004185   Basu A;Bhattacharyya R (Thin Film Technolopgy Group, National Physical Laboratory, New Delhi-110 012) : Spectral characteristics of an inhomogeneous film determination of refractive index profile from reflectance/trnasmittance spectrum. J Optics 2002, 31(2), 73-86.

The refractive index profile with depth in silica films that are several microns thick and may be inhomogeneous to a greater or lesser extent, deposited on silicon substrates, has been determined from the measured reflectance vs wavelength spectral curves. As compared to some sophisticated and complex cuve-fitting optimization techniques used by other researchers for this prpose, a simplified approach has been adopted here. On the basis of studies by the authors of the variations with wavelength of the envelopes of the reflectance/transmittance extrema for different inhomogeneous film models, the most likely model of the inhomogeneous silica film has been identified as a starting point. The calculated reflectance vs wavelength curve of this model film-coated substrate has been fitted with the experimental data using a constrained optimization technique to determine the refractive index profile and thickness of the film. The procedure has been illustrated for a few silica films, and the ranges of uncertainty in the determined film paramaters have been indicated.

5 illus, 16 ref

004184   Basu A;Bhattacharya R (NO, Thin Film Technology Group, National Physical Laboratory, New Delhi-110 012) : Spectral characteristics of an inhomogeneous film reflectance and transmittance spectra for different film refractive index profiles. J Optics 2002, 31(2), 59-72.

The reflectance and transmittance spectra of an optical thin film exhibit a number of maxima and minima and the envelopes of these extrema are used in the `envelope method' to determine the refractive index, extinction coefficient and thickness of the film. This method works quite well so long as the film is homogeneous. But when the film is inhomogeneous, the determination of the refractive index profile, i.e. variation of refractive index with depth, from the transmittance/reflectance spectra is not a straight-forward task, even when the film is weakly absorbibng. In order to aid this determination, the trends of the reflectance/trnasmittance extrema envelope curves with increasng wavelength have been studied for different types of film inhomogeneities and compared with the results for a homogeneous film having a refractive index equal to the average refractive index of the inhomogeneous film. The earlier studies in the direction have been extended and a more comprehensive study undertaken.

3 illus, 2 tables, 6 ref

003263   Wahab L A (National Centre for Radiation Research & Technology, , Cairo, Egypt) : Thermal studies on (Ge_0.9Sn_0.1Se₂)_{1-x<>DAgx chalcogenide glasses.} Indian J pure appl Phys 2002, 40(12), 873-8.

The effect of silver on teh phenomena accompanying the thermally induced structural changes in Ge_{0.9Sn0.1Se2 chalcogenide glass has been investigated using DSC measurements. Glass stability and kinetic resistance to crystallization are shown in terms of glass forming tendency (Kgl), crystallization enthalpy (ΔHc) and crystallization energy (E). Studies of the crystallization kinetics using the isothermal and non-isothermal single scan techniques shows that, random nuclei are alaready present in as-quenched alloys and growth occurred in two dimensions.}

7 illus, 2 tables, 20 ref

003262   Singh D;Yadav R R;Tiwari A K (Physics Dep, University of Allahabad, Allahabad-211 002) : Ultrasonic attenuation in semiconductors. Indian J pure appl Phys 2002, 40(12), 845-49.

The ultrasonic phonon-viscosity loss and thermo-elastic loss have been studied in octahedral semiconductors along <60>100<62>, <60>110<62> and <60>111<62> crystallographic directions as a function of high temperature (≅ 300K). For this evaluation, the temperature dependence of second-and third-order elastic constants starting with two basic parameters has been computed. The thermo-elastic loss is very small as compared to phonon-viscosity loss. The behaviour of temperature dependence of ultrasonic attenuation is the same as in other semiconducting materials.

8 tables, 22 ref

003261   Satyanarayana Rao T;Veeraiah N;Rambabu C (Physics Dep, Nagarjuna University PG Centre, Nuzvid, Andhra Pradesh-521 201) : Excess volume, viscosity and compressibility of binary mixtures consisting of o-chlorophenol, 0-cresol and M-cresol with n-n-diethyl acetamide at different temperatures. Indian J pure appl Phys 2002, 40(12), 850-6.

The densities, viscosities and ultrasonic velocities of binary mixtures of o-chlorophenol, o-cresol, m-cresol with N,N-diethyl acetamide have been determined at 308, 15, 318.15 K over the whole composition-range, using density bottle, ostwald viscometer, and with single crystal ultrasonic pulse echo-interferometer respectively. These data have been utilized to estimate the excess volume (V^E), excess viscosity (η^E), excess compressibility (K_s^E), excess inter-molecular free-lenth, and Gurunberg and Nissan parameter d. Values of V^E for o-chlorophenol + N,N-diethyl acetamide system and m-cresol + N,N-diethyl acetamide system are negative at all temperatures but, for o-cresol + N-N diethyl acetamide V^E values are positive at lower mole fraction of o-cresol and increase with increase in temperature. η^E values are positive for all the systems and the magnitude of η^E decreases with increase of temperature in all cases. K_s^E values are negative for all the systems over the whole composition-range. Analysis of these suggests the absence of any strong speciefic interactions.

6 illus, 33 ref

003260   Saibabu G;Vasanth Kumar N;Ramachandra Reddy A;Srikanth D (Department of Physics, Raiway Jounior College, Kazipet, Warangal-506 003) : Study of ionic onductivity in KBr: (CrO₄)<. Indian J pure appl Phys 2002, 40(12), 862-6.

