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.
4π spectrometer of β-decay electrons with Si(Li)-detectors Alekseev, I.E.; Bakhlanov, S.V.; Bazlov, N.V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
June 2023, Letnik:
1051
Journal Article
Recenzirano
We present a description of the originally developed β-spectrometer consisting of two Si(Li)-detectors with sensitive area thickness above 8 mm and 4π-geometry. The full absorption spectrometer ...allows for direct measurements of β-spectra, disregarding the corrections to response function induced by the electron backscattering from the crystal surface. In case of β-spectra of transitions to the excited state of the daughter isotope additional 3″ BGO-detector is used in order to detect the γ-quanta in coincidence with the pair of Si(Li)-spectrometers.
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.
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.
Resonance excitation of the
83
Kr first nuclear level (
E
= 9.4 keV) by solar axions formed via the Primakoff mechanism is sought. The γ- and X-ray photons and the conversion and Auger electrons ...arising from the excited-level relaxation are detected with a gas proportional counter of a low-background detector in the underground Baksan Neutrino Observatory. The following experimental constraint is obtained for the product of the axion–photon coupling constant and the axion mass:|
g
A
γ
×
m
A
| ≤ 6.3 × 10
-17
In the framework of the hadronic-axion model, this corresponds to a new axion-mass constraint of
m
A
≤ 12.7 eV at 95% C.L.
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.
Abstract
The work is devoted to the study of the porous structure formation of anodic alumina films at the initial stage of aluminium anodizing. SEM images of the surface morphology of the oxalic ...acid anodic films were analyzed. It was shown that at the initial stage, both major and minor pores are formed, the diameter ratio of which is about 1.16 and does not depend on the anodizing voltage. The results obtained indicate that the minor pores in the anodic films are located inside hexagonal cells composed of the major pores.
Abstract
Deterioration of the operation parameters of p-type Si surface-barrier detector and Si(Li) p-i-n detector upon irradiation by alpha-particles was investigated. The detectors were irradiated ...at room temperature up to a total number of the registered α-particles
N
α
equal to 6 × 10
9
. Prolonged irradiation has resulted in a deterioration of the detectors energy resolution ability and it was found that the increase of α-peaks broadening can be described by a linear function of
N
α
with a slope Δσ/Δ
N
α
∼ (1.4–1.8) × 10
–9
keV/α for both detectors. Resolution deterioration was associated with the increase of the detectors leakage current, which proceeds linearly with the number of absorbed α-particles with the slope ΔI/Δ
Nα
∼ (7-17) × 10
-17
A/α. The increase of the detectors reverse current was related with appearance of radiation-induced defect level at 0.56 eV above the valence band.
A single-stage centrifugation method is used for the precipitation and crystallization of a solution of a hybrid halide perovskite compound of the CH
3
NH
3
PbI
3
composition. The perovskite films ...are annealed in the temperature range of 80–140°C, during which the excess of the
N
-methylpyrrolidone solvent was removed by evaporation. The X-ray phase analysis of the synthesized perovskite layer is carried out. The morphology of the surface of the layers after crystallization and the transmission spectra in the optical range are studied. The experiments and research results showed that the optimal temperature regime for the formation and crystallization of lead triiodide methylammonium perovskite films is 100–110°C. The perovskite layers obtained in these processing regimes have a surface morphology with a uniform granular crystal structure and are highly uniform. Moreover, in solar cells based on perovskite-like CH
3
NH
3
PbI
3
structures with an annealing temperature of 100–110°C, the short-circuit currents reached 16.0 mA/cm
2
. At the same time, at annealing temperatures of perovskite layers above 120°С, the maximum value of the short-circuit currents did not exceed 14.0 mA/cm
2
.
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
.
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