020226   Gaur N K;Srivastava A (Physics Dep, Barkatullah University, Bhopal-462 026, Email: archanasaran@rediffmail.com ) : Low temperature properties of La2/3Ba1/3MnO3 perovskite manganite. Indian J pure appl Phys 2008, 46(6), 451-3.

The evolution of cohesive and thermal properties of La_2/3Ba_1/3MnO₃ perovskite manganite was studied as a function of temperature (1K ≤ T ≤ 10K) by means of Rigid Ion Model (RIM). The heat capacity as a function of temperature computed from this model are, generally, in good agreement with their available experimental data measured with relaxation calorimetry technique. In addition, the results on the cohesive energy (φ), molecular force constant (f), Restrahalen frequency (v_o), Debye temperature (ΘD) and Gruneisen parameter (g) are also reported.

020225   Gangwar S P;Gangwar R P S;Kanaujia B K;Paras (Electronics and Communication Engineering Dep, S R M S College of Engineering & Technology, Bareilly-243 202, Email: bkkanaujia@yahoo.co.in ) : Resonant frequency of circular microstrip antenna using artificial neural networks. Indian J Radio Space Phys 2008, 37(3), 204-8.

Novel method of using artificial neural networks (ANNs) for the calculation of the resonant frequency of electrically thick and thin circular microstrip patch antenna has been adopted in this paper. It is useful for the computer-aided design (CAD) of microstrip antennas. The results obtained using ANNs are compared with the measured and calculated values reported by other authors. The theoretical resonant frequency values obtained using ANNs are in very good agreement with measured and calculated values reported by other researchers.

020224   Gahtori B;Lal R;Agarwal S K;Das A;Chakraborty T;Rao A (Superconductivity Div, National Physical Laboratory, New Delhi-110 012, Email: bhaskergahtori@yahoo.co.in) : Superconducting transition temperature of co-doped Y_0.95Pr_0.05Ba₂(Cu_1-xMn_x)₃ O_7-δ superconductors for x ≤ 0.02. Indian J pure appl Phys 2008, 46(8), 575-9.

Values of the superconducting transition temperature T_c extracted from the resistivity and ac susceptibility of Y_0.95Pr_0.05Ba₂(Cu_1-xMn_x)₃O_{7- δ} (x ≤ 0.02) are found to follow the same qualitative variation with the Mn content. Both lead, in particular, to lower T_c for the x=0.005 sample than those of the x=0.0, 0.0075 and 0.01 samples. Comparing T_c with difference of resistivities with and without Pr for various x, it has been argued that electronic effects dominate over the potential scattering in suppressing T_c below x=0.02. Superconducting volume fraction f_g (as deduced through imaginary part χ" of the ac susceptibility at the peak temperature) when considered in conjunction with the average grain size for the =0.005 sample, indicates that the smaller size of the grains in =0.005 sample leads to stronger fluctuations. This is an additional source for the larger T_c degradation in the x=0.005 sample.

020223   Gadani D H;Vyas A D (NO, C U Shah Science College, Ashram Road, Ahmedabad-380 014, Email: dhgadani@yahoo.com ) : Measurement of complex dielectric constant of soils of Gujarat at X- and C-band microwave frequencies. Indian J Radio Space Phys 2008, 37(3), 221-9.

Dielectric constant and dielectric loss of soils collected from different districts of Gujarat state for various moisture contents have been measured at X- and C-band microwave frequencies. It has been observed that the dielectric constant of soils depend on the moisture content in the soils and frequency of measurement. Dielectric constant of soils increases slowly with increase in the moisture content in the soil up to the transition moisture, after which it increases rapidly with moisture content. The measured values of complex permittivity of dry and wet soils are compared with the values calculated from the empirical models and are found to be in agreement. The observed complex permittivity is used to calculate emissivity of soils for various moisture contents. It has been found that emissivity of soils decreases with increase in moisture content in the soil.

020222   El-Kheshen A A;El-Batal F H;Marzouk S Y (Glass Research Dep, National Research Centre, Dokki, Cairo,Egypt, Email: aelkheshen1@yahoo.com) : UV-visible, infrared and Raman spectroscopic and thermal studies of tungsten doped lead borate glasses and the effect of ionizing gamma irradiation. Indian J pure appl Phys 2008, 46(4), 225-38.

Ultraviolet-visible, infrared and Raman spectroscopy together with thermal properties were measured for undoped and WO₃ - doped (up to 10%) lead borate glasses. Also, the effect of gamma irradiation was followed by UV-visible measurements. The UV-visible spectrum of the undoped glass reveals before irradiation intense ultraviolet bands due to the combined effects of trace iron impurities (Fe³⁺) and Pb²⁺ ions which remain unchanged with the addition of WO₃. Infrared and Raman measurements show characteristic bands due to borate group and the possible sharing of lead-oxygen and tungsten-oxygen groups. The studied glasses show obvious resistance to gamma irradiation. The thermal and density data are correlated with the introduction of highly polarizable and heavy (W⁶⁺) ions and to the change in structural arrangement with varying glass composition.

020221   El-Badry B A;Zaki M F;Hegazy T M;Ahmed Morsy A (Physics Dep, Univ Coll for Girls, Ain Shams Univ, Cairo, Egypt) : Neutron response study using poly allyl diglycol carbonate. Pramana J Phys 2007, 69(4), 669-74.

The results of an experimental work aimed at improving the performance of the CR-39 nuclear track detector for neutron dosimetry applications are reported. A set of CR-39 plastic detectors was exposed to ²⁵²Cf neutron source, which has the emission rate of 0.68 x 10⁸s^-1, and neutron dose equivalent rate 1 m apart from the source is equal to 3.8 mrem/h. The detection of fast neutrons performed with CR-39 detector foils, subsequent chemical etching and evaluation of the etched tracks by an automatic track counting system was studied. It is found that the track density increases with the increase of neutron dose and etching time. The track density in the detector is directly proportional to the neutron fluence producing the recoil tracks, provided the track density is in the countable range. This fact plays an important role in determining the equivalent dose in the field of neutron dosimetry. These results are compared with previous work. It is found that our results are in good agreement with their investigations.