The ionic conductivity of pure KBr and KBr crystals doped with chromate anion has been measured in the temperature range of 200-600<144>% of chromate anion in as-grown state. Further, the effects of quenching and annealing on conductivity of KBr crystals doped with 0.75 mole % chromate ion are measured. Conductivity versus temperature plots show that, as concentration of impurity anions increases, the conductivity decreases in extrinsic associated region. As the concentration increases to 0.75 mole %, the conductivity increased to high value compared to 0.5 mole %. But, it is less than that of pure crystals. Extrinisic un-associated region shows a slight variation in conductivity but, tends to be same that of as-grown pure KBr crystals. Variation in conductivity of doped KBr crystals are explained on the basis of formation of complexes with background inpurities, formation of neutral pairs, introduction of fresh dislocations, etc. The variation in conductivity due to quenching and annealing is explained on the basis of dissociations and aggregation of complexes, vanishing of newly introduced dislocations, etc. Corresponding activation energy values are evaluated.

2 illus, 1 table, 14 ref

003259   Raj Kumar;Singh P N;Upadhyay M (Physics & Electronics Dep, Dr R M L Avadh University, Faizabad-224 001) : Expression for energy and specific heat for <60>111<62>+<60>100<62> tunneling model. Ultra Scient phys Sci 2002, 14(3), 545-8.

Within the frame work of two parameter octahedral potential for a dipolar impurity in ionic crystal, it is possible for impurity to posses minimum energy orientational configurations in two crystallographic directions simultaneously. Two possible combinations are <60>111<62> and <60>110<62> and <60>111<62>-<60>100<62>. Taking second model here it has been found out the expressions for energy corresponding to different degeneracies and specific heat.

1 ref

003258   Pujari S R;Bhosale P N;Rao P M R;Patil S R (Fluorescence Spectroscopy Laboratory, Chemistry Dep, Shivaji University, Kolhapur-416 004) : Structural and optical studies of perylene-doped polymer thin films. Indian J pure appl Phys 2002, 40(12), 896-900.

Thin films of perylene in polystyrene matrix have been prepared by spin coating technique. The concentration of polystyrene is kept constant to 1 wt% while that of perylene dopant varied in the range 1X10^-5-1X10^-1 wt%. The thickness of the films depends upon the concentration of perylene and varies from 45.48 to 582.16 nm. The structural aspects of the films were studied by recording the X-ray diffractogram of the films. The results of X-ray diffraction analysis reveal the crystalline nature of the film. The optical properties were studied by recording absorption, excitation and fluorescence spectra. The band gap energy of perylene in polymer films was calculated from absorption curves. The fluorescence spectra of the films show monomeric as well as dimeric emission bands. the films with lower concentration of perylene show monomeric emission similar to that of dilute solution, while the films with higher concentration of perylene exhibit structure-less broad emission. These emission bands appeared at 509 and 525 nm are attributed arising from dimmer, formed in the ground-state by parallel orientational alignment of neighbouring molecules. The additional bands observed in the blue region of the absorption and excitation spectra of the films containing higher concentration of perylene confirm the formation of ground-state dimer.

6 illus, 1 table, 19 ref

003257   Lal R;Sharma N D (Physics Dep, Kurukshetra University, Kurukshetra-136 119) : Mossbauer spectroscopic study of soils collected from Panipat region. Indian J pure appl Phys 2002, 40(12), 914-16.

Mossbauer spectroscopy of ⁵⁷Fe has been used to study some soil samples picked up from regions where the growth of crops is not normal as well as from the fertile part of the land in the Panipat district of Haryana. The ferrous-ferric ratios in these samples were determined. An attempt has also been made to correlate the Fe²⁺/Fe³⁺ ratio with pH values of the samples. The importance of these results lies in the necessity of application of suitable micronutrients in the area where the growth of crops is below normal.

2 illus, 1 table, 7 ref

003256   Kumhar R P;Shah S;Singh R K (School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore-452 017) : Effect of plasmons on superconducting transition temperature of Ba_0.6K_0.4BiO₃: a three square well approach. Indian J pure appl Phys 2002, 40(12), 879-86.

By assuming the existence of a low energy plasmon in attractive interaction, the cooper pairing theory is extended for cubic perovskite Ba_{0.6K0.4BiO3. Three square well model for the three interactions namely, electron-phonon, electron-plasmon and Coulomb in the calculation of superconducting transition tempeature (Tc) has been employed. The analytical solutions for the energy gap equation allow one to visualise the relative interplay of various interactions. To correlate the Tc with various coupling strengths (λph, λpl and μ^*) curves of Tc are presented with them. The values of the coupling strength and of the Coulomb interaction parameter indicate that, the superconductor is in the intermediate coupling regime. The superconducting transition temperature of optimally doped Ba-K-BiO is estimated as 25 K, for λph=0.6, λpl=0.1 and μ*=0.18. The low energy plasmons play a key role in raising Tc with the increased λpl values. The analysis points to the importance of both plasmons and optical phonons in determining the effective electron-electron interaction leading to superconductivity in doped cubic perovskites.}

6 illus, 24 ref

003255   Kher R S;Dhoble S J;Khokhar M S K;Chougaonkar M (Physics Dep, Government Autonomous PG Science College, Bilaspur-495 001) : Luminescence in divalent impurity activated LiF single crystals. Indian J pure appl Phys 2002, 40(12), 867-72.

LiF single crystals doped with varying concentrations of Ba, Sr and Ca have been grown by Bridgeman technique and their thermo-luminescence (TL) and TL emission spectrum induced by γ-irradiation at room temperature for doses between 10³ to 10⁵ R have been recorded. In the TL glow curves, peaks around 380, 425 and 500 K are produced irrespective of the impurity added, but, the relative intensity of these glow peaks varies for different dopants. At low γ-exposure the TL efficiency increases with decrease in the ionic radius of the dopant. The dependence of various TL peaks on γ-exposure shows that, low temperature peaks have got their optimum intensity as compared to high temperature TL peaks.

9 illus, 19 ref

003254   Khanna K M;Karap Kirui M S (Physics Dep, Moi University, Box-3900, Eldoretm Kenya) : Anharmonic apical oxygen vibration in high-T_c superconductors. Indian J pure appl Phys 2002, 40(12), 887-95.

Using time-independent perturbation theory, a theoretical calculation has been performed for the transition temperatures for various high-T_c oxide compounds. It has been assumed that, three electrons are responsible for the superconducting current. Whereas two of these electrons form an exotic bound pair, the third electrons form an exotic bound pair, the third electron causes perturbation H'=βx³+yx⁴ with respect to apical oxygen vibrations. From the calculations, the transition temperatures are found to be realistic and comparable with experimental results.

3 illus, 1 table, 23 ref

003253   Katare R K;Joshi S K;Shrivastava B D;Patel R N;Mishra A (Physics Dep, Government Post-Graduate Arts and Science College, Ratlam-457 001) : Xanes and EXAFS studies of some copper (II) mixed-ligand complexes. Indian J pure appl Phys 2002, 40(12), 908-13.

X-ray K-absorption spectroscopic studies have been carried out on four copper (II) mixed-ligand complexes. The complexes are: I[Cu(asp)(H₂O)₂], II-[Cu(asp)(imH)], 2H₂O, III-[Cu(asp)(py)], Cu(asp)(py)], [Cu(asp)(bz-imH)],2 H₂O, in which aspartic acid has been used as primary ligand and water (H₂O), imidazole (imH), pyridine (py)and benzimidazole (bz-imH) have been used as secondary ligands. Various X-ray absorption parameters e.g., chemical shift, edge-width and shift of the principal absorption maximum have been obtained in the study. These parameters have been utilized to explain the nature of bonding and structure of the complexes. Further, the observed chemical shifts have been correlated with percentage covalency in these complexes. Average metal-ligand bond distances have also been estimated using EXAFS data. The studies establish significant correlation between various parameters for these complexes.

3 illus, 2 tables, 27 ref

003252   Kapoor K;Dass N (Physics Dep, College of Engineering Roorkee, Roorkee-247 667) : Melting temperature of helium to high pressures. Indian J pure appl Phys 2002, 40(12), 917-18.

The melting temperature, T_m, is calculated in the pressure range of 0.2-185.0 kbars in case of helium. The results so obtained are compared with the available data. The agreement is very good in the whole pressure range. Further, the pressure corresponding to the melting maximum in helium is found to be 17800 kbars.

^ssc1 illus, 2 tables, 6 ref

003251   Ghahramany N;Nouri M (Physics Dep, Shiraz University, Shiraz-71548, Iran) : An alternative approach to the extraction of structure functions in deep inelastic e-p scattering at 5 to 20 GeV. Ultra Scient phys Sci 2002, 14(3), 437-50.

Two structure functions W₁ (x, Q²) and W₂ (x, Q²) are determined by using the cross sections measured in the deep inelastic electron-proton scattering experiments at Stanford Linac in the energy range of 5 to 20 GeV. An alternative mathematical approach have been used in such determination, resulting in a larger number of points in the graphs of the structure functions.

3 illus, 3 tables, 4 ref

003250   Ghahramany N;Asadi M V Z;Boroun G R (Physics Dep, University of Shiraz, Shiraz, 71454, Islamic Republic of Iran) : Quasi-elastic electron-deuteron scattering and calculation of neutron electromagnetic form factors at Q<. Ultra Scient phys Sci 2002, 14(3), 509-16.

Electric and Magnetic form factors of neutron are calculated via electron-deuteron scattering at 1.522-5.507 GeV energy using SLAC group data. The study of results show that the neutron electric form factor is not equal to zero; rather it has small value indicating, in spite of the fact that total charge is almost neutral, there is a nonuniform charge distribution within the neutron and magnetic form factor follows the dipole fit.

4 illus, 2 tables, 10 ref

003249   Dhar R;Pandey R S;Agrawal V K (Physics Department, Ewing Christian College, Allahabad-211 003) : Optical and thermodynamic studies of binary mixtures of nematic liquid crystals from homologous members of alkyloxybenzoic acid. Indian J pure appl Phys 2002, 40(12), 901-7.

Transition temperature (T_p, transition enthalpy (ΔH) and transition entropy (ΔS) for the binary mixtures of heptyloxybenzoic acid (HOBA) and decyloxybenzoic acid (DOBA) in different mole ratios have been determined using differential scanning calorimeter (DSC). The phase diagrams for the heating and cooling cycles have been drawn which show the cutectic composition of DOBA-HOBA binary system in the ratio of 48:52 mole per cent. A wide range smectic C (SmC) phase (range <126>40°C) followed by the nematic (N) phase (range <126>34°C) has been observed around the cutectic composition of DOBA-HOBA binary system. SmC-N and N-I (isotropic) transition temperatures (T_c-n and T_N-I) have been found to vary, almost linearly, with the mole fraction of components. indicating the system as an ideal mixture. For the eutectic composition of the HOBA-DOBA system, it has been possible to bring down SmC phase to 60°CC with enhanced temperature range, whereas no member of the alkyloxybenzoic acid series has SmC phase below 92°C.

7 illus, 1 table, 25 ref

003248   Das S K;Sengupta S (Physics Dep, Maulana Azad College, Rafi Ahmed Kidwai Road, Kolkata-700 013) : Quantum and classical propagation of a Gaussian ensemble: two examples. Curr Sci 2002, 83(10), 1231-4.

Discusses two remarkable examples in which position and momentum probability density functions using an arbitrary Gaussian ensemble (described by a non-coherent Gaussian wave packet) develop identically both in classical and quantum mechanics. The first case is propagation in free space and the second in a harmonic oscillator potential. In both cases quantum potential and quantum force (defined in Bohm's theory) are non-zero. This may be stated to be the outcome of the investigation.

7 ref

003247   Changdar S N (Physics Dep, Bose Institute, Kolkata) : Diffusive motion in aqueous solutions. Indian J pure appl Phys 2002, 40(12), 857-61.

Reports that employing techniques which increase the thermal motion of the constituent particles or by varying the composition of the binary and ternary systems, much information can be gathered about liquids and, in the respect, diffusion study in liquids is an important tool. It is very interesting and very important to observe the change in diffusion coefficient in some aqueous solution with the introduction of known amounts of some other salts or acids. This study of coupled flow has been undertaken by several groups of workers. A sliding cell method based on radioactive tracer technique has been developed in the laboratory of the author and it has been used to measure diffusion coefficient in H₃PO₄-H₂O system containing different amount of salts of this weak acid.Different radioactive isotopes like Na-22, Na-24, Hg-203, Ga-72, Cs-134, Cs-137, Ti-204, P-32 etc., have been used in the laboratory for diffusion measurements in different systems. Irreversible thermodynamical principles have been applied to explain the observed results. Both H₂O and D₂O have been employed as solvents and the breaking of their structures with the introduction of salts have been explained.

4 illus, 17 ref

003246   Brar L K;Paranjape M;Guha A;Raychaudhuri A K (Physics Dep, Indian Institute of Science, Bangalore-560 012) : Design and development of the scanning force microscope for imaging and force measurement with sub-nanonewton resolution. Curr Sci 2002, 83(10), 1197-9.

2 illus, 8 ref

002034   Singh A K (Dep Math, V S S D Coll, Kanpur-208002) : MHD free convection and mass transfer flow with heat source and thermal diffusion. J Energy Heat Mass Transfer 2001, 23(2), 227-49.

Deals with the study of free convection and mass tranfer flow of an incompressible, viscous and electrically conducting fluid past a continuously moving infinite vertical porous plate in presence of large suction and under the influence of uniform magnetic field considering heat source and thermal diffusion. Introducing the usual similarity transformations, the equations of momentum, energy and concentration are made similar. To obtain local similarity solutions of the problem the similarity equations are solved using perturbation technique. The velocity, temperature and concentration fields are shown graphically to observe the effects of parameters entering in the problem. The skin-friction coefficient, rate of heat and mass transfer are shown in tabular form. A thorough discussion of different results is presented.

7 illus, 4 tables, 30 ref

002033   Mahapatra S K (NO, Birla Engng Coll Campus, Qrs No.3r-32, Professor Colony, Orissa-768018) : Combined radiation and conduction heat transfer analysis in the presence of participating medium by discrete ordinate method. J Energy Heat Mass Transfer 2001, 23(2), 213-25.

Thermal radiation plays a substantial role in the transport phenomena in heat intrinsic devices such as combustion chambers, insulation systems, etc. Numberical modelling of radiation transport phenomena for a participating medium gives rise to non-linear integro-differential equation, which does not have the closed form solution. A two-dimensional square enclosure has been considered as the physical model. The square enclosrue comprises of isothermal vertical walls and insulated horizontal walls. The walls are considered to be gray, opaque, diffusely emitting and absorbing. The radiative transfer is affected due to absorbing and emitting characteristics of the medium. Discrete ordinate method has been adopted for modelling the radiative transport equation and is numerically solved by finite volume method. The quardrature scheme of Carlson and Lathrop has been used. The energy eauation is numerically solved with central difference scheme. The effect of various parameters characterizing the participating medium are illustrated on the energy transfer and temperature field is illustrated.

6 illus, 2 tables, 11 ref

002032   Lenin K;Pydi Setty Y; (Dep Chem Engng, Reg Enging Coll, Warangal) : Drying of solids in a continuous fluidized bed. J Energy Heat Mass Transfer 2001, 23(2), 135-51.

Investigates drying charactristics of solids in a continuous fluidized bed. Experiments were performed using solids of uniform size as well as a binary solid mixture and comparison was made between the two. Effect of gas flow rate, solids flow rate, initial moisture content of solid sand temperature on drying characteristics like drying rate and average moisture content of solids was investigatged. Comparison of drying behavior between continuous fluidized bed and a batch fluidized bed dryer was also made. Analytical expressions have been obtained for predicitng average moisture content in a continuous fluidized bed dryer using the RTD models like Tanks-in-series model and Fractional Tank Extention Model (FTEM). The drying kinetic models thus obtained were fitted to the experimental drying data to test the validation of the model. The models were found to fit the data perfectly and the values of the model parameter, number of stages, N were obtained for typical experiments.

6 illus, 2 tables, 9 ref

002031   De Sarkar A;Khanra B C (Condensed Matter Physics Group, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Calcutta-700 064) : MC model studies of CeO₂ - metal interaction in Pt-Rh nanocatalysts. Indian J Chem-Sect A 2002, 41(9), 1784-8.

MC simulation technique has been used to investigate the effects of gradual reduction of Pt-Rh/ceria and the concomitant change in the metal-support interaction on the composition of Pt-Rh nanocatalysts. For all nanoparticle sizes the Pt fraction at the basal layer of the Pt₅₀rH₅₀ systems is found to increase with metal-support interaction. The Pt fraction is highest at the basal layer and reaches approximately the particle-average value of 50% at the fourth layer from the the base. In the rest of the particle surface, which is exposed to the reacting gases, the Pt fraction is highest when metal-support interaction is weak; and decreases gradually with higher strength of metal-support interaction.

