We present a covariant wave-packet approach to neutrino flavor transitions in vacuum. The approach is based on the technique of macroscopic Feynman diagrams describing the lepton number violating ...processes of production and absorption of virtual massive neutrinos at the macroscopically separated spacetime regions ('source' and 'detector'). Accordingly, the flavor transitions are a result of interference of the diagrams with neutrinos of different masses in the intermediate states. The statistically averaged probability of the process is representable as a multidimensional integral of the product of the factors which describe the differential flux density of massless neutrinos from the source, differential cross section of the neutrino interaction with the detector and a dimensionless factor responsible for the flavor transition. The conditions are analyzed under which the last factor can be treated as the flavor transition probability in the usual quantum mechanical sense.
The concept of coherence in the scattering of neutrinos and antineutrinos off nuclei is discussed. Motivated by the results of the COHERENT experiment, a new approach to coherence in these processes ...is proposed, which allows a unified description of the elastic (coherent) and inelastic (incoherent) contributions to the total cross section for neutrino and antineutrino scattering off nuclei at energies below 100 MeV. Experiments and physical problems for coherent scattering of (anti)neutrinos off nuclei are briefly discussed. The extended appendix covers the main points and conclusions of the proposed approach in pedagogical detail.
Neutrino-nucleus
and antineutrino-nucleus
interactions, when the nucleus conserves its integrity, are discussed with coherent (elastic) and incoherent (inelastic) scattering regimes taken into ...account. In the first regime the nucleus remains in the same quantum state after the scattering and the cross-section depends on the quadratic number of nucleons. In the second regime the nucleus changes its quantum state and the cross-section has an essentially linear dependence on the number of nucleons. The coherent and incoherent cross-sections are driven by a nuclear nucleon form-factor squared
term and a
term, respectively. One has a smooth transition between the regimes of coherent and incoherent (anti)neutrino-nucleus scattering. Due to the neutral current nature these elastic and inelastic processes are indistinguishable if the nucleus recoil energy is only observed. One way to separate the coherent signal from the incoherent one is to register
quanta from deexcitation of the nucleus excited during the incoherent scattering. Another way is to use a very low-energy threshold detector and collect data at very low recoil energies, where the incoherent scattering is vanishingly small. In particular, for
and neutrino energies of 30–50 MeV the incoherent cross-section is about 15–20% of the coherent one. Therefore, the COHERENT experiment (with
) has measured the coherent elastic neutrino nucleus scattering (CE
NS) with the inelastic admixture at a level of 15–20%, if the excitation
quantum escapes its detection.
In present article gold cementation features from cyanide solutions using dendritic zinc powders are studied. The powders were obtained by electroextraction from alkaline solutions. Powders with ...different physical properties were obtained by means of change in current density (from 0.5 to 2 A/m2) and NaOH concentration in solution (from 100 to 400 g/dm3) at the constant zinc concentration (10 g/dm3). The physical properties of mentioned powders were studied using SEM (Jeol JSM-6390LA), BET (Gemini VII 2390) and laser diffraction (Sympatec HELOS & RODOS). It is shown that electrolytic powders have high specific surface area, which is 1.8–2.6 times larger than the surface area of the zinc powder currently used for cementation. At that electrolytic powders particle size is 8-22 times larger than the particle size of powder currently used for cementation. The reason of high specific surface area is the electrolytic zinc powders dendritic structure. It was found that the obtained powders precipitate gold from cyanide solutions with a greater efficiency in a wide range of productivity. Laboratory unit simulating Merrill-Crow technology was used for cementation. Immediately ahead conducting the experiments, Na2SO3 was added to the solution in excess to remove dissolved oxygen. Zinc powders were plated by dendritic lead before loading into the laboratory setup by cementation. Lead was added as acetate (Pb (CH3COO)2). The consumption of lead acetate was 10% by weight of zinc. Correlation between the powders physical properties and the gold extraction is shown.
