Volume 64, Number 1-2, 2019
Theoretical, Mathematical, and Computational Physics
Gauge Backgrounds from Generalized Commutators – A Review Ciprian Sorin Acatrinei Romanian Journal of Physics 64,
101 (2019)
We review the generation of the known gauge backgrounds - and of some new ones - from commutation relations. The gauge connections corresponding to electromagnetism, Yang-Mills theory and Einstein gravity are obtained by assuming specific commutation relations between the phase-space variables of a first quantized theory. Extending the procedure to noncommuting coordinates leads to new types of dynamics, which are explored. In particular, the conditions for the coexistence of an electromagnetic background and a noncommutative two-form are presented, as well as a generalized mechanism for dimensional reduction. The noncommutative deformation of a gravitational background is also constructed. A different perspective is allowed by the so-called Feynman approach to the Maxwell equations. We review it, together with its extension to the noncommutative case. Finally, a few related topics, including the Wigner problem, are briefly overviewed.
Anomaly-Free Gauge Models: a Causal Approach D. R. Grigore Romanian Journal of Physics 64,
102 (2019)
The gauge invariance of some massless Yang-Mills models can be proved for a large class of groups using Polchinski flow equations approach. In this paper we provide an alternative proof based on the causal approach. The proof is purely algebraic and is based on the analysis of the anomalies. More precisely, one can prove that the anomalies are verifying some consistency equations of Wess-Zumino type. In the massless $SU(2)$ Yang-Mills case, this is enough to prove that they are absent. The same is true for QED.
An Analytical Study of (2 + 1)-Dimensional Physical Models Embedded Entirely in Fractal Space Marwan Alquran, Imad Jaradat, Dumitru Baleanu, Ruwa Abdel-Muhsen Romanian Journal of Physics 64,
103 (2019)
In this article, we analytically furnish the solution of $(2+1)$-dimension\-al fractional differential equations, with distinct fractal-memory indices in all coordinates, as a trivariate $(\alpha ,\beta ,\gamma )-$fractional power series representation. The method is tested on several physical models with inherited memories. Moreover, a version of Taylor's theorem in fractal three-dimensional space is presented. As a special case, the solutions of the corresponding integer-order cases are extracted by letting $\alpha ,\,\beta ,\,\gamma \rightarrow 1$, which indicates to some extent for a sequential memory.
Darboux Transformation and Higher-Order Solutions of the Sasa-Satsuma Equation Lijuan Guo, Yi Cheng, Dumitru Mihalache, Jingsong He Romanian Journal of Physics 64,
104 (2019)
We derive a general $n$-fold Darboux transformation (DT) matrix $T_n$ for the integrable Sasa-Satsuma equation. The elements of the matrix $T_n$ are expressed in compact determinant forms. Through the detailed analysis of the linear instability phenomenon, different kinds of solitons on a continuous wave background are obtained by using the DT, including $W$-shaped first-order and second-order rational solutions, coexisting $W$-shaped second-order rational solutions, first-order semi-rational solutions, first-order and second-order periodic solutions, first-order half-periodic solutions, and second-order breather-positon solutions.
Nuclear Physics
Prompt Emission Calculations for 233U(nth,f) A. Tudora, A. Matei Romanian Journal of Physics 64,
301 (2019)
Detailed prompt emission results of two refined models (one including the sequential emission treatment and another based on a residual temperature distribution) describing very well all experimental data of $^{233}$U(n$_\mathrm {th}$,f) are for the first time reported. They answer to the international request of accurate nuclear fission data for the fissile nucleus of the Th-U fuel cycle.
TOF Using NE102 for Neutron Energy Characterization C. Bordeanu, M. Straticiuc, V.D. Mosu, O. Muresan, D.T. Moisa, R. Andrei, L.S. Craciun, I. Burducea, C.A. Pistol, T.R. Esanu, C. Ionescu Romanian Journal of Physics 64,
302 (2019)
Time of Flight TOF technique was used for the first time in our laboratory to measure the neutrons energy from nuclear reactions. For the first time two home-made plastic scintillators NE102 were use for time measurement.