5 illus, 1 table, 16 ref

002030   Anjali Devi S P;Kandasamy R (Dep Math, Bharathiar Univ, Coimbatore-641046) : Effects of heat and mass transfer on MHD laminar boundary layer flow over a wedge with suction or injection. J Energy Heat Mass Transfer 2001, 23(2), 167-78.

An approximate numerical solution for the steady MHD laminar boundary-layer flow over a wall of the wedge with suction or injection in the presence of species concentration and mass diffusion has been obtained by solving the governing equations using R. K. Gill method. The fluid is assumed to be viscous and electrically conducting Boussinesq fluid. A magnetic field is applied transversely to the direction of the flow. Numerical claculations upto third level of truncation are carried out for different values of dimensionless parameters in the problem and an analysis of the results obtained show that the flow field is influenced appreciably by the magnetic field and suction or injection at the wall of the wedge.

7 illus, 7 ref

001099   Zomorrodian M E (Department of Physics, Ferdowsi University, Mashhad, Islamic Republic of Iran) : Measurement of α_s in e+e- annihilations. Indian J Phys-Pt A 2002, 76(6), 567-71.

Measures the coupling constant α_s between the quark and the gluon by two different methods. In the first method, count the number of jets per event are counted and the the number of two and three jet events are compared. The ratio of three to two-jet events gives us α_s. The second method employs the jet clustering algorithm introduced by the JADE group. The results for both methods are in good quantitative agreement with the QCD theory. Our results are also consistent with those obtained from other experiments.

8 illus, 12 ref

001098   Weisser D C;Lobanov N R (Nuclear Physics Dep, Research School of Physical Sciences and Engineer, Australian National University, Canberra, ACT 0200, Australia) : ANU LINAC upgrade using multi-stub resonators. Pramana J Phys 2002, 59(5), 821-7.

Proposal has been prepared to upgrade the LINAC at ANU, using re-plated PbSn split loop resonators performing at 3.6 MV/m, and the addition of two - and three-stub resonators. The system is designed to provide 6 MeV/a.m.u. ¹⁰⁷Ag starting with gas-stripped beam from the 14 UD, which is then foil-stripped before the LINAC. No major changes to the beam optics components will be required other than addition of a large bore rebuncher in the middle of the 180° achromat. Models of the two - and three-stub resonators have been built and optimized for the goal frequency, for the separation of accelerating and other modes as well as for the minimization of the current in the demountable joints. A copper prototype has been constructed and is being plated with PbSn for cold testing.

5 illus, 13 ref

001097   Watekar P R;Nanda Goswami M L;Biswas J C; Acharya H N (Department of Electronics and Electrical Comm, Engg. Indian Institute of Technology, Kharagpur-721 302) : Fluorescence and SEM-EDAX studies of erbium-doped SiO₂-GeO₂ preforms processed by MCVD. Indian J Phys-Pt A 2002, 76(6), 527-9.

The experimental studies on fluorescence and SEM-EDAX of the Er-doped SiO₂-GeO₂ glass in the form of preforms with different solution doping periods and doping concentrations are reported. The fluorescence lifetimes of erbium ions in different preforms are measured. The work will be useful for fiber-optic amplifiers.

5 illus 1 table 5 ref

001096   Variale V et al (NO, Istituto Nazionale di Fisica Nucleare (INFN)-Sezione di Bari, Italy) : EBIS for charge state breeding in the SPES project. Pramana J Phys 2002, 59(5), 765-73.

The `Charge state breeder', BRIC (breeding ion charge) is in construction at the INFN section of Bari (Italy). It is based on EBIS scheme and it is designed to accept radioactive ion beam (RIB) with charge state +1 in a slow injection mode. This experiment can be considered as a first step towards the design and construction of a charge breeder for the SPES project. The new feature of BRIC, with respect to the classical EBIS, is given by the insertion, in the ion chamber, of a rf-quadrupole aiming at filtering the unwanted masses and then making a more efficient containment of the wanted ions. The breeder design, the simulation results of the electron and ion beam propagation and the construction problems of the device have been reported.

5 illus, 12 ref

001095   Upreti U C;Narlikar A V (Natn Phys Lab, , New Delhi-110 012) : Exploring the site occupancy effects of equal low concentrations of Zn and Fe dopants on order parameter fluctuations in Y123 bulk samples. Indian J pure appl Phys 2002, 40(11), 795-800.

In the mean field region have been investigated (MFR). Effects on order parameter dimensionality(OPD) and excess conductivity (Δσ) due to separate equal (0.5%) due to separate equal (0.5%) low-concentration substitutions of Zn and Fe at the Cu-sites in Y 123 polycrystallien bulk superconductor samples. The OPD dependence on change of Cu-site low disorder dopant and the effects of OPD variation on the interlayer coupling, on its cross-over behaviour, on superconductivity suppression and anisotropy are discussed. It is seen that the OPD increases by Fe doping but is independent of intrinsic disorder in pure as well as in the Fe doped sample. The system anisotropy is invariant to (raised with) Zn (Fe) low disorder. In pure and Zn doped samples, the dimensionality behaviour enables us to estimate the c-direction coherence length (ξc) and consequently, the Josephson coupling strength (J). At these dopign levels, there is no significant change in J due to Zn, whereas the OPD behaviour in Fe doped sample does not allow estimation of us to estimate ξc and J.

2 illus, 44 ref

001094   Taneja R;Jain N C (Dep Math, Univ Raj, Jaipur-302 004) : Nonlinear analysis of free convection flow in a rotating wavy channel with temperature dependent heat source. J Energy Heat Mass Transfer 2001, 23(4), 473-81.

Examines the problem of unsteady free convection flow in presence of a temperature dependent heat source in a rotating wavy channel with travelling thermal waves. The couple nonlinear partial differential equaitons governing the flow have been solved using perturbation technique and expressions for different functions have been obtained.

