013269   Reicha F M;Elabsy A M;Atta A A;Elmahdy M M (Physics Dep, Faculty of Science, Mansoura Univ, Mansoura-35516, Egypt) : Structure of electropolymerized polyacrylonitrile. J Polym Mater 2004, 21(4), 445-54.

In the work polyacrylonitrile-homopolymer (PAN) is prepared by the electrochemical polymerization technique. Elemental analysis, IR, UV-visible, and X-ray spectroscopies were used to investigate the prepared samples. The fabricated samples exhibited the formation of different amorphous-like structures depending on the current density of preparation. The molecular weight obtained from the viscosity measurements is enhanced with increasing the current density. Thermogravimetric analysis emphasized that the synthesized homopolymer is stable up to a temperature of 215°C. All the formed samples are found to be soluble in organic solvents (DMF, DMSO). It is seen from the UV-visible spectra that the optical energy gaps for homopolymers decrease with enhancing the current density. The optical measurements indicated the presence of a well-defined transition which may be attributed to π-π^* transition.

4 illus, 4 tables, 40 ref

013268   Prasad R S;Kumar K (Dep of Physics, Magadh University, Bodh-Gaya-824 234, Bihar, Email: rsp_phys@rediffmail.com) : Electronic spectrum of octaazacubane (N₈). Indian J Phys 2004, 78(12), 1391-3.

MRINDO/S calculation augmented by singly-excited configuration interaction was performed on octaazacubane. Ionization potentials, singlet and triplet excitations and the singlet-triplet splittings in octaazacubane have been reported. The importance of outer (Rydberg) atomic orbitals is stressed and it is found that none of the transitions leads to an excited state with considerable Rydberg character.

3 tables, 18 ref

013267   Prajapati J H;Patel S G;Oza A T (Dep of Physics, Sardar Patel University, Vallabh Vidyanagar-388 120, Anand, Gujarat, Email: headphyspu@rediffmail.com) : Infrared spectra of charge transfer complexes of bis(N-ethylsalicylaldiminato)Cu<. Indian J Phys 2004, 78(12), 1365-70.

Charge transfer complexes of bis(N-ethylsalicylaldiminato)Cu^II with organic acceptors like TCNQ, TCNE, TNF, DDQ, chloranil and iodine have been prepared and studied with Fourier transform infrared spectroscopy. The electron donating chelate is isostructural to the methyl analog in which metal chains are found in one crystallographic direction. The spectra obtained in the range of 400-4000 cm^-1 are mainly governed by the donor spectrum. Only above 1700 cm^-1, the acceptor bands are visible. DDQ and chloranil both containing chlorine atoms interact more strongly as compared to other acceptors. The electronic absorption envelopes are identified. The nature of transition, band tailing effect and free-carrier absorption are also analyzed. Observed steric effects of ethyl groups compared to methyl groups are discussed.

8 illus, 7 tables, 16 ref

013266   Ponnusamy V;Ramasamy V (Physics Dep, Annamalai University, Annamalainagar-608 002) : Thermostimulated luminescence sensitivity changes in biotite-granitic quartz as a result of annealing. Indian J Phys 2004, 78(11), 1199-1203.

The TSL sensitivity change can be observed usually after the quartz is heated to a high thermal treatment. In literature, the change of 110°C TSL peak was reported to be an increase in many studies. In the present investigation, the change in 150°C TSL peak sensitivity as a function of annealing temperature and annealing time was demonstrated. Granitic quartz shows there is slow enhancement in sensitivity up to 800°C. Below 200°C, negligible effect of sensitivity was observed. The number of peaks present in the glow curve and its order of kinetics is found by partial heating method and are confirmed by dose response. The trap population is a trap geochrometer to date a cooling age of a granitic host, if the TSL sensitivity is a measure of the population of associated TSL traps.

5 illus, 16 ref

013265   Pandey K;Chaturvedi R (Mathematics & Astronomy Dep, Lucknow University, Lucknow-226 007) : Weak-waves in reacting gases. Proc Natn Acad Sci India-Sect A 2004, 74(Pt III), 285-96.

An attempt has been made to obtain and discuss the growth and decay of weak discontinuities in characteristic plane for reacting gases, when chemical reaction between n species are taken as the source of non-equilibrium effects. The critical amplitutde of the initial compressive-disturbance has been determined and it is shown that any compressive-wave with an initial amplitude greater than critical one will terminate into a shock-wave, while compressive-waye with an initial amplitude less than the critical one will result in a decay. With the help of Laplace-transformation exact solutions and solution upto first order of small quantities have been obtained and discussed for expansion-wave.

1 illus, 17 ref

013264   Panda T C;Mishra S K;Das A K (Mathematics Dep, Berhampur University, Berhampur-760 007, Orissa) : Turbulent free jet with suspended particulate matter (SPM). Proc Natn Acad Sci India-Sect A 2004, 74(Pt III), 297-310.

Mathematical model analysis of turbulent free jet envisaging the physical processes like Brownian diffusion, drag force and volume fraction in relation to dust loading in the atmosphere has been studied for better monitoring and prediction. The analysis presented the modified form of Reynolds equations for turbulent boundary layer to account for the interactions due to physical processes that arise due to presence of SPM. Crank-Nicholson implicit finite difference scheme has been employed for model validation. The model prediction depicts the interdependence of SPM and mixing length. The analysis is in good agreement with Schlichting and experimental results of Reichardt. Consideration of volume fraction and Brownian diffusion of SPM helps in the migration of SPM through a longer distance.

