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Karpeshin F.F.,Mendeleev Institute for Metrology | Trzhaskovskaya M.B.,RAS Petersburg Nuclear Physics Institute
Physical Review C | Year: 2017

Two-photon optical pumping of the 7.6-eV nuclear isomer in the singly ionized atoms of Th229 is considered. Differences between two mechanisms of the pumping, nuclear excitation in the electronic transition (NEET) and bound internal conversion (BIC), are derived and analyzed numerically. The BIC mechanism turns out to be more effective, by orders of magnitude, in accordance with previous calculations. Moreover, a numerical smallness in the NEET scheme is explicitly pointed out concerning singly and doubly charged ions. That is related to the smallness of the final vertex, responsible for conservation of energy. In the case of BIC, the calculated pumping rate of the isomer for the most effective scheme may be as high as 0.03s-1. © 2017 American Physical Society.

Karpeshin F.F.,Mendeleev Institute for Metrology | Trzhaskovskaya M.B.,RAS Petersburg Nuclear Physics Institute
Nuclear Physics A | Year: 2015

Description of the Bohr-Wesskopf effect in the hyperfine structure of few-electron heavy ions is a challenging problem, which can be used as a test of both QED and atomic calculations. However, for twenty years the research has actually been going in a wrong direction, aimed at fighting the Bohr-Weisskopf effect through its cancellation in specific differences. Alternatively, we propose the constructive model-independent way, which enables the nuclear radii and their momenta to be retrieved from the hyper-fine splitting (HFS). The way is based on analogy of HFS to internal conversion coefficients, and the Bohr-Weisskopf effect - to the anomalies in the internal conversion coefficients. It is shown that the parameters which can be extracted from the data are the even nuclear momenta of the magnetization distribution. The radii R2 and - for the first time - R4 are obtained in this way by analysis of the experimental HFS values for the H- and Li-like ions of 209Bi. The critical prediction concerning the HFS for the 2p12 state is made. The present analysis shows high sensitivity of the method to the QED effects, which offers a way of precision test of QED. Experimental recommendations are given, which are aimed at retrieving data on the HFS values for a set of a few-electron configurations of each atom. © 2015 Elsevier B.V.

Karpeshin F.F.,Mendeleev Institute for Metrology | Trzhaskovskaya M.B.,RAS Petersburg Nuclear Physics Institute
Physics of Atomic Nuclei | Year: 2015

Pressing problems concerning the optical pumping of the 7.6-eV 229mTh nuclear isomer, which is a candidate for a new nuclear optical reference point for frequencies, are examined. Physics behind the mechanism of the two-photon optical pumping of the isomer is considered. It is shown that, irrespective of the pumping scheme, a dominant contribution comes, in accord with what was proven earlier for the 3.5-eV isomer, from the resonance 8s–7s transition. Details of an optimum experimental scheme are discussed. It is shown that, after isomer excitation, the atom involved remains with a high probability in an excited state at an energy of about 0.5 eV rather than in the ground state, the required energy of the two photons being equal to the energy of the nuclear level plus the energy of the lowest 7s state of the atom. The estimated pumping time is about 1.5 s in the case where the field strength of each laser is 1 V/cm. © 2015, Pleiades Publishing, Ltd.

Antonov N.V.,Saint Petersburg State University | Gulitskiy N.M.,Mendeleev Institute for Metrology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

The field theoretic renormalization group and operator product expansion are applied to the Kazantsev-Kraichnan kinematic model for the magnetohydrodynamic turbulence. The anomalous scaling emerges as a consequence of the existence of certain composite fields ("operators") with negative dimensions. The anomalous exponents for the correlation functions of arbitrary order are calculated in the two-loop approximation (second order of the renormalization-group expansion), including the anisotropic sectors. The anomalous scaling and the hierarchy of anisotropic contributions become stronger due to those second-order contributions. © 2012 American Physical Society.

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.

Ivanov V.G.,Pulkovo Observatory | Korzinin E.Y.,Mendeleev Institute for Metrology | Karshenboim S.G.,Max Planck Institute of Quantum Optics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We continue our account of relativistic recoil effects in muonic atoms and present explicitly analytic results at first order in electron-vacuum- polarization effects. The results are obtained within a Grotch-type approach based on an effective Dirac equation. Some expressions are cumbersome and we investigate their asymptotic behavior. Previously, relativistic two-body effects due to the one-loop electron vacuum polarization were studied by several groups. Our results found here are consistent with the previous result derived within a Breit-type approach (including ours) and disagree with a recent attempt to apply a Grotch-type approach. © 2014 American Physical Society.

Karshenboim S.G.,Max Planck Institute of Quantum Optics | Karshenboim S.G.,Pulkovo Observatory | 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.

Aleksandrov V.S.,Mendeleev Institute for Metrology | Neronov Y.I.,Mendeleev Institute for Metrology
JETP Letters | Year: 2011

Nuclear magnetic resonance spectra of the hydrogen isotopic analogs TH and TD on the triton resonance and HT, HD, and H 2 on the proton resonance in the gas phase have been studied. The triton and proton spectra from a single sample have been recorded simultaneously by using the inductivity of a common receiver LC circuit. The energies of the interaction between the magnetic moments of the nuclei of the hydrogen isotopic analogs have been determined: J tp = 299. 3(1) Hz, J td = 45. 5(1) Hz, and J pd = 43. 3(1) Hz. The ratio of the resonance frequencies of the HT molecule nuclei: F t(TH)/F p(HT) = 1. 066693898(2), which is equal to the ratio of the magnetic moments of the nuclei in the bound state, has been obtained. If the value Δσ(TH) = 2. 04 × 10 -8 calculated previously is used for the difference in the screening of nuclei in the HT molecule, then the ratio of the magnetic moment of the triton to the magnetic moment of the proton is μ t/μ p = 1. 066693920(2), where the statistical standard deviation of the data is given in the parentheses in the units of the last digit. © 2011 Pleiades Publishing, Ltd.

Burmistrova N.A.,Mendeleev Institute for Metrology
Measurement Techniques | Year: 2015

An algorithm is proposed for evaluating inconsistent measurement data obtained in key comparisons of national standards. It is based on the procedure of modifying the measurement uncertainty in a way so as to form a set of metrologically compatible measurement results. Application of this algorithm is illustrated for the example of the CCQM-K5 key comparisons. The algorithm is compared with other methods. © 2015, Springer Science+Business Media New York.

Neronov Yu.I.,Mendeleev Institute for Metrology | Seregin N.N.,Mendeleev Institute for Metrology
Metrologia | Year: 2014

In order to determine the difference in the screening of protons in water and protons in hydrogen, the authors used cylindrical samples and recordied NMR signals in the field of an electromagnet (B = 2.142 T) and a superconducting magnet (B = 11.747 T). The use of two magnets allows the influence of the volume magnetic susceptibility of the samples to be eliminated. The difference in the chemical shift for protons in water and hydrogen is found to be σ(H 2) - σ(H2O) = 608.0(±1.5) × 10 -9 at 25.0 °C. The value of proton screening in hydrogen σ(H2) is known from the literature: σ(H2) = 26 288(±2) × 10-9. With this in mind, for the screening of protons in water we have σ(H2O) = 25 680(±2.5) × 10-9 at 25.0 °C. The new result should be compared with the result for the screening of protons in water σ(H2O) = 25 694(±14) × 10-9 at 25.0 °C, which is shown in the list of fundamental physical constants (CODATA). This comparison shows that, although the two results were obtained by completely different methods, they agree within the limits of uncertainty. © 2014 BIPM & IOP Publishing Ltd.

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