4 illus, 10 ref

001093   Taneja R;Jain N C (Dep Math, Univ Raj, Jaipur-302 004) : Nonlinear analysis of free convection flow in a rotating wavy channel with temperature dependent heat source. J Energy Heat Mass Transfer 2001, 23(4), 473-81.

Examines the problem of unsteady free convection flow in presence of a temperature dependent heat source in a rotating wavy channel with travelling thermal waves. The coupled nonlinear partial differential equations governing the flow have been solved using perturbation technique and expressions for different function have been obtained.

4 illus, 10 ref

001092   Taki G S;Chakraaborty D K;Bhandari R K (Variable Energy Cyclotron Centre, Department of Atomic Energy, , Block-AF, Bidhan Nagar, Kolkata-700 064) : 6.4 GHz ECR ion source at VECC. Pramana J Phys 2002, 59(5), 775-80.

The 6.4 GHz ECR ion source that was indigenously developed a few years ago has been operating continuously for injecting oxygen and neon beams to the cyclotron since 1997. VEC-ECR is a single stage high magnetic field ion source provided with a negatively biased electron repeller placed on the axis, near the injection mirror point. The supply of cold electrons and use of low mass mixing gas improve the stability of ECR plasma. Very recently, the effect of aluminum oxide coating on the copper plasma chamber wall has been studied. The plasma chamber wall was coated with aluminum by vacuum evaporation method and then exposed to oxygen gas to form aluminum oxide. It was noticed that the process substantially shifts the charge state distribnution to the higher charge state with an enhancement of ion current by an order of magnitude. With the aluminized plasma chamber, the VEC-ECR can now produce 12 μA of O⁷⁺, 6.5μA of Ar¹²⁺, 1.5μA of Kr²⁰⁺ and 1.0 μA of Xe ³¹⁺.

3 illus, 2 tables, 9 ref

001091   Srivastava V P (Dep of Math, Babu Banarasi Das National Institute of Technology and Management, Chinhut, Lucknow-227 105) : Particle-fluid suspension flow induced by peristaltic waves in a circular cylindrical tube. Bull Calcutta Mathl Soc 2002, 94(3), 167-84.

A long wave approximation is adopted to analyse the problem of peristaltic pumping of a particle-fluid suspension in a circular cylindrical tube. Analytical solutions in closed form up to the second order approximation (in terms of ratio of mean tube radius to the wavelength) are presented. Criteria for negative values to appear in mean velocity profiles are established.

51 ref

001090   Sreshthaputra A;Haberl J;Andrews M J (Dep Architecture, Texas A&M Univ Coll Stn, Texas-77843-3123) : 3-D studies of heat transfer and airflow in an unconditioned Thai buddist temple. J Energy Heat Mass Transfer 2001, 23(4), 455-71.

3-D Computational Fluid Dynamics (CFD) simulations, DOE-2 simulations, and measurements associated with the heat transfer performance of an unconditioned 100-year-old Buddhist temple located in Bangkok, Thailand. The heat transfer characteristics of this traditionally designed temple are reviewed and compared with modern designs using measurements. By comparison with DOE-2 and local measurements the overall performance of the CFD simulation has been validated. Large-scale, 3-D CFD simulations indicated poor thermal comfort conditions in this temple. The CFD/DOE_2 simualtion suggested several remedial changes that could be implemented to improve the indoor comfort.

9 illus, 1 table, 21 ref

001089   Singh P et al (Nuclear Physics Division, Bhabha Atomic Research Centre, , Mumbai-400 085) : Status report on the folded tandem ion accelerator at BARC. Pramana J Phys 2002, 59(5), 739-44.

The folded tandem ion accelerator (FOTIA) facility set up at BARC has become operational. At present, it is used for elemental analysis studies using the Rutherford backscattering technique. The beams of ¹H, ⁷Li, ¹²C, ¹⁶O and ¹⁹F have been accelerated up to terminal voltages of about 3 MV and are available for experiments. The terminal voltage is stable within ±2 kV. Present status of the FOTIA and future plans are discussed.

3 illus, 9 ref

001088   Shrivastava P;Wanmode Y D;Hannurkar P R (Centre for Advanced Technology, , PO CAT, Indore-452 013) : Preliminary design of high-power wave-guide/transmission system for multimegawatt CW requirements of 100 MeV proton LINAC. Pramana J Phys 2002, 59(5), 829-34.

Development of a 100 MeV CW proton LINAC has been planned at CAT. This LINAC will be needing CW rf power in the frequency ranges of 350 MHz and 700 MHz for its RFQ and DTL/CCDTL/SFDTL structures respectively. The power to the accelerating structures will be produced by either 1 MW CW or 250 kW CW klystrons/inductive output tubes (HOM IOTs). The power needed by respective feed points in the structure is max. 250 kW which will be powered by splitting the power from 1 MW klystron/klystrode into four channels by using a wave-guide system. In case of using 250 kW tubes the power to the structures will be provided directly from each tube. Two types of wave-guide transmission system have been considered, viz. WR 2300 for 350 MHz rf needs and WR 1500 for 700 MHz rf needs. The typical wave-guide system has been designed using the 1 MW CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window. The circulator and each power divider is terminated into the isolated ports by high power CW loads. Out of the four channels three channels have phase shifters. Describes the technological aspects and design specifications-considerations for these stringent requirements.

2 illus, 5 tables, 4 ref

001087   Sengar S;Dhoble S J;Chandra B P;Bhat B C (Department of Physics, Government Model Science College, Pachpedhi, Jabalpur-482 001, Chhatisgarh) : Photoluminescence and thermoluminescence in Pr<. Indian J Phys-Pt A 2002, 76(6), 531-5.

