180 research outputs found
Investigation of the Earth Ionosphere using the Radio Emission of Pulsars
The investigation of the Earth ionosphere both in a quiet and a disturbed
states is still desirable. Despite recent progress in its modeling and in
estimating the electron concentration along the line of sight by GPS signals,
the impact of the disturbed ionosphere and magnetic field on the wave
propagation still remains not sufficiently understood. This is due to lack of
information on the polarization of GPS signals, and due to poorly conditioned
models of the ionosphere at high altitudes and strong perturbations. In this
article we consider a possibility of using the data of pulsar radio emission,
along with the traditional GPS system data, for the vertical and oblique
sounding of the ionosphere. This approach also allows to monitor parameters of
the propagation medium, such as the dispersion measure and the rotation measure
using changes of the polarization between pulses. By using a selected pulsar
constellation it is possible to increase the number of directions in which
parameters of the ionosphere and the magnetic field can be estimated.Comment: 13 pages, 4 figures, Baltic Astronomy, vol.22, 53-65, 201
Deep excursion beyond the proton dripline. II. Toward the limits of existence of nuclear structure
Prospects of experimental studies of argon and chlorine isotopes located far beyond the proton dripline are studied by using systematics and cluster models. The deviations from the widespread systematics observed in
28
,
29
Cl
and
29
,
30
Ar
have been theoretically substantiated, and analogous deviations have been predicted for the lighter chlorine and argon isotopes. The limits of nuclear structure existence are predicted for Ar and Cl isotopic chains, with
26
Ar
and
25
Cl
found to be the lightest sufficiently long-living nuclear systems. By simultaneous measurements of protons and
γ
rays following decays of such systems as well as their
β
-delayed emission, an interesting synergy effect may be achieved, which is demonstrated by the example of
30
Cl
and
31
Ar
ground-state studies. Such a synergy effect may be provided by the new EXPERT setup (EXotic Particle Emission and Radioactivity by Tracking) being operated inside the fragment separator and spectrometer facility at GSI, Darmstadt.Helmholtz Association de Alemania. IK-RU-002Russian Science Foundation. 17-12-01367Polish National Science Center. UMO2015/17/B/ST2/00581Polish Ministry of Science and Higher Education. 0079/DIA/2014/43Helmholtz- CAS Joint Research Group de Alemania. HCJRG-108Ministerio de Educación y Ciencia, España. FPA2016-77689-C2-1-RMinistry of Education, Youth and Sports de la República Checa. LTT17003 y LM201504
Digital receivers for low-frequency radio telescopes UTR-2, URAN, GURT
This paper describes digital radio astronomical receivers used for decameter
and meter wavelength observations. This paper describes digital radio
astronomical receivers used for decameter and meter wavelength observations.
Since 1998, digital receivers performing on-the-fly dynamic spectrum
calculations or waveform data recording without data loss have been used at the
UTR-2 radio telescope, the URAN VLBI system, and the GURT new generation radio
telescope. Here we detail these receivers developed for operation in the strong
interference environment that prevails in the decameter wavelength range. Data
collected with these receivers allowed us to discover numerous radio
astronomical objects and phenomena at low frequencies, a summary of which is
also presented.Comment: 24 pages, 15 figure
НОРМЕННАЯ ИДЕНТИФИКАЦИЯ ОШИБОК НЕГАРАНТИРОВАННОЙ КРАТНОСТИ
Error correction capability of unguaranteed errors multiplicity by codes BCH based on the norming decoding is investigated. A searching algorithm of forming vectors of error with multiplicity greater than the guaranteed by code is proposed.Исследуется корректирующая способность ошибок негарантированной кратности БЧХ-кодами на основе норменного декодирования. Предлагается алгоритм поиска образующих векторов ошибок, имеющих кратность больше, чем гарантированная кратность корректируемых ошибок
Study of the unbound nucleus N-11 by elastic resonance scattering
4 pages, 4 figures, 2 tables.-- PACS nrs.: 21.10.Pc, 25.40.Ny, 27.20.+n.Resonances in the unbound nucleus N-11 have been studied, using the resonance scattering reaction C-10+p. The data give evidence for three states above the C-10+p threshold with energies 1.30, 2.04, and 3.72 MeV. These states can be interpreted, in a potential-model analysis, as the ground state and the first two excited states with spin-parity 1/2(+), 1/2(-), and 5/2(+) arising from the shell-model orbitals 1s(1/2), Op(1/2), and Od(5/2). A narrow state superposed on a broad structure found at higher energy could be interpreted as the mirror state of the 3/2(-) in Be-11 shifted down in energy. This shift would suggest a large radius of the potential.We acknowledge financial support from the European Community under Contract No. CHGE-CT94-0056 (Human Capital and Mobility, Access to the GANIL large scale facility) and from the Russian
