020014   Gujar S P;Ghodke S R;Gokhale M P (Laser & Plasma Technology, Bhabha Atomic Research Centre, Mumbai) : Software for computation of laser beam photon distribution in curved reflecting cavity. BARC Newsl 2003, 237(Oct), 128-31.

Knowledge of photon density distribution in a given experimental region is very important for computation of yield in a photochemical experiment. Reports development of interactive user-friendly software for computation of photon density in a curved reflecting cavity. The curved reflecting cavity consists of two curved reflecting mirrors placed at a variable distance. A laser beam is introduced from a small hole in one of the mirrors, at a suitably chosen angle of incidence.

3 illus

020013   Ghosh D;Deb A;Sahoo S R;Haldar P K;Patra K K; Ghosh J (Nuclear and Particle Phys Res Centre, Phys Dep, Jadavpur Univ, Kolkata-700 032) : Proton emission in asymmetric nuclear interactions at 14.5 AGeV: evidence of strong dynamical fluctuation. Indian J pure appl Phys 2004, 42(6), 403-06.

An analysis of data of medium energy protons emitted in ²⁸Si - AgBr interactions at 14.5 AGeV reveals the existence of strong emission asymmetry in the azimuthal plane which is found to depend on the target excitation. A comparison with the data of ³²S-AgBr(at 200 AGeV) and ¹⁶O-AgBr (at 60 AGeV) interations indicates that emission asymmetry depends on the projectile mass and energy.

2 illus, 2 tables, 6 ref

020012   Ghosh D;Deb A;Bandyopadhyay P;Mondal M;Patra K K;Ghosh J;Lihiri M (Nuclear and Particle Physics Research Centre, Phys Dep, Jadavpur Univ, Kolkata-700 032) : Multi-pion production in hadron-nucleus interactions-self-similar or self-affine. Indian J pure appl Phys 2004, 42(6), 398-402.

Two-dimensional factorial moments analysis of multi-particle production in gama^--AgBr interactions at 350 GeV/c with real phase-phase-space partition is performed by considering anisotropy of phase space. It is observed that multi-particle production process is self-affine rather than self-similar. The importance of two-dimensional analysis for the interpretation of data in terms of intermittency is also demonstrated.

1 illus, 2 tables, 11 ref

020011   Gaur S J;Das R C;Tak A K;Sahu G K;Patankar R A;Bhowmick G K;Manohar K G;Thakur K B;Jagatap B N (NO, Bhabha Atomic Research Centre, Mumbai) : Surface evaporation of metal substrates by a high power strip electron beam source: laser spectroscopy based characterisation and monitoring. BARC Newsl 2003, 237(Oct), 121-6.

Zirconium atomic vapor is generated using an in-house developed strip-focused electron gun capable of delivering up to 100 KW of power. Tunable diode laser based absorption spectroscopic technique is implemented to characterize the zirconium vapour above the source. Atom density is measured at various vertical heights from the two-dimensional source (117 mm x 7 mm) for electron beam powers ranging from 40 kW. These results are interpreted in terms of the vapour flow models reported in the literature.

3 illus, 1 table, 5 ref

020010   Gadkari S C;Katti V R;Manmeet Kaur;Muthe K P; Debnath A K (Technical Physics & Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai-400085) : H₂S sensing properties of H₂SO₄treated SnO₂: Pd thin films in temperature cycling mode. Asian J Phys 2003, 12(2-3), 303-9.

Preparation and characterization of gas sensors based on thin films of SnO₂:Pd to monitor trace amounts of H₂S in air are reported. Sensors have been exposed to 100% relative humidity to study the incorporation of hydoxyl group (-OH) in the film and its effects on gas sensing properties. Films have been subsequently treated with dilute sulphuric acid and characterized using different techniques such as X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, IR spectroscopy and electrical resistance measurements. IR studies reveal the presence of two types of hydorxyl groups (-OH) in the film; as `free surface -OH' and hydrogen bonded -OH. The two types of -OH have been found to improve the H₂S sensing properties of the sensor by modifying the concentrations of the two types of hydoxyl groups. Operating the sensors in a continous temperature cycling mode was resulted in reporducible response and faster recovery times.

11 illus, tables, 26 ref

020009   Falciai R;Trono C (IFAC-CNR, OPtics and Photonics, 64, 50127 Firenze, Italy) : Effects of temperature on glued fiber Bragg grating sensors. Asian J Phys 2003, 12(2-3), 213-7.

Fiber Bragg grating sesors are often utilised for the control of structures to which the fiber can be attached or within which it can be embaded. The procedure of fixing or embedding the fibre to the structure under contorl is critical point. Measurements were performed on gratings glued on different samples made of strips of commercial glass or iron. The samples were heated or cooled inside an oven or a thermo-cryostat. The Bragg wavelength shift was detected by means of an optical spectrum analyzer. The results of measurements made under different experimental conditions will be repoted. These show a good linear relation between the temperature variation and the Bragg wavelength shift, but also reveal probelms related to the glue hardening or to the partial ungluring of the gratings, depending on the sample material and on the glue used.