3 illus, 1 table, 20 ref

020220   Dubey R K;Menon V J;Tripathi D N (Physics Dep, Banaras Hindu University, Varanasi-221 005, Email: jayaram_bhu@yahoo.co.in) : Rigorous treatment of scattering by quantum zero-range interactions. Indian J pure appl Phys 2008, 46(5), 295-305.

New rigorous treatment of solving the Schr”dinger scattering equation for a general contact potential U(χ) has been developed. It is proved that if U(χ) is regarded as a distribution characterized by a tiny length scale b then the wave function Ψ and its derivative Ψ' become continuous across the apparent singular point χ = 0. Hence, the reflection and transmission coefficients can be constructed for many cases namely usual d(δ), controversial δ'(χ) and entirely new quasi δ'(χ) interactions.

020219   Dhurandhar H;Shanker Rao T L;Lad K N;Arun Pratap (Condensed Matter Physics Lab, Applied Physics Dep, Faculty of Technolo, M S University of Baroda, Vadodara-390 001) : Thermodynamic properties of magnetic liquid metals in undercooled region. Indian J pure appl Phys 2008, 46(6), 371-4.

The experimental study of the thermodynamic properties of liquid metals has been confined usually to the stable liquid range of temperature and pressure. Nevertheless, there is a significant range between the melting point and the glass transition over which the liquid state can exist in a metastable equilibrium provided that crystallization can be avoided. The specific heat of undercooled liquid metals is a very important thermodynamic parameter. Appropriate knowledge of ΔC_p^l-x i.e. the difference of specific heats of undercooled liquid and the corresponding crystalline solid can be utilized to derive accurate results for the parameters like ΔG, ΔS and ΔH. However, the experimental determination of C_p in undercooled system is difficult due to its metastable nature. Still, it is possible to arrive at an expression for the ΔC_p^l-x, if the value of ΔC_p^m i.e. specific heat difference at melting point and the nature of variation of ΔC_p^l-x in undercooled region can be estimated. The ΔG for pure liquid Co and Ni have been estimated using linear temperature dependence of ΔC_p in the undercooled region. Further, a general expression has been used which is valid in a large temperature range. The calculated results for ΔG are in excellent agreement with experimental data. Other thermodynamic parameters like ΔS and ΔH are also evaluated.

020218   Dey T K (Postgraduate Department of Physics, L S College, B R A Bihar University, Muzaffarpur-842 001, Email: tkdeyphy@gmail.com) : Theory for transport properties of non-spherical molecules of molecular fluids. Indian J pure appl Phys 2008, 46(6), 403-5.

The transport properties of molecular fluids of non-spherical molecules via the Gaussian overlap potential with constant energy have been studied using perturbation method with a non-spherical reference system. Using Verlet-weis method, the effective diameter and radial distribution function have been derived. The theory is applied to calculate the transport properties such as shear viscosity and thermal conductivity of benzene. In all these cases, the agreement is found to be fairly good.

020217   Dey R M;Pandey M;Bhattacharyya D;Patil D S; Kulkarni S K (Physics Dep, Pune Univ, Pune-411 007, Email: ravi@physics.unipune.ernet.in) : Diamond like carbon coatings deposited by microwave plasma CVD:XPS and ellipsometric studies. Bull Mater Sci 2007, 30(6), 541-6.

Diamond-like carbon (DLC) films were deposited by microwave assisted chemical vapour deposition system using d.c. bias voltage ranging from -100 V to -300 V. These films were characterized by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry techniques for estimating sp³/sp² ratio. The sp³/sp² ratio obtained by XPS is found to have an opposite trend to that obtained by spectroscopic ellipsometry. These results are explained using sub-plantation picture of DLC growth. The results clearly indicate that the film is composed of two different layers, having entirely different properties in terms of void percentage and sp³/sp² ratio. The upper layer is relatively thinner as compared to the bottom layer.

5 illus, 2 tables, 17 ref

020216   Deshmukh S H;Burghate D K;Shilaskar S N; Chaudhari G N;Deshmukh P T (Postgraduate Department of Physics, Shri Shivaji Science College, Amravati-444 603) : Optical properties of polyaniline doped PVC-PMMA thin films. Indian J pure appl Phys 2008, 46(5), 344-8.

Optical transmission and UV-VIS absorption spectra have been recorded in the wavelength range 450-1000 nm for different compositions of polyaniline doped PVC-PMMA thin films. The absorption coefficient (α), optical energy gap (E_opt), refractive index (n₀), optical dielectric constant (ε_∞'), constant B and ratio of carrier concentration to the effective mass (N/m*) have been evaluated. The effects of doping percentage of polyaniline on these parameters have been discussed and the nonlinear behaviour for all the parameters are investigated.

020215   Dandekar S S;Kelkar D S (Physics Dep, Institute of Science, Nagpur, Email: sushama_3sep@yahoo.co.in) : Application of polypyrrole as an electromagnetic interference shielder. Indian J pure appl Phys 2008, 46(3), 215-6.

Pyrrole has been polymerized chemically using FeCl₃ as an oxidizing agent on the substrate of nylon-6 film. Electromagnetic interference (EMI) studies are conducted on polypyrrole film (10 x 10 cm size; 35-40 μm thick) which was fabricated into the square shape. The EMI test is conducted in the frequency range 100-10000 MHz as per MIL STD-285. Attenuation values(db) obtained at various frequencies are recorded. The results indicate that the attenuation values are reaching a maximum of about 3 db at 200 and 3000 MHz. EMI shielding effectiveness (EMI SE) has also been found to be a function of thickness of polypyrrole film. The values of EMI SE are calculated and found to be 2.1 db for 0.004 cm thick film of polypyrrole.

