correction for the Uehling term is also considered. The results are presented for muonic hydrogen and deuterium atoms and for muonic 3He and 4He ions. © 2012 American Physical Society. Source

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