8 illus, tables, 4 ref

020008   Falate R;Fabris J L;Miiller M;Kalinowski J (Centro Federal de Educacao Technologica do Parana, , Av. Sete de Setembro 3165-80230-901 Curitiba, Brazil) : Long period grating sensor to monitor fuel quality. Asian J Phys 2003, 12(2-3), 205-11.

Production and characterisation of Long Period Gratings in fibre optics are discussed. The gratings are written in standard single-mode fibre using the electrical arc technique, while their transmission spectrum is used to control the grating length. Optical characterisation and wavelength with temperature and refractive index of the external medium are shown. An application of the LPG as a sensor to monitor the fuel quality (Brazilian standard mixture of ethanol and gasoline) is presented.

6 illus, tables, 16 ref

020007   Biswas D J;Nilaya J P (Laser & Plasma Technology Div, Bhabha Atomic Research Centre, Mumbai) : Switchless operation of a TEA CO₂ laser. BARC Newsl 2003, 237(Oct), 195.

1 illus, 4 ref

020006   Balagi V;Prasad K R;Kataria S K (Electronics Div, Bhabha atomic Research Centre, Mumbai-400 085) : Effect of high gamma background on neutron sensitivity of fission detectors. Indian J pure appl Phys 2004, 42(6), 390-7.

Tests were performed on two parallel plate and two cylindrical fission detectors in pulse and dc mode. the effect of gamma background on neutron sensitivity was studied in thermal neutron flux from 3Onv to 6Onv over which gamma field intensity ranging from 230kR/h to 3.7MR/h was superposed. In the case of one of the parallel plate detectors the fall in neutron sensitivity was observed to be 3.7% at 1MR/h and negligible below 1MR/h. In the case of one of the cyclindrical counters the fall in neutron sensitivity was negligible below 500kR/h and 37% at 1 MR/h. The data was used to derive the design parameters for a wide range fission detector to the procured for PFBR instrumentation for operation at 600°C and gamma background of 1MR/h.

6 illus, 3 tables, 15 ref

020005   Aynyas M;Sanyal S P (Phys Dep, S V P G Coll, Bhopal-462 030) : Effect of doping on dynamical properties of diluted magnetic semiconductors. Indian J pure appl Phys 2004, 42(6), 440-4.

The effect of doping of Mn^{2+ impurity on vibrational properties of IV-VI compounds using three body force rigid ion model has been investigated. Pb-Mn-Te and Sn-Mn-Te systemic with different Mn+ ion concentraion been considered. Results show faster sofering of TA mode at L Point in the Brillouin zone due to Mn2+> substitution.}

3 illus, 2 tables, 15 ref

020004   Aswal V K (Solid State Div, Bhabha Atomic Research Centre, Mumbai) : Small-angle scattering from micellar solutions. BARC Newsl 2003, 237(Oct), 37-42.

Micellar solutions are the suspension of the colloidal aggregates of the surfactant molecules in aqueous solutions. The structure (shape and size) and the number density of these aggregates, referred to as micelles, depend on the molecular architecture of the surfactant molecule, presence of additives, and the solution conditions such as temperature, concentration etc. Small-angle scattering is a powerful technique to study the micellar solutions. Depending on the radiation used there are two well-established techniques, namely, small-angle neutron scattering (SANS) and small-angle x-ray scattering (SAXS). These two techniques provide complementary information ont he micelles. Made a combined use of SANS and SAXS to the study of the counterion condensation in ionic micelles.

020003   Aswal D K;Singh A;Gupta S K;Yakhmi J V;Sahni V C;Viswanadham C S;Goswami G L;Gupta L C (Technical Physics and Prototype Engineering Div, Bhabha Atomic Research Centre, Mumbai) : Transport and magnetic properties of HTS/CMR multilayers. BARC Newsl 2003, 237(Oct), 210.

Reports magneto-transport and magnetization studies of heterostructures comprising of alternately stacked YBa₂Cu₃O₇(YBCO) and La_1-xPb_xMnO₃ (LMPO) layers. The c-axis oriented bi-layer and four-layer YBCO/LPMO heterostructures were prepared in-situ on (100) SrTiO₃ substrates using pulsed laser deposition. Zero-field cooled (ZFC) and field-cooled (FC) magnetization data show that in a four-layer structure the LPMO layers get antiferromagnetically coupled when the thermodynamic-fluctuation induced Cooper pairing begins in the YBCO layers, which is well supported by the magnetization versus applied field data. Evidence of antiferromagnetic coupling is also reflected in the temperature dependence of the magnetoresistance.

5 illus, 15 ref

020002   Al-Share M (Phys Dep, Mu'tah Univ, P B Box 7, Mu'tah-Karak-Jordan) : Determination of the rotaional constants A and C for a slightly perturbed SiH₃CCH molecule. Indian J pure appl Phys 2004, 42(6), 423-428.

The ratational constant, A₀, for the ground state of SiH₃CCH molecule was calculated using a technique which was used earlier for CH₃CCH [Tam H S & Roberts J A, Struct Chem, 1 (1990) 211] and CH₃CH [Al-Share M, Hajsaleh J, Quian S W & Roberts J A, Struct Chem, 5 (1994) 109]. This technique is based on calculating the moment of inertia tensors in the bent configuration due to the V₁₀ vibrational state, which is associated with the SiCC bending motion. These values of the moment of inertia were fitted with the values calculated from the rotational constant B, which is found by measuring the rotational frequencis in the mocrowave and infrared regions experimentally. From the fitting the bending angle SiCC and the asymmetry parameters were determined for v₁₀=1,2,3, and 4 bending vibrational states.