Lasers, Plasmas, and Beam Physics
Theoretical Investigation of X-Ray Lasing in Argon by Photo-Ionization from $K$ and $L$ Shells C. Iorga, V. Stancalie Romanian Journal of Physics 64,
501 (2019)
We theoretically investigate the X-ray lasing in argon gas by means of inner-shell photo-ionization pumping scheme driven by X-ray free electron laser (XFEL) radiation. Atomic data calculations performed within a fully relativistic model potential code reveal the dominant transitions from the $K$ and $L$ shells which may be used in argon lasing experiments. Our study shows that the photo-ionization pumping scheme is most efficient $(\sigma _{2p}/\sigma _{total} \approx 94\%)$ for populating the $2p^{-1}$ state belonging to Ar$^{1+}$, thus creating inversion on the $2p-3s$ transition, assuming the XFEL pulse is tuned between the two $L$ edges at $270$ eV. The generalized one-dimensional Maxwell-Bloch approach is employed in order to model the amplification process at $5.65$ nm for this transition. The present simulations show strong amplification resulting in X-ray pulses of up to $100\;\upmu $J energy with narrow spectral bandwidth. We report X-ray pulse characteristics, such as output energy, time and spectral profile, for the radiation mentioned above as resulted from the simulation.
Trapped Electron Mode Turbulence: Test Modes Approach V. V. Baran, D. Palade, M. Vlad, F. Spineanu Romanian Journal of Physics 64,
502 (2019)
We perform a test mode analysis for the case of the dissipative TEM instability in slab geometry, by studying the influence of the statistical properties of a turbulent background on the frequencies and growth rates of the test modes. Our approach naturally incorporates the ion trajectory diffusion and ion stochastic trapping present already in the quasilinear and, respectively, weakly nonlinear stages of the turbulence evolution.
Condensed and Soft Matter Physics
Confined fluid 3He: Thermodynamic Properties and Critical Behavior in Quasi-One Dimension G.H. Bordbar, M.A. Rastkhadiv Romanian Journal of Physics 64,
601 (2019)
A variational approach has been used to study the behavior of fluid $^3$He confined in a single-wall carbon nanotube at finite temperature $(1-4$ K$)$. We have calculated the energy of system by employing the variational method based on the quantum cluster expansion of the energy. Then, some thermodynamic properties such as entropy, free energy, equation of state, compressibility and specific heat have been investigated. This study has been done for a density range of $0.1 - 1.0$ nm$^{-1}$ and three different carbon nanotube radii, $R=0.3, 0.48$ and $0.8$ nm. Our result for the equation of state shows a liquid-gas second order phase transition for this confined system at a density and temperature which depend on the nano-tube radius. The critical behavior of this system has been studied, and the relevant critical exponents have been verified by Griffiths inequality. The remarkable point of this study is the low density and pressure of transition point in comparison with no confined case. This phenomenon is differentiated from the strong adsorption of $^3$He atoms by the carbon nanotube wall.
Environmental and Earth Physics
Factors Affecting Indoor Radon Variations: A Case Study in Schools of Eastern Macedonia Z. Stojanovska, B. Boev, Z. S. Zunic, K. Ivanova, A. Šorša, I. Boev, Z. Ćurguz, P. Kolarž Romanian Journal of Physics 64,
801 (2019)
The subject of this study is the radon concentrations variations, measured with a nuclear track detectors in a total of 58 premises in all 29 primary schools of 4 municipalities in the eastern part of the Republic of Macedonia. Despite a relatively small territory, the variability of radon concentrations proved to be significant. The geometric means (geometric standard deviations) of radon concentrations in the examined municipalities were in the range from GM=71 Bq/m$^3$ (GSD=2.08) to GM=162 Bq/m$^3$ (GSD=2.69), while for the entire region it was: GM=96 Bq/m$^3$ (GSD=2.47). The influence of the geographical and geological features of the school site as well as the building characteristics on the radon variations were investigated. The analysis showed that type of municipality, building materials, basement and geology have significant effects and respectively describe 6\%, 16\%, 22\%, 39\% of the radon total variability.
