The 2x2 Demonstrator, a prototype for the Deep Underground Neutrino Experiment (DUNE) liquid argon (LAr) Near Detector, was exposed to the Neutrinos from the Main Injector (NuMI) neutrino beam at Fermi National Accelerator Laboratory (Fermilab). This detector is a prototype of a new modular design for a liquid argon time-projection chamber (LArTPC), comprising a two-by-two array of four modules, each further segmented into two optically isolated LArTPCs. The 2x2 Demonstrator features a number of pioneering technologies, including a low-profile resistive field shell to establish drift fields, native 3D ionization pixelated imaging, and a high-coverage dielectric light readout system. The 2.4-tonne active mass detector is flanked upstream and downstream by supplemental solid-scintillator tracking planes, repurposed from the MINERvA experiment, which track ionizing particles exiting the argon volume. The antineutrino beam data collected by the detector over a 4.5 day period in 2024 include over 30,000 neutrino interactions in the LAr active volume—the first neutrino interactions reported by a DUNE detector prototype. During its physics-quality run, the 2x2 Demonstrator operated at a nominal drift field of 500 V/cm and maintained good LAr purity, with a stable electron lifetime of approximately 1.25 ms. This paper describes the detector and supporting systems, summarizes the installation and commissioning, and presents the initial validation of collected NuMI beam and off-beam self-triggers. In addition, it highlights observed interactions in the detector volume, including candidate muon antineutrino events.
Physics, Nuclear and particle physics. Atomic energy. Radioactivity
Safi Rafie-Zinedine, Joachim Schulz, Johan Bielecki
et al.
Single-particle imaging at X-ray free-electron lasers relies on suitable sample injection of nanoscale macromolecules and particles into the gas phase at room temperature. A coaxial liquid-sheet strategy considerably extended the range of suitable samples to include conductivities from zero to 40000 µS cm−1 – a more than about an eightfold increase in range compared with conventional electrosprays. A helium chamber atmosphere in combination with an engineered gas-sheet protected aerosol formation against corona discharge and reduced background noise more than threefold. These results suggest new avenues to qualify ever more demanding biological and material science samples for single-particle imaging in the future.
Nuclear and particle physics. Atomic energy. Radioactivity, Crystallography
The BESIII collaboration, M. Ablikim, M. N. Achasov
et al.
Abstract Based on (10087 ± 44) × 106 J/ψ events recorded with the BESIII detector, we search for the rare charmonium weak decays J / ψ → D s − ρ + + c . c . $$ J/\psi \to {D}_s^{-}{\rho}^{+}+\textrm{c}.\textrm{c}. $$ and J / ψ → D s − π + + c . c . $$ J/\psi \to {D}_s^{-}{\pi}^{+}+\textrm{c}.\textrm{c}. $$ No signal is observed, and upper limits on the branching fractions at the 90% confidence level are set as B J / ψ → D s − ρ + + c . c . < 8.0 × 10 − 7 $$ \mathcal{B}\left(J/\psi \to {D}_s^{-}{\rho}^{+}+\textrm{c}.\textrm{c}.\right)<8.0\times {10}^{-7} $$ and B J / ψ → D s − π + + c . c . < 4.1 × 10 − 7 $$ \mathcal{B}\left(J/\psi \to {D}_s^{-}{\pi}^{+}+\textrm{c}.\textrm{c}.\right)<4.1\times {10}^{-7} $$ . Our results provide the most stringent experimental constraints on these decays.
Nuclear and particle physics. Atomic energy. Radioactivity
The adsorption of O3 molecules (ozone) on graphene, N-doped graphene, Ga-doped graphene, and -Ga-N- co-doped graphene with an emphasis on O3 detection was examined in this work. The physical characteristics of -Ga-N-co-doped graphene are significantly altered upon O3 adsorption, which makes it a suitable choice for O3 detection molecular sensors. The interaction between the O3 molecule and the adsorbent is explained on the basis of their adsorption energy, adsorption distance and charge transfer. It was found that the adsorption of ozone molecules on the -Ga-N- co-doped graphene was more favorable in energy than that on the pristine one, representing the superior sensing performance of -Ga-N- co-doped system. In our work, we estimated the charge transfer between the O3 molecule and doped graphene nanostructures based on Mulliken population analysis. The calculated adsorption energy value shows the ozone molecule more firmly adsorbs on the surface of -Ga-N- co-doped graphene nanostructures (Eads = –1.74 eV) than that of pristine graphene (Eads = –0.41 eV), deriving from a stronger covalent bond between the ozone molecule and the -Ga- N- co-doped graphene nanostructures. Our findings thus suggest that -Ga-N- co-doped graphene could be a highly efficient gas sensor device for O3 detection in the environment.
Nuclear and particle physics. Atomic energy. Radioactivity, Thermodynamics
Abstract We revisit the minimal tension (k = 1) string theory on AdS3 × S3 × 𝕋4. We propose a new free-field description of the worldsheet theory and show how localization of string amplitudes emerges from the path integral. We exemplify our proposal by reproducing the worldsheet partition function of the psu $$ \mathfrak{psu} $$ (1, 1|2)1 WZW model and providing explicit expressions for spectrally-flowed vertex operators and DDF operators. We compute string correlators in the path integral formalism and obtain a precise tree-level match with correlation functions of the boundary symmetric orbifold.
