National Centre for Nuclear Research

This manuscript presents a comprehensive study of the synthesis of high-entropy TiCrFeCoNi alloy (HEA) thin films via pulsed magnetron sputtering (PMS).The research investigates the impact of various modulation frequencies on the material properties of the synthesized films. By employing Shannon entropy as a novel method to characterize the complexity and homogeneity of high-entropy thin films, we offer new insights into the synthesis process under various thermodynamic conditions. The initial characterization of the alloy, using calculated parameters such as mixing entropy, enthalpy of mixing, and others, sets the stage for a deeper understanding of the alloy's formation and stability. The experimental methodology encompasses target synthesis, sputtering system setup, sample synthesis, and comprehensive process and sample characterization, including EDS analysis, surface and cross-sectional analyses using SEM, and mechanical property assessments via nanoindentation. Results indicate that modulation frequency significantly influences the plasma discharge process, and consequently, the composition, microstructure, and mechanical properties of the HEA films. EDS analysis confirms the successful synthesis of the target alloy composition, and surface and cross-sectional analyses reveal the effects of modulation frequency on film morphology and structure. Mechanical property measurements highlight the variations in hardness and Young’s modulus among the synthesized films. The study elucidates the role of PMS parameters, especially modulation frequency, in controlling the synthesis of high-entropy thin films, paving the way for optimizing film properties for advanced material applications. Graphical Abstract

A bstract Using 7.33 fb − 1 of e ⁺ e − collision data samples collected with the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, we search for the radiative decay ${D}_s^{+}\to \gamma \rho {(770)}^{+}$ D s + → γρ 770 + for the first time. A hint of ${D}_s^{+}\to \gamma \rho {(770)}^{+}$ D s + → γρ 770 + is observed with a statistical significance of 2.5 σ . The branching fraction of ${D}_s^{+}\to \gamma \rho {(770)}^{+}$ D s + → γρ 770 + is measured to be (2.2 ± 0.9 stat . ± 0.2 syst . ) × 10 − 4 , corresponding to an upper limit of 6.1 × 10 − 4 at the 90% confidence level.

Developing advanced and economically viable technologies for the capture and utilization of carbon dioxide (CO2) is crucial for sustainable energy production from fossil fuels. Converting CO2 into valuable chemicals and fuels is a promising approach to mitigate atmospheric CO2 levels. Among various methods, photocatalytic reduction stands out for its potential to reduce emissions and produce useful products. Here, novel perovskite ZnMoFeO3 (ZMFO) nanosheets are presented as promising semiconductor photocatalysts for CO2 reduction. Experimental results show that ZMFO has a narrow bandgap, exceptional visible light response, large specific surface area, high crystallinity, and various surface‐active sites, leading to an impressive photocatalytic CO2 reduction activity of 24.87 µmolg⁻¹h⁻¹ and strong stability. Theoretical calculations reveal that CO2 conversion into CO and CH4 on the ZMFO surface follows formaldehyde and carbine pathways. This study provides significant insights into designing innovative perovskite oxide‐based photocatalysts for economical and efficient CO2 reduction systems.

The National Centre for Nuclear Research is planning to build a facility based on a free-electron laser (FEL) photon source. It is the first center to build this kind of facility in Eastern Europe. The laser radiation source relies on a superconducting linear electron accelerator. Ultimately, electrons are to be accelerated to energies of 72 MeV, 187 MeV and 280 MeV. To safely operate such kind of accelerator, the design of a shielding bunker is required, capable of attenuating the secondary radiation generated by electrons lost from the beam. This paper proposes a model for the energy and spatial distribution of such electrons. The proposed model will be used in subsequent calculations of the distribution of secondary radiation emitted by both the beamline and some devices essential for the operation of the PolFEL accelerator, such as superconducting niobium accelerating cavities, titanium liquid helium tanks filled with liquid helium, surrounded by μ-metal steel cryomodules containing a steel tube filled with liquid nitrogen, mirrors reflecting the resulting laser beams based on copper blocks, and electron beam deflecting electromagnets made of iron and copper. It was calculated that to reproduce a complex beam loss of 1 W/m, the total lost electron flux as a source of secondary radiation should be 1.7991 × 10 ¹³ e/s for 72 MeV, 1.1537 × 10 ¹³ e/s for 187 MeV and 1.1012 × 10 ¹³ e/s for 280 MeV. Preliminary Monte Carlo calculations of the designed source were performed, obtaining the energy and spatial distributions of the lost electrons.