Aging Studies of Low pH Cement-Based Materials Used for Aluminum Radioactive Waste Conditioning T.A. Lychagina, D.I. Nikolayev, M. Balasoiu, M. Nicu, L. Ionascu, A.C. Dragolici, F. Dragolici Romanian Journal of Physics 64,
802 (2019)
The microstructure of promising cement-based materials for the conditioning of low and intermediate level radioactive waste (LILW) was studied using neutron diffraction. In order to evaluate the stability of the hardened cement matrix and for taking into consideration the need for long-term durability in disposal conditions, the samples of cement-based materials were measured each year, in the period from 2016 to 2018, at the SKAT instrument in function at the IBR-2 reactor. The sample with the most stable composition was determined.
Neutron Tomography Studies of Cement-Based Materials Used for Radioactive Waste Conditioning S.E. Kichanov, K.M. Nazarov, D.P. Kozlenko, M. Balasoiu, M. Nicu, L. Ionascu, A.C. Dragolici, F. Dragolici, B.N. Savenko Romanian Journal of Physics 64,
803 (2019)
The internal structure of several promising cement-based materials for the conditioning of low and intermediate level radioactive waste (LILW) were studied using neutron tomography in order to assess the effectiveness and stability of the hardened cement matrix, taking in consideration the need for long term durability in disposal conditions. The spatial distributions of water-containing pores, as well as the arrangement of pores and cracks inside the studied cement-based matrices, were determined on the base of specific interactions of neutrons with various components of the cement samples and the application of modern mathematical algorithms for three-dimensional imaging data analysis. The distributions of the water-containing pores, the lengths and thicknesses of the selected cement-based samples were put in evidence, being a case study for optimizing the concrete matrix to be validated and further applied in the radwaste conditioning.
Assessment of Chemical Parameters and Natural Radionuclides Concentrations in Carbonated Natural Mineral Water and Contribution to Radiation Dose Ion Ion, Alina Catrinel Ion, Marian Romeo Calin, Ileana Radulescu, Daniela Bogdan Romanian Journal of Physics 64,
804 (2019)
This study has great importance for assuring the quality of natural mineral waters especially regarding the radioactivity concentration: highlighted in the Council Directive 2009/54/EC of June 2009 and Council Directive 2013/51/Euratom of October 2013 on the exploitation and marketing of natural mineral waters, laying down requirements for the protection of the health of the general public with regard to radioactive substances in water intended for human consumption. Seasonal influence over the chemical composition due to long period of water sample collection was studied regarding the major-ion composition and possible rain infiltrations. In this regard, strong correlations were found between Ca$^{2+}$, Mg$^{2+}$ and HCO$_{3}^{-}$ content for the present sample collection. The activity concentrations of gross alpha and gross beta, of $^{40}$K and from natural decay chains of $^{238}$U, $^{232}$Th were determined, as well as the associated effective dose for these radionuclides. The results obtained for the effective doses calculated for an adult member in Romania, derived from the intake of naturally occurring radionuclides in water vary between: 1.24-2.08 ($\upmu $Sv/yr) for $^{40}$K; 0.90–3.45 for $^{238}$U; 1.00–7.21 ($\upmu $Sv/yr) for $^{232}$Th and 11.24–46.00 ($\upmu $Sv/yr) for $^{226}$Ra. The obtained values are below the World Health Organization (WHO) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) recommended reference levels.
