024206   Chakraborty A K;Mallik B (Spectroscopu Dep, Indian Association for the Cultivation of Science, 2A & 2B, S.C. Mullick Road, Jadavpur, Kolkata-700 032, Email: spbm@mahendra.iacs.res.in) : Kinetics of unusual photoinduced currents in the solid state of some ferrocene derivatives. Indian J Phys 2009, 83(3), 291-300.

Kinetics of change in photoinduced currents (during illumination and after switching off light source) in the solid state of some ferrocene derivatives, namely, ferrocenecarboxylic acid, acetylferrocene, ferrocenecarbaldehyde, hydroxymethyl ferrocene have been studied in dry nitrogen gas atmosphere. Unusual/anomalous photocurrent versus time profiles were observed in some ferrocene derivatives at certain cell temperatures. The kinetics of current changes under photoexcitation and after switching off the light source have been observed to be complicated in nature. Temperature-dependent behavior of the studied kinetics indicates that charge carrier trapping/ detrapping and recombination processes are significantly temperature dependent. These processes have an important role in causing the temperature dependent unusual/anomalous photocurrent versus time profiles in the ferrocene derivatives studied.

4 illus, 31 ref

023111   Tel E;Aydin E G;Kaplan A;Aydin A (Faculty of Arts and Science, Gazi Univ, 06500 Ankara, Turkey, Email: eyuptel@gazi.edu.tr) : New calculations of cyclotron production cross sections of some positron emitting radioisotopes in proton induced reactions. Indian J Phys 2009, 83(2), 193-212.

In this study, new calculations on the excitation functions of ^{13C(p,n)13N, 14N(p,α)11C, 15N(p,n)15O, 160(p,α)13N, 18O(p,n)18F, 62Ni(p,n)62Cu, 88Zn(p,n)68Ga and 72Ge(p,n)72As reactions have been carried out in the 5-40 MeV incident proton energy range. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve hybrid model, geometry dependent hybrid model, the cascade exciton model and full exciton model. Equilibrium effects were calculated according to Weisskopf-Ewing model. The calculated results have been compared with experimental data taken from literature.}

8 illus, 1 table, 59 ref

023110   Sinha S K;Chakraborty S;Bandyopadhyay S (Chemistry Dep, Molecular Modeling Laboratory, Indian Institute of Technology, Kharagpur-721 302, Email: sanjoy@chem.iitkgp.ernet.in) : Effect of unfolding on the thickness of the hydration layer of a protein. Indian J Phys 2009, 83(1), 49-64.

Properties of water in the hydration layer around a protein is intimately correlated with its function. A knowledge of the thickness of the hydration layer is important to understand its role in guiding the folding-unfolding of the protein. We have performed atomistic molecular dynamics simulations of the folded native and a partially unfolded molten globule structure of the villin headpiece subdomain or HP-36 in aqueous solution to estimate the effect of unfolding on the thickness of hydration layer around different segments of the protein. In particular, several dynamic properties of water around different segments of the folded native and the unfolded structure have been calculated by varying the thickness of the hydration layers. It is found that unfolding of a segment of the protein is correlated with the dynamics of water around it, i.e., within the first hydration layer. The effect of unfolding on water properties has been found to diminish when water molecules present beyond the first hydration layer were included in the calculations.

4 illus, 3 tables, 71 ref

023109   Sharma M;Yashonath S (Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560 012, Email: yashonat@sscu.iisc.ernet.in) : How does contrasting dependence of impurity-atom diffusivity on the density of host disordered medium arise?. Indian J Phys 2009, 83(1), 31-47.

Reports results of molecular dynamics investigations into neutral impurity diffusing within an amorphous solid as a function of the size of the diffusant and density of the host amorphous matrix. We find that self diffusivity exhibits an anomalous maximum as a function of the size of the impurity species. An analysis of properties of the impurity atom with maximum diffusivity shows that it is associated with lower mean square force, reduced backscattering of velocity autocorrelation function, near-exponential decay of the intermediate scattering function (as compared to stretched-exponential decay for other sizes of the impurity species) and lower activation energy. These results demonstrate the existence of size-dependent diffusivity maximum in disordered solids. Further, we show that the diffusivity maximum is observed at lower impurity diameters with increase in density. This is explained in terms of the Levitation parameter and the void structure of the amorphous solid. We demonstrate that these results imply contrasting dependence of self diffusivity (D) on the density of the amorphous matrix, p. D increases with p for small sizes of the impurity but shows an increase followed by a decrease for intermediate sizes of the impurity atom. For large sizes of the impurity atom, D decreases with increase in p. These contrasting dependence arises naturally from the existence of Levitation Effect.

