arXiv subjects

R. Nagy

Publications and source records attributed to R. Nagy.

13 recordsLinked to original sources

arXiv2026

$K^{*}(892)^0$ production and the time between freeze-outs in $^{40}$Ar+$^{45}$Sc collisions by NA61/SHINE at the CERN SPS

The analysis of the production of strange $K^{*}(892)^0$ resonances allows us to better understand the temporal evolution of high-energy nucleus--nucleus collisions. In particular, the ratio of $K^{*}(892)^0$ to charged kaon yields is used to determine the time interval between chemical and kinetic freeze-outs. In this paper, the first measurements of $K^{*}(892)^0$ production in central $^{40}$Ar+$^{45}$Sc collisions at the CERN Super Proton Synchrotron are reported. They were performed by NA61/SHINE at collision center-of-mass energies per nucleon pair $\sqrt{s_\mathrm{NN}}$ = 8.8, 11.9, 16.8 GeV. The obtained $\langle K^{*}(892)^0 \rangle/\langle K^{+} \rangle $ and $\langle K^{*}(892)^0 \rangle/\langle K^{-} \rangle$ mean multiplicity ratios are compared with corresponding results in $p$+$p$ collisions, allowing for an estimate of the time interval between chemical and thermal freeze-outs in the $^{40}$Ar+$^{45}$Sc system. These are the first such results reported for $^{40}$Ar+$^{45}$Sc collisions.

nucl-ex↗

arXiv2025

A Compact Incubation Platform for Long-Term Cultivation of Biological Samples for Nitrogen-Vacancy Center Widefield Microscopy

Nitrogen-vacancy (NV) centers in diamond provide a versatile quantum sensing platform for biological imaging through magnetic field detection, offering unlimited photostability and the ability to perform long-term observations without photobleaching or phototoxicity. However, conventional stage-top incubators are incompatible with the unique requirements for NV widefield magnetometry to study cellular dynamics. Here, we present a purpose-built compact incubation platform that maintains precise environmental control of temperature, CO$_2$ atmosphere, and humidity while accommodating the complex constraints of NV widefield microscopy. The system employs a 3D-printed biocompatible chamber with integrated heating elements, temperature control, and humidified gas flow to create a stable physiological environment directly on the diamond sensing surface. We demonstrate sustained viability and proliferation of HT29 colorectal cancer cells over 90 hours of continuous incubation, with successful magnetic field imaging of immunomagnetically labeled cells after extended cultivation periods. This incubation platform enables long-term cultivation and real-time monitoring of biological samples on NV widefield magnetometry platforms, opening new possibilities for studying dynamic cellular processes using quantum sensing technologies.

physics.bio-ph↗

arXiv2025

Proposal from the NA61/SHINE Collaboration for update of European Strategy for Particle Physics

Building on the current program's success and driven by new physics challenges, the NA61/SHINE Collaboration proposes to continue measuring hadron production properties in reactions induced by hadron and ion beams after CERN Long Shutdown 3. These measurements are of significant interest to the heavy-ion, cosmic-ray, and neutrino physics communities and will focus on: - Investigating hadron production in the light-ion systems to explore the diagram of high-energy nuclear collisions, and to obtain new insight into the unexpected violation of isospin (flavor) symmetry recently observed by the experiment; - Measuring charm-anticharm correlations to gain unique insights into the production locality of charm and anticharm quark pairs; - Examining strangeness and multi-strangeness production to improve our understanding of the early Universe's evolution and neutron star formation; - Measuring cross sections relevant for cosmic-ray measurements, significantly boosting searches for new physics in our Galaxy; - Conducting hadron production measurements with proton, pion, and kaon beams for neutrino physics, enhancing the precision of hadron production data needed for initial neutrino flux predictions in neutrino oscillation experiments; - Measuring hadron production processes relevant for understanding the flux of atmospheric neutrinos, as well as neutrinos and muons from spallation sources. To achieve these objectives, a detector upgrade and a beam upgrade are required, with data-taking planned for the period 2029-2032 and beyond.