The Contribution of the Natural Radionuclides to the Radiological Hazard at the National Radioactive Waste Repository Baita-Bihor, Romania Liviu C. Tugulan, Octavian G. Duliu, Felicia N. Dragolici, Calin Ricman Romanian Journal of Physics 64,
805 (2019)
To determine at which extent the remained radioactive rocks pose a treat to workers, high-resolution gamma spectrometry was used to estimate the contribution of the natural radionuclides $^{40}$K and $^{232}$Th and $^{238}$U radioactive series to the annual effective dose within the National Radioactive Waste Repository Baita, Bihor County, Romania. By using the activity to dose conversion coefficients as recommended by United Nations Scientific Committee on the Effects of Atomic Radiation Report (2012), the final results obtained for the annual dose due to natural radionuclides showed values between 0.29 $\pm $ 0.09 and 1.98 $\pm $ 0.14 mSv/y with an average value of 0.46 $\pm $ 0.45 mSv/y, values which are significantly lower than the thermoluminescence dosimeter (TLD) results previously reported of 1.55 $\pm $ 0.11 mSv/y. The relatively steadiness of the total annual effective dose distribution within repository as previously determined by TLD as well as its average value higher than those due to natural radioactivity of the Repository rocks points towards a significant contribution of the radon as well as of the radioactive waste. Notwithstanding this fact, as the access in Repository is allowed few days in an year and restricted to authorized personnel, the annual effective dose is well below 1 mSv/y so any health threat to Repository workers could be consider as negligible.
Characterization and Discrimination of Plant Fossils by ATR-FTIR, XRD and Chemometric Methods Steluţa Gosav, Antoaneta Ene, Magdalena Aflori Romanian Journal of Physics 64,
806 (2019)
In this paper we have investigated some samples of fossil leaves and their related mineral matrices using Attenuated Total Reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD) and Cluster Analysis and Principal Component Analysis chemometric methods. By using ATR-FTIR technique, we have identified the presence of organic and inorganic chemical groups in the studied samples. The organic carbon, derived from the decomposition of plants, was identified in ATR-FTIR spectra of fossil leaf samples by the presence of two sharp absorption peaks at around 2926 and 2852 cm$^{-1}$ which had a higher intensity than those of the mineral matrix. An improvement of the discrimination power between the biotic and abiotic materials by using ATR-FTIR spectra in combination with chemometrics was achieved. Also, the mineralogical and elemental composition of the samples obtained by XRD technique is discussed.
Potential Vorticity Dynamics and Tropopause Fold M.D. Andrei, M. Pietrisi, S. Stefan Romanian Journal of Physics 64,
807 (2019)
Extra tropical cyclones evolution depends a lot on the dynamically and thermodynamically interactions between the lower and the upper troposphere. The aim of this paper is to demonstrate the importance of dynamic tropopause fold in the development of a cyclone which affected Romania in 12$^{\mathrm {th}}$ and 13$^{\mathrm {th}}$ of November, 2016. The coupling between a positive potential vorticity anomaly and the jet stream has caused the fall of dynamic tropopause, which has a great influence in the cyclone deepening. This synoptic situation has resulted in a big amount of precipitation and strong wind gusts. For the study, ALARO limited area spectral model analyzes ({\em e.g.}, 300 hPa Potential Vorticity, 1,5 PVU field height, 300 hPa winds, mean sea level pressure), data from the Romanian National Meteorological Administration meteorological stations, cross-sections and satellite images (water vapor and RGB) were used. Accordingly, the results of this study will be used in operational forecast, for similar situations which would appear in the future, and can improve it.
Applied and Interdisciplinary Physics
Ion Beam Irradiation Effects in KINTEX-7 FPGA Resources L.N. Cojocariu, V.M. Placinta Romanian Journal of Physics 64,
901 (2019)
A comprehensive set of measurements has been pursued by our group to detect and characterize Single Event Upsets (SEUs) at the level of configuration memory (CRAM) and other logic resources on the chip such as random-access memory (BRAM) or user-accessible Flip-Flop registers (FFs). The device under study was a Xilinx Kintex-7 Field Programmable Gate Array (FPGA) build on TSMC’s 28 nm technology node. Careful attention was given to the device behaviour when the integrity of its configuration memory was corrupted due to SEU occurrence. The device sensibility to its configuration corruption due to the SEU was further investigated employing SEM IP core as a primary mitigation solution for CRAM integrity. Both software and electrical parameters have been recorded with a custom-made radiation hardness qualification test bench. The SEU rates and cross-sections were determined based on data collected during test beam sessions using several ion species with different Linear Energy Transfer (LET).
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