Volume 59, Number 12, 2014
Mathematical and Theoretical Physics
Application of Extended tanh Function Method on KdVBurgers Equation with Forcing Term Reza Abazari Romanian Journal of Physics 59,
311 (2014)
In this paper, with the aid of a symbolic computation system such as Maple, an extended Tanh function method is applied to determine the exact solutions for KdVBurgers equation with forcing term. Several new soliton solutions and periodic solutions can be obtained if we take some special parameters in these solutions. The employed methods are straightforward and concise, and they can also be applied to other nonlinear evolution equations arising in mathematical physics problems.
A New Class of Accelerating Cosmological Models with Variable G & Λ in Sáez and Ballester Theory of Gravitation Chanchal Chawla, R.K. Mishra, Anirudh Pradhan Romanian Journal of Physics 59,
1225 (2014)
The physical behavior of cosmological solutions to Einstein’s field equations for a spatially homogeneous and anisotropic Bianchi typeI spacetime have been investigated by taking into account the affect of time varying cosmological parameters viz., gravitational constant ($G$), cosmological constant ($\Lambda$) and deceleration parameter ($q$) in scalartensor theory of gravitation proposed by Sáez and Ballester (Phys. Lett. A 113:467, 1986). The concept of time dependent deceleration parameter with some proper assumption yields the average scale factor $a(t) = (\sinh(\alpha t))^{\tfrac{1}{n}}$ , with $n$ and $\alpha$ being positive constants. For $0 < n \le 1$, this generates a class of accelerating models while for $n > 1$, universe models exhibit phase transition from early decelerating phase to present accelerating phase which is corroborated with the results from recent astronomical and astrophysical observations. Moreover, the variability of $G$ has been assumed via the relation $8\pi G \propto a^m$ ($m$ being positive constant) while the time varying behavior of $\Lambda$ has been derived. It is observed that $\Lambda$ is a positive decreasing function of time, which is in good agreement with the results from recent Supernovae Type Ia observations. Some physical and geometric properties of the model along with physical acceptability of cosmological solutions have been discussed in detail.
Homotopy Analysis Method for Solving Coupled Ramani Equations A. Jafarian, P. Ghaderi, Alireza K. Golmankhaneh, D. Baleanu Romanian Journal of Physics 59,
2635 (2014)
In this manuscript, coupled Ramani equations are solved by means of an analytic technique, namely the homotopy analysis method (HAM). The HAM is a capable and a straightforward analytic tool for solving nonlinear problems and does not need small parameters in the governing equations and boundary/initial conditions. The result of this study presents the utility and sufficiency of HAM method. Comparisons demonstrate that there is a good agreement between the HAM solutions and the exact solutions.
Local Fractional Variational Iteration Method for Diffusion and Wave Equations on Cantor Sets XiaoJun Yang, Dumitru Baleanu, Yasir Khan, S.T. MohyudDin Romanian Journal of Physics 59,
3648 (2014)
In this work, the local fractional variational iteration method is employed to handle the subdiffusion and wave equations and the analytical solutions are obtained. The present method is efficient and implicit to investigate the differential equations with the local fractional derivatives.
Quantum Criticality of Two Generalized Dicke Models: with Either Quadratic Field Terms or with DipoleDipole Interaction Yueming Wang, Minglong Zhao Romanian Journal of Physics 59,
4956 (2014)
In this work we analytically derived the critical behavior of zerotemperature quantum phase transition for two generalized Dicke models: one model includes quadratic field terms (the $A^2$term) and the other one has dipoledipole interaction. It was pointed out that both the $A^2$term and dipoledipole interaction lead to a corrected position of the critical point, amounting to inducing a shift of radiation field frequency and atomic transition frequency.
A Regular Black Hole in the Braneworld Alexis Larranaga, Carlos Benavides, Christian Rodriguez Romanian Journal of Physics 59,
5764 (2014)
We find a new black hole solution in RandallSundrum II braneworld scenario in the presence of an anisotropic perfect fluid in the brane inspired by the noncommutative geometry, thought to be an effective description of a quantumgravitational spacetime. We find that the curvature singularity at the origin is smeared out by the noncommutative fluctuations and study the horizon structure to show that the geometry admits two, one or no horizon depending on the value of the mass parameter M with respect to two threshold masses which depend on the noncommutative geometry induced minimal length. On the thermodynamics side, we show that the black hole temperature, instead of a divergent behaviour at small scales, admits both a minimum and a maximum value, before cooling down towards a zero temperature remnant.