nucl-ex↗

arXiv2025

Optimizing SPION Labeling for Single-Cell Magnetic Microscopy

This study explores the correlation between iron mass on cell surfaces and the resultant magnetic field. Human colorectal cancer cells (HT29 line) were labeled with varying concentrations of SPIONs and imaged via a NV center widefield magnetic microscope. To assess the labeling efficacy, a convolutional neural network trained on simulated magnetic dipole data was utilized to reconstruct key labeling parameters on a cell-by-cell basis, including cell diameter, sensor proximity, and the iron mass associated with surface-bound SPIONs. Our analysis provided quantitative metrics for these parameters across a range of labeling concentrations. The findings indicated that increasing SPION concentration enhances both the cell-surface iron mass and magnetic field strength, demonstrating a saturation effect. This methodology offers a coherent framework for the quantitative, high-throughput characterization of magnetically labeled cells, presenting significant implications for the fields of cell biology and magnetic sensing applications.

physics.bio-ph↗

arXiv2025

Comparing radial migration in dark matter and MOND regimes

Multiple studies on radial migration in disc galaxies have proven the importance of the effect of resonances with non-axisymmetric components on the evolution of galactic discs. However, the dynamical effects of classic Newtonian dynamics with dark matter (DM) differ from MOdified Newtonian Dynamics (MOND) and might trigger different radial migration. A thorough analysis of radial migration considering these two gravitational regimes might shed some light on different predictions of DM and MOND theories. We aim to quantitatively and qualitatively compare the effects of resonances and stellar radial migration (churning) in a Milky Way-like (MW-like) galaxy in the DM and MOND regimes. We performed simulations of a MW-like galaxy to analyse the effect of non-axisymmetric structures (galactic bar and spiral arms) considering various parameters of the spiral structure. We conducted a two-dimensional numerical simulation consisting of the integration of $2 \cdot 10^6$ stars in a static rotating galactic potential for $6~\mbox{Gyr}$. We analysed the change in the star's position, the guiding radius, as well as the frequency phase space. We investigated DM and MOND approaches. The outcome of the simulation shows that the radial migration is much more pronounced in the MOND regime compared to the DM one. Compared to the DM approach, in the MOND regime, we observe up to five times as many stars with a maximum change in the guiding radius of more than $1.5~\mbox{kpc}$ during the time interval from $2-6~\mbox{Gyr}$.Analysis of the frequency phase space reveals that the most prominent resonances in all DM and MOND configurations are the co-rotation resonance with the spiral arms ($m=p=1$), outer Lindblad resonance with the galactic bar and spiral arms, and the co-rotation resonance ($m=2$, $p=1$) with the superposition of the galactic bar and spiral arms, $2 \Omega = \Omega_b + \Omega_{sp}$.

astro-ph.GA↗

arXiv2024

Quantum enhanced electric field mapping within semiconductor devices

Semiconductor components based on silicon carbide (SiC) are a key component for high-power electronics. Their behavior is determined by the interplay of charges and electric fields, which is typically described by modeling and simulations that are calibrated by nonlocal electric properties. So far, there are no experimental methods that allow for the 3D mapping of both the electric field and the concentrations of free charge carriers inside an electronic device. To fulfill this information gap, we propose an operando method that utilizes single silicon vacancy (VSi) centers in 4H-SiC. The VSi centers are at various positions in the intrinsic region of a pin-diode. To monitor the local static electric field, we perform Stark shift measurements based on photoluminescence excitation (PLE), which allows us to infer the expansion of the depletion zone and therefore to determine the local concentration of dopants. Besides this, we show that our measurements allow us to additionally obtain the local concentration of free charge carriers. The method presented here therefore paves the way for a new quantum-enhanced electronic device technology, capable of mapping the interplay of mobile charges and electric fields in a working semiconductor device with nanometer precision.

quant-ph↗

arXiv2024

Deep Learning-based Detection and Segmentation of Edge-on and Highly Inclined Galaxies

Edge-on galaxies have many important applications in galactic astrophysics, but they can be difficult to identify in vast amounts of astronomical data. To facilitate the search for them, we have developed a deep learning algorithm designed to identify and extract edge-on galaxies from astronomical images. We utilised a sample of edge-on spiral galaxies from the Galaxy Zoo database, retrieving the corresponding images from the Sloan Digital Sky Survey (SDSS). Our dataset comprises approximately $16,000$ galaxies, which we used to train the YOLOv5 algorithm for detection purposes. To isolate galaxies from their backgrounds, we trained the SCSS-Net neural network to generate segmentation masks. As a result, our algorithm detected $8,000$ edge-on galaxies, for which we compiled a catalogue including their parameters obtained from the SDSS database. We describe the basic properties of our sample, finding that most galaxies have redshifts $0.02<z<0.10$, have low values of $b/a$ and are mostly red, which is expected from edge-on galaxies and is consistent with our training sample, as well as other literature. The cutouts of the detected galaxies can be used for future studies and the algorithm can be applied to data from future surveys as well.