020214   Choudhury N;Sarma B K (Physics Dep, Pub Kamrup College, Baihata Chariali-781 381) : Structural characterization of nanocrystalline PbS thin films synthesized by CBD method. Indian J pure appl Phys 2008, 46(4), 261-5.

Nanocrystalline PbS thin films have been deposited on glass substrates by Chemical Bath Deposition (CBD) technique using polyvinyl alcohol (PVA) in the preparation of matrix solution. Four matrix solutions with four different molarities (0.25 to 1.00) of lead acetate are used to deposit the films. The X-ray diffractograms of the samples show preferred orientation along (111) and (200) planes. The crystallite sizes of the films are found to vary from 2.0 to 4.4 nm. The crystallites are found to be under strain which varies between 1.33 x 10^-1 and 0.32 x 10^-1. The bandgaps of the nanocrystalline PbS are determined from UV spectrograph and are found to be with in the range 1.9-2.6 eV. The morphological properties of the films are determined by Scanning Electron Microscopy (SEM).

020213   Chauhan C K;Joseph K C;Parekh B B;Joshi M J (NO, Saurashtra University, Rajkot-360 005, Email: mshilp24@rediffmail.com) : Growth and characterization of struvite crystals. Indian J pure appl Phys 2008, 46(7), 507-12.

Struvite or ammonium magnesium phosphate hexahydrate (AMP) containing urinary stones are infection stones associated with urea splitting organisms, which are more common in women. Struvite crystals having different morphologies were grown by single diffusion gel growth technique in silica gel. The crystals were characterized by powder XRD, FT-IR, TGA and dielectric study. Kinetic and thermodynamic parameters were evaluated from thermogram. Dielectric study showed that the value of dielectric constant is found to decrease as the frequency increased. The ac resistivity and ac conductivity were also evaluated at different frequency.

020212   Chanda A;Verma S;Jacob C (Materials Science Centre, Indian Institute of Technology, Kharagpur-721 302, Email: cxj14_holiday@yahoo.com) : Etching of GaAs substrates to create As-rich surface. Bull Mater Sci 2007, 30(6), 561-5.

Several different cleaning procedures for GaAs (100) substrates are compared using X-ray photo-electron spectroscopy and optical microscopy. This work emphasizes the effect of the last etching step: using either IIC1, HF-ethanol (5<128>% or static deionized water after IIC1 cleaning. All the procedures except HCl solution (1:1) produce an As-rich surface. Also, none of the etchants except HF-ethanol solution produce Ga or As-rich (oxide free) surfaces. Optical microscopic study shows different etch pits produced due to etching in different solutions.

7 illus, 2 tables, 13 ref

020211   Chanchal;Garg A K (Physics Dep, N A S College, Meerut-250 001, Email: chanchalakg05@rediffmail.com) : MREI-model calculations for layered mixed crystals of the series Hf S_2-xTe_x (0≤χ≤2). Indian J pure appl Phys 2008, 46(5), 330-3.

Optical phonon frequencies for IR active modes have been calculated for layered mixed crystals in the series Hf S_2-xTe_x (0≤χ≤2) using MREI-model. The model is simple and involves only two adjustable parameters. Various force constants and the values of local and gap modes have been reported. The model has been found to work reasonably well and the calculated values agree with the experimental values.

020210   Boopathy K;Nesaraj A S;Rajendran V (Physics Dep, Government College of Engineering, Salem-636 011, Email: boopathy_gce@yahoo.co.in) : Preparation, characterization and sintering behaviour of Sr doped PbZrO₃ powders by self-propagating combustion method. Indian J pure appl Phys 2008, 46(4), 270-5.

Sr doped PbZrO₃ (Pb_1-xSr_xZrO₃ ; x=0, 0.05, 0.10, 0.15 and 0.20) ceramics have been prepared by glycine-nitrate self-propagating combustion technique. The ceramic powders have been heat treated at 800°C for 6 h in order to get phase pure compounds. The prepared powders are characterized by XRD, density and BET surface area measurements. The XRD patterns obtained on these powders show the formation of pure orthorhombic phase of PbZrO₃ without any impurities. Thin sections of circular components of these powders, made by uniaxial compression, are subjected to annealing at different temperatures in the range 900-1100°C for 2 h in order to throw light on their sintering behaviour. The surface morphology of the sintered components are studied by SEM.

020209   Bodhaye A;Sanyal S P;Mukovskii Y M (Physics Dep, Barkatullah University, Bhopal-462 026, Email: ashish77kumar@gmail.com) : Structural, magnetic and magneto-resistance properties of La_0.88Ca_0.12MnO₃ single crystals. Indian J pure appl Phys 2008, 46(7), 484-7.

La_0.88Ca_0.12MnO₃ single crystals of high quality have been prepared by using floating zone technique. Their composition and structure are verified using X-ray diffraction and EDAX. The temperature dependence of the resistance along ab-plane and c-axis has been measured in the temperature range 77 K to room temperature in the magnetic fields up to 8 T. The R-T data along ab-plane and c-axis shows a similar behaviour and it is the characteristics of insulating behaviour having the resistance 0.7 MΩ at 90 K and 16.1 Ω at 300 K. The insulating behaviour persists under the magnetic field up to H = 8 T. There is no resistance peak or electronic transition over the whole temperature range studied. However, there is a notable change of resistance at about 120 K, seemingly related to paramagnetic insulator to ferromagnetic insulator transition and is confirmed by magnetization measurement transition at a temperature T_c = 122 K. The sharp peak around the same temperature in the heat capacity measurement indicates the onset of long range ordering. The magnetoresistance measured at different magnetic fields shows similar kind of behaviour with some marginal change in the magnitude along ab-plane and c-axis.

020208   Bhatt N K;Vyas P R;Gohel V B;Jani A R (Physics Dep, Gujarat University, Ahmedabad-380 009, Email: bhattnisarg@hotmail.com) : High-pressure study of Na: a mean-field potential approach. Indian J pure appl Phys 2008, 46(6), 443-6.

