arXiv subjects

Andrey Alexandrov

Publications and source records attributed to Andrey Alexandrov.

14 recordsLinked to original sources

arXiv2026

Measurement of 80-200 MeV/n $^{16}$O nuclear cross-section on Carbon and Polyethylene targets with the nuclear emulsion detector of the FOOT experiment

Accurate knowledge of nuclear fragmentation cross-sections is essential for optimizing charged particle therapy. In this study, conducted within the framework of the FOOT (FragmentatiOn Of Target) experiment, we present the first measurements with a large angular acceptance of total charge-changing cross-section and the cross-section for the production of fragments (production cross-section) for $^{16}$O ions interacting with Carbon (C) and Polyethylene (C$_2$H$_4$) targets in the kinetic energy range of 80 to 200 MeV/nucleon. Measurements were performed using the Emulsion Cloud Chamber (ECC) technique, which combines high spatial resolution and angular acceptance, up to 45$^\circ$. The results are compared with Monte Carlo model predictions. Moreover, the total charge-changing and fragment production cross-sections for $^{16}$O on Hydrogen in the same energy range are derived.

nucl-ex↗

arXiv2025

Model-Independent Machine Learning Approach for Nanometric Axial Localization and Tracking

Accurately tracking particles and determining their coordinate along the optical axis is a major challenge in optical microscopy, especially when extremely high precision is needed. In this study, we introduce a deep learning approach using convolutional neural networks (CNNs) that can determine axial coordinates from dual-focal-plane images without relying on predefined models. Our method achieves an axial localization precision of 40 nanometers-six times better than traditional single-focal-plane techniques. The model's simple design and strong performance make it suitable for a wide range of uses, including dark matter detection, proton therapy for cancer, and radiation protection in space. It also shows promise in fields like biological imaging, materials science, and environmental monitoring. This work highlights how machine learning can turn complex image data into reliable, precise information, offering a flexible and powerful tool for many scientific applications.

eess.IV↗

arXiv2024

First direction sensitive search for dark matter with a nuclear emulsion detector at a surface site

Fine-grained nuclear emulsion films have been developed as a tracking detector with nanometric spatial resolution to be used in direction-sensitive dark matter searches, thanks to novel readout technologies capable of exploiting this unprecedented resolution. Emulsion detectors are time insensitive. Therefore, a directional dark matter search with such detector requires the use of an equatorial telescope to absorb the Earth rotation effect. We have conducted for the first time a directional dark matter search in an unshielded location, at the sea level, by keeping an emulsion detector exposed for 39 days on an equatorial telescope mount. The observed angular distribution of the data collected during an exposure equivalent to 0.59 g days agrees with the background model and an exclusion plot was then derived in the dark matter mass and cross-section plane: cross-sections higher than $1.3 \times 10^{-28}$ cm$^{2}$ and $1.7 \times 10^{-31}$ cm$^2$ were excluded for a dark matter mass of $10$ GeV$/c^2$ and $100$ GeV$/c^2$, respectively. This is the first direction sensitive search for dark matter with a solid-state, particle tracking detector.

astro-ph.CO↗

arXiv2023

Super-resolution imaging for the detection of low-energy ion tracks in fine-grained nuclear emulsions

We propose a new wide-field imaging method that exploits the Localized Surface Plasmon Resonance phenomenon to produce super-resolution images with an optical microscope equipped with a custom design polarization analyzer module. In this paper we describe the method and apply it to the analysis of low-energy carbon ion tracks implanted in a nuclear emulsion film. The result is then compared with the measurements of the same tracks carried out at an electronic microscope. The images set side by side show their close similarity. The resolution achieved with the current microscope setup is estimated to be about 50 nm.

astro-ph.IM↗

arXiv2022

Deep Learning for direct Dark Matter search with nuclear emulsions

We propose a new method for the discrimination of sub-micron nuclear recoil tracks from an instrumental background in fine-grain nuclear emulsions used in the directional dark matter search. The proposed method uses a 3D Convolutional Neural Network, whose parameters are optimised by Bayesian search. Unlike previous studies focused on extracting the directional information, we focus on the signal/background separation exploiting the polarisation dependence of the Localised Surface Plasmon Resonance phenomenon. Comparing the proposed method with the conventional cut-based approach shows a significant boost in the reduction factor for given signal efficiency.

hep-ex↗

arXiv2020

The FragmentatiOn Of Target Experiment (FOOT) and its DAQ system

The FragmentatiOn Of Target (FOOT) experiment aims to provide precise nuclear cross-section measurements for two different fields: hadrontherapy and radio-protection in space. The main reason is the important role the nuclear fragmentation process plays in both fields, where the health risks caused by radiation are very similar and mainly attributable to the fragmentation process. The FOOT experiment has been developed in such a way that the experimental setup is easily movable and fits the space limitations of the experimental and treatment rooms available in hadrontherapy treatment centers, where most of the data takings are carried out. The Trigger and Data Acquisition system needs to follow the same criteria and it should work in different laboratories and in different conditions. It has been designed to acquire the largest sample size with high accuracy in a controlled and online-monitored environment. The data collected are processed in real-time for quality assessment and are available to the DAQ crew and detector experts during data taking.

