114 research outputs found
Analysis of Reconstructions Cardioesophageal Junction of the Teres Ligament in Treatment Hiatal Hernias
The article's abstract is no available
Bethe-Sommerfeld conjecture for periodic operators with strong perturbations
We consider a periodic self-adjoint pseudo-differential operator
, , in which satisfies the following conditions:
(i) the symbol of is smooth in \bx, and (ii) the perturbation has
order less than . Under these assumptions, we prove that the spectrum of
contains a half-line. This, in particular implies the Bethe-Sommerfeld
Conjecture for the Schr\"odinger operator with a periodic magnetic potential in
all dimensions.Comment: 61 page
Kinetics of thermo heterogeneous process under non-isothermal terms on the titanium carbide : a study on the different irradation conditions
Please read abstract in the article.http://jomardpublishing.com/journals.aspx?lang=en&id=13am2023Physic
Radiation resistance of composite scintillators
Radiation resistance of composite scintillators containing grains of organic or inorganic single crystals has been analysed. The analysis is based on the study of composite scintillators containing grains Gd₂SiO₅:Ce (GSO:Ce), Gd₂Si₂O₇:Ce(GPS:Ce), Al₂O₃:Ti, Y₂SiO₅:Ce (YSO:Ce) or Y₃Al₅O₁₂:Ce (YAG:Ce) . This paper presents the results of research and suggests possible mechanisms as well as processes of radiation changes that occur in scintillators due to irradiation. It also discusses how these effects can affect the scintillation characteristics of composite scintillators exposed to radiation.Проаналізовано радіаційну стійкість композиційних сцинтиляторів, на основі гранул органічних та неорганічних монокристалів. Аналіз ґрунтується на вивченні композиційних сцинтиляторів, що містять гранули Gd₂SiO₅:Ce (GSO:Ce), Gd₂Si₂O₇:Ce(GPS:Ce), Al₂O₃:Ti, Y₂SiO₅:Ce (YSO:Ce) або Y₃Al₅O₁₂:Ce (YAG:Ce). Представлені результати досліджень та запропоновано можливі механізми та процеси радіаційних змін, що виникають у сцинтилляторах під дією іонізуючого опромінення. Також представлено, як ці ефекти впливають на радіаційну стійкість композиційних сцинтиляторів.Проанализирована радиационная стойкость композиционных сцинтилляторов, содержащих гранулы органических и неорганических монокристаллов. Анализ основан на изучении композиционных сцинтилляторов, содержащих гранулы Gd₂SiO₅:Ce (GSO:Ce), Gd₂Si₂O₇:Ce(GPS:Ce), Al₂O₃:Ti, Y₂SiO₅:Ce (YSO:Ce) або Y₃Al₅O₁₂:Ce (YAG:Ce). Представлены результаты исследований и предлагаются возможные механизмы и процессы радиационных изменений, происходящих в сцинтилляторах под действием ионизирующего облучения. Также представлено, как эти эффекты влияют на радиационную стойкость композиционных сцинтилляторов
Quantum magnetism in two dimensions: From semi-classical N\'eel order to magnetic disorder
This is a review of ground-state features of the s=1/2 Heisenberg
antiferromagnet on two-dimensional lattices. A central issue is the interplay
of lattice topology (e.g. coordination number, non-equivalent nearest-neighbor
bonds, geometric frustration) and quantum fluctuations and their impact on
possible long-range order. This article presents a unified summary of all 11
two-dimensional uniform Archimedean lattices which include e.g. the square,
triangular and kagome lattice. We find that the ground state of the spin-1/2
Heisenberg antiferromagnet is likely to be semi-classically ordered in most
cases. However, the interplay of geometric frustration and quantum fluctuations
gives rise to a quantum paramagnetic ground state without semi-classical
long-range order on two lattices which are precisely those among the 11 uniform
Archimedean lattices with a highly degenerate ground state in the classical
limit. The first one is the famous kagome lattice where many low-lying singlet
excitations are known to arise in the spin gap. The second lattice is called
star lattice and has a clear gap to all excitations.
Modification of certain bonds leads to quantum phase transitions which are
also discussed briefly. Furthermore, we discuss the magnetization process of
the Heisenberg antiferromagnet on the 11 Archimedean lattices, focusing on
anomalies like plateaus and a magnetization jump just below the saturation
field. As an illustration we discuss the two-dimensional Shastry-Sutherland
model which is used to describe SrCu2(BO3)2.Comment: This is now the complete 72-page preprint version of the 2004 review
article. This version corrects two further typographic errors (three total
with respect to the published version), see page 2 for detail
Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2
We present a precise measurement of the deuteron longitudinal spin asymmetry
A_1^d and of the deuteron spin-dependent structure function g_1^d at Q^2 < 1
GeV^2 and 4*10^-5 < x < 2.5*10^-2 based on the data collected by the COMPASS
experiment at CERN during the years 2002 and 2003. The statistical precision is
tenfold better than that of the previous measurement in this region. The
measured A_1^d and g_1^d are found to be consistent with zero in the whole
range of x.Comment: 17 pages, 10 figure
Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs
We present a determination of the gluon polarization Delta G/G in the
nucleon, based on the helicity asymmetry of quasi-real photoproduction events,
Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final
state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV
polarized muon beam scattered on a polarized 6-LiD target. The helicity
asymmetry for the selected events is = 0.002 +- 0.019(stat.) +-
0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta
G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3
(GeV}/c)^2.Comment: 10 pages, 3 figure
The Deuteron Spin-dependent Structure Function g1d and its First Moment
We present a measurement of the deuteron spin-dependent structure function
g1d based on the data collected by the COMPASS experiment at CERN during the
years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the
first moment of g1d(x), and for the matrix element of the singlet axial
current, a0. The results of QCD fits in the next to leading order (NLO) on all
g1 deep inelastic scattering data are also presented. They provide two
solutions with the gluon spin distribution function Delta G positive or
negative, which describe the data equally well. In both cases, at Q^2 = 3
(GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3
in absolute value.Comment: fits redone using MRST2004 instead of MRSV1998 for G(x), correlation
matrix adde
A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target
New high precision measurements of the Collins and Sivers asymmetries of
charged hadrons produced in deep-inelastic scattering of muons on a
transversely polarised 6LiD target are presented. The data were taken in 2003
and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at
160 GeV/c. Both the Collins and Sivers asymmetries turn out to be compatible
with zero, within the present statistical errors, which are more than a factor
of 2 smaller than those of the published COMPASS results from the 2002 data.
The final results from the 2002, 2003 and 2004 runs are compared with naive
expectations and with existing model calculations.Comment: 40 pages, 28 figure
Measurement of the Spin Structure of the Deuteron in the DIS Region
We present a new measurement of the longitudinal spin asymmetry A_1^d and the
spin-dependent structure function g_1^d of the deuteron in the range 1 GeV^2 <
Q^2 < 100 GeV^2 and 0.004< x <0.7. The data were obtained by the COMPASS
experiment at CERN using a 160 GeV polarised muon beam and a large polarised
6-LiD target. The results are in agreement with those from previous experiments
and improve considerably the statistical accuracy in the region 0.004 < x <
0.03.Comment: 10 pages, 6 figures, subm. to PLB, revised: author list, Fig. 4,
details adde
- …