Study of anharmonicity through Grneisen parameter is carried out for elemental Na at finite temperatures and pressures. The mean-field potential (MFP) approach has been employed in conjunction with the local pseudopotential to evaluate Helmholtz free energy at elevated temperatures and pressures. The calculated pressure and temperature variation of thermodynamic Grneisen parameter (γth), pressure dependence of isothermal bulk modulus (B_T) and total free energy at T = 300-K have been calculated. Results obtained are satisfactorily compared with the experimental and other first principles data.

020207   Bhagatji A;Nischal N K;Gupta A K;Tyagi B P (Photonics Div, Instruments Research & Development Establishment, Raipur Road, Dehradun-248 008akgupta@irde.res.in) : Fractional order Fourier transform-based fringe-adjusted joint transform correlator. Indian J pure appl Phys 2008, 46(3), 176-86.

Extended fractional Fourier transform (FRT) based fringe-adjusted joint transform correlator (JTC) for real-time target recognition applications has been implemented. In real-time situation, the input scene is captured using a charge-coupled device camera. The joint input images are fractional Fourier transformed and the joint power spectrum (JPS) has been recorded. Thus obtained JPS is multiplied by a pre-synthesized fringe-adjusted filter (FAF) to yield fractional fringe-adjusted JPS (FrFJPS). The FRT based fringe-adjusted JTC (FrFJTC) has been found to yield better results in comparison to the conventional fringe-adjusted JTC (FJTC). Three performance measure parameters; correlation peak intensity, peak-to-correlation energy and peak-to-sidelobe ratio have been calculated. Computer simulation and experimental results are presented.

020206   Barua A G;Bhuyan S (Physics Dep, Gauhati University, Guwahati-781 014, Email: agohainbarua@yahoo.com) : Interaction of 4 μm laser beam with absorption lines of sulphur dioxide. Indian J pure appl Phys 2008, 46(9), 617-20.

Interaction of a free electron laser beam of wavelength 4 μm with rotational lines of sulphur dioxide has been studied. Values of transmittance, averaged over intervals of 0.1 cm^-1, are obtained for absorber thickness 0.01, 0.1 and 1 atm-cm, using the quasi-random model of molecular band absorption. From these values, intensities of the high resolution absorption lines of SO₂ are simulated in the frequency interval 2499.0115 - 2499.9910 cm^-1.

020205   Barman J;Sarma K C;Sarma M;Sarma K (Instrumentation & USIC Dep, Gauhati University, Guwahati, Email: jayanta_barman2006@ yahoo.com) : Structural and optical studies of chemically prepared CdS nanocrystalline thin films. Indian J pure appl Phys 2008, 46(5), 339-43.

Chemical bath deposition (CBD) technique has been used to prepare cadmium sulphide (CdS) thin films for various applications. Structural analysis of the films has been done by using Philips X-Pert PRO system analytical diffractrometer. Data collected by X-pert graphics software are used to identify the crystal structure, phase, grain size and lattice constant of films. XRD data have been obtained for optimizing the growth conditions for deposition. Ultra violet visible (UV-VIS) spectroscopy and scanning electron microscopy (SEM) are used to characterize the sample.

020204   Banerjee P;Suri A K;Suman;Chatterjee A;Datta A (Time and Frequency Section, National Physical Laboratory, New Delhi-110 012) : Evaluation of performance of GPS controlled rubidium clocks. Indian J pure appl Phys 2008, 46(5), 349-54.

Global Positioning System (GPS) controlled rubidium clock systems are now being used widely for many precise timing applications. They also play the role of the reference time and frequency source in many laboratories. This demands the evaluation of performance of such clocks to assess their reliability. For this purpose, a special experimental campaign has been planned. The epoch time has been found to be reliable within 60 ns and frequency offset does not exceed few parts in 10^-12. But the receiver takes few hours to achieve initial lock. Short-term stability in locked condition has been poorer than that of the rubidium clock in free running condition.

020203   Baghmar D;Bhardwaj P;Gupta D C;Gaur N K (Physics Dep, Barkatullah University, Bhopal-462 026, Email: deoshreebaghmar@gmail.com) : Structural phase transition of AgI under high pressure. Indian J pure appl Phys 2008, 46(6), 417-9.

The effect of high pressure over the structural stability of silver iodide (AgI) has been investigated. The structural properties of silver iodide have been calculated using Two Body Potential Model, comprising of Long-Range (L-R) Coulomb and van der Waals interactions and Short-Range (S-R) Hafemeister Flygare (HF) type overlap repulsive interactions. The phase transition pressure (P_t) and relative volume collapse Δ[V(P_t)/V(O)] as a function of pressure calculated by us for zinc-blende (B₃) and tetragonal (B_T) structure are found to be in good agreement with the available experimental data.

020202   Anup Kumar V;Vasudevan Nair N (Physics Dep, M G College, Thiruvananthapuram, Kerala-695 004, Email: anupaparna@yahoo.co.in) : Mossbauer study on the effect of nano-sized titanium substitution in Mn Zn ferrite. Indian J pure appl Phys 2008, 46(6), 432-6.

Manganese zinc ferrites with nano-sized titanium of composition Mn_0.8Zn_0.2Ti_xFe_(2-x)O₄ for x = 0 to 0.2 were synthesized by solid state reaction method. Nanosized titanium was prepared by tartarate gel method. M”ssbauer spectra of these samples were taken at room temperature using Co⁵⁷ source. From the M”ssbauer spectra, the internal magnetic field, isomer shift, quadrupole splitting, recoilless fraction and the Debye temperature of these samples were calculated for the iron nucleus at the two non-equivalent sites. It is observed that addition of titanium decreases the internal magnetic field and also produces changes in the isomer shift of both the sites. The electric quadrupole splitting and recoilless fraction decrease with the increase in titanium concentration. These observed phenomena are interpreted on the basis of super exchange interaction and the reaction between Fe²⁺ and Ti⁴⁺.