The working conditions of tools during plastic working operations are determined by, among other things, temperature, loads, loading method, and processing speed. In sheet metal forming processes, additionally, lubricant and tool surface roughness play a key role in changing the surface topography of the drawpieces. This article presents the results of friction analysis on the edge of the punch in a deep drawing process using the bending under tension test. A DC04 steel sheet was used as the test material. The influence of various types of titanium nitride and titanium coatings applied on the surface of countersamples made of 145Cr6 cold-work tool steel was tested by means of high-intensity plasma pulses, magnetron sputtering, and electron pulse irradiation. The influence of the type of tool coating on the evolution of the coefficient of friction, the change in the sheet surface topography, and the temperature in the contact zone is presented in this paper. An increase in the coefficient of friction with sample elongation was observed. Countersamples modified with protective coatings provided a more stable coefficient value during the entire friction test compared to dry friction conditions. The electron pulse irradiated countersample provided the highest stability of the coefficient of friction in the entire range of sample elongation until fracture. The skewness Ssk of the sheet metal tested against the coated countersamples was characterized by negative value, which indicates a plateau-like shape of their surface. The highest temperature in the contact zone during friction with all types of countersamples was observed for the uncoated countersample.

The radiation adaptive response (or radioadaptation) effect is a biophysical and radiobiological phenomenon responsible for, e.g. the enhancement of repair processes, cell cycle and apoptosis regulation or enhancement of antioxidant production in cells/organisms irradiated by low doses and low dose-rates of ionising radiation. This phenomenon, however, is not always present, which creates many problems both for experimenters and theoreticians. Here we propose a comprehensive and complete theoretical model of radioadaptation grounded in mathematical concept of dose- and time-related probability function of the adaptive response appearance. This can be used in the context of two special cases of the adaptive response: the Raper–Yonezawa (priming dose) effect or constant low-dose-rate irradiation (e.g. for high natural background). This complete theoretical approach is supported by Monte Carlo simulations and real-experimental data used for model calibration and validation.

A bstract Using e ⁺ e − collision data collected by the BESIII detector at BEPCII corresponding to an integrated luminosity of 30 fb − 1 , we measure Born cross sections and effective form factors for the process ${e}^{+}{e}^{-}\to {\Xi}^0{\overline{\Xi}}^0$ e + e − → Ξ 0 Ξ ¯ 0 at forty-five center-of-mass energies between 3.51 and 4.95 GeV. The dressed cross section is fitted, assuming a power-law function plus a charmonium(-like) state, i.e., ψ (3770), ψ (4040), ψ (4160), ψ (4230), ψ (4360), ψ (4415) or ψ (4660). No significant charmonium(-like) state decaying into ${\Xi}^0{\overline{\Xi}}^0$ Ξ 0 Ξ ¯ 0 is observed. Upper limits at the 90% confidence level on the product of the branching fraction and the electronic partial width are provided for each decay. In addition, ratios of the Born cross sections and the effective form factors for ${e}^{+}{e}^{-}\to {\Xi}^0{\overline{\Xi}}^0$ e + e − → Ξ 0 Ξ ¯ 0 and ${e}^{+}{e}^{-}\to {\Xi}^{-}{\overline{\Xi}}^{+}$ e + e − → Ξ − Ξ ¯ + are also presented to test isospin symmetry and the vector meson dominance model.

This paper presents a study on performance optimization and resonant frequency modification of terahertz detectors by the use of hyper-hemispherical silicon superstrate lenses. The detectors are patch-TeraFETs, i.e., field-effect transistors with monolithically integrated patch antennas fabricated with a commercial 65-nm CMOS foundry process and designed for an operation frequency of 580 GHz. We demonstrate a strong improvement of the optical noise-equivalent power ( optical NEP , referenced against the total radiation power) reaching a value of 16 pW/√Hz. We show furthermore, that the resonance frequency can be efficiently fine-tuned by the choice of the material and the thickness of a dielectric layer placed between the transistor and the superstrate lens. The resonance frequency can be shifted by more than 15% of the center frequency (up to 100 GHz for the 580 GHz devices). The design of the on-chip optics can be employed for post-fabrication tailoring of the detector’s resonance frequency to target specific spectral positions.

Self-Interacting Dark Matter models can successfully explain dark matter (DM) production through interactions confined within the dark sector. However, they often lack measurable experimental signals due to their secluded nature. Including a feeble interaction with the visible sector through a Higgs portal leads not only to potential detection avenues and richer thermal production dynamics, but also to a possible explanation of the initial dark sector population through the freeze-in mechanism. In this work we study, by solving the full system of coupled Boltzmann equations for the number densities and temperatures of all the involved states, three scenarios of this type where the DM is: a real scalar with broken ℤ2, a complex scalar with unbroken ℤ3, and a ℤ3 scalar with an additional scalar mediator. All of these models have viable dark matter candidates in a cannibal phase while having different detection profiles. We show that cosmological bounds can be either exacerbated or evaded by changing the dark sector interactions, leading to potential signatures in long-lived particle and indirect detection experiments.

We investigate the variation of statistical properties of the fissile nucleus, especially entropy, and nuclear level density, along different fission paths. The calculations were focused on comparing axial and triaxial trajectories leading to fission of 296 Lv. We observe that change of shell effects and their suppression rates with deformation can substantially influence fission dynamics. Furthermore, the fission process exhibits iso-entropic behavior at high excitation energies, while pronounced entropy variations are observed at lower energies. We derive a deformation-dependent level density parameter that plays a critical role in estimating the survival probability of a superheavy nucleus. The competition between different fission paths was further studied by employing a master equation approach, thereby demonstrating the critical role of entropy and thermodynamic properties in shaping fission dynamics within multidimensional deformation spaces.