4 illus, 1 table, 18 ref

020001   Akkurt I (NO, Suleyman Demirel University Fen-Edebiyat Fak, Fizik Bol, Isparta, Turkey) : Determination of live-time efficiency of a photonuclear experiment. Indian J pure appl Phys 2004, 42(6), 387-9.

The live-time efficiency has been calculated and corrected to obtain the absolute magnitude of the experimental yield. The percentage efficiency of the data acquisition system used in a photoneutron experiment at Maxlab in Lund (Sweden) has been determined).

4 illus, 4 ref

018983   Waghode A N;Hanspal N S;Ruziwa;Nassehi V; Wakeman (Advanced Separation Technologies Group, Chemical Engineering Dep, Loughborough Univ, Leicestershire LE 11 3TU U K) : Computational fluid dynamics of free, porous and coupled flows. Indian chem Engr 2004, 46(1), 3-6.

Analyses and simulate coupled free and porous flow phenomena. The practivel application of this concept is found in designing in covnentional filteration equipment for both cross flow and dead-end filtration techniques. The present work is a preliminary step towards the creation of a noval design and analysis tool for the specific case of high performance pleated aeronautical cartridge filters. A two-dimensional computational code has been developed and is capable of modelling individual free, porous and coupled free/porous flows for Newtonian and non-Newtonian regimes. Results are presented for simple rectangular domains in form of pressure contours and velocity vector plots. The developed code has been validated against curved geometries such as concentric circular domains. This proves athe geometrical flexibility of the numerical scheme and possiblity of its extension to more complex geometry found in pleated cartridge filters.

9 illus, tables, 16 ref

018982   Chaudhari A (Dep of Physics, Dr. B A M Univ, Aurangabad 431004) : Effect of deformation and dielectric fillings on electromagnetic propagation through waveguides. Sadhana 2003, 28(6), 1011-8.

The effect of depression and protrusion of verticals walls and dielectric fillings on electromagnetic propagation through x-band rectangular waveguides is studied using the finite element method. The effect of these deformations and dielectric filling on TE₁₀, TE₂₀ mode cut off frequencies and passband is studied. The results are compared with those of x-band rectangular waveguides with depression and protrusion with air medium. TE₁₀, TE₂₀ mode cut of frequencies for waveguides with depression and protrusion and filled with dielectric medium are less than that for air medium. However, the band with in some cases of dielectric medium is larger that for air medium.

5 illus, 5 tables, 21 ref

018099   Yadav R A;Singh I D (Spectroscopy Laboratory, Dep of Physics, Banaras Hindu Univ, Varanasi-221005) : Normal modes and quality factors of spherical dielectric responators: I - Shielded dielectric sphere. Pramana J Phys 2004, 62(6), 1255-71.

Electromagnetic ethe oretic analysis of shielded homogeneous and isotropic dielectric, spheres has been made. Characterstic equaitons for the TE and TM modes have been derived. Dielectric spheres of radii of the order of μm size are found suitable for the optical frequency region whereas for the microwave region radii of the order of mm size are found suitable. Parameters suitable for their application in the optical and microwave frequency ranes have been used to compute the frequencies corresponding to the normalmodes for the TE and TM modes. Expressions for the quality factors for realistic resonators, i.e., for a dielectric sphere with a non-zero conductivity and a metal sheild with a finite conductivity have also been derived for the TE and TM modes. Computations of the quality factors have been made for resonators with parameters suitable for the optical and the microwave regions.

6 tables, 20 ref

018098   Vibhu I;Mishra A;Gupta;Shukla J P (Dep of Physics, Univ of Lucknow, Lucknow-226007) : Ultrasonic and infrared study of molecular interactions in ternery mixtures of 1-naphthol and 2-napthol with 2-propanone in benzene. Pramana J Phys 2004, 62(5), 1147-55.

The measurements of ultrasonic velocity and density were made for the ternary mixture of 1-naphthol/2-naphthol with 2-propanone in benzene at 20, 30 and 40°C in mole fraction range o f0.000 to 0.45. Adiabatic compressibility and intermolecular free length have been evaluated using ultrasonic velocity data. The non-linear variation of ultrasonic velocity and allied parameters with mole fraction indicated solute-solute interactions through hydrogenbonding between unlike molecules. Results of ultrasonic velocity and density measurements are further supported by FT-IR spectra. The change in transmittance as well as the shift in the frequency of the representative peak of the OH stretching in FT-IR spectra give inferences about the complex formation.

4 illus, 1 table, 26 ref

018097   Tutuculer H;Koc R (Dep of Physics, Faculty of Engineering, University of Gaziantep, 27310 Gaziantep Turkey) : Differential relalizations of the two-mode bosonic and fermionic Hamiltonians : A unified approach. Pramana J Phys 2004, 62(5), 993-1005.