10 illus, 3 tables, 19 ref

023108   Senthil K;Sarojini R (R&D Physics Dep, KASC, Coimbatore-29, TamilNadu, Email: senthil_pdf@rediffmail.com) : Curcumin-DNA interaction studied by fourier transform infrared spectroscopy. Int J Biotechnol Biochem 2009, 5(3), 251-9.

Curcumin is a non-toxic, dietary, natural polyphenol known for its potent anti-inflammatory, antioxidant, antimutagenic and anticarcinogenic effects and also considered as a cancer chemo-preventive agent. The strong interaction of curcumin with biomolecules and the non-covalent interactions are known to play a decisive role in its mechanism of action. While the antioxidant activity of this polyphenolic compound is well known, their bindings to DNA are not folly investigated. The present study was designed to examine the interactions of curcumin with calf thymus DNA in aqueous solution at physiological conditions using constant DNA concentration (25mM) and various drug/DNA(phosphate) ratios of 1/50 to 1/5. Fourier Transform Infrared(FT-IR) spectroscopy was used to determine curcumin binding modes, the stability of DNA secondary structure in curcumin-DNA complexes in aqueous solution. Spectroscopic evidence shows that at low curcumin concentration(r=l/50) curcumin binding is mainly through the guanine N-7 atom (indirectly through H-bonding). When the concentration increases (r>1/10) drug binding to G,T,A and bases occurs(indirectly) with a partial helix stabilization as a result of weak intercalation into DNA duplex.

2 illus, 36 ref

023107   Sangawar V S;Johari M (NO, Govt. Vidarbha Institute of Science & Humanities, Amravati-444 604, Email: joharimeeta@yahoo.co.in) : Effect of irradiation of laser beam on polymer blends. Indian J Phys 2009, 83(2), 163-9.

Irradiation of He-Ne LASER beam on polystyrene (PS) and poly vinyl chloride (PVC) polyblend sample for different time intervals viz. 3, 5,7,10 and 15 min. Structural and electrical properties have been studied before and after irradiation. It has been found that irradiation increases the dc electrical conductivity due to creation of new charge carriers in the polyblend sample.

2 illus, 1 table, 15 ref

023106   Saharay M;Balasubramanian S (Chemistry Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560 064, Email: bala@jncasr.ac.in) : Ab initio molecular dynamics investigations of structural, electronic and dynamical properties of water in supercritical carbon dioxide. Indian J Phys 2009, 83(1), 13-29.

Ab initio molecular dynamics simulations of a solitary perdeuterated water molecule solvated in supercritical carbon dioxide have been performed along an isotherm at three different densities. Electron donor-acceptor interactions between the oxygen atom of water and the carbon atom of CO₂ as well as hydrogen bonded interactions between the two molecules have been shown to play a dominant role in the solvation. The mean dipole moment of the water molecule increases with the density of the solution, from a value of 1.85 D at low density to around 2.15 D at the highest density. The increase in the solvent density causes the water molecule to exhibit a range of behavior, from a free molecule to one that interacts strongly with CO₂. A blue shift in the bending mode of water has been observed with increasing solvent density. The carbon dioxide molecules which are present in the first neighbor shell of water are found to exhibit larger propensity to deviate from a linear geometry in their instantaneous configurations.

11 illus, 64 ref

023105   Roy A K;Chakrabarty S (Physics Dep, Visva Bharati Univ, Santiniketan-731 235, Email: subrata502002@yahoo.co.in) : Relativistic quark model with quantum chromodynamics, P-states of quarkonia and scalar-vector confinement. Indian J Phys 2009, 83(2), 213-25.

In this paper we try to understand several phenomenological issues related to the mass spectra of P-states quarkonia in a relativistic quark model. We give particular emphasis on understanding the most recent experimental data within a relativized scalar-vector confining potential. In this paper we extend the previous works on the studies of quark confinement in non-relativistic QCD, using a formalism which uses a covariant Hamiltonian in the centre of mass frame. The spin-structure of the potential is obtained from the reduction of Bethe-Salpeter equation into Breit-interaction.

3 tables, 16 ref

023104   Raghuwanshi S K;Talabattula S (Applied Photonics Lab, Electrical Communication Engineering Dep, Indian Institute of Science, Bangalore-560 012, Email: sanjeevkr@ece.iisc.ernet.in) : Analytical approximation solution for 3-D optical waveguides. Indian J Phys 2009, 83(2), 127-51.

The rectangular dielectric waveguide is the most commonly used structure in integrated optics, especially in semi-conductor diode lasers. Demands for new applications such as high-speed data backplanes in integrated electronics, waveguide filters, optical multiplexers and optical switches are driving technology toward better materials and processing techniques for planar waveguide structures. The infinite slab and circular waveguides that we know are not practical for use on a substrate because the slab waveguide has no lateral confinement and the circular fiber is not compatible with the planar processing technology being used to make planar structures. The rectangular waveguide is the natural structure. In this review, we have discussed several analytical methods for analyzing the mode structure of rectangular structures, beginning with a wave analysis based on the pioneering work of Marcatili. We study three basic techniques with examples to compare their performance levels. These are the analytical approach developed by Marcatili, the perturbation techniques, which improve on the analytical solutions and the effective index method with examples.