A bstract KM3NeT/ORCA is a water Cherenkov neutrino detector under construction and anchored at the bottom of the Mediterranean Sea. The detector is designed to study oscillations of atmospheric neutrinos and determine the neutrino mass ordering. This paper focuses on an initial configuration of ORCA, referred to as ORCA6, which comprises six out of the foreseen 115 detection units of photo-sensors. A high-purity neutrino sample was extracted, corresponding to an exposure of 433 kton-years. The sample of 5828 neutrino candidates is analysed following a binned log-likelihood method in the reconstructed energy and cosine of the zenith angle. The atmospheric oscillation parameters are measured to be ${\sin}^2{\theta}_{23}={0.51}_{-0.05}^{+0.04}$ sin 2 θ 23 = 0.51 − 0.05 + 0.04 , and $\Delta {m}_{31}^2={2.18}_{-0.35}^{+0.25}\times {10}^{-3}{\textrm{eV}}^2\cup \left\{-2.25,-1.76\right\}\times {10}^{-3}$ Δ m 31 2 = 2.18 − 0.35 + 0.25 × 10 − 3 eV 2 ∪ − 2.25 − 1.76 × 10 − 3 eV ² at 68% CL. The inverted neutrino mass ordering hypothesis is disfavoured with a p-value of 0.25.

The branching fraction of ${D}^{+}\to {K}_S^0{\pi}^0{e}^{+}{\nu}_e$ is measured for the first time using 7.93 fb−1 of e+e− annihilation data collected at the center-of-mass energy $\sqrt{s}$ = 3.773 GeV with the BESIII detector operating at the BEPCII collider, and is determined to be $\mathcal{B}\left({D}^{+}\to {K}_S^0{\pi}^0{e}^{+}{\nu}_e\right)=\left(0.881\pm {0.017}_{\textrm{stat}.}\pm {0.016}_{\textrm{syst}.}\right)\%$. Based on an analysis of the ${D}^{+}\to {K}_S^0{\pi}^0{e}^{+}{\nu}_e$ decay dynamics, we observe the S-wave and P-wave components with fractions of fS-wave = (6.13 ± 0.27stat. ± 0.30syst.)% and ${f}_{{\overline{K}}^{\ast }{(892)}^0}=\left(93.88\pm {0.27}_{\textrm{stat}.}\pm {0.29}_{\textrm{syst}.}\right)\%$, respectively. From these results, we obtain the branching fractions $\mathcal{B}\left({D}^{+}\to {\left({K}_S^0{\pi}^0\right)}_{S-\textrm{wave}}{e}^{+}{\nu}_e\right)=\left(5.41\pm {0.35}_{\textrm{stat}.}\pm {0.37}_{\textrm{syst}.}\right)\times {10}^{-4}$ and $\mathcal{B}\left({D}^{+}\to {\overline{K}}^{\ast }{(892)}^0{e}^{+}{\nu}_e\right)=\left(4.97\pm {0.11}_{\textrm{stat}.}\pm {0.12}_{\textrm{syst}.}\right)\%$. In addition, the hadronic form-factor ratios of ${D}^{+}\to {\overline{K}}^{\ast }{(892)}^0{e}^{+}{\nu}_e$ at q2 = 0, assuming a single-pole dominance parameterization, are determined to be ${r}_V=\frac{V(0)}{A_1(0)}=1.43\pm {0.07}_{\textrm{stat}.}\pm {0.03}_{\textrm{syst}.}$ and ${r}_2=\frac{A_2(0)}{A_1(0)}=0.72\pm {0.06}_{\textrm{stat}.}\pm {0.02}_{\textrm{syst}.}$.

The e + e − → D s + D s 1 ( 2536 ) − and e + e − → D s + D s 2 * ( 2573 ) − processes are studied using data samples collected with the BESIII detector at center-of-mass energies from 4.530 to 4.946 GeV. The absolute branching fractions of D s 1 ( 2536 ) − → D ¯ * 0 K − and D s 2 * ( 2573 ) − → D ¯ 0 K − are measured for the first time to be ( 35.9 ± 4.8 ± 3.5 ) % and ( 37.4 ± 3.1 ± 4.6 ) % , respectively. The e + e − → D s + D s 1 ( 2536 ) − and e + e − → D s + D s 2 * ( 2573 ) − cross sections are measured, and a resonant structure at around 4.6 GeV with a width of 50 MeV is observed in both processes with a statistical significance of 7.2 σ and 15 σ , respectively. The state is observed for the first time in e + e − → D s + D s 2 * ( 2573 ) − and could be the Y ( 4626 ) found by the Belle oration in the D s + D s 1 ( 2536 ) − final state, since they have similar masses and widths. There is also evidence for a structure at around 4.75 GeV in both processes. Published by the American Physical Society 2024