The ZELAN : Pr³⁺ crystalline phosphor prepared by solid state diffusion method has been reported. Photoluminescence and effects of ionising radiation on luminescence have been investigated in ZBLAN : Pr³⁺. Photoluminescence study indicates that the intensity of emission at 400 nm is due to ³P₂→³H₄ transition of Pr³⁺ ions. The defects created by ionising radiation are studied by thermoluminescence technique. Thermoluminescence studies indicate two prominent glow peaks at 120 and 350°C due to two defect centres the positions of which are found to depend on the radiation dose and Pr³⁺ concentration in ZBLAN. Defect accumulation was noted to be strongly dependent on the level of γ-exposure. A suitable explanation of these results is suggested.

7 illus, 24 ref

001086   Sanyal D C;Dasgupta S (Dept of Math, University of Kalyani, Kalyani-741 235) : Unsteady flow of dusty conducting incompressible fluid through a rectangular tube. Bull Calcutta Mathl Soc 2002, 94(4), 297-304.

The unsteady flow of a dusty incompressible conducting viscous fluid through a long uniform reactangular tube under arbitrary pressure gradient is studied in presence of a uniform magnetic field perpendicular to the direction of the flow. Laplace transformation has been used to solve the problem. Numerical calculations are done to observe the variations of velocities of the fluid for constant and harmonically oscillating pressure gradient.

2 illus, 4 ref

001085   Repnow R (NO, Accelerator group of Max-Planck-Institut Fuer Kernphysik, Heidelberg, Germany) : Progress and upgrading of the Heidelberg high current injector. Pramana J Phys 2002, 59(5), 835-48.

Specialized rf-accelerator system HSI consisting of two RFQ's and 8 rf seven-gap cavities was built for injection of high intensities of singly charged heavy ions into the Heidelberg heavy ion storage ring TSR. With different ion sources, this system now is used to deliver positive or negative, atomic and molecular ion beams with energies between 150 keV/a.m.u. and 5.3 MeV/a.m.v. final energy. For a future replacement of the MP-tandem-postaccelerator-system the new HSI-accelerator is to be equipped with an ECR source for high intensities of highly charged ions. An advanced commercial ECR source with a 18 GHz rf klystron and an adjustable extraction system for adaption of a wide range of injection energies has been commissioned at the manufacturer and is delivered. Test bench operation presently is in preparation at Heidelberg. A stripper section with an achromatic charge state selector is under construction between injector and postaccelerator. Other ion sources, e.g., for ultra cold H⁺₃ molecular ion beams are under development.

7 illus, 6 tables, 10 ref

001084   Rashid M H;Bhandari R K (Variable Energy Cyclotron Centre, , Sector-1, Block-AF, Bidhan Nagar, Kolkata-700 064) : Concept of multipole magnetic field rotation in ECRIS. Pramana J Phys 2002, 59(5), 781-94.

The conventional type of magnetic well is formed by superposition of two types of magnetic field, axial bumpy field and radial multipole field. It is used to contain plasma that consists of neutrals, ions and electrons. These particles are in constant motion in the well and energetic electrons create plasma by violent collisions with neutrals and ions. The confined electrons are constantly heated by ECR technique in the presence of magnetic field. It has been shown theoretically how the electron motion is influenced in terms of heating, containment and azimuthal uniformity of plasma, by the axial rotation of the multipole magnetic field. Feasibility of achieving a rotating magnetic multipole field is discussed. Slightly larger size of the multipole electromagnet can be used for improvement of the ECR ion source (ECRIS).

10 illus, 27 ref

001083   Rajneesh Kumar;Ranjit Singh;Chadha T K (Dep of Math, Kurukshetra University, Kurukshetra) : Eigen value approach to dynamic problem of heat flux dependent micropolar thermoelastic solid. Bull Calcutta Mathl Soc 2002, 94(4), 305-18.

The disturbance due to a mechanical source in a homogeneous isotropic heat flux dependent micropolar thermoelastic solid is investigated by employing eigen value approach after applying the Laplace and the Fourier transformations. The integral transforms have been inverted by using a numerical technique to obtain the components of the displacement, force stress, couple stress and temperature distribution in the physical domain for L-S and G-L theories of micropolar generalized thermoelasticity and are shown graphically.

4 illus, 23 ref

001082   Prakash P N (Nuclear Science Centre, , P.O. Box 10502, Aruna Asaf Ali Marg, New Delhi-110 067) : Superconducting linear accelerator system for NSC. Pramana J Phys 2002, 59(5), 849-58.

Reports the construction of a superconducting linear accelerator as a booster to the 15 UD Pelletron accelerator at Nuclear Science Centre, New Delhi. The LINAC will use superconducting niobium quarter wave resonators as the accelerating element. Construction of the linear acceleartor has progressed sufficiently. Details of the entire accelerator system including the cryogenics facility, RF electronics development, facilities for fabricating niobium resonators indigenously, and present status of the project are presented.

7 illus, 18 ref

001081   Porcellato A M;Palmieri V;Bertazzo L;Capuzzo A;Giora D;Stivanello F;Stark S Y;Kar S (NO, INFN, Laboratori Nazionali di Legnaro (Pd), Italy) : Production, installation and test of Nb-sputtered QWRs for ALPI. Pramana J Phys 2002, 59(5), 871-80.

Eight cryostats, each housing 4 sputtered Nb/Cu, 160 MHz, quarter wave resonators (QWR), are now in operation in ALPI. Two of house high β cavities others are equipped with medium β resonators. Another medium β cryostat is ready these to be installed in the early 2002. Pb/Cu medium β accelerating cavities are present only in four cryostats and they will have their Pb superconducting (SC) layer replaced by sputtered Nb soon. The substitution of the Pb SC layer in ALPI medium β resonators did not interfere with ALPI operation; the upgrading of resonators went on parallel to the cryostat maintenance programme. The average accelerating field of these rresonators, at the design power of 7 W , overcomes 4 MV/m, whereas, when pB electroplated, their average value was 2.7 MV/m. The sputtered resonator combines the good SC characteristics of Nb with the higher thermal conductivity and better stability to change of He bath pressure, which is typical of copper resonators. This leads to a very high reliability, as routinely experienced during beam acceleration.