The discovery of coherent neutrino–nucleus scattering in the COHERENT experiment opened a source of new information for fundamental investigations in the realms of neutrino and nuclear physics, as ...well as in the realms of searches for new physics beyond the Standard Model. Owing to substantial momentum transfers, a feature peculiar to the kinematical region of this experiment is that the effect of coherence is mixed with a sizable incoherent contribution rather than being seen in a pure form. On one hand, this leads to additional systematic uncertainties in studying the neutrino component of the coherence effect as such. On the other hand, this makes it possible to study a dynamical transition between the coherent and incoherent scattering modes and, in principle, to separate them experimentally. In our opinion, a consistent measurement of the coherent and incoherent cross sections for (anti)neutrino scattering on a nucleus in the same experiment seems a unique possibility, and its implementation would of course provide new data for neutrino physics, as well as for nuclear and new physics. In the present study, it is shown that this possibility is implementable not only in experiments that explore coherent neutrino and antineutrino scattering on various nuclei at accelerators, where the neutrino energy reaches several hundred MeV units but also in reactor experiments, where antineutrino energies do not exceed 10 MeV. The respective estimation is based on the approach that controls qualitatively a ‘‘smooth transition’’ of the cross section for (anti)neutrino–nucleus scattering from a coherent (or elastic) to an incoherent (inelastic) mode. In the former case, the target nucleus remains in the initial quantum state, while, in the latter case, its quantum state changes. Observation of a specific number of photons that have rather high energies and which remove the excitation of the nucleus after its inelastic interaction with (anti)neutrinos is proposed to be used as a signal from such an inelastic process. An upper limit on the number of such photons is obtained in this study.
Abstract
This paper proposes an approach to formalizing the process of constructing segments of software system users by relational interactive logic. The segment description is specified as a system ...of logical equations and inequalities. The role of variables in such a system is played by relational terms, each of which represents some qualitative or quantitative characteristic of the user. To automatize this approach, a software solution architecture diagram is proposed, which provides the construction and interpretation of a system of logical equations.
Error reasons of gold analytical determination in the chemical plant sludge are studied. The studied sludge is waste of BaCl2 production. According to preliminary estimates it contains gold in ...sufficient quantity for industrial extraction. Comparison of direct sludge fire assay analysis and sludge dissolution in aqua regia, followed by gold atomic absorption determination in solution is made. The negative effect of Na+, Ca2+, Ba2+, Zn2+ ions presence in studied solutions was shown. Error quantitative estimate at alkali metals introducing into standard solutions is given. It is shown that Ca2+ and Ba2+ ions contribute the most error. Error increases linearly at addition of Ca2+ and Ba2+ ions. Growth error gradually slow down at increasing Na+, Zn2+ ion content.
ABSTRACT
Baikal-GVD has recently published its first measurement of the diffuse astrophysical neutrino flux, performed using high-energy cascade-like events. We further explore the Baikal-GVD cascade ...data set collected in 2018–2022, with the aim to identify possible associations between the Baikal-GVD neutrinos and known astrophysical sources. We leverage the relatively high angular resolution of the Baikal-GVD neutrino telescope (2–3 deg.), made possible by the use of liquid water as the detection medium, enabling the study of astrophysical point sources even with cascade events. We estimate the telescope’s sensitivity in the cascade channel for high-energy astrophysical sources and refine our analysis prescriptions using Monte-Carlo simulations. We primarily focus on cascades with energies exceeding 100 TeV, which we employ to search for correlation with radio-bright blazars. Although the currently limited neutrino sample size provides no statistically significant effects, our analysis suggests a number of possible associations with both extragalactic and Galactic sources. Specifically, we present an analysis of an observed triplet of neutrino candidate events in the Galactic plane, focusing on its potential connection with certain Galactic sources, and discuss the coincidence of cascades with several bright and flaring blazars.
Platinoan vysotskite metacrystals with inverse zoning are described. Their size is up to 0.5 mm. Association of these metacrystals are characterized by a “paracrystalline microboudinage” ...texture—specifically, corroded vysotskite fragments of the first (Pd
0.51
Pt
0.27
Ni
0.20
Fe
0.02
)S and second (Pd
0.49
Pt
0.30
Ni
0.18
Fe
0.03
)S generations, square vysotskite microcrystals of the third generation (Pd
0.47
Pt
0.32
Ni
0.19
Fe
0.02
)S overgrown with fourth-generation vysotskite (Pd
0.45
Pt
0.33
Ni
0.19–0.21
Fe
0.01
)S; these generations are overgrown with fifth-generation vysotskite (Pd
0.45
Pt
0.35
Ni
0.18
Fe
0.02
)S with rims of sixth-generation vysotskite (Pd
0.43
Pt
0.37–0.38
Ni
0.16–0.17
Fe
0.02
)S and the highest-Pt vysotskite of the seventh generation (Pd
0.44
Pt
0.43
Ni
0.09
Fe
0.02
Ru
0.01
)S. Platinoan vysotskite metacrystals are surrounded by halo of small skeletal microcrystals cooperite (Pt
0.96–0.97
Ni
0–0.03
Ru
0.01
)S. Platinoan vysotskite and cooperite develop in low-grade metamorphosed Co–Ni–Cu sulfide ores of the Oktyabrskoe deposit within the Noril
’
sk ore field, where these minerals replaced ferrous chlorite and corrensite, hydrogrossular, chalcopyrite, pentlandite, cubanite, and fassaite.
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