A method of development to determine the eigenvalues of eigenfunction of two-boson 2 X 2 matrix Hamiltonians that inculde a wide class of quantum optical models. The quantum Hamiltonians are trasformed in the form of the one variable differential equation an the conditions for their solvability are discussed. Presents two different trasformation procedure and we show our approach unify various approaches based on Lie algebraic technique. As an application, solutions of the modified Jaynes-Cummings and two-level Jahn-Teller Hamiltonians are studied.

34 ref

018096   Sud K K;Purohit G;Bhullar A S (Dep of Physics, Coll of Science Campus, M.L.S. Univ, Udaipur 313002) : Electron dichorism effects in the relativistic (e,2e) process for K-shell ionizatoin of atoms. Pramana J Phys 2004, 62(5), 1157-66.

Presents theoretical demonstration of electron dichroism in the relativistic (e,2e) process for K-shell ionization of atoms in non-coplanar asymmetric geometry. The theoreticall formalism has been developed in plane wave Born apporximation and in this approximation the triple differential cross-section (TDCS) has been expressed as a product of kinematical factors and atomic structure functions. The longitudinal spin asymmetry in the relativistic (e,2e) process on K-shell of atoms has been shown to depend on the interference between the transition charge and component of the transition current in the direction perpendicular to the scattering plane. Further, the Iongitudinal spin asymmetry has been shown to depend on incident electron energy, atomic number of the target, azimuthal angle of the objected electron and scattered electron angle.

4 illus, 30 ref

018095   Storer R;Oertzen G V (School of Chemistry, Physics and Earth Sciences, Flinders Univ, G.P.O.Box 2100, Adelaide 5001 Austraila) : Current drive for rotamak plasmas. Pramana J Phys 2004, 62(5), 1083-9.

Experiments which have been undertaken over a number of years have shown that rotating magnetic field can drive a significant non-linear Hall current in a plasma. Successful experiments of this concept have been made with a device called rotamak. In its original configuration this device was a field reversed configuration without a toroidal magnetic field but with a mertical field to establish the MHD equilibrium. However, modifications have shown that current can also the driven if a central current-carrying rod is used to provide an applied toroidal field. The new rotamak has been a spherical tokamak magnetic field structure.

5 illus, tables, 13 ref

018094   Srivastava M K;Chauhan R K (Institute Instrumentation Centre, Indian Institute of Technology, Roorkee-247667) : Triple differential cross-sections for near threshold (e,2e) process for hydrogen. Pramana J Phys 2004, 62(5), 1073-82.

The triple differential cross-sections for ionizaton of hydrogen at incident energies in the rabge 17.6 eV to 13.7 eV are calculated in the distorted-wave. Born approximation in the equal energy sharing and ϑ_ab = 180° kinetmatics. It is found that a maximum in the crossection, as was observed in the case of helium under similar conditions is also found here at excess energy E_es≤1.0 eV. This `maximum' becomes more pronounced as E_ex decrease indicating dominance of short range e-e correlations at these low energies. The angular distribution of the siglet and triplet partial waves and the asmmetry parameter have been analysed.

8 illus, tables, 31 ref

018093   Sinha S K;Barhai (Dep of Applied Physics, Birla Institute of Technology, Mesra 835215) : Interface defects in GaN/sapphire studied using rutherford backscattering spectroscopy and channeling. Pramana J Phys 2004, 62(6), 1293-8.

GaN on sapphire was grown by MOCVD technique. Rutherford backscattering spectra together with channeling among [0001] axis were recorded to study the defects at the interfact. Detailed calculations shows that the defects at GaN/sapphire interface are due to dislocations which are distributed into the whole thickness of the film and are mainly aligned on the growth directoin.

4 illus, 2 tables, 10 ref

018092   Singhal J K (Dep of Physics, Government College, Sawai Madhopur-322001) : Bounds on charged lepton mixing with exotic charged leptons. Pramana J Phys 2004, 62(5), 1029-40.

Examine the effects of mixing induced light heavy chargedlepton neutral currents on the partial wave amplitude for the process ι⁺ι ^{-→ ZZ(with ι = e,μ or_T}. By limit at high energy (√ =Λ), obtains bounds on light heavy charged lepton mixing parameters sin² (2θ^a_L) where θ^a_L is the mixing angle of the ordinary charged lepton with us exotic partner. For (2Λ = 1 TeV, no bound is obtined on sin²(2θ^a_L) for m_E <0.69 Te V. However, sin²(2θ^a_L ≤ 1.52 x 10^{-5 for m_E} = 56 TeV, (2θ^a_L ≤ 2.41 x 10^-7 for m_E = 10 TeV. Similarity for Λ = ∞ no bound is obtined on sin²(2θ^a_L) for m_E <60> 1.97 TeV and sin² (2θ^a_L ≤3.88x10^-2 for m_E = 10 TeV.

2 illus, tables, 14 ref

018091   Singh P J;Gupta K K (Dep of Physics, Government MSJ (PG) College, Bharatpur-321001) : Fluid structure and molecular interaction of acetophenone derivatives. Pramana J Phys 2004, 62(5), 1129-37.

