The resonant excitation of the
83
Kr first excited nuclear level (
E
= 9.4 keV) by solar axions whose fluxes depend on the axion–electron coupling constant
g
Ae
is sought. The γ- and X-ray photons ...and the conversion and Auger electrons from the excited-level relaxation are detected with a gas proportional counter of a low-background detector in the underground Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences). As a result, a new constraint
≤ 1.50 × 10
–17
(90% C.L.) has been obtained for the axion–electron and axion–nucleon coupling constants, which corresponds to new constraints on the axion mass
m
A
≤ 320 eV and
m
A
≤ 4.6 eV in the KSVZ and DFSZ axion models, respectively.
Solar neutrino experiments Derbin, A V
Physics Uspekhi,
01/2014, Letnik:
57, Številka:
5
Journal Article
Recenzirano
The main results of solar neutrino experiments are presented, ranging from the pioneering Cl-Ar experiment up to the most recent Borexino data. Solar neutrino fluxes and spectra are given for two ...versions of the standard solar model, and radiochemical and electronic detectors are briefly described. The results of - and pep-neutrino detection by Borexino are presented. The LMA-MSW oscillation solution of the solar neutrino problem is considered.
A search for resonant absorption of solar axions by
169
Tm
nuclei was carried out. A newly developed approach involving low-background cryogenic bolometer based on
Tm
3
Al
5
O
12
crystal was used ...that allowed for significant improvement of sensitivity in comparison with previous
169
Tm
based experiments. The measurements performed with 8.18 g crystal during 6.6 days exposure yielded the following limits on axion couplings:
|
g
A
γ
(
g
AN
0
+
g
AN
3
)
≤
1.44
×
10
-
14
GeV
-
1
and
|
g
Ae
(
g
AN
0
+
g
AN
3
)
≤
2.81
×
10
-
16
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Axions with an energy of 8.4 keV emitted in the
М
1 transition in
169
Tm nuclei in the Sun are sought in the
→
169
Tm* →
(8.4 keV) reaction of resonant absorption by
169
Tm nuclei on the Earth using ...a
thulium garnet crystal as a bolometric detector. The flux of monochromatic 8.4‑keV axions has been calculated. New constraints on the axion–nucleon coupling constants have been obtained and, as a result, new upper bounds on the axion mass
eV and
eV have been obtained at 90% C.L. in the KSVZ and DFSZ models, respectively.
The composition, structure and mechanical properties of Ti–Al–Ta–N coatings obtained by high-power impulse magnetron sputtering and direct current magnetron sputtering have been studied using ...energy-dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, and nanoindentation. It has been established that for high-power impulse sputtering, the current and power of the magnetron discharge increase exponentially during the pulse and reach peak values that are an order of magnitude higher than similar characteristics for magnetron sputtering at direct current. A high level of ionization of the sputtered particles caused a significant increase in the number of ions in the particle flux deposited on the substrate. The suppression of the growth of columnar grains and the formation of a denser and more homogeneous microstructure were ensured by an increase in the intensity of ion bombardment of the growing coating. This made it possible to improve its mechanical characteristics.
Precise measurement of beta spectra was always of great importance in some fundamental problems, including those of neutrino physics. The results obtained by measuring the spectrum of a
Ce–
Pr source ...with setups of two types to a precision substantially improved in relation to earlier investigations are presented. The correctness of a theoretical fit is tested using the shape of the
Pr (0
)
Nd (1
) allowed beta transition.
Operation of a model of a compact neutron source that can be used to calibrate dark-matter and electron-antineutrino detectors and to determine their response functions is demonstrated. The ...calibration neutron source in question is a combination of the
Cf radionuclide, which undergoes spontaneous fission, producing neutrons, and an original silicon semiconductor detector. The latter provides a time reference for the neutron-emission instant by recording signals from fission fragments.
The 169Tm nuclide has first nuclear level at 8.41 keV with magnetic type transition to the ground state and, therefore, can be used as a target nucleus for the search of resonant absorption of solar ...axions. We plan to use a Tm-containing crystal of a garnet family Tm3Al5O12 as a bolometric detector in order to search for the resonant absorption of solar axions. With this perspective in mind, a sample of the Tm3Al5O12 crystal was grown and tested for its bolometric and optical properties. Measurements of chemical and radioactive contaminations were performed as well. In this paper we present the test results and estimate the requirements for a future low-background experimental setup.
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