020201   Anshu;Rani S;Agarwal A;Sanghi S;Kishore N; Seth V P (Applied Physics Dep, Guru Jambheshwar University of Science & Technology, Hisar-125 001, Email: ans_gju@yahoo.com) : Study of electron paramagnetic resonance in vanadyl doped tungsten lithium borate glasses. Indian J pure appl Phys 2008, 46(6), 382-4.

Glasses with composition xWO₃.(30-x)Li₂O.70B₂O₃ containing 2 mol % V₂O₅ have been prepared over the range 0≤ x≤ 15 (x is in mol % and in steps of 2.5). The electron paramagnetic resonance (EPR) spectra of VO²⁺ in these glasses have been recorded on X-band (v ≈ 9.14 GHz) at room temperature (RT). The spin Hamiltonian parameters, dipolar hyperfine coupling parameter, P and Fermi contact interaction parameter, K, have been calculated. It has been found that V⁴⁺ ions in these glasses exist as VO²⁺ in octahedral coordination with a tetragonal distortion. Results suggest that the tetragonality of the V⁴⁺O₆ complex changes with change in WO₃:Li₂O ratio. Values of theoretical optical basicity have also been calculated.

020200   Amarjit;Gangwar R P S (Electronics and Communication Engineering Dep, College of Technology, G B Pant University of Agriculture and Technology, Pantnagar-263 145) : Finite element approach for evaluation of extinction cross-section of realistically distorted raindrops. Indian J Radio Space Phys 2008, 37(2), 114-20.

Evaluation of extinction cross-sections (ECS) of realistically distorted raindrop is carried out by using finite element method (FEM) on modified Pruppacher-and-Pitter (MPP) raindrop model for horizontal and vertical polarizations in centimeter and millimeter wave frequency range with mean raindrop radii from 0.025 to 0.35 cm. The results obtained from FEM are compared with existing models based on first order perturbation evaluation technique (FOPET) and volume integral equation formulation (VIEF) using MPP. The results obtained are in good agreement with the results of these models with 6% mean variation in horizontal polarization for both the models and 7% and 10% mean variations are observed in vertical polarization in these models respectively.

020199   Ali A;Tariq M;Nabia F (Chemistry Dep, Jamia Millia Islamia (Central University), New Delhi-110 025) : Experimental and predicted viscosities of binary mixtures of benzene and chloroalkanes at different temperatures using Isdale's group contribution method. Indian J pure appl Phys 2008, 46(8), 545-51.

Experimental viscosities, η of pure benzene, 1,2-dichloroethane (DCE), 1,1,2,2-tetrachloroethane (TCE) and those of their binary mixtures, having benzene as a common component, have been measured over the whole composition range at 298.15, 303.15, 308.15, 313.15 and 318.15 K. The experimental η data were then fitted to standard polynomial against composition. Using h values, the deviations in viscosities, Δη , excess Gibbs free energies of activation of viscous flow, ΔG^*E, entropies, ΔS^* and enthalpies, ΔH^* of activation of viscous flow have been calculated. The sign and magnitude of these parameters were found to be sensitive towards interactions prevailing in the studied systems. Further, the excess molar volumes, V^E were calculated using data for both the binary mixtures. Moreover, Grunberg-Nissan and Isdale's group contribution methods have been used to calculate the viscosities of mixtures and the results were discussed in terms of average percentage deviations (APD) in experimentally and theoretically calculated viscosities.

020198   Alaria M K;Srivastava V (Microwave Tubes Area, Central Electronics Engineering Research Institute, Pilani 333 031, Email: mukesh_pilani@yahoo.co.in) : Analysis of a coupled-cavity slow wave structure for a TWT. Indian J Radio Space Phys 2008, 37(2), 139-42.

Describes an approach of designing a coupled-cavity slow wave structure (CC-SWS) for a high power traveling wave tube (TWT) using HFSS code, which is a 3-D high frequency electromagnetic simulator. The criteria of deciding the initial design parameters of a cavity are first discussed. Method of computing the dispersion and impedance characteristics of the CC-SWS has been discussed. Analysis was carried out for single and double-slot CC-SWS with coupling slots. Mesh size was optimized for speed and maximum accuracy. The CPU time on Pentium-4, 2.66 GHz system with 1 GB RAM was less then 25 min for three or four cavities. Results of HFSS are matched with the experimental results for a C-band coupled cavity SWS and also compared with the results of analytical method.

020197   Agrawal P;Parmar P;Mallick R;Bajpai R (Electronics Dep, St. Aloysius College (Autonomous), Jabalpur-482 001, Email: dr_p_agrawal@hotmail.com) : Study of surface morphology and characterization of polymethyl methacrylate:polychlorotrifluoro ethyelene polyblend using SEM, DSC and X-ray diffraction techniques. Indian J pure appl Phys 2008, 46(3), 193-7.

Effect of varying wt % ratio of PMMA:PCTFE polyblends on its surface morphology and structure has been reported. The value of intermediate glass transition temperature of the blend shows a homogeneous blending of the two polymers. The scanning electron micrographs also confirm the homogeneous blending of the two polymers for very low concentration of polychlorotrifluoro ethyelene (PCTFE) in polymethyl methacrylate (PMMA) matrix. The role of PCTFE as plasticizer is confirmed by the decreasing glass transition temperature of the polyblend material with increasing concentration of PCTFE in PMMA matrix. At and after 5 wt % of PCTFE the blend shows heterogeneous surface morphology. Crystallinity of the blends is found to decrease with increasing PCTFE, concentration. X-ray diffractograms and SEM micrographs also show great amount of heterogeneity of the two constituents of PMMA:PCTFE polyblend at 95:5 wt% composition ratio. Appreciable blending and fascinating set of properties are found to be for lower wt% ratio of PCTFE in PMMA matrix.

