Volume 65, Number 34, 2020
Theoretical, Mathematical, and Computational Physics
Observables of Complex PTSymmetric “Shifted” Potentials R.J. Lombard, R. Mezhoud, R. Yekken Romanian Journal of Physics 65,
105 (2020)
We study complex PTsymmetric potentials, with real eigenvalues, corresponding to a complex coordinate shift $(x + i \frac {c}{2})$ of a real even potential. In this case, the rules to achieve a coherent quantum mechanics are known. They allow the calculation of observables, which are found to be independent on $c$. This result is illustrated by few analytical or semi analytical examples. On the other hand, trying to test this property numerically faces problems linked to the difficulty of finding the proper solutions of the Schr\"odinger equation. In particular, the large distance behaviour of the wave functions generates instabilities. As an example, we have studied the $(x + i \frac {c}{2})^4$ potential.
Discrete Field Theories through Space Noncommutativity Ciprian Sorin Acatrinei Romanian Journal of Physics 65,
106 (2020)
Noncommutativity can be used to naturally discretize the space on which a field theory is defined. This is of particular interest for fermions, given that the (in)famous doubling problem of usual lattice field theory does not appear anymore. The resulting discrete equations of motion are solved including their generic nonlocal sector, which is precisely interpreted. No classical divergences appear. The continuum limit is taken explicitely and confirms the interpretation of the discrete field configurations. Although the present work reviews mainly the context of planar physics, the methodology can be adapted to higher dimensional or nonflat setups.
Entanglement Quantification Using Various Inseparability Criteria for Correlated Photons T. Abebe, N. Gemechu, K. Shogile, S. Hailemariam, Ch. Gashu, Sh. Adisu Romanian Journal of Physics 65,
107 (2020)
In this paper, a detailed comparison among the exhibited nature of entanglement of the cavity radiation of the nondegenerate threelevel cascade laser with a coherently driven parametric amplifier and coupled to a twomode thermal reservoir by applying different inseparability criteria is presented. Although the achievable degree of entanglement is generally found to vary with the applied inseparability criteria, there are cases for which more than three of the applied criteria lead to a significant degree of entanglement for certain parameters. In particular, DuanGiedkeCiracZoller (DGCZ) criterion, logarithmic negativity, HilleryZubairy, and CauchySchwartz inequality inseparability criteria predict a similar pattern of entanglement except when the atoms are initially prepared in a maximum atomic coherent superposition. The presence of the parametric oscillator leads to an increase in the degree of squeezing and entanglement. Moreover, the degree of entanglement for the cavity radiation is significantly enhanced with the linear gain coefficient.
New Painlevé–Integrable (2+1) and (3+1)Dimensional KdV and MKdV Equations AbdulMajid Wazwaz Romanian Journal of Physics 65,
108 (2020)
In this work, we study new Painlevéintegrable (2+1) and (3+1)dimensional Kortewegde Vries (KdV) and modified Kortewegde Vries (mKdV) equations. We use the Painlevé analysis to confirm the integrability of both KdV and mKdV equations. We show the auxiliary function for each new equation possesses distinct structures compared to standard KdV and standard mKdV equations. We derive multiplesoliton solutions for each developed equation.
Atomic, Molecular, and Optical Physics
Surface Waves in a Layered Medium Characterized by Stepwise Nonlinear Dielectric Permittivity S. E. Savotchenko Romanian Journal of Physics 65,
202 (2020)
We describe the new peculiarities of the surface electromagnetic wave propagation along a dielectric slab sandwiched by a nonlinear medium characterized by dielectric permittivity depending on electric field amplitude in a stepwise form. The wave propagation leads to a symmetric optical domain formation along the dielectric slab. The optical domain can form at slab thicknesses not exceeding the critical value. The dielectric constant inside the domain at wave amplitude greater than the threshold field value becomes different from the dielectric constant of the entire nonlinear medium.
Nuclear Physics
Radiation Protection Assessment for Commissioning a Fast Neutron Source Based on the p(^{7}Li,n)^{7}Be Inverse Reaction at the 9 MV Tandem Accelerator of IFINHH Irina Dinescu, Gheorghe CătaDanil Romanian Journal of Physics 65,
302 (2020)
This paper reports the results for a radiation protection assessment done at the 9 MV Tandem Accelerator of Horia Hulubei National Institute for Physics and Nuclear Engineering for commissioning of a fast neutron source based on the ^{7}Li(p,n)^{7}Be inverse reaction. The assessment is based on the results obtained via numerical simulation with the use of FLUKA Monte Carlo simulation code. We have calculated the secondary radiation fields generated in different areas of the Tandem building during the acceleration process and the residual activity induced after a certain operation time.
