277 research outputs found
The main structural element of a reinforced concrete supports: mathematical modeling of mechanical vibrations
The problem of mathematical modeling of a reinforced concrete supports mechanical vibrations is considered. The basic vibrations of the main structural element (a road) are taken into account. The eigenfrequencies of the first three vibration modes of the rod are determined without and with prestressing of the rod. Participation factor of the basic, second and third modes is investigated
Observation of inverse diproton photodisintegration at intermediate energies
The reaction pp->{pp}_s\gamma, where {pp}_s is a proton pair with an
excitation energy E_{pp}<3 MeV, has been observed with the ANKE spectrometer at
COSY-Juelich for proton beam energies of T_p=0.353, 0.500, and 0.550 GeV. This
is equivalent to photodisintegration of a free 1S_0 diproton for photon
energies E\gamma ~ T_p/2. The differential cross sections measured for c.m.
angles 0 deg.<\theta_{pp}<20 deg. exhibit a steep increase with angle that is
compatible with E1 and E2 multipole contributions. The ratio of the measured
cross sections to those of np->d\gamma is on the 10^{-3}-10^{-2} level. The
increase of the pp->{pp}_s\gamma cross section with T_p might reflect the
influence of the Delta(1232) excitation.Comment: 4 pages + 4 figure
Meson-production experiments at COSY-Juelich
Selected results from experiments at COSY-Juelich are presented: an attempt
to measure the mass of the eta meson with high precision (ANKE facility), first
steps towards the detection of rare eta decays (WASA), and several measurements
of KKbar-pair production (ANKE, COSY-11, MOMO).Comment: Proceedings of QNP2009, Beijing, Sept. 2009; to be published in
Chinese Physics C. 6 pages, 5 figure
The energy dependence of the pp->K+ n Sigma+ reaction close to threshold
The production of the Sigma+ hyperon through the pp->K+nSigma+ reaction has
been investigated at four energies close to threshold, 1.826, 1.920, 1.958, and
2.020 GeV. At low energies, correlated K+pi+ pairs can only originate from
Sigma+ production so that their measurement allows the total cross section for
the reaction to be determined. The results obtained are completely consistent
with the values extracted from the study of the K+-proton correlation spectra
obtained in the same experiment. These spectra, as well as the inclusive K+
momentum distributions, also provide conservative upper limits on the Sigma+
production rates. The measurements show a Sigma+ production cross section that
varies roughly like phase space and, in particular, none of the three
experimental approaches used supports the anomalously high near-threshold
pp->K+ nSigma+ total cross section previously reported [T. Rozek et al., Phys.
Lett. B 643, 251 (2006)].Comment: Submitted to PR
New determination of the mass of the eta meson at COSY-ANKE
A value for the mass of the eta meson has been determined at the COSY-ANKE
facility through the measurement of a set of deuteron laboratory beam momenta
and associated 3He center-of-mass momenta in the d+p -> 3He+X reaction. The eta
was then identified by the missing-mass peak and the production threshold
determined. The individual beam momenta were fixed with a relative precision of
3 x 10^-5 for values around 3 GeV/c by using a polarized deuteron beam and
inducing an artificial depolarizing spin resonance, which occurs at a
well-defined frequency. The final-state momenta in the two-body d+p -> 3He+eta
reaction were investigated in detail by studying the size of the 3He momentum
ellipse with the forward detection system of the ANKE spectrometer. Final
alignment of the spectrometer for this high precision experiment was achieved
through a comprehensive study of the 3He final-state momenta as a function of
the center-of-mass angles, taking advantage of the full geometrical acceptance.
The value obtained for the mass, m(eta)=(547.873 +- 0.005(stat) +- 0.027(syst))
MeV/c^2, is consistent and competitive with other recent measurements, in which
the meson was detected through its decay products.Comment: 11 pages, 11 figures, 3 tables, published versio
On the Difference in Action of the Laser Light with Wavelength Near 2mm on Biotissue in Gas and Water Media
It is shown that unlike action in the air environment, section of the biotissue in the water environment (physiological solution) is performed by the steam-gas stream which is formed as a result of superintensive boiling in thin (about 0.1 mm) a liquid layer in which absorbed laser radiation. Coagulation of the biotissue, adjacent to a section, happens due to heat which is produced via vapor condensation.
Keywords: laser radiation in urology, a laser enucleation of the BPH, laser removal of the bladder cancer
Near threshold eta meson production in the d+d->alpha+eta reaction
The d+d->alpha+eta reaction has been investigated near threshold using the
ANKE facility at COSY-Juelich. Both total and differential cross sections have
been measured at two excess energies, Q=2.6 MeV and 7.7 MeV, with a
subthreshold measurement being undertaken at Q=-2.6 MeV to study the physical
background. While consistent with isotropy at the lower energy, the angular
distribution reveals a pronounced anisotropy at the higher one, indicating the
presence of higher partial waves. Options for the decomposition into partial
amplitudes and their consequences for determination of the s-wave eta-alpha
scattering length are discussed.Comment: 8pp, fig.3 added, normalisation in eq.4.1 correcte
The production of K+K- pairs in proton-proton collisions at 2.83 GeV
Differential and total cross sections for the pp -> ppK+K- reaction have been
measured at a proton beam energy of 2.83 GeV using the COSY-ANKE magnetic
spectrometer. Detailed model descriptions fitted to a variety of
one-dimensional distributions permit the separation of the pp -> pp phi cross
section from that of non-phi production. The differential spectra show that
higher partial waves represent the majority of the pp -> pp phi total cross
section at an excess energy of 76 MeV, whose energy dependence would then seem
to require some s-wave phi-p enhancement near threshold. The non-phi data can
be described in terms of the combined effects of two-body final state
interactions using the same effective scattering parameters determined from
lower energy data.Comment: 12 pages, 12 figures, 3 table
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