Dielectiric constants of the binary mixtures of acetophone, p-choloroacetophenone, p-methylacetophenone and o-hydroxacetophenone in dilute solutions of benzene and 1,4-dioxane were measured at 303 K and at frequency 100 kHz. The low frequency molecular dynamics of acetophenone and its derivatives have been studied by evaluating the Kirkwood correlation factor g, molar polarization P₂, excess correlation factor δg and excess free energy ΔG. The dipolar contributin to excess free energy of mixing arising from long-range electrostatic interaction and short-range interaction between identical molecules has been assesseds separately. The presence of α- and β-multimers in the above systems was identified. The results have been used to interpret the fluid structure in such mixtures.

4 illus, tables, 16 ref

018090   Singh M P;Bhandari C M (Dep of Physics, Univ of Allahabad, Allahabad-211002) : High-temperature thermoelectric behaviour of lead telluride. Pramana J Phys 2004, 62(6), 1309-17.

Usefulness of a material in thermoelectric devices is temperature specific. The central problem in thermoelectric material research is the selection of materials with high figure-of-merit in the given temperature range of operation. It is of considerable interest to know the utility range of the material, which is decided by the regarding effect of minority carrier conduction. Lead telluride is among the best-known materials for use in the temperature range 400-500K. Presents a detailed theoretical investigation of the role of minority carriers in degrading the thermoelectric properties of lead telluride and outlines and temperature range for optimal performance.

4 illus, 35 ref

018089   Singh K;Sandhu G K;Lark B S (Dep of Physics, Guru Nanak Dev Univ, Amritsar-143005) : Molar extinction of solutions of some organic compounds. Pramana J Phys 2004, 62(5), 1139-45.

Molar extinction coefficients of aqueous solutions of some organic compounds, viz. foramide (CH₃, N-methlformamide (C₂NO), NN-dimethylformamide (C₃H₇MP), NN-dimethlacetamide (C₂H₉NO), 1,4-dioxane (C₄H₈O₂), succinimide (C₄H₅NO₂), andsolutions of acetamide (C₄H₅NO) and benzoic acid (C₇H₆O₂), in 1-4, dioxane (C₄H₈O₂) have been determined by narrow beam γ transmission method at 81, 356, 511, 662, 1332 keV. The experimental values of mass atteunation cofficient of these compounds have been used to calculate effective atomic numbers and electron densities. The additivity rule earlier used for aqueous solution has been extended to non-aqueous (1,4-dioxane) solutions.

2 illus, 10 ref

018088   Sadeghi E (Dep of Physics, Yasourj Univ, Yasouj-75914-353) : Energy levels in rectangular quantum well wires based on a modified profile of the heterojunction. Pramana J Phys 2004, 62(5), 1167-72.

The effect of spatially dependent mass on the energy levels in a rectangular quantum wire with finit barrier potential is considered. The heterojunction is modelled by an error function rather than functions to more accurately model the material tansition region at the interface between the two materials. The carrier ground state is calculated using the envelope function approximation for Ga_0.47Ins_0.53As/In_0.53As/InP and GaAs/Ga_0.63Al_0.37 As systems. The results are lower than those reported before, and are in better agreement with the experimental points.

2 illus, 12 ref

018087   Ramana Murty G A;Naga Raju G;Vijayan V;Ranjan Rautray T;Seetharami Reddy B;Lakshminarayan S;Narasimham;Bhuloka Reddy S (Swami Jnanananda Laboratories for Nuclear Research, Andhra Univ, Visakhapatnam 530003) : Simultaneous K plus L shell ionised atoms during heavy-ion collison process. Pramana J Phys 2004, 62(6), 1303-7.

The faction of simultaneous K plus L shell ionized atoms is estimated in Fe, Co and Cu elements using carbon ions at different projectile energies. The results indicate that the fraction of simultaneous K plus L shell ionizaton probability decreases with increase in projectile energy as well as with increase in the atomic number of the target atoms.

1 illus, 1 table, 18 ref

018086   Ramakrishna A (Dep of Physics, Indian Insitute of Technology, Kanpur 208016) : On the dual symmetry between absorbing and amplifying random media. Pramana J Phys 2004, 62(6), 1273-9.

Re-eximes the dual summetry between absorbing and amplifying random media. By analysing the physically allowed choie of the sign of the square root to determine the complex wave vector in a medium draws a broad set conclusion that enables to resolve the apparent paradox of the dual symmetry and also to anticipate the large local electromagnetic field enhancements in amplifying random media.

2 illus, 25 ref

018085   Modi K B;Gajera J D;Pandya M P;Vora H G;Joshi H H (Dep of Physics, Saurashtra Univ, Rajkot 360 005) : Far-infrared specktral studies of magnesium and aluminium co-substituted lithium ferrites. Pramana J Phys 2004, 62(5), 1173-80.

Polycrystalline Mg_xAl_2xLio5(1-x)O₄(0.0, 0.2, 0.5, 0.6 and 0.7) ferrites were prepared by standard ceramic method, and charcterized by X-ray diffraction and infrared absorption spectroscopy. The spectra show two significant absorption bands in the wave number range of 400-1000 cm^-1 arising from interatomic vibrations in the tetrahedral and octahedral coordination compounds. The decrease in intensity an increase in broadness of bands with concentration (x) are explained on the basis of cation distribution. The force constants and bul modules are found to decrease with Mg-Al content (x) which suggested weaking of interatomic bonding. An alternate method for the determination of bulk moduls, longitudinal and trasverse velocities in suggested. The magnetic and electrical properties of these compounds are explained in the light of structural and optical properties.

2 illus, 2 tables, 26 ref

018084   Meena B L;Bali R (Dep of Mathematics, Univ of Rajasthan, Jaipur-302004) : Conformally flat tiled Bianch type-V cosmological models in general relativity. Pramana J Phys 2004, 62(5), 1007-14.

Investigates two conformally flat tilted Bianch Type-V cosmological models and general relativity. To get a determine solution, Assumes a supplementary condition A = Bⁿ between metric potentials where n is a constant. The behaviour of the model for n = 2 is discussed in detail. Various physical and geometrical aspects of the models are also discussed.

24 ref

018083   Lahinri R;Arvind;Sain A (Dep of Physics, Indian Institute of Scinece, Bangalore-560012) : Brownian motion in a classical ideal gas: A microscopic approach Langevin's equation. Pramana J Phys 2004, 62(5), 1015-28.

Presents an insightful `derivation' of the Langevin equation and the fluctuation dissipation the orem in the specific context of a heavier partle moving throug an ideal gas of much ligher particles. The Newton's low of montion (mx = F) for the heavy partile reduces to a Langevin equation (valid on a coarser time-scale) with the assumption that the lighter gas particles follow a Boltzmann velocity distribution. Starting from the kinematics of the random collisions shows that (1) the average froce <193>F<209> ∝-x^. and (2) the correlation function of the fluctuating force η = F- <193>F<209> is related to the strength of the average force.

3 illus, tables, 21 ref

018082   Konar S;Das S (Dep of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302) : Neutrino propagation in a weekly magnetized medium. Pramana J Phys 2004, 62(6), 1241-54.

Neutrino-photon processes, forbidden in vacuum, can take place in the presence of thermal medium and /or an external electro-magnetic filed, medicated by the corresponding charged leptons (real or virtual). Such interactions affect the propagation of netrinos through a magnetized plasma. Investigates the neutrino-photon absorptirve processes, at the one-loop level, for massless neutrinos in a weekly magnetized plasma. Finds that there is no correction to the absorptive part of the axial-vector-vector amplitude due to the presence of a magnetic field, to the linear order in the field strength.

2 illus, 26 ref

018081   Khare A;Lakshmi Arayan A;Sukhatme AU (Institute of Pyhsics, Sachivalay Marg, Bhubaneswar-751005) : Local indentities involving Jacobi elliptic functions. Pramana J Phys 2004, 62(6), 1201-29.

Derives a number of local identities involving Jacobi elliptic functions and use them to obtain several new results. First presents an alternative, simpler derivation of the cyclic identities discovered by the recently, along with an extension to several new cyclic identities. Second we obtain a generalization to cyclic identities in which successive terms have a multiplicative phase factor exp (2iπ/s), where is any integer. Third, systematizes the local identities by derving four local `master identities' analogous to the master identities for the cyclic sums discussed previously. Fourth, points but that many of the local identities can be thought of as extact discretization of standard non-linear differential equations satisfied by the Jacobi elliptic functions. Finally, obtains explicit answers for a number of definite integrals and simpler forms for several idefinite integrals involving Jacobi elliptic functions.

6 ref

018080   Kamilov I K;Ibragimov K O;Aliev K M;Abakarova N S (Laboratory of Nonclinear Dynamic and Chaos, Instiute of Physics, Daghestan Scientific Center of RAS, ) : Recombination instability and domaination in p-Ge(Au). Pramana J Phys 2004, 62(5), 1111-19.

Results of an experimental study of short and long p-Ge(Au), samples are presented and compared qualitatively with data furnished by the one-diamensional theoretical model describing the evolution of domain instability in a two-parametric space `voltage V-emission coefficient β'. According to the theory, single-, double-, and multi-subdomain states and order-disorder-order transitions via intermittency have been observed in the system with increasing voltage. Three operation regins of the system are found, depending on the region of the parametric space; ohmic, quenched (pulsing) and transit-time. In short samples, a second portion with S-switching is revealed in the current-voltage characteristic.

5 illus, tables, 18 ref

018079   Jahangirdar C J;Tiwari L B (Applied Physics Division, Institute of Chemical Technology, Univ of Mumbai, Mumbai-400 019) : Effect of dichlorodimethylsilane on plasma-treated cotton fabric. Pramana J Phys 2004, 62(5), 1099-1109.

Cotton fabric was treated with dichlorodimethysilane (DCDMS) solution by two methods. In the first method, the fabrics were directly dipped into DCDMS solution for different time intervals and in the second method,the fabric was first subjected to radiofrequency (RF) plasma treatment for different durations and optimized exposure power condition and then immersed in DCDMS solutions. The physical properties of cotton fabrics, treated with DCDMS in the presence/absence of air plasma have been compared with those of the control fabrics. Changes in the surface morphology structure and compostion were observed through scanning electron microsocopy and attenuated total reflectance-IR. The change in colour parameters of the fabric due to the treatment was assessed by Dataflash 100 colour measurement spectrophotometer with colourtools QC 1.3 colour quality software. The water repellent property of untreated and modified fabrics was studied using AATCC test method 39 (1971). The effectiveness of the water repellent property was checked by washing the treated fabrics up to ten cycles.

6 illus, 4 tables, 13 ref

018078   Ingle S G;Patil N M (Kavikulguru, Institute of Technology and Science, Ramtek 441106) : Nucleation of domains under the influence of temperature in Ba₅ Ti₂O₇CI₄. Pramana J Phys 2004, 62(5), 1121-8.

It is found that the nucleation of domains can take place in Ba₅Ti₂O₇CI₄ under the influence of temperature unlike in many other ferroelectrics. The nucleated domain can also be removed from the structure under the randomizing effect of temperature. These observations have been explained on the basis of a nucleation model of Ingle and coworkers suggested for KNbO₃. Similarity of physical situation in KNbO₃ and Ba₅Ti₂O₇CI₄ regarding the exitence of ordered point defects inducing nucleation of domains around them has been highlited. This surprising similarity is suggested to be due to the physical process occurring at the phase trasition under the influence of temperature is shown to be identical with the nature of nucleation occurring under the influence of externally applied stress, and/or DC electric field. A new technique of identifying point defects responsible for nucleation of domains is reported.

7 illus, tables, 18 ref

018077   Ghosh T B;Dhabal S (Dep of physics and Meteorology, Indian Institute of Technology, Kharagpur 721302) : On diffusion-controlled interface microstructure of vapor deposited bilayer thin film of Sn/Cu. Pramana J Phys 2004, 62(6), 1319-25.

Depth dependent concentration profiles for bilayer film of Sn (500 Armstrong)/Cu (500 Armstrong) are determined at different temperatures by X-ray photoelectron spectroscopy (XPS). Although the nature of the diffusion profile for the sample studied immediately after deposition could be explained by the existing laws, the profiles for others are found to be distinctly different and are not explained by the theories of nucleation and growth of the inter-metallic phases. Measured value of the inter-diffusion coefficient of Cu points out to the grain boundary as well as interstitial diffusion processes. It is also observed that the compositions across the bulk of the film become uniform on annealing at higher temperature and the width of this region increase with annealing. However, the compositon close to the surface is found to be entirly different from that of the bulk even on prolonged heating. The findings possible demostrate the importance of physical surface in influencing the solid-state reactions.

3 illus, 18 ref

018076   Gadkari M S;Singh N L (Dep of Physics, Fac of Sci, M.S. Univ of Baroda, Vadodara-390002) : Particle-induced reations on rhodium. Pramana J Phys 2004, 62(5), 1059-72.

Excitation functions for ¹⁰³Rh (α, xn) ¹⁰³Rh (α, xn); x =1-3 reactions were measured up to 50 MeV bombarding energy using stacked foil activation tehnique ahd high purity germanium (HPGe) <103>

8 illus, 1 table, 28 ref

018075   Chandra S (School of Physical Sciences, SRTM Univ, Nanded 431606) : Comment on :Universal relation between spectroscopic constant. Pramana J Phys 2004, 62(5), 1181-6.

Kaur and Mahajan [1] have claimed to derive a universal relation in G= 1.91578(±0.09727) + 0.97111(±0.03809) in Δ between the Sutherland parameter Δ(= w_e²/2D_e) and the dimensionless parameter G(=8w_ex_e/B_e) for ground as well as excited electronic states of diatomic moelcules. Validity of this relation is checked and we find that the relation is not correct. Next, we checked the validity of the relaton Δ = 2.2.r_e for the alkali group diatomic molecules. This relation is also found not to be correct.

2 illus, 2 tables, 4 ref

018074   Chandra B P;Chandra V K (School of Studies in Physics, Pt. Ravi Shankar Shukia Univ, Raipur 492010) : Dislocation unpinning model of acoustic emission from alkali halide crystals. Pramana J Phys 2004, 62(6), 1281-92.

Reports the dislocation unpinning model of acoustic emission (AE) from alkali halide crystals. Equations are derived for the strain dependence of the transient AE pulse rate, peak value of the AE pulse rate and total number of AE pulse emitted. It is found that the AE pulse rate should be maximum for a particular strain of the crystals. The peak value of the AE pulse rate should depend on the volume and strain rate of the crystals, and also on the pinning time of disolcations. Since the pinning time of dislocation decrease with increasing strain rate, the AE pulse rate should be weakly dependent on the strain rate of the crystals. The total number of AE should be weakly dependent on the strain rate of the crystals. The total number of AE should increase linearly wiht deformation and then it should attain a saturation value for the large deforamtion. By measuring the strain dependence of the AE pulse rate at a fixed strain rate, the time of constant τ_s for surface annihilaton of dislocations and the pinning time τ_P of the dislocation can be determined. A good agreement is found between the theretical and experimental results related to the AE from alkali halide crystals.

6 illus, 19 ref

018073   Biswas S;Chowdhury (Dep of Physics, Univ of Kalayani, Kalyani -741235) : The CWKB approach to non-reflecting potential and cosmological implications. Pramana J Phys 2004, 62(6), 1231-9.

