The European Physical Journal Plus最新文献

Due to the progressive increase in size of the latest Cherenkov-type detectors, it is becoming increasingly important to design a suitable compensation system based on coils of the Earth’s magnetic field to ensure the correct operation of the photomultipliers (PMTs). Until now, most studies have assessed the correct functioning of such a system by the proportion of PMTs experiencing more than 100 mG of magnetic field perpendicular to their axis. In the present study, we discuss whether this evaluation parameter is the most appropriate and propose the average residual perpendicular magnetic field (< B_{{{text{perp}}}}>) as an alternative that more closely reflects the loss of detection efficiency of PMTs. A compensation system design is also proposed that offers good results as well as being economical to optimize this parameter.

This study investigates a new technique for etching solid-state nuclear track detectors (SSNDs) and compares it to the conventional chemical etching approach. The CR-39 nuclear track detector created alpha particle tracks with a 6.25 N NaOH etching solution. Revealing the ion-induced latent tracks in the material of the detector involves the inevitable step of a chemical etching process. In contrast to the conventional chemical etching approach, a new technique via plasma-induced chemical etching is presented in this study to reduce the etching time. According to the photomicrographs, for chemical etching, we observed that the tracks started appearing at 1 h and developed at 5 h. In contrast, the tracks started appearing with the plasma-induced etching method at 15 min and were fully developed at 60 min. The plasma etching process recorded higher track densities (7177.0 ± 33.7 Track/mm²) than chemical etching by water bath (5238.0 ± 5.7 Track/mm²), possibly due to its short etching time, allowing latent tracks to be revealed without increasing overlap. The bulk etch rate for CR-39 in plasma etching was faster than in chemical etching. The enhanced V_T/V_B ratio resulting from the plasma etching leads to an overall improvement in the track revelation process. The outcomes indicated that the optimum etching time for CR-39 irradiated with alpha particle energy of 5.47 MeV is 2 h for chemical etching and 60 min for plasma-induced etching. Plasma technology has shown its efficacy in the etching process by significantly reducing the time required for etching SSNDs and etching efficiency similar to that of the chemical etching method.

In this work, we developed a computational study using Geant4 to investigate potential alterations in particle cascades resulting from multiple interactions between a high-energy particle in air, (hbox {CO}_2), and (hbox {CH}_4) environments. Given the extensive range of parameters involved in the research, this study focuses exclusively on the behaviour of protons and neutrons within the cascade for two specific energies of the incident proton, namely 0.5 and 10 GeV. The chosen environment is a cubic box measuring (10^3~hbox {km}^3). Our findings reveal distinct differences in the cascade characteristics among the three gases. The distribution of protons and neutrons throughout the environment varies depending on the type of gas and the depth along the axis of incidence. Specifically, for ((hbox {CH}_4)), a higher production of protons was observed, whereas for ((hbox {CO}_2)), neutron production was more pronounced under certain conditions. Simulations of the Bragg peak were also conducted, where we observed a shift in the maximum energy loss due to ionisation depending on the environment.

The hexagonal boron nitride (h-BN) monolayer, owing to its applications in biological materials, multi-function composites and optoelectronic devices, has drawn a lot of interest recently. Here, the structural and electronic characteristics of monolayered h-BN sheets doped with sulfur (S) are theoretically explored through density functional theory calculations. Our primary focus was on how the dopant site and concentration is responsible for geometry and energy gap variation. The interatomic distances and position of the substitutional S atoms control the position of defect-related intermediate bands and the band gap of doped material. Strikingly, an indirect bandgap of doped system shows semiconducting behavior, which is narrower than the one for pristine sheet. Different structural arrangements (hexagonal and rectangular) of S defects at the BN monolayer provide a general design for defect engineering which is congenial for its applications in deep UV optoelectronic, electronic, and transistor-based devices.

In this study, a cost-effective flexible sensor based on manganese-doped zinc tungstate/graphene oxide composite nanoparticles (ZnWO₄/GO: Mn NPs) was fabricated. ZnWO₄/GO: Mn NPs were successfully synthesized via the coprecipitation method; using an ultrasonic-assisted spin-spray coating technique, synthesized NPs were deposited on polyethylene terephthalate (PET) to form a flexible composite film. The synergistic combination of ultrasonic irradiation and spray coating resulted in defect-free, uniform films with enhanced bonding to the PET substrate. The prepared film's optical response and structural features were investigated under ultraviolet, and ion beam-induced luminescence excitations, along with XRD, EDX-Mapping, FESEM, and FTIR measurements. Also, the ionizing radiation sensitivity of the prepared composite film was investigated using ²⁴¹Am source. XRD, FTIR, and EDX-Mapping elemental results showed characteristic peaks of ZnWO₄ and related elements in the samples. FESEM image showed that prepared NPs are approximately 96–264 nm in diameter. The addition of GO to ZnWO₄ increases the particle size, likely due to the interaction between ZnWO₄ nanoparticles and GO sheets. The band gap energy of the prepared ZnWO₄/GO: Mn film was decreased by doping and obtained (sim) 3.28 eV. According to the measurements, the flexible ZnWO₄/GO: Mn film showed prominent blue-green luminescent, centered at 400–500 nm visible regions and high ionizing ray sensitivity which is comparable with commercial ZnS: Ag. The current–voltage (I–V) characteristics were analyzed under both dark and UV-irradiated conditions, revealing that Mn-doped ZnWO₄/GO exhibited the highest UV sensitivity (3.5) compared to ZnWO₄ (1.5) and ZnWO₄/GO (2.5). The photocurrent response of the samples, assessed through cyclic light activation, showed peak currents of 130, 180, and 200 nA for ZnWO₄, ZnWO₄/GO, and ZnWO₄/GO:Mn, respectively. The enhanced UV response of the Mn-doped composite is attributed to bandgap engineering, oxygen adsorption/desorption processes, and reduced dark current, leading to an improved signal-to-noise ratio. These findings highlight the potential of Mn-doped ZnWO₄/GO nanocomposites for UV detection applications. The results indicate that prepared nanocomposite has the potential for practical applications in future optoelectronic fields and display.