Fission Channel Influence on ^{236}Pu Shape Isomer R.A. Gherghescu Romanian Journal of Physics 65,
303 (2020)
Fission channels barriers are calculated within the binary macroscopicmicroscopic method. A specialized single particle twocenter shell model has been developed to achieve the proton and neutron level schemes evolution during the fission process. The microscopic part of the deformation energy is obtained by the smoothing procedure of Strutinsky method. The macroscopic part is calculated with the Yukawaplusexponential model for a charged liquid drop. The fission barrier is obtained by adding the two quantities. A minimization within the deformation space of the two semiaxis ratios for the emerging fragments provides the final deformation energy considered as the fission barrier. The results are applied to the decay of ^{236}Pu. A proton gap in the level scheme provides a minimum in shell correction which accommodates a possible shape isomer.
Physics of Elementary Particles and Fields
Transport Coefficients of Strongly Interacting QuarkGluon Plasma Using Dual QCD Hadronic Bag Garima Punetha, H.C. Chandola Romanian Journal of Physics 65,
401 (2020)
Utilizing the magnetic symmetry based dual QCD model of nonAbelian gauge theory, the qualitative feature of the strongly interacting QGP have been understood within the framework of dual QCD hadronic bag. The study of the nonequilibrium and dissipative effects observed during the phase transition have been studied by investigating the temperature behavior of transport coefficients along with the relaxation times for quarks and gluons. These transport parameters provide proper understanding about the nonequilibrium dynamics of the system. The behavior of shear and bulk viscosity confirms the nonmonotonic and nonconformal behavior of QGP near the critical temperature. The high temperature behavior of QGP appears to be conformal and behaves like an ideal relativistic gas.
Condensed and Soft Matter Physics
Effect of Spark Plasma Sintering on the Interphase Exchange Coupling in SmCo_{5}+20%Fe Hard/Soft Nanocomposites R. Hirian, B. V. Neamţu, A. Ferenczi , O. Isnard, I. Chicinaş, V. Pop Romanian Journal of Physics 65,
603 (2020)
The hard/soft SmCo_{5}+20wt% αFe exchange coupled nanocomposite powders are obtained by mechanical milling of SmCo5 and αFe powders. The compact densities range between 35% and 70% of the theoretical value. The sintered compacts show the same coercivity as the nanocomposite powders, 0.8 T, while the remanence and energy product were diminished. The plasma sintered nanocomposite SPS compacts are found to contain two hard magnetic phases: SmCo_{5} and Sm_{2}(Co_{0.8}Fe_{0.2})_{17}, the latter being detrimental to the coercivity of the hard/soft nanocomposite.
Surface PlasmonPolaritons. Superficial Modes M. Apostol Romanian Journal of Physics 65,
604 (2020)
The surface plasmonpolaritons are identified on a straight, long, circular wire (either metallic or dielectric). They are radial magnetictype dispersive modes, excited by unipolar currents, except for the symmetric mode, which is nondispersive. This latter mode may guide an electromagnetic wave along the surface, dispersionless and with the speed of light in vacuum. A similar situation occurs for other finitesize bodies, like a halfspace, a sphere, etc. It is emphasized that the surface plasmonpolaritons are superficial, discontinuous electromagnetic modes.
Biophysics and Medical Physics
Spectroscopic Insights on the Binding of Rutin to Bovine Serum Albumin N. Sandu, C. G. Chilom, A. I. Popescu Romanian Journal of Physics 65,
703 (2020)
The interaction between rutin and bovine serum albumin (BSA) was studied using UVVis, FTIR spectroscopy, and fluorimetry under physiological conditions. UVVis and FTIR spectra put in evidence the effective interaction between rutin and BSA that provoked structural changes in BSA. The BSA fluorescence quenching induced by rutin, put in evidence a static quenching mechanism. The values of binding constants at 25°C and 35°C revealed a moderate binding. The thermodynamic parameters indicate that the interaction is mainly driven by electrostatic and also by van der Waals and hydrogen bonds. The effects of cations: Ca^{2+}, Mg^{2+}, Fe^{2+}, and Cu^{2+} on BSA denaturation by urea were investigated. It was found that rutin stabilizes the structure of BSA, even in the presence of urea. Also, it was noticed that the divalent cations, Fe^{2+} and Cu^{2+}, have a more stabilizing effect on the structure of complex, rutin – BSA, in comparison with Ca^{2+} and Mg^{2+}.
