3,837 research outputs found
The main directions of the field development systems improvement and the potential of oil extraction increase in Ukraine
The main reasons for reduction of oil and gas extraction in Ukraine are presented. The priority directions for improving the oil and gas field development systems and the potential increase of oil and gas extraction volumes in Ukraine are substantiated. The possibility of involvement of passive reserves of oil in active development and increase of the annual oil extraction by implementation of modern oil and gas technologies are forecasted
Open Problems in Particle Condensation
particle condensation is a novel state in nuclear systems. We
briefly review the present status on the study of particle
condensation and address the open problems in this research field:
particle condensation in heavier systems other than the Hoyle state, linear
chain and particle rings, Hoyle-analogue states with extra neutrons,
particle condensation related to astrophysics, etc.Comment: 12 pages. To be published in J. of Phys. G special issue on Open
Problems in Nuclear Structure (OPeNST
Polarization-dependent electric potential distribution across nanoscale ferroelectric Hf0.5Zr0.5O2 in functional memory capacitors
Exposure of Nuclear Track Emulsion to a Mixed Beam of Relativistic N, C, and Be Nuclei
A nuclear track emulsion was exposed to a mixed beam of relativistic
N, C, and Be nuclei having a momentum of 2 GeV/ per
nucleon. The beam was formed upon charge exchange processes involving C
primary nuclei and their fragmentation. An analysis indicates that C
nuclei are dominant in the beam and that N nuclei are present in it. The
charge topology of relativistic fragments in the coherent dissociation of these
nuclei is presented.Comment: ISSN 1063-7788, Pleiades Publishing, Ltd., 201
Observation of Plasma Focusing of a 28.5 GeV Positron Beam
The observation of plasma focusing of a 28.5 GeV positron beam is reported.
The plasma was formed by ionizing a nitrogen jet only 3 mm thick. Simultaneous
focusing in both transverse dimensions was observed with effective focusing
strengths of order Tesla per micron. The minimum area of the beam spot was
reduced by a factor of 2.0 +/- 0.3 by the plasma. The longitudinal beam
envelope was measured and compared with numerical calculations
Energy loss of pions and electrons of 1 to 6 GeV/c in drift chambers operated with Xe,CO2(15%)
We present measurements of the energy loss of pions and electrons in drift
chambers operated with a Xe,CO2(15%) mixture. The measurements are carried out
for particle momenta from 1 to 6 GeV/c using prototype drift chambers for the
ALICE TRD. Microscopic calculations are performed using input parameters
calculated with GEANT3. These calculations reproduce well the measured average
and most probable values for pions, but a higher Fermi plateau is required in
order to reproduce our electron data. The widths of the measured distributions
are smaller for data compared to the calculations. The electron/pion
identification performance using the energy loss is also presented.Comment: 15 pages, 10 figures, accepted for publication in Nucl.Instrum.Meth.
Nonquasiparticle states in half-metallic ferromagnets
Anomalous magnetic and electronic properties of the half-metallic
ferromagnets (HMF) have been discussed. The general conception of the HMF
electronic structure which take into account the most important correlation
effects from electron-magnon interactions, in particular, the spin-polaron
effects, is presented. Special attention is paid to the so called
non-quasiparticle (NQP) or incoherent states which are present in the gap near
the Fermi level and can give considerable contributions to thermodynamic and
transport properties. Prospects of experimental observation of the NQP states
in core-level spectroscopy is discussed. Special features of transport
properties of the HMF which are connected with the absence of one-magnon
spin-flip scattering processes are investigated. The temperature and magnetic
field dependences of resistivity in various regimes are calculated. It is shown
that the NQP states can give a dominate contribution to the temperature
dependence of the impurity-induced resistivity and in the tunnel junction
conductivity. First principle calculations of the NQP-states for the prototype
half-metallic material NiMnSb within the local-density approximation plus
dynamical mean field theory (LDA+DMFT) are presented.Comment: 27 pages, 9 figures, Proceedings of Berlin/Wandlitz workshop 2004;
Local-Moment Ferromagnets. Unique Properties for Moder Applications, ed. M.
Donath, W.Nolting, Springer, Berlin, 200
Nuclear Track Emulsion in Search for the Hoyle’s State in Dissociation of Relativistic 12C Nuclei
Study of production of ensembles of alpha-particle triples associated with the Hoyle state (the second excited state 0+ 2 of the 12 C nucleus) in peripheral dissociation of relativistic 12C nuclei is started. Stacks of pellicles of nuclear track emulsion exposed to 12C of energy from hundreds MeV to few GeV per nucleon serve as the material of the study. The Hoyle state decays are reconstructed via measurements of emission angles of α-particles with accuracy that allows one to identify the unstable 8Be nucleus. A role in the Hoyle state of alpha-particle bonds corresponding to 8Be is determined
Evolution of the spectrum and the metal-insulator transition in local approximations for many-electron models
In the framework of the many-electron s-d exchange model and Hubbard model,
self-consistent equations are derived for the one-particle retarded Green's
function in the many-electron Hubbard X-operator representation. We analyze the
general structure of the single-site approximations and their connection with
the coherent potential approximation (CPA) and dynamic effective field theory
(DMFT). Using the self-consistent approximation, we examine in detail the
picture of the evolution of the electron spectrum with the model parameters
(coupling constants, the concentration of charge carriers). The influence of
various factors (Kondo many-electron scattering, smearing due to damping,
dynamics of localized moment subsystem) on the shape of the density of states
N(E) in the interacting system is investigated. It is shown that the use of the
locator representation allows to avoid in some cases the non-analyticity in
approximate expressions for the Green's functions. Our approach enables one to
reproduce, at certain values of the parameters, three-peak structure of N(E)
near the metal-insulator transition.Comment: 26 pages, in Russian, Physics of Metals and Metallography, accepte
Precise measurement of the W-boson mass with the CDF II detector
We have measured the W-boson mass MW using data corresponding to 2.2/fb of
integrated luminosity collected in proton-antiproton collisions at 1.96 TeV
with the CDF II detector at the Fermilab Tevatron collider. Samples consisting
of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement
MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most
precise measurement of the W-boson mass to date and significantly exceeds the
precision of all previous measurements combined
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