Foundation RFFI.Peer reviewe
High-resolution measurement of the time-modulated orbital electron capture and of the decay of hydrogen-like Pm ions
The periodic time modulations, found recently in the two-body orbital
electron-capture (EC) decay of both, hydrogen-like Pr and
Pm ions, with periods near to 7s and amplitudes of about 20%,
were re-investigated for the case of Pm by using a 245 MHz
resonator cavity with a much improved sensitivity and time resolution. We
observed that the exponential EC decay is modulated with a period s, in accordance with a modulation period s as obtained
from simultaneous observations with a capacitive pick-up, employed also in the
previous experiments. The modulation amplitudes amount to and
for the 245 MHz resonator and the capacitive pick-up,
respectively. These new results corroborate for both detectors {\it exactly}
our previous findings of modulation periods near to 7s, though with {\it
distinctly smaller} amplitudes. Also the three-body decays have been
analyzed. For a supposed modulation period near to 7s we found an amplitude , compatible with and in agreement with the preliminary
result of our previous experiment. These observations could
point at weak interaction as origin of the observed 7s-modulation of the EC
decay. Furthermore, the data suggest that interference terms occur in the
two-body EC decay, although the neutrinos are not directly observed.Comment: In memoriam of Prof. Paul Kienle, 9 pages, 1 table, 5 figures Phys.
Lett. B (2013) onlin
Crossing the Dripline to 11N Using Elastic Resonance Scattering
The level structure of the unbound nucleus 11N has been studied by 10C+p
elastic resonance scattering in inverse geometry with the LISE3 spectrometer at
GANIL, using a 10C beam with an energy of 9.0 MeV/u. An additional measurement
was done at the A1200 spectrometer at MSU. The excitation function above the
10C+p threshold has been determined up to 5 MeV. A potential-model analysis
revealed three resonance states at energies 1.27 (+0.18-0.05) MeV (Gamma=1.44
+-0.2 MeV), 2.01(+0.15-0.05) MeV, (Gamma=0.84 +-$0.2 MeV) and 3.75(+-0.05) MeV,
(Gamma=0.60 +-0.05 MeV) with the spin-parity assignments I(pi) =1/2+, 1/2- and
5/2+, respectively. Hence, 11N is shown to have a ground state parity inversion
completely analogous to its mirror partner, 11Be. A narrow resonance in the
excitation function at 4.33 (+-0.05) MeV was also observed and assigned
spin-parity 3/2-.Comment: 14 pages, 9 figures, twocolumn Accepted for publication in PR
Search for {\eta}'(958)-nucleus bound states by (p,d) reaction at GSI and FAIR
The mass of the {\eta}' meson is theoretically expected to be reduced at
finite density, which indicates the existence of {\eta}'-nucleus bound states.
To investigate these states, we perform missing-mass spectroscopy for the (p,
d) reaction near the {\eta}' production threshold. The overview of the
experimental situation is given and the current status is discussed.Comment: 6 pages, 3 figures; talk at II Symposium on applied nuclear physics
and innovative technologies, September 24th - 27th, 2014, Jagiellonian
University, Krak\'ow Poland; to appear in Acta Physica Polonica
Study of Proton and Deuteron Pickup Reactions 2H(10Be,3He)9Li an 2H(10Be,4He)8Li with 44 A MeV 10Be Radioactive Beam at ACCULINNA-2 Fragment Separator
The proton and deuteron pickup reactions 2H(10Be,3He)9Li and\\
2H(10Be,4He)8Li radioactive beam produced by the new fragment separator
ACCULINNA-2 at FLNR, JINR\@. These measurements were initially motivated as
test reactions intended for the elucidation of results obtained in the study of
the extremely neutron-rich 7H and 6H systems created in the 2H(10Be,3He)9Li and
2H(10Be,4He)8Li reactions using the same setup. In the 2H(10Be,3He)9Li reaction
the 9Li ground-state () and its first excited state (2.69~MeV, )
were identified in the low-energy region of its excitation spectrum. The
differential cross sections for the 9Li g.~s.) population were extracted at
forward center-of-mass angles () and compared with the FRESCO
calculations. Spectroscopic factor of , derived by a model for the
10Be9Li(g.s.) clustering was found in accord with the experimental
data. The energy spectrum of 8Li populated in the 2H(10Be,4He)8Li reaction
shows the strong peak which corresponds to excitation of the second excited
state of 8Li (2.25 MeV, ). The fact that the ground and the first excited
states of 8Li were not observed is fully consistent with Shell-Model
calculations carried out for the 10Be g.\,s. and 8Li level structure applying
momentum selection rules
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