Results of research and the complex assessment of beech forest natural seed regeneration on clearcuts of wet beech sites of Ukrainian Carpathians are presented.
The exclusive photoproduction reactions $\gamma p \to J/\psi(1S) p$ and
$\gamma p \to \psi(2S) p$ have been measured at an $ep$ centre-of-mass energy
of 318 GeV with the ZEUS detector at HERA using ...an integrated luminosity of 373
pb$^{-1}$. The measurement was made in the kinematic range $30 < W < 180$ GeV,
$Q^2 < 1$ GeV$^2$ and $|t| < 1$ GeV$^2$, where $W$ is the photon--proton
centre-of-mass energy, $Q^2$ is the photon virtuality and $t$ is the squared
four-momentum transfer at the proton vertex. The decay channels used were
$J/\psi(1S) \to \mu^+ \mu^-$, $\psi(2S) \to \mu^+ \mu^-$ and $\psi(2S) \to
J/\psi(1S) \pi^+ \pi^-$ with subsequent decay $J/\psi(1S) \to \mu^+ \mu^-$. The
ratio of the production cross sections, $R = \sigma_{\psi(2S)} /
\sigma_{J/\psi(1S)}$, has been measured as a function of $W$ and $|t|$ and
compared to previous data in photoproduction and deep inelastic scattering and
with predictions of QCD-inspired models of exclusive vector-meson production,
which are in reasonable agreement with the data.
The passive Q-switching of 1.66-{mu}m Er{sup 3+}:YAlO{sub 3} lasers with the help of some saturable absorbers is studied. Giant 200-ns pulses are generated by using a Cr{sup 2+}:ZnSe crystal as a ...saturable absorber. (control of laser radiation parameters)
Magnetoresistive ceramic samples La
0.7
Ca
0.3 −
x
Sr
x
MnO
3 ± δ
sintered at temperatures of 1150 and 1350°C are investigated using X-ray diffraction, microscopic, resistance, and magnetic (χ,
55
Mn ...NMR) measurements. The specific features of the influence of the composition on the type and parameters of the perovskite structure, its imperfection, the porous crystallite structure, the metal-semiconductor and ferromagnetic-paramagnetic phase transitions, the
55
Mn NMR spectra, and the magnetoresistance effect are established. The magnetic phase diagram is constructed. The conclusions are drawn regarding the nonuniformity of the distribution of ions and vacancies around manganese involved in the high-frequency electron-hole exchange (Mn
3+
ai Mn
4+
) and the nanostructured separation of the perovskite structure containing anion and cation vacancies, with the concentrations and magnetoresistance effect decreasing and the lattice parameters and phase transition temperatures increasing as calcium is replaced by strontium.
A
bstract
Scaled momentum distributions for the strange hadrons
and
were measured in deep inelastic
ep
scattering with the ZEUS detector at HERA using an integrated luminosity of 330 pb
−1
. The ...evolution of these distributions with the photon virtuality,
Q
2
, was studied in the kinematic region 10
< Q
2
<
40000 GeV
2
and 0
.
001
< x <
0
.
75, where
x
is the Bjorken scaling variable. Clear scaling violations are observed. Predictions based on different approaches to fragmentation were compared to the measurements. Leading-logarithm parton-shower Monte Carlo calculations interfaced to the Lund string fragmentation model describe the data reasonably well in the whole range measured. Next-to-leading-order QCD calculations based on fragmentation functions, FFs, extracted from
e
+
e
−
data alone, fail to describe the measurements. The calculations based on FFs extracted from a global analysis including
e
+
e
−
,
ep
and
pp
data give an improved description. The measurements presented in this paper have the potential to further constrain the FFs of quarks, anti-quarks and gluons yielding
and
strange hadrons.
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