6 illus, 14 ref

001080   Podder J;Hossain T (Department of Physics, Bangladesh University of Engineering & Technology, Dhaka-1000, Bangladesh) : Study of heteroatom effect on graphitic carbons derived from anthracene phenanthrene-sulphur system by thermal and optical analysis. Indian J Phys-Pt A 2002, 76(6), 537-41.

The carbonaceous mesophase as a precursor to graphitization has been examined from polynuclear organic compounds, such as anthracene-sulphur and phenanthrene-sulphur systems with the aid of Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA) and finally by the polarized-light technique. With the continued addition of sulphur-hydrogen mole ratio, the latent heat of fusion (i.e. activation energy) and as such the graphitizability of the carbons have been found to decrease. In addition to dehydrogenation, sulphur caused crosslinking between layer planes thus preventing the formation of oriented layers, typical of the graphic structure.

20 ref, 13 illus

001079   Perumallu V;Balaji C (Heat Transfer and Thermal power Lab, Dep Mech Engng, Indian Inst Technology Madras, Chennai-600036) : A numerical simulation of natural convection from external longitudinal fins over a horizontal cylinder. J Energy Heat Mass Transfer 2001, 23(4), 417-33.

Reports the results of a numerical study of natural convection heat transfer from a horizontal cylinder with external longitudinal fins made of aluminium. The effect of Rayleigh number, number of fins and aspect ratio on Nusselt number is studied. Based on a parametric study, a correlation for Nusselt number is also proposed. Natural convection heat transfer from a horizontal cylinder is studied and results are compared with the available data.

13 illus, 10 ref

001078   Panwar S;Ishwar Singh (Department of Basic Science, College of Engineering & Technology, Gurukul Kangri Vishwa Vidyalaya, Hardwar-249 404, Uttranchal) : Anomalous electrical resistivity and hall constant of Anderson lattice with finite-f-band width. Indian J Phys-Pt A 2002, 76(6), 557-60.

Studies on extension of the periodic Anderson model by considering finite F-band width. A variational method is used to study the temperature dependence of electronic transport properties of Anderson lattice for different values of the f-band width. The electrical resistivity p(T) and Hall constant R_H(T) calculated show qualitatively the features experimentally observed in heavy fermion materials. Finds that as f-band width increases, the low temperature peak in p(T) disappears, while the low-temperature peak in R_H (T) becomes sharper.

2 illus 25 ref

001077   Pande S A;Moonooku Prasad;Kulkarni N; Hannurkar P R (Centre for Advanced Technology, , Indore-452 013) : Preliminary design studies of a 100 MeV H<. Pramana J Phys 2002, 59(5), 859-69.

It is proposed to construct a spallation neutron source (SNS) at Centre for Advanced Technology (CAT) based on a 1 GeV proton synchrotron with 100 MeV H^- LINAC as injector. Additionally, the LINAC can form the first 100 MeV part of a 1 GeV proton LINAC to be built in future for accelerator driven system (ADS) applications. A configuration of the 100 MeV LINAC is being explored which will consist of an H^- ion source, a 4-6 MeV RFQ followed either by a 20 MeV drift tube LINAC (DTL) and 100 MeV separated function drift tube LINAC (SDTL) or a coupled cavity drift tube LINAC (CCDTL) structure. Results of preliminary physics design studies of the RFQ-SDTL, RFQ-CCDTL and RFQ-DTL-SDTL configurations are being presented. The design of the 4.5 MeV RFQ is discussed along with the matching sections between the RFQ-SDTL/DTL and RFQ-CCDTL. The choice of the accelerator configuration and that of various parameters of the individual accelerator structures under consideration are discussed. The design objectives are to arrive at a configuration which eases heat removal for CW operation and which is less prone to halo formation in order to reduce the beam loss at higher energies.

8 illus, 4 tables, 8 ref

001076   Osswald F;Rebmeister R (NO, Institut de Recherches Subatomiques, 67037 Strasbourg Cedex 2, France) : Beam optics optimization of a negative-ion sputter source. Pramana J Phys 2002, 59(5), 795-804.

Negative-ion sputter source has been studied in order to increase the beam intensity delivered by the Vivitron tandem injector. The aim was to characterize the influence on the beam intensity of some factors related to the configuration of the source such as the shape of the target holder, the target surface topography and the anode/cathode voltage. Reports the results carried out by experimentation on a test facility and on the injector itself as well as the investigations performed with computer simulations.

7 illus, 15 ref

001075   Norton G (NO, National Electrostatics Corp, Middleton, Wisconsin, USA) : New Developments in dessign and applications for pelletron accelerators. Pramana J Phys 2002, 59(5), 745-51.

Most of the developments over the last several years related to Pelletron accelerator are in the field of accelerator mass spectrometry (AMS) and other low beam current applications with the exception of a very high DC electron recirculation Pelletron. High precision AMS systems based on tandem Pelletrons from 500 kV to 5MV terminal potential are now in use for routine high precision AMS measurements. Their performance have been reported. In addition, there has been significant advancement in the design of the multi-cathode SNICS source for the use of both gas and solid samples within a single source. The latest performance of these sources have been discussed. New diagnostics is being developed for very low beam currents. The latest design of the low current beam profile monitor (LCBPM) have been presented.

4 illus, 1 table, 10 ref