Environmental and Earth Physics
Assessment of Natural Radionuclides in Soil Samples in Specific Areas on the Territory of Lithuania M. Pečiulienė, V. Vasiliauskienė, V. Klima, D. Jasaitis Romanian Journal of Physics 65,
807 (2020)
The activity concentrations of soil samples collected from different locations of Lithuania were determined by using HPGe detector based on highresolution gamma spectrometry system. The following three unique areas in Lithuania have been chosen for the research. Vilnius city is the capital of Lithuania and this is the city with the largest population in the country which is dominated by an anthropogenic environment. Juodkrantė is a recreation area located near the Baltic Sea and Curonian Spit which is included on the UNESCO World Heritage List and has a natural environment and minimal urbanization. Visaginas is special for the nuclear power plant (which is currently being decommissioned). It is the only nuclear power plant in the Baltic States built close to the border with Belarus on the shore of Drūkšiai Lake. The activity concentrations of naturally occurring radionuclides ^{40}K, ^{226}Ra, and ^{232}Th have been measured in different brands of the soil samples taken from Vilnius and Juodkrantė districts and in the technogenic soil samples from the territory of Visaginas Nuclear Power Plant. Among all identified natural radionuclides, the highest level was that of ^{40}K, i.e. the mean value was 414 ± 71 Bq kg^{−1}, while the minimum level was that of ^{232}Th, i.e. the mean value was 4.8 ± 0.8 Bq kg^{−1}. The mean value of ^{226}Ra activity concentration was 13.9 ± 2.0 Bq kg^{−1}. Having measured the activity concentrations of naturally occurring radionuclides ^{232}Th, ^{226}Ra, and ^{40}K, the possible impact of natural radiation on a human has been assessed by calculating the absorbed dose rate (nGy h^{−1}). The average values of calculated absorbed dose rates in the samples were found 27.71 nGy h^{−1} in Vilnius, 23.25 nGy h^{−1} in Juodkrantė, and 28.65 nGy h^{−1} in Visaginas. In the paper, the annual effective dose (mSv) was also calculated: the minimum annual effective dose was found in Vilnius (0.034 mSv) and the maximum in Visaginas (0.035 mSv).
“MetroMC” Research Group: Computational Physics in Ionizing Radiation Metrology M. Zadehrafi, C. Olaru, S. Ciobanu, G. Ormenisan, L. C. Tugulan, A. Luca, M.R. Ioan Romanian Journal of Physics 65,
808 (2020)
The aim of this work is to highlight the undisputable needs and the suitability of computational physics in ionizing radiation metrology. In this matter, a new young research group has been developed within the Department of Radioisotopes and Radiation Metrology (DRMR) from Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFINHH), Romania. The abovementioned research group named “MetroMC” (Monte Carlo in Metrology) is marking the start point of its research activity, in this actual form, through this paper. For this purpose, a simple theoretical experiment has been performed in order to compare the results obtained by approaching the same problem by various Monte Carlo codes that are currently being used by the group members (MCNP, GEANT4, and EGSnrs).
Interpreting the Fundamental Frequency of Resonance for Transylvanian Basin A. Coman, E. F. Manea, C.O. Cioflan, M. Radulian Romanian Journal of Physics 65,
809 (2020)
The purpose of this study is to identify and to map the fundamental frequency of resonance for the Transylvanian Basin using the computation of H/V spectral ratios from 20 threecomponent single station measurements of ambient vibrations. This spectral curve exhibits multiple peaks suggesting lateral variations within the subsoil of this area. The fundamental frequency of resonance along Transylvanian Basin varies from very low values (0.07 Hz) up to 11.2 Hz. For some stations, higher mode peaks are detected in the frequency domain of 0.35–4.9 Hz.
Applied and Interdisciplinary Physics
A Possible Use of Optical Fibers in Radiation Monitoring/Dosimetry E. Bădiţa, C. Vancea, I. Călina Romanian Journal of Physics 65,
902 (2020)
The performance and potential of singlemode optical fibers for radiation monitoring/dosimetry applications were evaluated. The results indicated a dependence of the radiation induced attenuation with dose for both of optical fibers investigated. The temperature did not change attenuation during the irradiation and after irradiation process. The highest radiation sensitivity was observed at 1550 nm. Due to high dose dependence and good reproducibility, the Gedoped optical fibers are identified as suitable for developing a new radiation dosimeter with a possible use in radiation monitoring applications.
Radiation Induced Absorption (RIA)Based Dosimetry M.R. Ioan, L.C. Tugulan, M. Zadehrafi, C. Olaru, G. Ormenisan, S. Ciobanu, G.V. Ioan Romanian Journal of Physics 65,
903 (2020)
In the case of almost all the applications of nuclear physics that make use of ionizing radiation, one of the most important parts is the associated absorbed dose, either we are talking about its direct involvement in the application itself or about the associated radiation protection measures. Due to the fact that the practical applications of ionizing radiation are expanding more and more, the dose measuring techniques are continuously evolving and are becoming more precise and more focused on specific applications, in order to better fit to the purpose. In this paper, an overview on the dose measuring techniques based on the Radiation Induced Absorption (RIA) effect is presented. These techniques are included in the bigger class of Solid State Dosimetry (SSD), and, even that they have many strong points and also drawbacks, there are the only ones that are being recommended to be used in some specific situations.