Discusses the method of calculating the reflection coefficient using complex trajectory WKB (CWKB) approximation to understand the non-reflecting nature of the potential U(x)= -U_o/Cosh²(x/a). Shows that the repeated reflections betweenthe turning points whose parts are in conformity with Bogoubo transformation technique are essential in obtaining the non-reflecting condition. Also discusses the implications of the results when applied to the particle production scenario. Uses the CWKB technique developed by one of the authors (SB) to obtain the results which agree very well with those obtained by extract quantum mechanical calculations.

2 illus, 13 ref

018072   Bhowmilk B B;Rajput (Netaji Subhas Vidyaniketan Higher Secondary School, , Basugaon -783372) : Anisotropic Lyra cosmology. Pramana J Phys 2004, 62(6), 1187-99.

Anisotropic Bianchi Type-I cosmological models have been studied on the basis of Lyra's geometry. Two types of models, one with constant decelatoin parameter and the other with variable declaration parameter have been derived by considering a time-dependent displacement field.

2 illus, 2 tables, 25 ref

018071   Bhattacharya S;Gohain Barua A;Konwar R; Changmai R (DCB Girls College, , Jorhat-785001) : Nature of the emission band of Dergaon meteorite in the region 5700-6700 Armstrong. Pramana J Phys 2004, 62(6), 1299-1301.

An emisson band system in the region 5700-6700 Armstrong from Dergaon stoney iron meterite which fell at Dergaon, India on March 2, 16.40 time (2001) was excited with the help of a continous 500 m W ar⁺ laser. The band system is attributed to silicate (olivine), a major component of the meteorite.

2 illus, 7 ref

018070   Bhattacharya K;Pal P B (Saha Insrtitute of Nuclear Physics, , 1/4F Bidhan Nagar, Kolkata-700064) : Inverse beta decay of arbitrarily polarized neutrons in a magnetic field. Pramana J Phys 2004, 62(5), 1041-58.

Calculates the cross-section of the inverse beta decay proces v_e+n→p+e,in a background magnetic field which is smaller than m²_p/e. Using next solutions of the Dirac equation in a constant magnetic field. Finds the cross-section for arbitary polarization of the intial neutrons. The cross-section depends on the direction of the incident neutrino even when the initial neutron is assumed to be at rest and has no net polarization. Possible implications of the result are discussed.

2 illus, tables, 11 ref

018069   Bailung H;Boruah D;Pal A R;Chutia J (Plasma Physics group, Material Sciences Division, Institute of Advanced Study in Science and Technology, Khanapara, Guwahati-781022) : Sheath characteristics in multi-componet plasma with negative ions. Pramana J Phys 2004, 62(5), 1091-8.

Properties of steady state ion sheath formed in front of negatively biased metal plate under the influence of negative ions have been invetigated in collisionless argon/SF₆ plasma. This experiment is carried out at a fixed discharge voltage and fixed filament heating power. In this experiment, the decrement in plasma pre-sheath potential drop as well as positive ion drift velocity toward the plate is experimentally recorded in the presence of negative ions. It is also found that the plasma positive ion density and plasma electron temperature decrease in the presence of negative ions. These factors attribute to the decreased of ion current toward the plate. Hence the usual ion sheath expands.

6 illus, tables, 10 ref

017113   Tiwari S C (Inst of Natural Philosophy, , 1, Kusum Kutir, Mahamanapuri, Varanasi-221 005) : On the anomalus extreme ultraviolet emission lines in helium-hydrogen plasma. Curr Sci 2004, 86(11), 1477.

017112   Tewari S P; Sood J (Dep of Physics and Astrophysics, Univ of Delhi, Delhi-110007) : Complex dieletric function and collective dynamics of one-dimensional weakly coupled quantum and classical hot plasmas. Indian J pure appl Phys 2004, 42(7), 518-23.

The complete expressions for the wave vetor and frequency dependent complex dieletric function for one-dimensional weakly coupled one component quantum and classical hot plamas have been derived. These expressions, which are valid for the entire domain of frequency and wave vetor, are used to obtain the knowledge about the collective dynamics of the plasma by computing the dynamical structure factor at different temperatures and were vetor. The results obtained we quite different from those in three-and two-dimensinal cases.

4 illus, 2 tables, 15 ref

017111   Tantawi R S (Dep of Mathematics, Faculty of Science, Zagazig Univ, Zagazig Egypt) : Effect of couplings of the n=2 states on excitation processes by protons and anti-protons impact on H(2s) atoms. Indian J pure appl Phys 2004, 42(7), 506-11.

Effect of couplings of the n=2 states on the n=3 excitation cross-sections in scattering of protons and antiprotons by hydrogen atoms being initially in the 2s state has been investigated by mean of the impact parameter approximation. The calulations take into account the n=1,2,3, and 4 states of the target and cover energy range from 3-2500 ke V. The study of influence of the electric charge of the projectile is a target of this investigatiion. Therefore, the exchange effects in the case of proton-induced reactions are ignore. The results of calcuations for protons are in reasonable agreement with a previous work.

3 illus, tables, 28 ref