astro-ph.GA↗

arXiv2023

Quantum sensing of electric field distributions of liquid electrolytes with NV-centers in nanodiamonds

To use batteries as large-scale energy storage systems it is necessary to measure and understand their degradation \textit{in-situ} and \textit{in-operando}. As a battery's degradation is often the result of molecular processes inside the electrolyte, a sensing platform which allows to measure the ions with a high spatial resolution is needed. Primary candidates for such a platform are NV-centers in diamonds. We propose to use a single NV-center to deduce the electric field distribution generated by the ions inside the electrolyte through microwave pulse sequences. We show that the electric field can be reconstructed with great accuracy by using a protocol which includes different variations of the Free Induction Decay to obtain the mean electric field components and a modified Hahn-echo pulse sequence to measure the electric field's standard deviation $\sigma_E$. From a semi-analytical ansatz we find that for a lithium ion battery there is a direct relationship between $\sigma_E$ and the ionic concentration. Our results show that it is therefore possible to use NV-centers as sensors to measure both the electric field distribution and the local ionic concentration inside electrolytes.

quant-ph↗

arXiv2022

Warp and flare of the Galactic disc revealed with supergiants by Gaia EDR3

The outer Galactic disc contains some features such as the warp and flare, whose origin is still debated. The Gaia data provide an excellent opportunity to probe the Galactic disc at large distances and study these features. We derive the density distributions of the average (old) whole population and the supergiants (representative of a young population), and we use them to constrain their warp and flare. By comparing the results, we study how the properties of these phenomena depend on the studied population. We used Lucy's deconvolution method to recover corrected star counts as a function of distance, from which we derive the density distribution. We find that supergiants have an asymmetric warp, reaching a maximum amplitude of $z_w=0.658$ kpc and minimum amplitude of $z_w=-0.717$ kpc at a distance of $R=[19.5,20]$ kpc, which is almost twice as high as the amplitude of the whole population of the disc. We find a significant flare of the whole population, especially in the thick disc. The scale height increases from $h_{z,thick}\approx 0.8$ kpc and $h_{z,thin}\approx 0.3$ kpc in the solar neighbourhood, to $h_{z,thick} \approx 3$ kpc and $h_{z,thin}\approx 0.7$ kpc in the remote regions of the Milky Way ($R\approx 18$ kpc). The supergiants' population has only a small flare.

astro-ph.GA↗

arXiv2020

Gaia-DR2 extended kinematical maps. Part III: Rotation curves analysis, dark matter, and Modified Newtonian dynamics tests

Recent statistical deconvolution methods have produced extended kinematical maps in a range of heliocentric distances that are a factor of two to three larger than those analysed in the Gaia Collaboration based on the same data. In this paper, we use such maps to derive the rotation curve both in the Galactic plane and in off-plane regions and to analyse the density distribution. By assuming stationary equilibrium and axisymmetry, we used the Jeans equation to derive the rotation curve. Then we fit it with density models that include both dark matter and predictions of the MOND (Modified Newtonian dynamics) theory. Since the Milky Way exhibits deviations from axisymmetry and equilibrium, we also considered corrections to the Jeans equation. To compute such corrections, we ran N-body experiments of mock disk galaxies where the departure from equilibrium becomes larger as a function of the distance from the centre. The rotation curve in the outer disk of the Milky Way that is constructed with the Jeans equation exhibits very low dependence on $R$ and $z$ and it is well-fitted both by dark matter halo and MOND models. The application of the Jeans equation for deriving the rotation curve, in the case of the systems that deviate from equilibrium and axisymmetry, introduces systematic errors that grow as a function of the amplitude of the average radial velocity. In the case of the Milky Way, we can observe that the amplitude of the radial velocity reaches $\sim 10\%$ that of the azimuthal one at $R\approx 20$ kpc. Based on this condition, using the rotation curve obtained from the Jeans equation to calculate the mass may overestimate its measurement.