019359   Zarnecki A F (Institute of Experimental Physics, Warsaw Univ, Hoza 69, 00-681 Warszawa, Poland, Email: Filip.Zarnecki@fuw.edu.pl) : Photon collider beam simulation with CAIN. Pramana J Phys 2007, 69(5), 937-41.

The CAIN simulation program was used to study the outgoing beam profile for the photon collider at ILC. The main aim of the analysis was to verify the feasibility of the photon linear collider running with 20 mrad electron beam crossing angle. The main problem is the distorted electron beam, which has to be removed from the interaction region. It is shown that with a new design of the final dipole, it should be possible to avoid large energy losses at the face of the magnet.

4 illus, 5 ref

019358   Yusoff A R M;Syahrul M N;Henkel K (Physics Dep, University Science Malaysia, Penang, Malaysia, Email: abdrashid_4@yahoo.com) : High resolution transmission electron microscope studies of a-Si:H solar cells. Pramana J Phys 2007, 68(6), 995-9.

Hydrogenated amorphous silicon (a-Si:H) single junction solar cells with high open circuit voltage (V_oc) are fabricated using a wide bandgap boron-doped Si:H p-layer deposited at high hydrogen dilution, low substrate temperature and with H2-plasma treatment that promotes nanocrystalline silicon (nc-Si:H) formation. This paper presents the structure of this p-type material characterized by high resolution transmission electron microscope (HRTEM). It is found that the p-layer that leads to high V_oc a-Si:H solar cells is a mixed-phase material that contains fine-grained nc-Si:H embedded in a-Si:H matrix.

2 illus, 4 ref

019357   Wu S Y;Zhang H M;Lu G D;Zhang Z H (Applied Physics Dep, Electronic Science and Technology Univ of China, Chengdu 610054, People's Republic of China, Email: shaoyi_wu@ 163.corn) : Electron paramagnetic resonance parameters and local structure for Gd<. Pramana J Phys 2007, 69(3), 451-7.

The electron paramagnetic resonance parameters, zero-field splittings (ZFSs) b⁰₂, b⁰₄, b⁴₄, b⁰₆, b⁴₆ and the g factors for Gd³⁺ on the tetragonal Y³⁺ site in KY₃F₁₀ are theoretically studied from the superposition model for the ZFSs and the approximation formula for the g factor containing the admixture of the ground ⁸S_7/2 and the excited ⁶L_7//2 (L=P, D, F, G) states via the spin-orbit coupling interactions, respectively. By analysing the above ZFSs, the local structure information for the impurity Gd³⁺ is obtained, i.e., the impurity-ligand bonding angles related to the four-fold (C₄) axis for the impurity Gd³⁺ center are found to be about 0.6° larger than those for the host Y³⁺ site in KY₃F₁₀. The calculated ZFSs based on the above angular distortion as well as the g factors are in reasonable agreement with the observed values. The present studies on the ZFSs and the local structure would be helpful to understand the optical and magnetic properties of this material with Gd dopants.

1 table, 38 ref

019356   Vasu V;Rama Krishna K;Kumar A C S (Production Engineering Dep, V R Siddhartha Engineering College, Vijayawada-520 007, Email: vvvasu@rediffmail.com) : Analytical prediction of forced convective heat transfer of fluids embedded with nanostructured materials (nanofluids). Pramana J Phys 2007, 69(3), 411-21.

Nanofluids are a new class of heat transfer fluids developed by suspending nanosized solid particles in liquids. Larger thermal conductivity of solid particles compared to the base fluid such as water, ethylene glycol, engine oil etc. significantly enhances their thermal properties. Several phenomenological models have been proposed to explain the anomalous heat transfer enhancement in nanofluids. This paper presents a systematic literature survey to exploit the characteristics of nanofluids, viz., thermal conductivity, specific heat and other thermal properties. An empirical correlation for the thermal conductivity of Al₂O₃ + water and Cu + water nanofluids, considering the effects of temperature, volume fraction and size of the nanoparticle is developed and presented. A correlation for the evaluation of Nusselt number is also developed and presented and compared in graphical form. This enhanced thermophysical and heat transfer characteristics make fluids embedded with nanomaterials as excellent candidates for future applications.

5 illus, 21 ref

019355   Varma R K (Physical Research Laboratory, Navrangpura, Ahmedabad-380 009, Email: ramkvarma@gmail.com) : Quantum manifestation of systems on the macro-scale-the concept of transition state and transition amplitude wave. Pramana J Phys 2007, 68(6), 901-11.

Quantum effects which have usually been associated with micro-scale phenomena can also arise on the macro-scale in situations other than the well-known macro-quantum phenomena of superconductivity and superfluidity. Such situations have been shown here to arise in processes involving inelastic scattering with bound or partially bound systems (not bound in all degrees of freedom), and the macro-quantum behaviour is associated with the state of the total system in transition in the process of scattering. Such a state is designated as a 'transition-state'. It is pointed out that we have already observed such manifestations for a particular system, the charged particles in a magnetic field where interference effects involving macro-scale matter waves along the magnetic field have been reported.

9 ref

019354   Sridhar K (Theoretical Physics Dep, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005, Email: Sridhar@theory.tifr.res.in) : Physics beyond the standard model and cosmological connections: A summary from LCWS06703-06. Pramana J Phys 2007, 69(5), 719-25.

The international linear collider (ILC) is likely to provide us important insights into physics sector that may supersede our current paradigm, viz., the standard model. In anticipation of the possibility that the ILC may come up in the middle of the next decade, several groups are vigourously investigating its potential to explore this new sector of physics. The Linear Collider Workshop in Bangalore (LCWS06) had several presentations of such studies which looked at supersymmetry, extra dimensions and other exotic possibilities which the ILC may help us discover or understand. Some papers also looked at the understanding of cosmology that may emerge from studies at the ILC. This paper summarises these presentations.

