On the 'Strong-Coupling' Generalization of the Bogoliubov Model

A generalized Bogoliubov model of the Bose gas in the ground state is proposed which properly takes into account both the long-range and short-range spatial boson correlations. It concerns equilibrium characteristics and operates with in-medium Schrodinger equations for the pair wave functions of bosons being the eigenfunctions of the second-order reduced density matrix. The approach developed provides reasonable results for a dilute Bose gas with arbitrary strong interaction between particles (the 'strong-coupling' case) and comes to the canonical Bogoliubov model in the weak-coupling regime.Comment: 6 pages, REVTEX, no figure

On the Strength Calculation of the Rotating parts

AbstractThe existing solutions of differential equations of equilibrium of an infinitesimal element of the rotating parts of an isotropic elastic solid known as the Navier equilibrium equations are considered. Examples of the flat disk calculation by solving the differential equilibrium equations by the sweep method and the finite element method in the modern program “Autodesk Simulation Multiphysics” are represented; paradoxical changes of radial and hoop stresses are revealed. An original method of derivation formulas based only on the principle of d’Alembert to calculate radial and hoop stresses in parts that operate under centrifugal (inertial) forces is proposed. The solution for rotating disks of any profile that corrects unnatural classical solutions is obtained. Analysis of the obtained new formulas for calculating stresses shows that it is necessary to reject the concept of “equal-strength disk” because of the inability to provide the equality of the hoop and radial stress in all sections of the disk. A new method of the optimum strength disk profile calculation, which requires a restriction of outer radius disk, is suggested. In designing of optimum strength rotating parts is recommended to limit outer disk radius of where [σ] − the allowable stress, ρ − density of the disk material; ω − angular velocity of disk rotation

The employment of fitting programs for deuteron polarization calculation in a nuclear polarized target

We have developed the fitting program used for deuteron polarization calculation. The simulation has been done for the deuterated 1,2-propanediol-D8 as a target material. Analyses of the uncertainties sources have been performed. The polarization calculated was P=+34.0% and P = -36.6% for above-mentioned target material

Calculation of the cross section for the reaction γ³He → pd at intermediate photon energies

The differential cross section and the asymmetry coefficient for the two-body photodisinteration of ³He by linearly polarized photons are calculated with wave functions for Bonn potential. Dependences of the observables on the components of the ³He wave function with the orbital angular momenta L, l ³ 1 are studied at photon energies Eg up to 300 MeV

Negative pion photoproduction off polarized deuteron target

It is discussed whether the target asymmetry (TA) for γn→π⁻p can be extracted from data on γd→π⁻pp. An exclusive experiment that enhances production of pions on neutron at rest and suppresses contributions of the recoil mechanism is shown to correspond to this purpose. The relation between the TAs for the reactions on deuteron and neutron is established taking into account pion and active nucleon rescattering in the final state and neglecting effects due to interaction with the spectator nucleon

SiPM MEPhI Megagrant Developments in Nuclear Medicine

AbstractThree projects has been started in our laboratory as part of megagrant “High energy physics and nuclear medicine with silicon photomultiplier detectors” in NRNU MEPHI. The goal of these projects is development of devices for nuclear medicine in which replacement of photomultiplier tubes (PMT) with solid-state silicon photomultipliers promises various advantages. The first project is full-body SPECT, where replacement of PMT's could reduce size of the detector module and improve spatial resolution while keeping other parameters. The second project is development of a TOF-PET module. Replacement of PMTs with silicon photomultipliers makes it possible to use that detector not only in high magnetic fields but also for Time-of-Flight measurements (higher signal-to-noise ratio on final image) due to very high timing resolution of a SiPM. And the last project is the SiPM-based position-sensitive Gamma-spectrometer for dose monitoring in neutron-capture therapy based on SiPM's

Investigation of polarized nucleon interaction (JINR – France – Ukraine International Collaboration)

The polarized targets are developed by Russia, France and Ukraine cooperation. We were equipped existing facility with the new holding coils magnet field to rotate the vector polarization as required by MPT project. The new results on spin- dependent total cross section difference DsL(np) were obtained by joint efforts

Resonant production of fermions in an axial background

We consider the resonant production of fermions from an oscillating axial background. The classical evolution of the axial field is given by that of a massive pseudovector field, as suggested by the renormalizability of the theory. We look upon both the massive and the massless fermion production from a perturbative point of view. We obtain the corresponding spectrum and angular distributions for the different spins or helicities in the particular case of a spatial-like axial field. We also extend our study to the non-perturbative regime in the massless case and compare the results with the perturbative ones.Comment: 16 pages, LaTeX, 12 figures; new comments and references added, version to appear in Phys. Rev.

Analysis of Ωb−(bss)\Omega_b^-(bss) and Ωc0(css)\Omega_c^0(css) with QCD sum rules

In this article, we calculate the masses and the pole residues of the ${1/2}^+$ heavy baryons $\Omega_c^0(css)$ and $\Omega_b^-(bss)$ with the QCD sum rules. The numerical values $M_{\Omega_c^0}=(2.72\pm0.18) \rm{GeV}$ (or $M_{\Omega_c^0}=(2.71\pm0.18) \rm{GeV}$) and $M_{\Omega_b^-}=(6.13\pm0.12) \rm{GeV}$ (or $M_{\Omega_b^-}=(6.18\pm0.13) \rm{GeV}$) are in good agreement with the experimental data.Comment: 18 pages, 18 figures, slight revisio

Double beta decay to the first 2+2^+ state within a boson expansion formalism with a projected spherical single particle basis

The Gamow-Teller transition operator is written as a polynomial in the dipole proton-neutron and quadrupole charge conserving QRPA boson operators, using the prescription of the boson expansion technique of Belyaev-Zelevinski type. Then, the $2\nu\beta\beta$ process ending on the first $2^+$ state in the daughter nucleus is allowed via one, two and three boson states describing the odd-odd intermediate nucleus. The approach uses a single particle basis which is obtained by projecting out the good angular momentum from an orthogonal set of deformed functions. The basis for mother and daughter nuclei have different deformations. The GT transition amplitude as well as the half lives were calculated for ten transitions. Results are compared with the available data as well as with some predictions obtained with other methods.Comment: 12 page