Physics Open最新文献

Formation of a compound nucleus and production of its evaporation residue are hindered by quasi-fission process. It reduces the evaporation residue cross section since it takes place before the target and projectile combines to form a composite nucleus. We study the quasifission barriers ($B_{qf}$) for 14 fusion reactions in the formation of superheavy element ²⁹⁸Og within the framework of the di-nuclear system model. In particular, the influence of entrance channel parameters on quasifission barriers has been investigated. We notice that the quasifission barriers decreases with an increase in angular momentum and fusion barrier height. We constructed semi-empirical formulae for $B_{qf}$ as a function of mean fissility. The fusion reaction ⁴⁸Ca+²⁵⁰Cf poses larger $B_{qf}$. The larger evaporation cross section is observed for this fusion reaction for 3n evaporation channel with the cross-section of 0.81pb. Similarly, a smaller evaporation cross-section of about 0.033pb is observed for ⁵¹Cr+²⁴⁷Pu fusion reaction for 4n evaporation channel with both projectile and target being deformed, unlike to the previous reaction with spherical projectile and deformed target.

The violation of Mermin’s inequalities is analyzed by making use of two different Bell setups built with pseudospin operators. Employing entangled states defined by means of squeezed and coherent states, the expectation value of Mermin’s polynomials $M_n$ is evaluated for $n=3$ and $n=4$. In each case, we analyze the correlator $〈M_n〉$ and identify the set of parameters leading to the violation of Mermin’s inequalities and to the saturation of the bound predicted by Quantum Mechanics.

The effective interaction of a neutrino with a photon in magnetized plasma is obtained from a strong field expansion in the electroweak standard model. The interaction is expressed by a Chern–Simons form of the neutrino current and the electromagnetic vector potential of the coupling strength proportional to $\frac{n_e}{B}\times e{G}_F$. The derivation of the interaction Lagrangian and its properties are presented.

Various photon attenuation software tools are being used widely by researchers to evaluate the radiation shielding parameters of the elements/compounds/composites theoretically. Attempts are being made by a few researchers to update and develop software tools of these kinds. However, the efficacy of these tools in terms of their comparison is yet to be explored. Thus, an attempt has been made in the present study to compare & explore the best tool among the widely used and most trusted tools, such as Phy-X, XCOM, FFAST and XMuDat photon attenuation databases, to evaluate the shielding parameters of PVA-based composites filled with bismuth and tungsten, and also for materials such as bismuth, tungsten, gold, copper, platinum, lead and barite. Careful analysis of the data obtained computationally and experimentally shows that, although the Phy-X tool provides various shielding parameters with multiple choices in the selection of energy range, it is noticed that this tool needs to be figured out for obtaining the absorption edges of the composites of interest precisely. The XCOM database provides sharp absorption edges; however, this tool gives multiple values of mass attenuation coefficients corresponding to a particular absorption edge energy. On the other hand, The FFAST tool provides sharp absorption edges along with X ray fine structure. However, the tool restricts to work with elements and compounds in the energy range 1 keV–433 keV, which limits the utilization of this tool. Furthermore, the XMuDat tool has a limiting option to work with the materials available in its library/database and provides the mass attenuation coefficient and four other parameters. However, the XMuDat provides a large number of data points, which helps to identify any minute deviation in the values of the parameters. Therefore, the present study suggests that the XMuDat tool is much more advantageous and reliable than the other tools for the detailed study of various radiation shielding parameters.

This study explored whether the introduction of connected automated vehicles (CAVs) into human-driven vehicles (HVs) can mitigate the social dilemma caused by defective HVs that seek to overtake other vehicles by making frequent lane changes. In this regard, a cellular automata traffic model based on the revised S–NFS model, dealing with a mixed flow field composed of CAVs and HVs with multiple lanes, was established. We perused precise game theoretical analysis on the basis of the result obtained from traffic flow analysis through multi-agent simulation (MAS). As a result, the social efficiency deficit, quantifying the extent of the social dilemma behind such a specific traffic flow system, elucidates that the introduction of CAVs does not eliminate the social dilemma caused by defective HVs unless CAVs account for the vast majority of the mixed flow.