31 ref

019353   Spira M;Niezurawski P;Krawczyk M;Zarnecki A F (NO, Baul-Scherrer-Institut, CH-5232 Villigen PSI, Switzerland, Email: maria.krawczyk@fuw.edu.pi) : Heavy neutral MSSM Higgs bosons at the photon linear collider - a comparison of two analyses. Pramana J Phys 2007, 69(5), 931-5.

Measurement of the heavy neutral MSSM Higgs bosons H and A production in the process γγ → A/H → bb at the Photon Linear Collider [1,2] has been considered in two independent analyses for the parameter range corresponding to the so-called 'LHC wedge'. Significantly different conclusions were obtained; signal-to-background ratio 36 vs. 2. Here assumptions and results of these two analyses are compared. It was found that differences in the final results are mainly due to different assumptions on γγ-Iuminosity spectra, jet definitions and selection cuts.

2 illus, 18 ref

019352   Soares B G;Souza F G;Manjunath A; Somashekarappa H;Somashekar R;Siddaramaiah (Institute de Macromoleculas, Universidade Federal do Rio de Janeiro, Centre de Tecnologia, Bl. J, Ilha do Fundo, 21945-970. Rio de Jeneiro, RJ, Brazil, Email: rs@uomphysics.net) : Variation of long periodicity in blends of styrene butadiene, styrene copolymer/polyaniline using small angle X-ray scattering data. Pramana J Phys 2007, 69(3), 435-43.

Small angle X-ray scattering data have been recorded for the blends of styrene butadiene, styrene copolymer/polyaniline using the beamline of the LNLS (Laboratorio Nacional de Luz sincroton-Campiiias, Brazil). Employing one-dimensional Hosemann's paracrystalline model, we have simulated the meridional reflections of these blends in order to compute the long periodicity and hence to find the variation with concentrations of the blends. Within the region of available experimental data observes that there is a linear relationship between long periodicity and concentration of blends. These parameters are compared with physical measurements like tensile strength to find the structure-property relation in these blends.

4 illus, 1 table, 19 ref

019351   Singhal J K;Sardar Singh;Nagawat A K (Physics Dep, Government College, Sawai Madhopur-322 001, Email: jksinghal@hotmail.com) : Distinguishing a SM-like MSSM Higgs boson from SM Higgs boson at muon collider. Pramana J Phys 2007, 68(6), 931-41.

Explores the possibility of distinguishing the SM-like MSSM Higgs boson from the SM Higgs boson via Higgs boson pair production at future muon collider. We study the behavior of the production cross-section in SM and-MSSM with Higgs boson mass for various MSSM parameters tan and m_A. Observes that at fixed CM energy, in the SM, the total cross-section increases with the increase in Higgs boson mass whereas this trend is reversed for the MSSM. The changes that occur for the MSSM in comparison to the SM predictions are quantified in terms of the relative percentage deviation in cross-section. The observed deviations in cross-section for different choices of Higgs boson masses suggest that the measurements of the cross-section could possibly distinguish the SM-like MSSM Higgs boson from the SM Higgs boson.

5 illus, 1 table, 25 ref

019350   Shoeb M;Mamo A;Fessahatsion A (Physics Dep, Aligarh Muslim Univ, Aligarh-202 002, Email: mshoeb202002@hotmail.com) : Cluster model of s- and p-shell ΛΛ hypernuclei. Pramana J Phys 2007, 68(6), 943-58.

The ΛΛ binding energy (B ΛΛ) of the s- and p-shell hypernuclei are calculated variationally in the cluster model and multidimensional integrations are performed using Monte Carlo. A variety of phenomenological A-core potentials consistent with the Λ-core energies and a wide range of simulated s-state ΛΛ potentials are taken as input. The BΛΛ of ΛΛ⁶He is explained and ΛΛ⁵He andΛΛ⁵H are predicted to be particle stable in the ΛΛ-core model. The results for s-shell hypernuclei are in excellent agreement with those of non-VMC calculations. The ΛΛ¹⁰Be in ΛΛ αα model is overbound for combinations of ΛΛ and Λ α potentials. A phenomenological dispersive three-body force, VΛα, consistent with the BΛ of Λ⁹Be in the Λαα model underbinds ΛΛ¹⁰Be. The incremental ΛBΛΛ values for the s- and p-shell cannot be reconciled, consistent with the finding of earlier analyses.

8 tables, 25 ref

019349   Senturk S;Demiray F;Ozsoy O (Physics Dep, Dumlupinar Univ, Kiitahya 43100, Turkey, Email: osozsoy@grnail.com) : Energy resolution methods efficiency depending on beam source position of potassium clusters in time-of-flight mass spectrometer. Pramana J Phys 2007, 69(3), 459-65.

Energy resolution of the time-of-flight mass spectrometer was considered. The estimations indicate that the time-lag energy focusing method provides better resolution for the parallel case while the turnaround time is more convenient for the perpendicular position. Hence the applicability of the methods used for the energy resolution depends on beam source arrangement.

5 illus, 1 table, 7 ref

019348   Sastry P U (Solid State Physics Div, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085,, Email: psastry@apsara.barc.ernet.in) : Electro-optical properties of tetragonal KNbO₃. Pramana J Phys 2007, 68(6), 1001-06.

Linear electro-optical tensor coefficients and optical susceptibility of tetragonal KNbOa are calculated using a formalism based on bond charge theory. Results are in close agreement with the experimental data. The covalent Nb-O bonding network comprising the distorted NbOe octahedral groups in the structure is found to be a major contributor to the electro-optic coefficients making these groups more sensitive to these properties than the KO₁₂ groups. The orientations of the chemical bonds play an important role in determining these properties.

4 illus, 21 ref

019347   Salamov D I;Unlu S;Cakmak N (Physics Dep, Anadolu Univ, Eskisehir, Turkey, Email: cselamov@anadolu.edu.tr) : Beta-transition properties for neutron-rich Sn and Te isotopes by Pyatov method. Pramana J Phys 2007, 69(3), 369-75.