Nuclear and particle physics. Atomic energy. Radioactivity
For many disciplines of science, all conceivable collisional cross-sections and reactions must be precisely known. Although recent decades have seen a trial of large-scale research to obtain such data, many essential atomic and molecular cross-section data are still missing, and the reliability of the existing cross-sections has to be validated. In this paper, we present projectile ionization, electron capture, and system breakdown cross-sections in carbon (C<sup>5+</sup>) ions and lithium (Li<sup>2+</sup>) ion collisions with atomic hydrogen based on the Monte Carlo models of classical and quasi-classical trajectories. According to our expectation, the QCTMC results show higher results in comparison to standard CTMC data, emphasizing the role of the Heisenberg correction constraint, especially in the low-energy regime. On the other hand, at high energy, the Heisenberg correction term has less influence as the projectile momentum increases. We present the total cross-sections of projectile ionization, electron capture, and system breakdown in C<sup>5+</sup> ions and Li<sup>2+</sup> ion collisions with atomic hydrogen in the impact energy range from 10 keV to 160 keV, which is of interest in astrophysical plasmas, atmospheric sciences, plasma laboratories, and fusion research.
Nuclear and particle physics. Atomic energy. Radioactivity
In nuclear reactors, the fuel cladding is exposed to high temperature and high pressure for a long period of time. Chalk River Unidentified Deposits (CRUD) will form on the surface of the fuel cladding during the conventional operation of pressurized water reactors, and the formation of the CRUD will affect the flow heat transfer on the surface of the fuel rods. In order to investigate the effect of surface fouling on the flow characteristics of the CRUD, as well as to explore the influence of cladding surface deposition layer on the active nucleation site density (NSD), the present study was based on the flow-boiling under atmospheric pressure. The flow boiling visualization experiment was conducted to simulate the actual fuel rod cladding with CRUD by using layer-by-layer deposition of SiO2, under two mass flow rates (0.12 m/s and 0.17 m/s) and three degrees of subcooling conditions (0, 3, 5 K), investigating the flow boiling heat transfer characteristics of fuel cladding Zr-4 non-deposition with two Zr-4 SiO2 depositions (1 μm and 3 μm). Focus on the relationship between the active nucleation site density Na with wall superheat, and analyze the main reasons for the differences under different operating conditions, and contrast differences in the active nucleation site density on the different of SiO2 deposited thicknesses, then compare it with existing models for the active nucleation site density. The results show that the deposited Zr-4 has a higher flow heat transfer capacity than the undeposited Zr-4, and this difference is mainly caused to the difference in surface porosity. The active nucleation site density increases on SiO2 deposited surfaces compared to undeposited surfaces, with a maximum in the 3 μm SiO2 deposited experimental group. Enhancing wall superheat increases the active nucleation site density, and the increase is more pronounced on surfaces with SiO2 deposits. For the same sample, under the condition that one of the degree of subcooling and flow rate is the same and the other is different, the difference in flow rate has a greater effect on the active nucleation site density than the degree of subcooling, and the increase in both flow rate and the degree of subcooling decreases the active nucleation site density. Based on the experimental data, nine prediction models were used for calculation and analysis, and the Končar model can better predict the active nucleation site density under the working conditions of this experiment.
Simon Caron-Huot, Frank Coronado, Anh-Khoi Trinh
et al.
Abstract How much spectral information is needed to determine the correlation functions of a conformal theory? We study this question in the context of planar supersymmetric Yang-Mills theory, where integrability techniques accurately determine the single-trace spectrum at finite ’t Hooft coupling. Corresponding OPE coefficients are constrained by dispersive sum rules, which implement crossing symmetry. Focusing on correlators of four stress-tensor multiplets, we construct combinations of sum rules which determine one-loop correlators, and we study a numerical bootstrap problem that nonperturbatively bounds planar OPE coefficients. We observe interesting cusps at the location of physical operators, and we obtain a nontrivial upper bound on the OPE coefficient of the Konishi operator outside the perturbative regime.
Nuclear and particle physics. Atomic energy. Radioactivity
Abstract According to the optical theorem, the imaginary part of the one-loop radiative shift of the electron energy in an external field (IP1L) determines the total probability of photon emission by the electron. We calculate IP1L and then the probability and power of radiation of an electron in a constant background tensor field, which simulates the violation of Lorentz invariance in the framework of the Standard Model Extension. Using current experimental constraints on the background field strength, we show that the considered radiation effect can manifest itself under astrophysical conditions at ultrahigh electron energy.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Georgia Paraskaki, Vanessa Grattoni, Tino Lang
et al.