7 illus, 2 tables, 19 ref

013263   Pal A;Anil Kumar (Dep of Chemstry, Kurukshetra University, Kurukshetra-136 119, Email: palchem@sify.com) : Speeds of sound and isentropic compressibilities of binary mixtures containing dipropylene glycol monobutyl ether with n-alkanols at 298.15 K. Indian J Phys 2004, 78(12), 1319-27.

Speeds of sound have been measured in dipropylene glycol monobutyl ether + methanol, 1-propanol, 1-pentanol, 1-heptanol, across the entire composition range, at the temperature 298.15 K and atmospheric pressure. The speed of sound values were combined with excess molar volume to obtain values for the product K_S,m of the molar volume and the isentropic compressibility K_S, and the corresponding quantities K^E_S,m were also calculated. The K^E_S,m values are negative for all mixtures. The deviation of the speeds of sound u^D from their values u^id in ideal mixtures were obtained for all measured mole fractions. These values are compared with mixing function δu. The behaviour of u, δu, u^d, and K^E_S,m as a function of composition and number of carbon atoms in the alcohol molecule is discussed.

4 illus, 5 tables, 38 ref

013262   Nath P P;Joarder R N (Physics Dep, Jadavpur University, Kolkata-700 032, Email: rnj@juphys.ernet.in) : Characteristic Bhatia-Thornton static structure and diffusion coefficients of liquid LiNa and KPb alloys. Indian J pure appl Phys 2005, 43(3), 180-3.

The liquid alloys, LiNa and KPb are strongly phase separating (ps) and compound forming (cf) alloys respectively and are known to have opposite ordering properties. The Bhatia-Thornton (BT) static structure factors are important indicators of the ordering properties and can best be understood in terms of ordering potential obtained from neutral pseudo atom method. How this difference in static structural behaviour could influence the dynamical property like self and mutual diffusion coefficients as a function of concentration of the lighter component has been investigated. The method of Helfand's linear trajectory principle has been used in the calculation and this gives results comparable with recent calculations based on VACF total memory function formalism. Both the methods yield D versus 1/T curve almost linear similar to what is found for pure liquid metals.

5 illus, 13 ref

013261   Naik S S;George L;Salvekar P S (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Inter-annual variability in the dynamics and physics of the mean onset date of monsoon over Indian region. Indian J Radio Space Phys 2004, 33(4), 241-51.

From observational and statistical studies, the mean onset date of southwest monsoon for India is 1^st June with standard deviation of 8 days. It view of this, the atmospheric circulation over India and neighbourrhood (EQ-25°N, 50°E-90°E) for the mean onset date is studied using NCEP reanalyzed data from surface-300 hPa for three different years, i.e. (i) year 2000 having normal onset, (ii) year 1999, early onset (i.e. 25^th May) and (iii) year 1997, late onset (i.e. 9^th June). The influence of all dynamical and physical parameters for all the three years are discussed study for understanding the dynamics and physics associated with onset conditions on 1^st June.

8 illus, 1 table, 6 ref

013260   Munish Kumar;Alagu Raja E;Prasad L C;Popli K L;Massand O P (Personnel Monitoring Section, Health, Safety and Environment Group, Bhabha Atomic Research Centre, Mumbai-400 094) : Numerical simulation of thermally stimulated luminescence arising from localized transitions. Indian J Phys 2004, 78(11), 1193-8.

The rate equations of localized transition model of thermoluminescence (TL) have been simulated by taking into account their stiff nature for wide range of recombination probabilities and frequency factors using linear and hyperbolic heating profiles without assuming the quasiequilibrium (QE) approximation. The shape factors μg calculated for simulated glow curves vary from 0.41-0.52 in linear heating profile and from 0.42-0.56 in hyperbolic heating profile. It is found that shape factors μg exhibit dependence on hearting rates, therby implying that QE approximation is not satisfied, hence supporting the doubt regarding validity of QE approximation expressed earlier by many workers. In conclusion, it is states that under very strong re-trapping, it is possible to get non-first order kinetics in localized transition model.

1 illus, 4 tables, 22 ref

013259   Mohapatra R K;Murty S V S (Planetary and Geosciences Div, Physical Research Laboratory, Ahmedabad-380 009) : Nitrogen isotopes in mantle-derived diamonds: indications of a multi-component structure. Curr Sci 2004, 87(11), 1577-80.

Mantle nitrogen trapped in diamonds is commonly defined by an isotopic composition (δ¹⁵N) of ″-5%c based on the central tendency of total combustion diamond data that vary from -25 to +18%. We present here the nitrogen isotopic data from stepped combustion of diamonds, which together with data from other mantle-derived materials suggest a multi-component structure of diamond-nitrogen. Mantle nitrogen sampled in diamonds apparently has δ¹⁵5N ″-15%, similar to that observed in mantle xenoliths and mid-oceanic ridge basalts (MORBs), while nitrogen in a minor population of diamonds from China is consistent with contributions from an ocean island basalt like mantle source.

2 illus, 1 table, 37 ref

013258   Modi B P;Mathai A J;Patel K D;Pathak V M; Srivastava R (Physics Dep, Sardar Patel University, Vallabh Vidyanagar-388 120, Email: kdptflspu@yahoo.com) : Stability of liquid metal Schottky contacts. Indian J pure appl Phys 2005, 43(3), 184-7.

All evolutionary aspects of Schottky barriers e.g. the factors contributing to the band alignment at metal-semiconductor interfaces, are still not well understood. Liquid metal-semiconductor interfaces provide an opportunity to probe them since their formation process eliminates or minimizes many influencing factors e.g. formation of oxide layer, changes in surface morphology due to impact of deposited metal atoms etc. when compared to the formation of solid metal semiconductor interfaces. However, the liquid state of metal possessing higher equilibrium thermodynamic energy, may induce instability at interfaces by inducing interfacial reactions ultimately showing up in ageing effect. The liquid metals namely Hg and Ga on p-type silicon show no such effect and hence can be fruitfully exploited for probing evolutionary aspects of metal-semiconductor interfaces through liquid metal route.

4 illus, 18 ref

013257   Modi B P;Mathai A J;Patel K D;Pathak V M; Srivastava R (Physics Dep, Sardar Patel University, Vallabh Vidyanagar-388 120, Email: kdptflspu@yahoo.com) : Stability of liquid metal Schottky contacts. Indian J pure appl Phys 2005, 43(3), 184-7.

All evolutionary aspects of Schottky barriers e.g. the factors contributing to the band alignment at metal-semiconductor interfaces, are still not well understood. Liquid metal-semiconductor interfaces provide an opportunity to probe them since their formation process eliminates or minimizes many influencing factors e.g. formation of oxide layer, changes in surface morphology due to impact of deposited metal atoms etc. when compared to the formation of solid metal semiconductor interfaces. However, the liquid state of metal possessing higher equilibrium thermodynamic energy, may induce instability at interfaces by inducing interfacial reactions ultimately showing up in ageing effect. The liquid metals namely Hg and Ga on p-type silicon show no such effect and hence can be fruitfully exploited for probing evolutionary aspects of metal-semiconductor interfaces through liquid metal route.

4 illus, 18 ref

013256   Mishra R;Tiwari M S (Physics and Electronics Dep, Dr H S Gour Vishwavidyalaya, Sagar-470 003) : Effect of transverse inhomogeneous electric field and loss-cone distribution on electrostatic ion-cyclotron instability in the ionosphere. Indian J Radio Space Phys 2004, 33(4), 223-33.

Dispersion relation, resonant energy transferred, growth rate and marginal stability of the electrostatic ion-cyclotron wave with general loss-cone distribution function in low-β homogeneous plasma in the presence of a transverse inhomogeneous electric field are discussed by investigating the trajectories of the particles. The wave is assumed to propagate obliquely to the static magnetic field. The whole plasma is considered to consist of resonant and non-resonant particles. It is assumed that resonant particles participate in energy exchange with the wave, whereas non-resonant particles support the oscillatory motion of the wave. Effects of the steepness of the loss-cone distribution and inhomogeneity in electric field on resonant energy transferred and growth rate of the instability are discussed. It is found that the effect of transverse electric field is to stabilized the wave, whereas the inhomoeneity in electric field acts as a source of free energy for the electrostatic ion-cyclotron wave and enhances the growth rate. Effect of steepness of loss-cone is also to enhance the growth rate. The results are interpreted for the space plasma parameters appropriate to the auroral aceleration region.

6 illus, 39 ref

013255   Midya S K;Chattopadhyay R;Pal C (Dep of Physics, Serampore College, Serampore, Hooghly-712 201) : OI 6300 Angstrum nightglow emission at Calcutta and its verification by Barbier's equation in terms of solar flare index. Indian J Phys 2004, 78(12), 1309-12.

Represents the empirical relations between the solar flare index (I_f} and ionospheric parameters for the descending phase of 21st solar cycle and to express Barbier's equation as a function of a single variable I_f for a comparison with observed data. Important results have been obtained from the critical analysis of the observation .

4 illus, 15 ref

013254   Madhavilatha K;Badarinath K V S (Forestry & Ecology Div, National Remote Sensing Agency, Balanagar, Hyderabad-500 037, Email: badrinath_kvs@nrsa.gov.in) : Effect of aerosols on erythemal ultraviolet radiation. Indian J Radio Space Phys 2005, 34(1), 56-61.

Seasonal variation of UV erythema (UV_ery) and its relation with aerosols over a typical urban Environment of Hyderabad India during 2001-2003. Drastic reduction in UV intensities has been observed during periods of high aerosol loading. Comparison of UV_ery intensities with aerosol optical depth on normal summer day and a day after heavy rainfall suggests ″ 45% increase in UV_ery intensities because of scavenging of particles in the atmosphere. Total columnar ozone showed negative correlation with UV_ery.

10 illus, 14 ref

013253   Lal M (Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Maharajanagar, Tirunelveli-627 011, Email: mlal@iig.iigm.res.in) : Study of infrasonic waves at low latitude northern hemisphere, India. Indian J Radio Space Phys 2005, 34(1), 62-6.

The infrasonic waves have been studied at the low latitude station Tirunelveli (8.7°N, 77.8°E), India, in northern hemisphere. Almost 50 events of the severe earthquake (Ms > 6.0) have been studied. The changes in surface pressure as well as acoustic waves produced have been recorded immediately after the earthquake. The Rayleigh waves-induced changes in surface pressure which cause significant changes in pressure have been recorded by all the systems. The arrival of acoustic waves followed by large decrease in pressure has also been recorded in almost all the cases. Only a few cases have been reported. The infrasonic waves between 10 and 100 s have been observed. The infrasonic waves produced from the unknown sources have also been observed. But their variation feature is different from the earthquake-induced infrasonic waves. The corresponding microbaroms obtained at this station show variation similar to the infrasonic waves.

6 illus, 27 ref

013252   Lakshmi N;Pandey A;Venugopalan K (Physics Dep, Mohanlal Sukhadia University, Udaipur, Email: nambakkat@yahoo.com) : Study of hyperfine fields in Co₂ScSn Heusler alloy. Indian J pure appl Phys 2005, 43(3), 203-6.

Heusler alloy Co₂ScSn has been prepared and studied. X-ray diffraction studies showed the structure to be L₂₁ type. Using Sn-119, Mossbauer studies were carried out to investigate the magnetic hyperfine fields present at the Sn site in this alloy. Applicability of the Blandin and Campbell model for this alloy is tested by calculating the hyperfine fields at Sn site. The results of these calculations are compared with the experimental results.

3 illus, 1 table, 20 ref

013251   Kumar M;Singh P P (Physics Dep, G.B. Pant University of Agriculture and Technology, Pantnagar-263 145) : Temperature dependence of thermal pressure. Indian J Phys 2004, 78(11), 1225-8.

Three models are developed to study the temperature dependence of thermal pressure. These models are based on the approximation that the product of the coefficient of the volume thermal expansion β and isothermal bulk modulus K_T remains constant, Suzuki formulation of thermal expansivity, Kumar formulation of equation of state. The results obtained for five materials are compared with the experimental data. It is found that the results based on the (αK₇) constant are smaller than the experimental data. On the other hand, the results based on the Suzuki formulation are higher. The results based on the Kumar formulation are found to lie in between these two sets of the data and are in good agreement with the experimental data. The similar trend of variation found for all the materials, demonstrates the superiority of the model based on the Kumar formulation.

5 illus, 2 tables, 16 ref

013250   Karki S S;Sinha S K (Dep of Physics, Trichandra Campus, Kathmandu, Nepal) : Semiclassical theory for thermodynamics of molecular fluid mixtures. Indian J Phys 2004, 78(12), 1349-57.

An effective pair potential for the semiclassical molecular fluid mixture is expressed in the effective Lennard-Jones (12-6) potential form, which includes the influence of the angle-dependent potential and quantum effects through the expressions of the effective diameter σ″_ab and well depth ∈″_ab. Employed the theory to estimate the thermodynamic properties of equimolar binary mixtures at zero pressures. Agreement with experiment for the excess properties such as excess Gibb's function, excess enthalpy and excess molar volume for N₂ + Ar, O₂ + Ar, H₂+Ne, D₂ + Ne and H₂ + D₂ are found to be good.

4 tables, 21 ref

013249   Kar S;Dadhich N;Visser M (Physics and Centre for Theoretical Studies Dep, Indian Institute of Technology, Kharagpu721 302, Email: sayan@cts.iitkgp.emet.in) : Quantifying energy condition violations in traversable wormholes. Pramana J Phys 2004, 63(4), 859-64.

The 'theoretical' existence of traversable Lorentzian wormholes in the classical, macroscopic world is plagued by the violation of the well-known energy conditions of general relativity. In this brief article we show: (i) how the extent of violation can be quantified using certain volume integrals and (ii) whether this 'amount of violation' can be minimised for some specific cut-and-paste geometric constructions. Examples and possibilities are also outlined.

16 ref

013248   Kalyana Raman S B;Arulmozhi K T (Physics Wing, DDE Annamalai University, Annamalainagar-608 002, Tamil Nadu) : ANFIS modelling for theoretical evaluation of ultrasonic velocities in binary liquid mixtures. Indian J Phys 2004, 78(12), 1335-9.

"Adaptive Neuro Fuzzy Inference System" - the ANFIS, a newly developed technique is applied for the first time to compute the velocity of ultrasonic waves in binary liquid mixtures. To test the validity of this method, three binary liquid systems, each with different nature of molecular interaction are studied. The computed values of U_mix are reported and compared with those obtained using some other theories.

3 illus, 5 tables, 12 ref

013247   Kalogera V (Physics and Astronomy Dep, Northwestern University, Evanston, IL 60208, USA, , Email: vicky@northwestern.edu) : Binary compact object inspiral: Detection expectations. Pramana J Phys 2004, 63(4), 673-83.

We review the current estimates of binary compact object inspiral rates in particular in view of the recently discovered highly relativistic binary pulsar J0737-3039. One of the robust results is that, because of this discovery, the rate estimates for binary neutron stars have increased by a factor of 6-7 independent of any uncertainties related to the pulsar population properties. This rate increase has dramatic implications for gravitational wave detectors. For initial LIGO, the most probable detection rates for double neutron star (DNS) inspirals is 1 event/(5-250) yr; at 95% confidence we obtain rates up to 1/1.5 yr. For advanced LIGO, the most probable rates are 20-1000 events/yr. These predictions, for the first time, bring the expectations for DNS detections by initial LIGO to the astrophysically relevant regime. We also use our models to predict that the large-scale Parkes multibeam pulsar survey with acceleration searches could detect an average of three to four binary pulsars similar to those known at present. In comparison, rate estimates for binaries with black holes are derived based on binary evolution calculation, and based on the optimistic ends of the ranges, remain an important candidate for inspiral detection in the next few years. We also consider another aspect of the detectability of binary inspiral: the effect of precession on the detection efficiency of astrophysically relevant binaries. Based on our current astrophysical expectations, large tilt angles are not favored. As a result the decrease in detection rate varies rather slowly with black hole spin magnitude and is within 20-30% of the maximum possible values.

3 illus, 28 ref

013246   Joseph V;santhanam V;Anceila D (Dep of Physics, Loyola College, Chennai-600 034) : Spectral and normal coordinate analysis on the molecule of bis(thiourea) cadmium chloride single crystal. Indian J Phys 2004, 78(12), 1381-4.

Single crystals of bis(thiourea) cadmium chloride (BTCC) have been grown saturated aqueous solution by slow evaporation method at room temperature. FTIR and FT Raman spectra have been recorded. The normal coordinate analysis has been carried out with an orthonormal set of symmetry coordinates following Wilson F-G matrix method. The potential energy distribution has also been evaluated.

2 illus, 1 table, 16 ref

013245   Gupta P D (Physics and Astrophysics Dep, University of Delhi, Delhi-110 007, Email: patrickdasgupta@yahoo.co.uk) : Short duration gamma ray bursts. Pramana J Phys 2004, 63(4), 845-50.

After a short review of gamma ray bursts (GRBs), we discuss the physical implications of strong statistical correlations seen among some of the parameters of short duration bursts (T₉₀ < 2 s). Finally, we conclude with a brief sketch of a new unified model for long and short GRBs.

22 ref

013244   Govinda Rajan K N;Sharma S D;Palaniselvam T; Vandana S;Bhatt B C;Vinatha S;Patki V S;Pendse A M;Kannan V (Radiological Physics & Advisory Div, Bhabha Atomic Research Centre, CT & CRS Building, Anuskhaktinagar, Mumbai-400 094, Email: grajanmpss@vsnl.com) : Traceable calibration of hospital <. J med Phys 2004, 29(2), 61-8.

A HDR 1000 PLUS well type ionization chamber, procured from Standard Imaging, USA, and maintained by Medical Physics & Safety Section (MPSS), Bhabha Atomic Research Centre (BARC), India, as a reference well chamber 1 (RWCH1), was traceably calibrated against the primary standard established by Radiological Standards Laboratory (RSL), BARC for ¹⁹²Ir HDR source, in terms of air kerma strength (AKS). An indigenously developed well-type ionization chamber, reference well chamber 2 (RWCH2) and electrometer system, fabricated by CD High Tech (CDHT) Instruments Private Ltd., Bangalore, India, was in turn calibrated against RWCH1. The CDHT system (i.e. RWCH2 and CDHT electrometer system) was taken to several hospitals, in different regions of the country, to check the calibration status of ¹⁹²Ir HDR sources. The result of this calibration audit work is reported here.

3 illus, 1 table, 6 ref

013243   Goswami U D;Boruah K (Physics Dep, Gauhati University, Guwahati-781 014) : Simulation for signature of higgs boson in UHE cosmic ray interactions through vaccum excitation. Indian J Phys 2004, 78(11), 1253-9.

Presents a new approach for signature of Higgs boson production in ultra high energy cosmic ray (UHECR) interactions using the thermofield theory. The idea is the decay of Higgs bosons that are produced through bubble formation due to vaccum excitation in an UHECR collision with air nuclei. Develope a model of hadronic interaction based on the GENCL code of the UAS experiment of CERN and CORSIKA code (Karlsruhe report), incorporating a fraction of energy transfer to bubble formation by phase transition due to vacuum excitation and subsequent multiparticle production via conversion of Higgs boson to heavy fermion pairs. Such events are exprected to have high multiplicity and excess muons. Compared the muon multiplicity distribution with and without this effect for different fractions of energy transfer to vacuum. It has been found that the Higgs boson production mechanism has significnat effect starting from E_p - 10¹⁸eV.

7 illus, 15 ref

013242   Gonzalez G (Physics and Astronomy Dep, Louisiana State University, 202 Nicholson Hall Baton Rouge, LA 70803, USA, Email: gonzalez@reef.phys.lsu.edu) : Gravitational wave detectors: New eyes for physics and astronomy. Pramana J Phys 2004, 63(4), 663-72.

Several interferometric gravitational wave detectors around the world are now starting to achieve better sensitivity to gravitational waves than ever before We describe the prospects these detectors offer for physics and astronomy and review the rapid progress and the present status of the detectors' sensitivities. We also report the progress made by the LIGO Scientific Collaboration in analysing the data produced by the LIGO and GEO detectors during the Collaboration's Science Runs.

2 illus, 15 ref

013241   Gnana Prakash A P;Cressler J D;Ke S C; Siddappa K (School of Electrical and Computer Engineering, Georgia Institute of Technology,, TSRB, 85 Fifth Street, Atlanta-30308, GA, USA) : Impact of high energy radiation effects on N-channel MOSFETs. Indian J Phys 2004, 78(11), 1187-92.

The effect of 30 MeV Li³⁺ ion and 8 MeV electron irradiations on the threshold voltage (V_TH), the voltage shift due to interface trapped charge (ΔV_Nit), the voltage shift due to oxide trapped charge (ΔV_Nat), the density of interface trapped charge (ΔN_ot) and the drain saturation current (I_{D Sat}) were studied as a function of fluence. The considerable increase in the ΔN_it and ΔN_ot, and decrease in V_TH and I_{D Sat} were observed in both types of irradiations. The observed difference in the properties of Li³⁺ ion and electron-irradiated MOSFETs are interpreted on the basis of energy loss process associated with the type of radiation. The study showed that the 30 MeV Li³⁺ ion irradiation produce more damage when compared to the 8 MeV electron irradiation because of the higher electronic energy loss value.

8 illus, 1 table, 21 ref

013240   Ghoshal S K;Gupta U;Gill K S (Applied Physics Dep, Guru Jambheshwar University, Hisar, Email: lordkrishnasib@yahoo.com) : Role of hydrogen and oxygen on the band gap of silicon quantum dots. Indian J pure appl Phys 2005, 43(3), 188-91.

A computer simulation using empirical pseudo-potential Hamiltonian has been performed to examine the variation of the band gap as a function of size and shape of small silicon (Si) quantum dots. It has been found that the gap decreases with Increasing dot size. Furthermore, the band gap increases as much as 0.13 eV and 0.35 eV on passivating the surface of the dot with hydrogen and oxygen, respectively. So both quantum confinement and surface passivation determine the optical and electronic properties of Si quantum dots. Visible luminescence is probably due to radiative recombination of electrons and holes in the quantum confined nanostructures. The entire energy spectrum starting from the very low lying ground state to the very high lying excited states for silicon dots having 5, 8, 17 and 18 atoms has been investigated. The role of surface states on the gap energy as well as on the HOMO-LUMO states has also been examined. The results for the size dependence of the HOMO-LUMO gap and the wave functions for the bonding-anti-bonding states have been presented. The role of hydrogen and oxygen passivation on the confinement is also discussed.

2 illus, 19 ref

013239   Ghosh D;Deh A;Sahoo S R;Halder P K;Mondal M (Nuclear and Particle Physics Research Centre, Physics Dep, Jadavpur University, Kolkata-700 032) : Dynamical fluctuation of proton emission in heavy ion interactions. Indian J Phys 2004, 78(11), 1249-52.

Deals with a study of intermittent behaviour of medium energy knocked out protons in emission angle and azimuthal angle space for the data of ²⁸Si-AgBr interaction at 14.5 AGeV. From intermittency exponent, the anomalous fractal dimension d_q and generalized dimension D_q are calculated. The variation of D_q with order q suggests monofractal and multifractal proton emission.

2 illus, 2 tables, 15 ref

013238   Ghosh D;Deb A;Sen Datta I;Patra K K;Ghosh I (Nuclear ad Particle Physics Research Centre, Physics Dep, Jadavpur University, Kolkata-700 032) : Proton fluctuation in nuclear collisions at a few GeV-self-similar or self-affine. Indian J Phys 2004, 78(11), 1143-7.

An investigation on experimental data of the medium energy target proton (grey particles) emitted in ¹²C -AgBr interactions at 4.5 A GeV and in ¹³Mg-AgBr interactions at 4.5 A GeV reveals that a better power - law behaviour is exhibited in self-affine analysis at H = 0.4 in carbon beam and at H = 0.8 in magnesium beam. This work reveals that the multiplicity fluctuation at this energy is not self similar but self-affine.

4 illus, 2 tables, 11 ref

013237   Ghanshyam;Sharma A K (Dep of Physics, Birla Institute of Technology, Sindri, Dhanbad-828 123, Jharkhand, Email: ghanshyaml23@rediffmail.com) : Transverse self-focusing and filamentation of a laser beam in a collisional magnetoplasma. Indian J Phys 2004, 78(12), 1385-9.

Anisotropic self-focusing of a Gaussian laser beam in a collisional magnetoplasma is examined analytically. The laser propagates transverse to the static magnetic field. The nonlinearity arises through the Ohmic heating of electrons and subsequent redistribution of plasma along the magnetic field. The magnetic field enhances the rate of self-focusing to a large extent. In the case of a plane-uniform laser beam, it is seen that it is unstable for small scale fluctuations, and the growth rate of instability increases rapidly with magnetic field.

3 illus, 5 ref

013236   Gambini R;Pullin J (Physics and Astronomy Dep, Louisiana State University, Baton Rouge, LA 70803, USA, Email: pullin@baton.phys.lsu.edu) : Canonical quantum gravity and consistent discretizations. Pramana J Phys 2004, 63(4), 755-63.

This paper covers some developments in canonical quantum gravity that occurred since ICGC-2000, emphasizing the recently introduced consistent discretizations of general relativity.

27 ref

013235   El-Bakry S Y;El-Bakry M Y (Physics Department, Faculty of Science, King Abdulaziz University Branch Madinah Munawwara, Kingdom of Saudi Arabia, Email: kemo_zx@hotmail.com) : Neural network representation for electron and positron collisions with sodium and potassium atoms. Indian J Phys 2004, 78(12), 1313-18.

An artificial neural network (ANN) has been designed to simulate the collisions of electrons and positrons with sodium and potassium atoms at low and intermediate energies. The ANN model has been trained based on experimental data to produce the total cross sections for each case. Levenberg-Marquardt algorithm (LMA) has been employed to train the ANN. The experimental, trained and calculated total collisional cross sections are compared. The designed ANN shows a good match to the experimental data.

7 illus, 20 ref

013234   Dhurandhar S V (NO, Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind Pune-411 007, Email: sdh@iucaa.ernet.in) : Data analysis techniques for gravitational wave observations. Pramana J Phys 2004, 63(4), 717-30.

Astrophysical sources of gravitational waves fall broadly into three categories: (i) transient and bursts, (ii) periodic or continuous wave and (iii) stochastic. Each type of source requires a different type of data analysis strategy. In this talk various data analysis strategies will be reviewed. Optimal filtering is used for extracting binary inspirals Fourier transforms over Doppler shifted time intervals are computed for long duration periodic sources; optimally weighted cross-correlations for stochastic background. Some recent schemes which efficiently search for inspirals will be described. The performance of some of these techniques on real data obtained will be discussed. Finally, some results on cancellation of systematic noises in laser interferometric space antenna (LISA) will be presented and future directions indicated.

2 illus, 25 ref

013233   Dave M;Vaidya R;Patel S S;Patel S G;Jani A R (Physics Dep, Sardar Patel University, Vallabh idyanagar-388 120) : Growth, structural and high pressure studies on MoS₂ single crystal. Indian J Phys 2004, 78(11), 1211-14.

MoS₂ is a member of transition metal dichalcogenides (TMDC) group. Single crystals of molybdenum disulphide (MoS₂) have been grown by a chemical vapour transport technique using iodine as transporting agent. The composition of the grown crystals was confirmed on the basis of energy dispersive analysis by X-ray (EDAX) and remaining structural characterization was accomplished by X-ray diffraction (XRD) studies. Lathice parameters, volume and X-ray density have been determined for the grown crystals. The particle size for number of reflections has been calculated using Scherr's ormula. The stacking fault probabilities were found for the grown crystals. The behaviour of resistance under pressure is thoroughly studied using Bridgman anvils. The variation of resistance with pressure has been carried out upto 6.5 GP₂.

2 illus, 5 tables, 13 ref

013232   Date G;Maharana J (NO, The Institute of Mathematical Sciences, CTT Campus, Taramani, Chennai-600 113) : Summary of quantum aspects of gravitation workshop. Pramana J Phys 2004, 63(4), 883-5.

This is a summary of the presentations at the parallel session on 'Quantum Aspects of Gravitation' (QAG) of the ICGC-2004.

5 ref

013231   Das S (Physics Dep, The University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, T1K 3M4, Canada, Email: saurya.das@uleth.ca) : Black-hole thermodynamics: Entropy, information and beyond. Pramana J Phys 2004, 63(4), 797-815.

We review some recent advances in black-hole thermodynamics including statistical mechanical origins of black-hole entropy and its leading order corrections from the view points of various quantum gravity theories. We then examine the problem of information loss and some possible approaches to its resolution. Finally, we study some proposed experiments which may be able to provide experimental signatures of black holes.

46 ref

013230   Das N C et al (Spectroscopy Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: rpshukla@magnum.barc.ernet.in) : Development of a 6.65 m off-plane eagle spectrometer for a high resolution vacuum ultraviolet beam-line at indus-I synchrotron radiation source. Curr Sci 2004, 87(11), 1523-9.

A 6.65 m vacuum ultraviolet (VUV) spectrometer has been designed and fabricated indigenously using concave grating (concave radius = 6.65 m) of frequency 4800 grooves/mm for carrying out spectro-scopic research of atomic and molecular gases and vapours using synchrotron as a source of radiation. The wavelength range of the spectrometer is 700-2000 Angstron. The reciprocal linear dispersion of the instrument is about 0.3 Angstron/mm. The experimentally estimated value of the wavelength resolution is 0.01 Angstron. The spectrometer has been tested by recording spectral lines of wavelengths 1228.79 Angstron (nitrogen), 1243.18 Angstron (nitrogen), 1261.55 Angstron (carbon), 1288.42 Angstron (nitrogen), 1930.9 Angstron (carbon) under a vacuum of 10^-5 torr by exciting residual gas molecules in a rotary pump evacuated discharge tube.

7 illus, 14 ref

013229   Dadhich N;Banerjee N (Physics Dep, Jadavpur University, Kolkata-700 0327, Email: narayan@juphys.ernet.in) : Summary of classical general relativity workshop. Pramana J Phys 2004, 63(4), 887-9.

This is a summary of the presentations at the parallel session in the classical general relativity workshop of the ICGC-2004.

013228   Chatterjee A;Majumdar P (Theory Group, Saha Institute of Nuclear Physics, Kolkata-700 064, Email: partha@theory.saha.ernet.in) : Universal canonical entropy for gravitating systems. Pramana J Phys 2004, 63(4), 851-8.

The thermodynamics of general relativistic systems with boundary, obeying a Hamiltonian constraint in the bulk, is determined solely by the boundary quantum dynamics, and hence by the area spectrum. Assuming, for large area of the boundary, (a) an area spectrum as determined by non-perturbative canonical quantum general relativity (NCQGR), (b) an energy spectrum that bears a power law relation to the area spectrum, (c) an area law for the leading order microcanonical entropy, leading thermal fluctuation corrections to the canonical entropy are shown to be logarithmic in area with a universal coefficient. Since the microcanonical entropy also has universal logarithmic corrections to the area law (from quantum space-time fluctuations, as found earlier) the canonical entropy then has a universal form including logarithmic corrections to the area law. This form is shown to be independent of the index appearing in assumption (b). The index, however, is crucial in ascertaining the domain of validity of our approach based on thermal equilibrium.

1 illus, 17 ref

013227   Chandra S (School of Physical Sciences, S R T M University, Nanded-431 606, Maharashtra, Email: sch@iucaa.ernet.in) : On temperature T₀₁ for molecular hydrogen. Indian J Phys 2004, 78(12), 1395-96.

Temperature T₀₁ for hydrogen molecule for the transition between the level J = 1 (ortho-H₂) and the level J = 0 (para-H₂) has been introduced by Spitzer et al. The work of Spitzer et al has been reinvestigated and that the concept of the temperature T₀₁ is not valid.

2 tables, 3 ref

013226   Calla O P N;Rai A R;Mathur P;Mathur D;Bohra D (International Centre for Radio Science, , "OM Niwas" A-23, Shastri Nagar, Jodhpur-342 003) : Estimation of emissivity and scattering coefficient of the constituents of vegetation at microwave frequencies. Indian J Radio Space Phys 2005, 34(1), 67-70.

