On the statistics of ~1.7 × 10
8
interactions of positively charged kaons on copper nuclei, coherent events of the
K
+
π
0
system production are selected. The cross sections for the Coulomb and ...coherent strong components and their interference in the region of the
K
*(892) meson are measured. The partial width for the decay
K
*(892) →
K
+
γ is determined. When studying the mass spectrum of the
K
+
π
0
system, an effect which can be interpreted as the interference of the chiral anomaly and the
K
*(892)
s
-channel amplitudes is found. This gives an estimate for the ratio of the observed amplitude of the chiral anomaly to the theoretical one:
A
exp
/
A
th
= 0.9 ± 0.24(stat.) ± 0.3(syst.).
Search for heavy neutrino in K+→μ+νH decay Sadovsky, A. S.; Kurshetsov, V. F.; Filin, A. P. ...
The European physical journal. C, Particles and fields,
02/2018, Letnik:
78, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A high statistics data sample of the
K
+
→
μ
+
ν
μ
decay was accumulated by the OKA experiment in 2012. The missing mass analysis was performed to search for the decay channel
K
+
→
μ
+
ν
H
with a ...hypothetic stable heavy neutrino in the final state. The obtained missing mass spectrum does not show peaks that could be attributed to existence of stable heavy neutrinos in the mass range
(
270
<
m
ν
H
<
375
)
MeV
/
c
2
. As a result, upper limits on the branching ratio and on the value of the mixing element
|
U
μ
H
|
2
are obtained.
Abstract A high statistics data sample of the $$K^{+}\rightarrow \mu ^{+}\nu _{\mu }$$ K+→μ+νμ decay was accumulated by the OKA experiment in 2012. The missing mass analysis was performed to search ...for the decay channel $$K^{+}\rightarrow \mu ^{+}\nu _{H}$$ K+→μ+νH with a hypothetic stable heavy neutrino in the final state. The obtained missing mass spectrum does not show peaks that could be attributed to existence of stable heavy neutrinos in the mass range $$(270< m_{\nu _{H}} < 375)$$ (270<mνH<375) MeV$$/c^{2}$$ /c2 . As a result, upper limits on the branching ratio and on the value of the mixing element $$|U_{\mu H}|^{2}$$ |UμH|2 are obtained.
Thermal analysis of aerosol size distributions provided size resolved volatility up to temperatures of 400°C during extensive flights over North America (NA) for the INTEX/ICARTT experiment in summer ...2004. Biomass burning and pollution plumes identified from trace gas measurements were evaluated for their aerosol physiochemical and optical signatures. Measurements of soluble ionic mass and refractory black carbon (BC) mass, inferred from light absorption, were combined with volatility to identify organic carbon at 400°C (VolatileOC) and the residual or refractory organic carbon, RefractoryOC. This approach characterized distinct constituent mass fractions present in biomass burning and pollution plumes every 5–10 min. Biomass burning, pollution and dust aerosol could be stratified by their combined spectral scattering and absorption properties. The “nonplume” regional aerosol exhibited properties dominated by pollution characteristics near the surface and biomass burning aloft. VolatileOC included most water‐soluble organic carbon. RefractoryOC dominated enhanced shortwave absorption in plumes from Alaskan and Canadian forest fires. The mass absorption efficiency of this RefractoryOC was about 0.63 m2 g−1 at 470 nm and 0.09 m2 g−1 at 530 nm. Concurrent measurements of the humidity dependence of scattering, γ, revealed the OC component to be only weakly hygroscopic resulting in a general decrease in γ with increasing OC mass fractions. Under ambient humidity conditions, the systematic relations between physiochemical properties and γ lead to a well‐constrained dependency on the absorption per unit dry mass for these plume types that may be used to challenge remotely sensed and modeled optical properties.
Abstract Despite the significance of H 2 O 2 -metal adducts in catalysis, materials science and biotechnology, the nature of the interactions between H 2 O 2 and metal cations remains elusive and ...debatable. This is primarily due to the extremely weak coordinating ability of H 2 O 2 , which poses challenges in characterizing and understanding the specific nature of these interactions. Herein, we present an approach to obtain H 2 O 2 –metal complexes that employs neat H 2 O 2 as both solvent and ligand. SnCl 4 effectively binds H 2 O 2 , forming a SnCl 4 (H 2 O 2 ) 2 complex, as confirmed by 119 Sn and 17 O NMR spectroscopy. Crystalline adducts, SnCl 4 (H 2 O 2 ) 2 ·H 2 O 2 ·18-crown-6 and 2SnCl 4 (H 2 O 2 )(H 2 O)·18-crown-6, are isolated and characterized by X-ray diffraction, providing the complete characterization of the hydrogen bonding of H 2 O 2 ligands including geometric parameters and energy values. DFT analysis reveals the synergy between a coordinative bond of H 2 O 2 with metal cation and its hydrogen bonding with a second coordination sphere. This synergism of primary and secondary interactions might be a key to understanding H 2 O 2 reactivity in biological systems.
Chromium trifluoride-doped fluoride glasses in the ZrF
4
–BaF
2
–LaF
3
–AlF
3
–NaF (ZBLAN) system with partial substitution of fluorine for chlorine have been synthesized. The spectral data obtained ...confirm that chromium ions enter the glass structure and exhibit broadband luminescence caused by the
4
T
2
→
4
A
2
transition in the Cr
3+
ion. The observed long-wavelength shift of the broadband luminescence band and Cr
3+
absorption bands in fluoride–chloride glass compared to fluoride glass corresponds to the expected behavior of the Cr
3+
luminescence and absorption spectra when fluoride ions are replaced by chloride ions, which should lead to a weakening of the strength of the crystal field acting on Cr
3+
ions. At room temperature, the luminescence of Cr
3+
ions at 888 and 908 nm is strongly quenched due to the thermally stimulated nonradiative transition from the
4
T
2
excited state to the
4
A
2
ground state.
Preparation of Extrapure Cesium Iodide Mastryukov, M. V.; Brekhovskikh, M. N.; Klimova, V. M. ...
Inorganic materials,
10/2020, Letnik:
56, Številka:
10
Journal Article
Recenzirano
This paper presents results of a physicochemical study of the preparation of extrapure-grade (99.998%-pure) cesium iodide from a technically pure product obtained by reacting cesium carbonate and ...hydriodic acid. The synthesized CsI was purified in two steps, involving vacuum drying and high-temperature distillation. We calculated kinetic constants of vacuum drying and evaluated water content as a function of temperature. The final step in removing regulated impurities from CsI was high-temperature distillation. Metallic impurities in the samples thus prepared were determined using inductively coupled plasma mass spectrometry and X-ray diffraction. The results are presented for the first time.
The spectral and kinetic properties of luminescence of fluorozirconate glasses 57ZrF
4
⋅33BaF
2
⋅ 6CeF
3
⋅4AlF
3
doped with 2–4 mol % of manganese ions have been studied. It has been demonstrated ...that increasing the doping ion concentration from 2 to 4 mol % is accompanied by the red shift of the
4
T
1
(
G
) →
6
A
1
band of Mn
2+
luminescence from 570 to 580 nm. The red shift is associated with an increase (with increasing concentration) in the number of Mn
2+
–Mn
2+
pairs, which give a longer wavelength luminescence than individual Mn
2+
ions. Analysis of the Mn
2+
luminescence kinetics showed no appreciable concentration quenching of Mn
2+
luminescence at doping concentrations up to 4 mol %. It has been shown that these glasses exhibiting broadband luminescence in the orange region of the spectrum have potential for practical application in white LEDs.
PDF