Based on Pyatov's method, the low-lying Gamow-Teller (GT) 1⁺ state energies and log(ft) values for ^{128, 130, 132}Sb and ^132,134,136I isotopes have been calculated. In this method, the strength parameter of the effective spin-isospin interaction is found by providing the commutativity of the GT operator with the central part of the nuclear Harniltonian. The problem has been solved within the framework of RPA. The calculation results have been compared with the corresponding experimental data.

3 illus, 1 table, 19 ref

019346   Roy P (NO, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005, Email: probir@theory.tifr.res.in) : Event-shape of dileptons plus missing energy at a linear collider as a supersymmetry/Arkani-Hamed-Dimopoulos-Dvali discriminant. Pramana J Phys 2007, 69(5), 895-901.

An event-shape analysis of the dileptons in the process e⁺e^- → l⁺l^- E, studied in ILC or CLIC, can clearly discriminate between a supersymmetric or a large extra dimensional (ADD) production mechanism.

5 illus, 1 table, 5 ref

019345   Rizzo T G (NO, Stanford Linear Accelerator Center, 2575 Sand Hill Rd., Menlo Park, CA 94025, USA, Email: rizzo@slac.stanford.edu) : Higher curvature effects in Arkani-Hamed-Dimopoulos-Dvali and Randall-Sundrum models. Pramana J Phys 2007, 69(5), 889-94.

Authors explore the collider phenomenology of terascale extra-dimensional models with gravitational actions that contain higher curvature terms. In particular, we examine how the classic collider signatures of the models of Arkani-Hamed, Dimopoulos and Dvali (ADD) and of Randall and Sundrum (RS) are altered by these modifications to the usual Einstein-Hilbert (EH) action. Not only are the detailed signatures for gravitationally induced processes altered but new contributions are found to arise due to the existence of additional scalar Kaluza-Klein (KK) states in the spectrum.

3 illus, 1 ref

019344   Rindani S D (Theory Group, Physical Research Laboratory, Navrangpura, Ahmedabad-380 009, Email: saurabh@prl.res.in) : Transverse polarization in γZ,HZ production. Pramana J Phys 2007, 69(5), 883-7.

With the use of transverse polarization (TP), a CP-odd and T-odd observable can be constructed when the final-state particles are self-conjugate. In the case of HZ production, this observable can be used to probe a certain effective four-point e⁺e^-ZH CP-violating coupling, not accessible without TP. Effective CP-violating ZZH coupling does not contribute to this observable. A similar observable in γZ production can be used to probe e⁺e^- γZ four-point couplings.

4 illus, 6 ref

019343   Richharia M K (Physics Dep, Government Science College (Autonomous), Jabalpur-482 001, Email: mkrichharia@yahoo.com) : Third harmonics of cosmic ray intensity on quiet days at Deep river neutron monitoring station. Pramana J Phys 2007, 68(6), 1007-12.

The cosmic ray (CR) intensity data recorded in Deep River Neutron Monitoring Station have been investigated on quietest days (QD) for third harmonics of daily variation during solar cycles 21 and 22. It has been observed that in spite of abrupt change in the amplitude and phase of tri-diurnal anisotropy in CR intensity, the amplitude is quite significant throughout the period of investigation with larger amplitude during the years 1980 and 1985. Thus, tri-diurnal anisotropy clearly shows 11-year variation at the mid latitude neutron monitoring station.

5 illus, 22 ref

019342   Rhee J T;Jamil M;Joen C;Yin B;Jeon Y J (Institute for Advanced Physics, Konkuk Univ, Seoul 143-701, Korea, Email: mjamil@konkuk.ac.kr) : Background neutron in the endcap and barrel regions of resistive plate chamber for compact muon solenoid/large hadron collider using GEANT4. Pramana J Phys 2007, 69(3), 377-86.

In this study the performance of double gap RPC has been tested by GEANT4 Monte Carlo simulation code. The detector response calculations taken as a function of the neutron energy in the range of 0.01 eV-1 GeV have been simulated through RPC set-up. In order to evaluate the response of detector in the LHC background environment, the neutron spectrum expected in the CMS muon endcap and barrel region were taken into account. A hit rate of about 165.5 Hz cm^-2, 34 Hz cm^-2, 33.6 Hz cm^-2, and 27.0 Hz cm^-2 due to an isotropic neutron source is calculated using GEANT4 standard electromagnetic package for a 20 x 20 cm² RPC in the ME1, ME2, ME3 and ME4, respectively. While for the same neutron source and using GEANT4 package a hit rate of about 0.42 Hz cm^-2, 0.7182 Hz cm^-2 was measured for the MB1 and MB4 stations respectively. Similar characteristics of hit rates have been observed for GEANT4 low electromagnetic package.

4 illus, 4 tables, 23 ref

019341   Raju K M;Srivastava R K;Kailash (Physics Dep, Mayank Shekhar Degree College, Korauwan, Kanpur, Dehat-209 301, Email: krishnamurtiraju@yahoo.com) : Temperature variation of higher-order elastic constants of MgO. Pramana J Phys 2007, 69(3), 445-50.

An effort has been made for obtaining higher-order elastic constants for MgO starting from basic parameters, viz. nearest-neighbor distance and hardness parameter using Coulomb and Born-Mayer potentials. These are calculated in a wide temperature range (100-1000 K) and compared with available theoretical and experimental results.

6 illus, 5 tables, 11 ref

019340   Rai S K (NO, Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad-211 019, Email: santnsh.ra.i@helsinki.fi) : Identifying new physics contributions in the Higgs sector at linear e<. Pramana J Phys 2007, 69(5), 815-18.

Loop-driven decay modes of the Higgs are sensitive to new physics contributions because of new particles in the loops. To highlight this we look at the dilepton-dijet signal in the dominant Higgs production channel at a linear e⁺e^- collider. We show that by taking a simple ratio between cross-sections of two different final states such contributions can be very easily identified.

1 illus, 6 ref