physics.ins-det↗

arXiv2019

Natural superheavy nuclei in astrophysical data

The paper presents the summary data of the authors' research within the framework of the OLIMPIYA project (the Russian acronym of {\bf OLI}viny iz {\bf M}eteoritov --- {\bf P}oisk tyazholykh {\bf I} sverkhtyazholykh {\bf YA}der / Olivines from meteorites: Search for heavy and superheavy nuclei) and results of track analysis for heavy cosmic ray nuclei (\emph{Z} = 26--129) in olivine crystals from meteorites using an original processing technique. A total of 21,743 tracks of nuclei heavier than iron have been identified in meteoritic matter to date to form the largest database within this charge range. The database includes three tracks of superheavy nuclei with the lifetimes of about a few decades, which can be considered as direct experimental evidence for the existence of natural superheavy nuclei from the "island of stability". Comprehensive comparative analysis of data from two meteorites with different cosmic ray exposure ages, Marjalahti (from 178 to 205 Myr) and Eagle Station (from 35 to 71 Myr), is presented for the first time. The results are discussed within the existing concepts of nuclei formation in astrophysical processes.

nucl-ex↗

arXiv2018

Super resolution plasmonic imaging microscopy for submicron tracking emulsion detector

NIT is a super fine-grained nuclear emulsion which has a detection capability for ionizing particle with nanometric resolution and record the track by a line of silver nanograin with a various of shape and size. The particle tracks need to be read out by some microscopic techniques, here we focused on the optical response of silver nanograins to realize the readout method beyond the diffraction limit. In this paper, super-resolution plasmonic imaging microscopy (SPRIM), which utilized the polarization-dependent optical response due to Localized Surface Plasmon Resonance (LSPR) was developed. The spatial resolution of SPRIM to identify the nanograin position was achieved 5 nm. We showed that the SPRIM clearly discriminated the 100 keV carbon ions tracks with the mean range of 270 nm from single nanograins with the diameter of 60 nm.The recognition efficiency of 100 keV carbon track was 49 % and the angular resolution was 17 degree.

physics.ins-det↗

arXiv2014

Concept of Classical and Quantum Free Acoustic Field

The concept of classical and quantum free acoustic (FA) field is theoretically considered. The equations of the free acoustic field are derived. They coincide in the mathematical form with Maxwell equations for the free electromagnetic (EM) field. It is accentuated, that the equations in the mathematical form of Maxwell equations for the free EM-field are universal equations of the Nature. They describe any free complex-vector physical field, vector-functions of which are analytical functions. In the case of a free acoustic field, it seems to be the strong indication taking into account the quantum Fermi liquid model of EM-field leading to the existence of phonons, accompanying the process of a photon formation, that FA-field and free EM-field are the display of the single united field, both the components of which can propagate simultaneously [however, with different velocities], for instance, in weakly absorbing media. The theory proposed can be the theoretical basis for the practical realization of superconducting states at high temperature in the materials with the strong interaction of electrons with acoustic field phonons and with microwave photons in magnetic resonance conditions.

quant-ph↗

arXiv2013

Symmetry of Differential Equations and Quantum Theory

The symmetry study of main differential equations of mechanics and electrodynamics has shown, that differential equations, which are invariant under transformations of groups, which are symmetry groups of mathematical numbers (considered within the frames of the number theory) determine the mathematical nature of the quantities, incoming in given equations. It allowed to proof the main postulate of quantum mechanics, consisting in that, that to any mechanical quantity can be set up into the correspondence the Hermitian matrix by quantization. High symmetry of Maxwell equations allows to show, that to quantities, incoming in given equations can be set up into the correspondence the Quaternion (twice-Hermitian) matrix by their quantization. It is concluded, that the equations of the dynamics of mechanical systems are not invariant under transformations of quaternion multiplicative group and, consecuently, direct application of quaternions with usually used basis \{e, i, j, k \} to build the new version of quantum mechanics, which was undertaken in the number of modern publications, is incorrect. It is the consequence of non-abelian character of given group. At the same time we have found the correct ways for the creation of the new versions of quantum mechanics on the quaternion base by means of choice of new bases in quaternion ring, from which can be formed the bases for complex numbers under multiplicative groups of which the equations of the dynamics of mechanical systems are invariant.