Features of longitudinal and transverse tensoresistances and the tenso-Hall effect in low-resistance n-Si crystals doped with phosphorus, antimony, and arsenic were studied. The impurity-specific mechanisms which lead to changes in the number of charge carriers (“incomplete ionization” and deactivation of impurities), as well as a change in the efficiency of the scattering on impurity density fluctuations were considered to explain the tensoresistive peculiarities. It is supposed that the dominant factor determining the efficiency of scattering on impurity density fluctuations is the value of the lattice strain introduced by the impurity itself. An increase in the transverse tensoresistance with pressure increasing revealed in n-Si samples doped with phosphorus and antimony was explained by the fluctuations of impurity density. For these samples, a maximum and instabilities on dependencies of the tenso-Hall effect are observed at 4.2 K. An increase in the measurement temperature, the manifestation of instabilities is weakened.

In a fusion reactor, DT reactions produce huge amount of neutrons which hit the structure material and produce heat and damages. To understand the production of nuclear heating and material damages, study of double differential cross section (DDX), energy differential cross section (EDX), penetrating range of incident particles and stopping power of target element was calculated for ⁵²Cr(n, p) and ⁵²Cr(n, a) reactions. The calculated data have been compared with the suitable experimental data collected from EXFOR and other. The contribution of compound, pre-equilibrium and direct reaction processes has been analyzed for the entire cross section calculation. The emission of charged particles at different angles has been discussed based on the reaction processes. Parameter adjustment has been applied to fit the experimental data.

The organic scintillator crystal 1,3,5-Triphenylbenzene (TPB) is a promising material for high-energy particle detection applications. The bulk size of unidirectional (<100> plane) TPB cylindrical crystal was grown by the unidirectional growth technique and their optical properties were analyzed to couple with a photomultiplier tube for detector device fabrications. The gamma retorts of the grown cylindrical crystal were tested with varying gamma energy sources ranging from 356 to 1275 keV. The Time of flight (TOF) experimental setup was constructed with a grown TPB crystal and Neutron-Gamma discrimination was demonstrated with a ²⁵²Cf fission source. The developed TPB crystal exhibits strong timing characteristics operates consistently and offers a great capability for discrimination over gamma radiations.

As a potential source of indoor radiation arising from radon, a range of building materials (white cement, gray cement, gravel, gypsum, granite, marble, vitrified tile, and brick) were studied for the specific activity of radium and radon gas exhalation rates. The activity of radium was determined using scintillation gamma-ray spectrometry. Exhalation rates were assessed using passive and active measurement methods. Radon mass exhalation rates from powdered building materials and radon surface exhalation rates from slab-type building materials were measured. Activity concentrations of ²²⁶Ra in powder and slab-type building materials were found in the range of (1.12 – 14.98) Bqkg⁻¹ and (17 – 308) Bqkg⁻¹, respectively. ²²²Rn mass exhalation rates (mBqkg⁻¹h⁻¹) from the building materials were in the range of 15.0 ± 0.8 (gray cement) to 1.1 ± 0.1 (gravel). Surface exhalation rates (mBqm⁻²h⁻¹) for slab-type materials have a range of 317 ± 9 (brick) to 8 ± 2 (marble). Strong positive correlations were found between the specific activity of radium and radon mass exhalation rates (r = 0.9408) and radon surface exhalation rates (r = 0.7167) for building materials investigated. Obtained data indicates that the building materials used influence indoor radon concentration in dwellings.

We presented a decagonal cladding and hexahedron core-based photonic crystal fiber (PCF) to sense chemicals in the terahertz frequency (THz). Circular air holes (CAHs) in the cladding region make up the proposed sensor. A wide variety of frequencies were evaluated to analyze the sensor's performance in terms of sensitivity, confinement loss, and effective material loss respectively. We designed and quantitatively analyzed the optical properties of our proposed hexahedron-based PCF sensor using the finite element method (FEM). Square-shaped air hole length, strut, and core size have also been researched to improve the performance of the proposed sensor's sensing components and fabrication tolerance. At ideal conditions, the suggested PCF sensor has a maximum relative sensitivity of 94.65%, confinement loss of 6.01 × 10⁻⁸ cm⁻¹, effective material loss (EML) of 9.16 × 10⁻⁴ cm⁻¹, and effective mode area (EMA) of 1.35 × 10⁻⁷ m². We are confident that the suggested sensor's optimized geometrical structure will be manufacturing-friendly, as well as the sensor's contribution to practical uses. Furthermore, our proposed PCF fiber will be ideal in the terahertz (THz) regions for various optical communication applications and medicinal signals.