Matter Collineations of BKSType Spacetimes M. Salti, M. Korunur, I. Acikgoz, F. Binbay, N. Pirinccioglu Romanian Journal of Physics 59,
6578 (2014)
In the present work, we classified the BKStype (we refer to BianchiKantowskiSachs type spacetimes collectively as the BKStype spacetimes) spacetimes (Bianchi typeV, Bianchi typeVI (m), Bianchi typeVII(m), KantowskiSachs) according to their matter collineations when the energymomentum tensor is degenerate and also when it is nondegenerate. We find that the dimension of matter collineations is infinite and we have improper matter collineations for the degenerate case (there are seven possibilities make the energymomentum tensor to be degenerate). Next, for the nondegenerate case of the energymomentum tensor, we obtain proper matter collineations and find the dimension of the group is finite.
A Note on Classification of Teleparallel Conformal Vector Fields in Bianchi TypeI SpaceTimes in the Teleparallel Theory of Gravitation Ghulam Shabbir, Hina Khan Romanian Journal of Physics 59,
7985 (2014)
Nuclear Physics
Weakly Bound Neutron Rich C Isotopes within RMF+BCS Approach G. Saxena, D. Singh Romanian Journal of Physics 59,
8694 (2014)
In the present investigations we have employed relativistic meanfield plus BCS (RMF+BCS) approach to carry out a systematic study for the ground state properties of eveneven C Isotopes. One of the prime reasons of this study has been to look into the role of low lying states in neutron rich region near neutron drip line. It is found that the occupancy of weakly bound neutron single particle states having zero orbital angular momentum ($l = 0$) with a well spread wave function due to the absence of centrifugal barrier, helps to cause the occurrence of nuclei with widely extended neutron density. Such nuclei are found to have characteristically very small twoneutron separation energy and large neutron r.m.s. radius akin to that observed in weakly bound systems.
The Role of the Core Polarization on C2 and C4 from Factors of fpShell Nuclei Fouad A. Majeed, Fatima M. Hussain Romanian Journal of Physics 59,
95105 (2014)
Inelastic electron scattering form factors for $fp$shell nuclei ^{42}Ca, ^{44}Ca, ^{46}Ti, ^{48}Ti, ^{50}Cr and ^{54}Fe are investigated taking into account higher energy configurations outside the $fp$shell. Higher energy configurations, which are called core polarization (CP) effects, are included through a microscopic theory that includes excitations from the core $1s1p$, $2s1d$ orbits and also from $2p1f$ shell to the higher allowed orbits with $6\hbar\omega$ excitations. The calculations are performed in the $FP$ model space by employing GXPF1 and FPD6 effective interactions while the core polarization are calculated with SkyrmeHartree Fock (Skx) and harmonic oscillator (HO) as residual interactions. The predicated total form factors are compared with the available experimental data and it is shown that the inclusion of the higher excited configuration are very essential in both the transition strength and momentum transfer dependence to obtain reasonable description of the data with no adjustable parameters.
Investigation of the Degeneracy Effect in Fast Ignition for Heterogeneous Fuel M. Mahdavi, B. Kaleji Romanian Journal of Physics 59,
106118 (2014)
In a fast ignition regime, with the conditions of highdensity and lowtemperature, the degenerate plasma can be obtained during the compression phase. In this paper, the effect of degeneracy in the energy transmitted from ions to electron collisions and in the radiation emissions from electrons is studied. The fuel ignition, propagating burn and the target energy gain for a typical fuel are calculated using the governing equations for ions and electrons in twonodes model, the hot spot with D/T fuel in node 1 and the cold fuel surrounding ignitor with D/^{3}He in node 2 by evaluating the degeneracy effect. In the obtained extremum ignition conditions, the target gain, minimum ignition temperature and the areal density of the hot spot are obtained as 145, 5 keV and 5.4 g/cm^{2}, respectively.
Medical Physics
Metrological Traceability Assurance in Production and Use of Radiopharmaceuticals for PET Imaging and Targeted Radiotherapy M. Sahagia, A. Luca, R. Ioan, A. Antohe, C. Ivan, B. Neacşu Romanian Journal of Physics 59,
119130 (2014)
The paper presents the implication of the Radionuclide Metrology Laboratory (RML) from IFINHH in solving the problems connected with the quality assurance of radiopharmaceuticals in production and use, by assuring the metrological traceability in the control of the radiometrological parameters: measurement of activity and radioactive concentration, radionuclide purity as well as measurement of the decay scheme parameters. The following problems are treated: (i) Absolute standardization of PET radionuclides: ^{64}Cu and ^{68}Ga and study of their decay scheme parameters; absolute standardization of radionuclides used in targeted  molecular radiotherapy (MRT): ^{153}Sm, ^{177}Lu, ^{186,188}Re and ^{89}Sr; calibration of the secondary standard ionization chamber and of some commercial radionuclide calibrators. (ii) Radionuclide purity analysis and its influence on the activity calculation. The aspects presented are an overview of published papers.