astro-ph.GA↗

arXiv2020

Structure of the outer Galactic disc with Gaia-DR2

AIMS. We calculate the stellar density using star counts obtained from Gaia DR2 up to a Galactocentric distance R=20 kpc with a deconvolution technique for the parallax errors. Then we analyse the density in order to study the structure of the outer Galactic disc, mainly the warp. METHODS. In order to carry out the deconvolution, we used the Lucy inversion technique for recovering the corrected star counts. We also used the Gaia luminosity function of stars with $M_G<10$ to extract the stellar density from the star counts. RESULTS. The stellar density maps can be fitted by an exponential disc in the radial direction $h_r=2.07\pm0.07$ kpc, with a weak dependence on the azimuth, extended up to 20 kpc without any cut-off. The flare and warp are clearly visible. The best fit of a symmetrical S-shaped warp gives $z_w= z_\odot+(37\pm 4.2(stat.)-0.91(syst.))$ pc $(R/R_\odot )^{2.42\pm 0.76(stat.) + 0.129 (syst.)} sin(\phi+9.3\pm 7.37 (stat.) +4.48 (syst.))$ for the whole population. When we analyse the northern and southern warps separately, we obtain an asymmetry of an $\sim25\%$ larger amplitude in the north. This result may be influenced by extinction because the Gaia G band is quite prone to extinction biases. However, we tested the accuracy of the extinction map we used, which shows that the extinction is determined very well in the outer disc. Nevertheless, we recall that we do not know the full extinction error, and neither do we know the systematic error of the map, which may influence the final result. The analysis was also carried out for very luminous stars alone ($M_G<-2$), which on average represents a younger population. We obtain similar scale-length values, while the maximum amplitude of the warp is $20-30\%$ larger than with the whole population. The north-south asymmetry is maintained.

astro-ph.GA↗

arXiv2020

Gaia-DR2 extended kinematical maps. Part II: Dynamics in the Galactic disk explaining radial and vertical velocities

Context: In our Paper I, by using statistical deconvolution methods, extended kinematics maps of Gaia-DR2 data have been produced in a range of heliocentric distances that are a factor of two to three larger than those analyzed previously by the Gaia Collaboration with the same data. It added the range of Galactocentric distances between 13 kpc and 20 kpc to the previous maps. Aims: Here, we investigate the dynamical effects produced by different mechanisms that can explain the radial and vertical components of these extended kinematic maps, including a decomposition of bending and breathing of the vertical components. This paper as a whole tries to be a compendium of different dynamical mechanisms whose predictions can be compared to the kinematic maps. Methods: Using analytical methods or simulations, we are able to predict the main dynamical factors and compare them to the predictions of the extended kinematic maps of Gaia-DR2. Results: The gravitational influence of Galactic components that are different from the disk, such as the long bar or bulge, the spiral arms, or a tidal interaction with Sagittarius dwarf galaxy, may explain some features of the velocity maps, especially in the inner parts of the disk. However, they are not sufficient in explaining the most conspicuous gradients in the outer disk. Vertical motions might be dominated by external perturbations or mergers, although a minor component may be due to a warp whose amplitude evolves with time. Here, we show with two different methods, which analyze the dispersion of velocities, that the mass distribution of the disk is flared. Despite these partial explanations, the main observed features can only be explained in terms of out-of-equilibrium models, which are either due to external perturbers or to the fact that the disk has not had time to reach equilibrium since its formation.

astro-ph.GA↗

arXiv2012

Radial migration of the Sun in galactic disk

Physics of the gravitational effect of the galactic bar and spiral structure is presented. Physical equations differ from the conventionally used equations. Application to the motion of the Sun is treated. The speed of the Sun is taken to be consistent with the Oort constants. Galactic radial migration of the Sun is less than +- 0.4 kpc for the four-armed spiral structure. The Sun remains about 75 % of its existence within galactocentric distances (7.8 - 8.2) kpc and the results are practically independent on the spiral structure strength. Thus, the radial distance changes only within 5 % from the value of 8 kpc. Galactic radial migration of the Sun is less than +- (0.3 - 1.2) kpc, for the two-armed spiral structure. The Sun remains (29 - 95) % of its existence within galactocentric distances (7.8 - 8.2) kpc and the results strongly depend on the spiral structure strength and the angular speed of the spiral arms. The radial distance changes within (3.8 - 15.0) % from the value of 8 kpc. If observational arguments prefer relevant radial migration of the Sun, then the Milky Way is characterized by the two-arm spiral structure.

astro-ph.GA↗