The free-electron laser (FEL) community is interested in taking full advantage of the high-repetition-rates of FELs run by superconducting machines while maintaining the spectral properties achieved with external seeding techniques. Since the feasibility of seed lasers operating at a repetition-rate of MHz and with sufficient energy in a useful wavelength range, such as the ultraviolet (UV) range is challenging, a seeded oscillator-amplifier scheme is proposed instead for generation of fully coherent and high-repetition-rate radiation. The process is triggered by an external seed laser while an optical feedback system feeds the radiation back to the entrance of the modulator where it overlaps with the next electron bunch. Downstream from the feedback system, the electron bunches are then used for harmonic generation. We discuss the optimization of dedicated simulations and we investigate the stability of this scheme with numerical simulations. As a result, we address the control of the reflectivity of the resonator as a key parameter to achieve a stable HGHG seeded radiation. Finally, we show the impact of the power fluctuations in the oscillator on the bunching amplitude with analytical and simulated results. The output FEL radiation wavelengths considered are 4.167 nm and 60 nm.
Nuclear and particle physics. Atomic energy. Radioactivity
Abstract We introduce and study a so-called Wilson-loop d log representation of certain Feynman integrals for scattering amplitudes in N $$ \mathcal{N} $$ = 4 SYM and beyond, which makes their evaluation completely straightforward. Such a representation was motivated by the dual Wilson loop picture, and it can also be derived by partial Feynman parametrization of loop integrals. We first introduce it for the simplest one-loop examples, the chiral pentagon in four dimensions and the three-mass-easy hexagon in six dimensions, which are represented by two- and three-fold d log integrals that are nicely related to each other. For multi-loop examples, we write the L-loop generalized penta-ladders as 2(L − 1)-fold d log integrals of some one-loop integral, so that once the latter is known, the integration can be performed in a systematic way. In particular, we write the eight-point penta-ladder as a 2L-fold d log integral whose symbol can be computed without performing any integration; we also obtain the last entries and the symbol alphabet of these integrals. Similarly we study the symbol of the seven-point double-penta-ladder, which is represented by a 2(L − 1)-fold integral of a hexagon; the latter can be written as a two-fold d log integral plus a boundary term. We comment on the relation of our representation to differential equations and resumming the ladders by solving certain integral equations.
Nuclear and particle physics. Atomic energy. Radioactivity
We study the variational principle and derivation of the field equations for different classes of teleparallel gravity theories, using both their metric-affine and covariant tetrad formulations. These theories have in common that, in addition to the tetrad or metric, they employ a flat connection as additional field variable, but dthey iffer by the presence of absence of torsion and nonmetricity for this independent connection. Besides the different underlying geometric formulation using a tetrad or metric as fundamental field variable, one has different choices to introduce the conditions of vanishing curvature, torsion, and nonmetricity, either by imposing them a priori and correspondingly restricting the variation of the action when the field equations are derived, or by using Lagrange multipliers. Special care must be taken, since these conditions form non-holonomic constraints. Here, we explicitly show that all of the aforementioned approaches are equivalent, and that the same set of field equations is obtained, independently of the choice of the geometric formulation and variation procedure. We further discuss the consequences arising from the diffeomorphism invariance of the gravitational action, and show how they establish relations between the gravitational field equations.
Due to the fact that the potential threat to the health to the public living
near nuclear power plants is largely determined by the level of air pollution
by radionuclides, identification of the dispersion conditions of pollutants
in the atmospheric boundary layer is of great importance in the development
of engineering protection means for nuclear facilities. In turn, the
engineering protection of nuclear power plants provides for the development
of automated radiation monitoring systems and their main components, i. e.
atmospheric boundary layer status monitoring systems. When analyzing and
predicting the radiation situation in the vicinity of nuclear power plants,
the determination of atmospheric dispersion variability parameters over time
is essential. This research is aimed at assessing interannual and
intra-annual variability of atmospheric dispersion parameters in the
Belorussian nuclear power plant siting region based on the atmospheric
boundary layer monitoring data. This study has revealed the relative
interannual stability of the main average annual atmospheric dispersion
characteristics throughout the observation period in 2015-2019. At the same
time, the average seasonal values of the atmospheric boundary layer
dispersion parameters are characterized by significant fluctuations thereof
over the annual course. The feasibility of such monitoring for other
potentially hazardous industrial facilities, such as thermal power plants and
chemical plants, is also noted.
Nuclear and particle physics. Atomic energy. Radioactivity
Saumya Ghosh, Sunandan Gangopadhyay, Prasanta K. Panigrahi
Abstract In this paper we consider the flat FRW cosmology with a scalar field coupled with the metric along with generalized Chaplygin gas and perfect fluid comprising the matter sector. We use the Schutz’s formalism to deal with the generalized Chaplygin gas sector. The full theory is then quantized canonically using the Wheeler–DeWitt Hamiltonian formalism. We then solve the WD equation with appropriate boundary conditions. Then by defining a proper completeness relation for the self-adjointness of the WD equation we arrive at the wave packet for the universe. It is observed that the peak in the probability density gets affected due to both fluids in the matter sector, namely, the Chaplygin gas and perfect fluid.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity