100 research outputs found
Rescaling of Nuclear Structure Functions
It is shown that nucleonic structure functions are and rescaled
in nuclei. The rescaling accounts for nuclear effects in the case of exact
scaling, while the rescaling is responsible for a corresponding
modification of quantum corrections. This result is obtained in the leading
order for all flavour combinations and connects the two known models for the
EMC-effect. Electroproduction and gluonic nuclear structure functions are
calculated.Comment: 9 pages, Latex, 2 figures appended (compressed and uuencoded
Quasielastic Versus Inelastic and Deep Inelastic Lepton Scattering in Nuclei at x > 1
We have made a thorough investigation of the nuclear structure function W_2A
in the region of 0.8 < x < 1.5 and Q^2 < 20 GeV^2, separating the quasielastic
and inelastic plus deep inelastic contributions. The agreement with present
experimental data is good giving support to the results for both channels.
Predictions are made in yet unexplored regions of x and Q^2 to assert the
weight of the quasielastic or inelastic channels. We find that at Q^2 < 4 GeV^2
the structure function is dominated by the quasielastic contributions for x <
1.5, while for values of Q^2 > 15 GeV^2 and the range of x studied the
inelastic channels are over one order of magnitude bigger than the quasielastic
one. The potential of the structure function at x > 1 as a source of
information on nuclear correlations is stressed once more.Comment: 17 pages, LaTeX, 13 PostScript figures, final version to be published
in Nuclear Physics
Gaseous Radiochemical Method for Registration of Ionizing Radiation and Its Possible Applications in Science and Industry
This work presents a new possibility of registration of ionizing radiation by
the flowing gaseous radiochemical method (FGRM). The specified method uses the
property of some solid crystalline lattice materials for a free emission of
radioactive isotopes of inert gas atoms formed as a result of nuclear
reactions. Generated in an ampoule of the detector, the radioactive inert gases
are transported by a gas-carrier into the proportional gas counter of the
flowing type, where the decay rate of the radioactive gas species is measured.
This quantity is unequivocally related to the flux of particles (neutrons,
protons, light and heavy ions) at the location of the ampoule. The method was
used to monitor the neutron flux of the pulsed neutron target "RADEX" driven by
the linear proton accelerator of INR RAS. Further progress of the FGRM may give
rise to possible applications in nuclear physics, astrophysics and medicine, in
the nondestructive control of fissionable materials, diagnostics of
thermonuclear plasma, monitoring of fluxes and measurement of spectra of
bombarding particles.Comment: 19 pages, 5 figure
Deep Inelastic Lepton Scattering in Nuclei at x > 1 and the Nucleon Spectral Function
The nuclear structure function F_2A(x) has been studied in the Bjorken limit
for (l, l') scattering on nuclei in the region of x > 1 and was found to be
very sensitive to the information contained in the nucleon spectral function in
nuclei, particularly the correlations between momenta and energies in the
region of large momenta. Calculations were done in a local density
approximation using two different spectral functions for nuclear matter.
Results are compared to those obtained for a spectral function which has been
evaluated directly for the finite nucleus, ^{16}O, under consideration. For
values of x around 1.5 and larger the quasiparticle contribution is negligible,
thus stressing the sensitivity of the present reaction to the dynamical
properties of nuclei beyond the shell model approach. Several approximations
which are usually employed in studies of the EMC effect have been analyzed and
their inaccuracy in this region is demonstrated. The results stress the fact
that the nuclear structure function contains important information on nuclear
dynamical correlations. Therefore further measurements of F_2A(x) in that
region and for many nuclei would be most welcome.Comment: 24 pages, LaTeX, 11 PostScript figures, final version to appear in
Nuclear Physics
Mesonic and Binding Contributions to the EMC Effect in a Relativistic Many Body Approach
We revise the conventional nuclear effects of Fermi motion, binding and
pionic effects in deep inelastic lepton scattering using a relativistic
formalism for an interacting Fermi sea and the local density approximation to
translate results from nuclear matter to finite nuclei. In addition we also
consider effects from rho-meson renormalization in the nucleus. The use of
nucleon Green's functions in terms of their spectral functions offers a precise
way to account for Fermi motion and binding. On the other hand the use of many
body Feynman diagrams in a relativistic framework allows one to avoid using
prescriptions given in the past to introduce relativistic corrections in a non
relativistic formalism. We show that with realistic nucleon spectral functions
and meson nucleus selfenergies one can get a reasonable description of the EMC
effect for x > 0.15, outside the shadowing region.Comment: 31 pages, LaTeX, 11 PostScript figures, final version to appear in
Nuclear Physics
Monitoring system for proton beam transport to the irradiation facilitie
A monitoring system online controls a proton beam passage from Linac to the experimental units by measuring a
secondary neutron radiation from the beam losses. The system consists of the neutron detectors in the transport path
and terminal controller connected to the computer. Monitor system allows to determine the beam losses and to detect
instability of the formative elements.Мониторная система в режиме реального времени контролирует прохождение пучка протонов линейного ускорителя до экспериментальных установок по вторичному нейтронному излучению от потерь пучка. Система состоит из детекторов нейтронов в канале транспортировки и терминального контроллера, соединённого с компьютером. Мониторная система позволяет определять потери пучка и контролировать работу формирующих элементов транспортного канала.Моніторна система в режимі реального часу контролює проходження пучка протонів лінійного прискорювача до ек-
спериментальних установок за вторинним нейтронним випромінюванням від втрат пучка. Система складається з детек-
торів нейтронів у каналі транспортування і термінального контролера, сполученого з комп'ютером. Моніторна система
дозволяє визначати втрати пучка і виявляти нестабільність роботи формуючих елементів транспортного каналу
Evolution of the nucleon structure in the lightest nuclei
The evolution of the nucleon structure as a function of atomic mass A is
considered for the first time for the lightest nuclei, D, 3H, 3He and 4He, with
an approach based on the Bethe-Salpeter formalism. We show that the pattern of
the oscillation of the structure functions ratio r^A(x) = F_2^A/F_2^N(D) varies
with A by changing the position of the cross-over point x_3 in which r^A(x) =
1, unlike the pattern for nuclei with masses A larger than 4, where only the
amplitude of the oscillation changes. In particular we find that the pattern of
F_2(x) modifications is controlled with the values (1 - x_3) = 0.32 (D/N), 0.16
(3He/D) and 0.08 (4He/D). The obtained results follow from the relativistic
consideration of the nuclear structure and allow us to define a whole class of
modifications of the partonic distributions in the nucleon bound in a nucleus.
The EMC effect is explained as a particular case of the considered class.Comment: Preprint of the publication submitted to Physics Letters B. 12 pages
(LaTeX) including 3 encapsulated figure
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