Graphical abstract

We propose a new deformation of the quantum harmonic oscillator Heisenberg–Weyl algebra with a parameter (a>-1). This parameter is introduced through the replacement of the homogeneous mass (m_0) in the definition of the momentum operator (hat{p}_x) as well as in the creation–annihilation operators ({hat{a}}^pm) with a mass varying with position x. The realization of such a deformation is shown through the exact solution of the corresponding Schrödinger equation for the non-relativistic quantum harmonic oscillator within the canonical approach. The obtained analytical expression of the energy spectrum consists of an infinite number of equidistant levels, whereas the wavefunctions of the stationary states of the problem under construction are expressed through the Hermite polynomials. Then, the Heisenberg–Weyl algebra deformation is generalized to the case of the Lie superalgebra (mathfrak {osp}left( {1|2} right)). It is shown that the realization of such a generalized superalgebra can be performed for the parabose quantum harmonic oscillator problem, the mass of which possesses a behavior completely overlapping with the position-dependent mass of the canonically deformed harmonic oscillator problem. This problem is solved exactly for both even and odd stationary states. It is shown that the energy spectrum of the deformed parabose oscillator is still equidistant; however, both even- and odd-state wavefunctions are now expressed through the Laguerre polynomials. Some basic limit relations recovering the canonical harmonic oscillator with constant mass are also discussed briefly.

In this work, we investigate the existence of wormholes within the framework of loop quantum cosmology, using isotropic dark matter as the source. We analyze three distinct density profiles and solve the modified gravity field equations alongside the stress-energy tensor conservation, applying appropriate boundary conditions to obtain traversable wormhole solutions. Each solution is shown to satisfy the geometric criteria for wormholes, and their regularity is verified by computing the Kretschmann scalar to ensure the absence of singularities under determined conditions. Additionally, we examine the stress-energy tensor to identify scenarios in which energy conditions are violated within this model. The wormhole geometry is further explored through embedding diagrams, and the amount of exotic matter required to sustain these structures is computed using the volume integral quantifier. Finally, we study the shadow produced by our wormhole solution, considering one of the dark matter density profiles, and compare it with observations of the M87 galaxy.

Investigations on the variable-coefficient nonlinear partial differential equations attract people's attention. In this paper, we investigate a damped variable-coefficient fifth-order modified Korteweg-de Vries equation for some fluids and cosmic plasmas. Under certain variable-coefficient constraints, we find that the equation is Painlevé integrable. By virtue of the real and complex simplified Hirota procedures, multiple real and complex soliton solutions are derived. Via the soliton wave ansatz method, we obtain some other analytic solutions such as the kink, bell, singular and periodic soliton solutions. Moreover, we discuss the influences of variable coefficients in the equation on those solitons graphically.

Numerous observations from spacecraft missions have revealed that the space plasmas can be best modeled through the incorporation of nonthermal distributions. In the contemporary analysis, we investigate electron-acoustic waves (EAWs) in nonthermal plasmas. These waves propagate as a result of temperature difference between two electron species, commonly referred to as hot ((T_{h})) and cold ((T_{c})) electrons with (T_{h}>T_{c}). Both the hot and cold electrons are assumed to follow the Vasyliunas-Cairns distribution with considerations for limiting cases involving kappa and Maxwellian distributions. The Poison-Vlasov model is incorporated to calculate the longitudinal dielectric response function of electron-acoustic mode. Exact numerical analysis is performed to solve the dispersion relation equation which enables the calculation of dispersion and damping rate of electron-acoustic waves (EAWs). The influence of relevant parameters e.g., nonthermality parameters, the temperature ratio between hot and cold electrons, and the ratio of the number density of hot electrons to the total electrons is examined on the real and imaginary frequencies of the mode. In view of global modeling of naturally occurring space plasmas, this investigation contributes well to the understanding of heliospheric plasmas e.g., solar wind and magnetosphere.

In this study, we explore a static, spherically symmetric black hole solution in the context of a self-interacting Kalb-Ramond field coupled with a global monopole. By incorporating the effects of Lorentz-violating term (ell) and the monopole charge (eta) in the KR field, we derive the modified gravitational field equations and analyze the resulting black hole spacetime. The obtained solution exhibits deviations from the Schwarzschild metric with topological defect, as it is influenced by the monopole charge and self-interaction potential. We investigate the thermodynamic properties of the black hole, including its Hawking temperature, entropy, and specific heat, revealing novel stability conditions. Additionally, we perform solar system tests such as perihelion precession, gravitational redshift, light deflection, and time delay of signals to impose constraints on the Lorentz-violating parameter and monopole charge. Our findings suggest that these parameters have to be significantly small, although there are different constraints imposed by individual tests, ranging from (10^{-9}le |ell |le 10^{-4}) and (10^{-9}le eta le 10^{-6}, textrm{m}^{-1}).