Elementary Particle Physics
Simulation of the Zenith Angle Dependence of Cosmic Muon Intensity in Slanic Salt Mine with GEANT4 Mehmet Bektasoglu, Halil Arslan Romanian Journal of Physics 59,
131139 (2014)
We have investigated the zenith angle distribution of muon intensities at three different depths of Slanic salt mine for the first time, using GEANT4 simulation package. Two of the locations, namely Level 8 of active Cantacuzino mine (188 m below the ground) and the touristic mine Unirea (210 m below the ground), are already accessible for different purposes including cosmic muon flux measurements. The other location (300 m below the ground) is not accessible yet, but an excavation is under consideration to house detector components of the proposed project LAGUNA. The medium that the primary cosmic muons were injected upon was simulated to be made of salt (NaCl) and muon intensities were recorded for each selected location below the ground. The exponent $n$ was extracted for each depth in salt by fitting the zenith angle distributions of muon intensities with the function $m \cos^n(\theta)$. The $n$ values were found to be $n_U = 2.86 \pm 0.09$, $n_C = 2.53 \pm 0.10$ and $n_L = 2.65 \pm 0.16$ for Unirea, Cantacuzino and the proposed excavation of LAGUNA, respectively. Results of these simulations can be checked with the results of future experiments to be performed at the site.
Thermal Properties of the Heavy Axial Vector Quarkonia E. Veli Veliev, K. Azizi, H. Sundu, G. Kaya Romanian Journal of Physics 59,
140154 (2014)
Using the additional operators coming up at finite temperature, we calculate the masses and decay constants of the $P$ wave heavy axialvector $\chi_{b1}$ and $\chi_{c1}$ quarkonia in the framework of thermal QCD sum rules. In the calculations, we take into account the perturbative two loop order $\alpha_s$ corrections and nonperturbative effects up to the dimension four condensates. It is observed that the masses and decay constants almost remain unchanged with respect to the variation of the temperature up to $T \simeq 100$ MeV, however after this point, the decay constants decrease sharply and approach approximately to zero at critical temperature. The decreasing in values of the masses is also considerable after $T \simeq 100$ MeV.
Condensed Matter
Fabrication and DC Characterizations of AlGaN/GaN High Electron Mobility Transistors with Undoped and Doped Donor Layers A. Hamdoune Romanian Journal of Physics 59,
155162 (2014)
Two AlGaN/GaN high electron mobility transistors (HEMTs) were fabricated, one of them had an undoped AlGaN donor layer and the second one had an ndoped AlGaN donor layer; and then they were characterized. With 0.15 µm gatelength and 75 µm gatewidth; the first device exhibited a maximum saturated drain current of 52.5 mA, a threshold voltage of –6 V, a maximum transconductance (g_{m}) of 115 mS/mm at –3.7 V gate bias, and a turnon voltage of 0.4 V. The second one exhibited a maximum saturated drain current of 78 mA, a threshold voltage of –9 V, a maximum transconductance of 150mS/mm at –7 V gate bias, and a turnon voltage of 1.25 V.
Environmental Physics
Assessment of Annual and Seasonal Variation of Indoor Radon Levels in Dwelling Houses from Alba County, Romania L.E. Muntean, C. Cosma, A. Cucos (Dinu), T. Dicu, D.V. Moldovan Romanian Journal of Physics 59,
163171 (2014)
Indoor radon was measured during four seasons in 12 houses and 7 blocks of flats respectively, with the alpha track CR39 detector. The passive track detectors were exposed for four consecutive intervals of three months each in order to find out the annual average of radon concentration and the correction factors corresponding to the intervals and zones of exposure. A comparison of the correction factors proposed by Cosma et al. (2009) and those proposed by Miles in the amended HPA protocol was also performed. The annual indoor radon concentration was 105±52Bq/m^{3}, a value in agreement with the results previously reported for the Transylvania area (115 Bq/m^{3}, 126 Bq/m^{3} respectively). In order to assess the relative indoor radon concentration we calculated the variation coefficient (CV), ranging between 0 and 85%, with an arithmetic average of 35.7%. The paper also presents the dependency of indoor radon on seasonal variations; the results highlighted significant differences between indoor radon in various seasons.
Assessement of Indoor Radon, Thoron and Their Progeny in Dwellings of Bareilly City of Northern India Using Track Etch Detectors Deepak Verma, M. Shakir Khan Romanian Journal of Physics 59,
172182 (2014)
The levels of radon, thoron and their progeny in the dwellings of Northern India have been determined by using twin chamber dosimeter cups. The concentrations of radon and thoron were found to vary from 16.62–155.12 Bq/m^{3} and 4.16–24.93 Bq/m^{3}. Their progeny concentrations were found to vary from 1.80–16.77 mWL and 0.112–0.674 mWL. The values of life time fatality risk and annual effective dose were found to vary from 0.24 x 10^{4}–1.21 x 10^{4} and 0.31–2.78 mSv/y, respectively. The variation in the above parameters strongly influenced by the type of dwelling construction and their ventilation conditions.