A vegetation canopy is a dielectric mixture consisting of discrete dielectric inclusions (leaves, stalks and fruits) distributed in a host material (air). The scattering and emission behaviour of vegetation canopy made up of neem-like trees has been studied. The estimation of emissivity, brightness temperature and scattering coefficient has been made using the measured values of dielectric constant. The measurement of dielectric constant of neem leaves has been carried out using waveguide cell method in the frequency range of X-band (8.2 GHz - 12.4 GHz) at 9.035 GHz. The estimations of emissivity, brightness temperature and scattering coefficient are made for incidence angles varying from 0° to 80° for both horizontal and vertical polarization. The results of emissivity and scattering coefficient so obtained have been presented.

4 illus, 8 ref

013225   Bojowald M (Max-Planck-Institut fur Gravitationsphysik, Albert-Einstein-Institut, 14476 Potsdam, Germany, Email: mabo@aei.mpg.de) : Loop quantum cosmology: Recent progress. Pramana J Phys 2004, 63(4), 765-76.

Aspects of the full theory of loop quantum gravity can be studied in a simpler context by reducing to symmetric models like cosmological ones. This leads to several applications where loop effects play a significant role when one is sensitive to the quantum regime. As a consequence, the structure of and the approach to classical singularities are very different from general relativity. The quantum theory is free of singularities, and there are new phenomenological scenarios for the evolution of the very early universe such as inflation. We give an overview of the main effects, focussing on recent results obtained by different groups.

1 illus, 41 ref

013224   Blanchet L (Institut d'Astrophysique de Paris (CNRS), Gravitation Relativiste et Cosmologie (GR<101>CO), 98 bis, boulevard Arago, 75014 Paris, France, Email: blanchet@iap.fr) : Equations of motion of compact binaries at the third post-Newtonian order. Pramana J Phys 2004, 63(4), 685-701.

The equations of motion of two point masses in harmonic coordinates are derived through the third post-Newtonian (3PN) approximation. The problem of self-field regularization (necessary for removing the divergent self-field of point particles) is dealt with in two separate steps. In the first step the extended Hadamard regularization is applied, resulting in equations of motion which are complete at the 3PN order, except for the occurrence of one and only one unknown parameter. In the second step the dimensional regularization (in d dimensions) is used as a powerful argument for fixing the value of this parameter, thereby completing the 3-dimensional Hadamard-regularization result. The complete equations of motion and associated energy at the 3PN order are given in the case of circular orbits.

1 illus, 29 ref

013223   Bhawal B (LIGO Laboratory, California Institute of Technology, Pasadena, CA 91125, Email: bbhawal@ligo.caltech.edu) : Physics of interferometric gravitational wave detectors. Pramana J Phys 2004, 63(4), 645-62.

The Caltech-MIT joint LIGO project is operating three long-baseline interferometers (one of 2 km and two of 4 km) in order to unambiguously measure the infinitesimal displacements of isolated test masses which convey the signature of gravitational waves from astrophysical sources. An interferometric gravitational wave detector like LIGO is a complex, non-linear, coupled, dynamic system. This article summarizes various interesting design characteristics of these detectors and techniques that were implemented in order to reach and maintain its operating condition. Specifically, the following topics are discussed: (i) length sensing and control, (ii) alignment sensing and control and (iii) thermal lensing which changes the performance and operating point of the interferometer as the input power to LIGO is increased.

17 illus, 13 ref

013222   Bhat B C (Radiological Physics & Advisory Div, Bhabha Atomic Research Centre, CT & CRS, Anushaktinagar, Mumbai-400 094) : Applications of thermoluminescent phosphors in medical physics. J med Phys 2004, 29(2), 41-7.

Thermoluminescent(TL) dosimeters have become a versatile system of dosimeters for assessment of dose in clinical applications of ionizing radiation. The advatages of TL dosimeters include high sensitivity, miniature size, tissue equvalence, low fading, re-usability and linear dose response. Being a passive device, TL dosimetry by mail provides an easy way for intercomaparison of dose in different institutions. This paper elucidates applications of TLD in some of the conventional and emerging fields of medical applications in radiodiagnosis, nuclear medicine and radiotherapy, including neutron.

27 ref

013221   Balaji Rao R;Naga Raju G;Veeraiah N (Physics Dep, Acharya Nagarjuna University P G Centre, Nuzvid-521 201) : Catalyzed crystallization and some physical properties of Li₂O-MgO-B₂O₃:TiO₂ glasses. Indian J pure appl Phys 2005, 43(3), 192-202.

Li₂O-MgO-B₂O₃:TiO₂ glasses were crystallized at three different temperatures. The samples were characterized by scanning electron microscopy and differential scanning calorimetry. Various physical properties viz., optical (optical absorption, IR spectra and thermoluminescence), magnetic (magnetic susceptibility and ESR spectra) have been studied as a function of temperature of crystallization. The investigation is further extended to the dielectric properties viz., dielectric constant, loss and a.c. conductivity over a moderately wide range of frequency and temperature. The analysis of these results indicated a considerable increase in the electrical insulating strength of the samples due to crystallization.

13 illus, 7 tables, 42 ref

013220   Anusionwu B C (NO, Federal University of Technology, Owerri, Nigeria) : Calculation of the viscosity of liquid Na-K and Na-Cs alloys. Indian J Phys 2004, 78(11), 1269-71.

A simple formalism relating thermodynamic and transport properties in liquid binary alloys has been applied to determine the viscosity of liquid alkali alloys. The formalism reproduced a qualitative trend of the estimated values of viscosity but there appears to be a significant quantitative disparity for this class of alloys.

1 illus, 10 ref