math-ph↗

arXiv2013

Classical and Quantum Electrodynamics Concept Based on Maxwell Equations' Symmetry

The symmetry studies of Maxwell equations gave new insight on the nature of electromagnetic (EM) field. Tey are reviewed in the work presented. It is drawing the attention on the following aspects. EM-field has in general case quaternion structure, consisting of four independent field constituents, which differ from each other by the parities under space inversion and time reversal. There exists physical conserving quantity, which is simultaneously invariant under both Rainich dual and additional hyperbolic dual symmetry transformation of Maxwell equations. It is spin in general case or spirality in the corresponding geometry. Generalized Maxwell equations for quaternion four-component EM-field are obtained. Invariants for EM-field, consisting of dually symmetric parts are found. The main postulate of quantum mechanics: "To any mechanical quantity can be set up in the correspondence the Hermitian matrix by quantization" was proved. Canonical Dirac quantization method was developed in two aspects. The first aspect is its application the only to observable quantities. The second aspect is the realization along with well known time-local quantization of space-local quantization and space-time-local quantization. It is also shown, that Coulomb field can be quantized in 1D and 2D systems. The photons in quantized EM-field are main excitations in oscillator structure of EM-field, which is equivalent to spin S = 1 "boson-atomic" 1D lattice structure, consisting of the "atoms" with zeroth rest mass. The photons of the first kind and of the second kind represent themselves respectively neutral chargeless spin 1/2 EM-solitons and charged spinless EM-solitons of Su-Schrieffer-Heeger family.

math-ph↗

arXiv2013

Ferromagnetic Ordering in Carbon Nanotubes, Incorporated in Diamond Single Crystals

The physical origin of the mechanism of the formation of ferromagnetic ordering in carbon nanotubes (NTs), produced by high energy ion beam modification of diamond single crystals in $\langle{110}\rangle$ and $\langle{111}\rangle$ directions has been found. It is concluded from analysis of experimental results on ferromagnetic spin wave resonance observed, that the only $π$-electronic subsystem of given NTs is responsible for the appearance of ferromagnetism. It is determined by asymmetry in spin density distribution in Su-Schrieffer-Heeger (SSH) topological soliton lattice. The formation of SSH topological soliton lattice is considered in the frames of generalized SSH-model of organic conductors, in which $π$-electronic subsystem is represented being to be 1D quantum Fermi liquid. The phenomenon of formation of uncompensated antiferromagnetic ordering coexisting with superconductivity at room temperature in carbon nanotubes, produced by high energy ion beam modification of diamond single crystals in $\langle{100}\rangle$ direction is argued.

cond-mat.str-el↗

arXiv2013

Ferrimagnetic Spin Wave Resonance and Superconductivity in Carbon Nanotubes

The phenomenon of ferrimagnetic spin wave resonance [uncompensated antiferromagnetic spin wave resonance] has been detected for the first time. It has been observed in carbon nanotubes, produced by high energy ion beam modification of diamond single crystals in $\ <{100}\ >$ direction. Peculiarities of spin wave resonance observed allow to insist on the formation in given nanotubes of $s^+$ superconductivity at room temperature, coexisting with uncompensated antiferromagnetic ordering.

physics.gen-ph↗

arXiv2011

Classical and Quantum Electrodynamics Concept Based on Maxwell Equations' Symmetry

The symmetry studies of Maxwell equations gave new insight on the nature of electromagnetic (EM) field. It has in general case quaternion single structure, consisting of four independent field constituents, which differ with each other by the parities under space inversion and time reversal. Generalized Maxwell equations for quaternion four-component EM-field are obtained. Invariants for EM-field, consisting of dually symmetric parts are found. It is shown, that there exists physical conserving quantity, which is simultaneously invariant under both Rainich dual and additional hyperbolic dual symmetry transformation of Maxwell equations. It is spin in general case and spirality in the geometry, when electrical and magnetic vectors $\vec{E}$, $\vec{H}$ are directed along coordinate axes in ($\vec{E}$, $\vec{H}$) functional space. It is additional proof for quaternion four component structure of EM-field to be a single whole. Canonical Dirac quantization method is developed in two aspects. The first aspect is its application the only to observable quantities. The second aspect is the realization along with well known time-local quantization of space-local quantization and space-time-local quantization. It is also shown, that Coulomb field can be quantized in 1D and 2D systems. New model of photons is proposed. The photons in quantized EM-field are main excitations in oscillator structure of EM-field, which is equivalent to spin S = 1 "boson-atomic" structure, like matematically to well known spin S = 1 boson matter structure - carbon atomic backbone chain structure in many conjugated polymers. They have two kind nature. The photons of the first kind and the second kind represent themselves respectively neutral chargeless EM-solitons and charged spinless EM-solitons of Su-Schrieffer-Heeger family.

quant-ph↗