12 illus, 30 ref

023103   Meher B R;Satish Kumar M V;Bandyopadhyay P (Biotechnology Dep, Indian Institute of Technology, Guwahati-781 039, Email: praban07@gmail.com) : Molecular dynamics simulation of HIV-protease with polarizable and non-polarizable force fields. Indian J Phys 2009, 83(1), 81-90.

The effect of polarization in biomolecular force field is investigated by performing Molecular Dynamics (MD) simulation of HIV-protease by using two AMBER force fields, namely ff99 (non-polarizable) and ff02 (polarizable). The results of simulation show that the overall structural fluctuation of HIV-protease is reduced in the polarizable simulation. Comparison with the NMR order parameters with the calculated values shows that although some residues are less flexible in the ff02 simulation, the dynamics of two β-hairpins (flaps), the most flexible part of the protein, is relatively insensitive to the effect of polarization. The flap-active site distance, a measure of flap opening, is distinctly more in the non-polarizable simulation. The water count and radial distribution functions are investigated near a representative residue of three types - charged, polar and hydrophobic. Both water count and radial distribution function differ significantly near the charged residue (catalytic Asp25) between the force fields. However, the water movement is similar near the polar (Ser37) and hydrophobic (Ile85) residues. The preliminary results of this investigation show that polarization is likely to influence both global and specific local motions of protein and solvent.

6 illus, 28 ref

023102   Jain S;Ajay Kumar;Bhatnagar K B (NO, Guru Premsukh Memorial College of Engineering, 245, Budhpur Village G.T. Karnal Road, Delhi-110 036, Email: jain_sanjay73@yahoo.com) : Periodic orbits around the collinear libration points in the restricted three body problem when the smaller primary is a triaxial rigid body and bigger primary is a source of radiation pressure. Indian J Phys 2009, 83(2), 171-84.

Periodic orbits belonging to the stromgren families A, B and C around the collinear libration points in the restricted three body problem have been studied when the smaller primary is a triaxial rigid body and more massive body is a source of radiation pressure. These families are determined in three different cases : (i) classical case, (ii) when bigger primary is a source of radiation pressure, (iii) when smaller primary is a triaxial rigid body and bigger primary is a source of radiation pressure. The Liapunov stability of each periodic solution has also been examined.

3 illus, 4 tables, 12 ref

023101   Chowdhuri S;Chakraborty D;Chandra A (Chemistry Dep, Indian Institute of Technology, Kanpur-208 016, Email: amalen@iitk.ac.in) : Pressure effects on diffusion in liquid ammonia : a simulation study using a combination of isobaric-isothermal and microcanonical molecular dynamics. Indian J Phys 2009, 83(1), 91-100.

The effects of pressure on translational and rotational diffusion in liquid ammonia are investigated by means of molecular dynamics simulations. Calculations are done at two different temperatures and at many different pressures by using a two-part protocol involving molecular dynamics in isobaric-isothermal ensemble in the first part and in microcanonical ensemble in the second part. Our results are analyzed in terms of pressure-induced changes in structural properties such as packing and hydrogen bond properties. Also, the present results of liquid ammonia are compared with corresponding results for other hydrogen bonded liquids that were reported in recent years.

7 illus, 4 tables, 21 ref

023100   Chakraborty S N;Talapatra S;Chakravarty C (Chemistry Dep, Indian Institute of Technology, Delhi, New Delhi-110 016, Email: charus@chemistry.iitd.ernet.in) : Relationship between crystalline order and melting mechanisms of solids. Indian J Phys 2009, 83(1), 65-79.

The mechanism for homogeneous nucleation of the liquid phase in Lennard-Jones solids is studied by combining the Landau free energy approach with some of the methodology developed to characterise transition path ensembles. The second-order bond orientational order parameter, O₆ which indexes the overall degree of crystalline order, is shown to provide a dynamically significant collective coordinate describing the melting process. Trajectories generated from configurations sampled in the vicinity of the maximum in the Landau free energy curve, F(O₆), are shown to have equal likelihood of teminating in either the solid or liquid-like free energy minima. It is also demonstrated that O₆ is necessary but not sufficient as a dynamical coordinate to describe melting and it is necessary to explore possiblities for additional coordinates which are critical for initiating melting. Our sudy suggests that the additional coordinates for describing the melting process would be some type of localised defect, much smaller in spatial extent than the size of the critical nucleus predicted by classical nucleation theory.

4 illus, 2 tables, 36 ref

023099   Arya B S;Aynyas M;Sanyal S P (Physics Dep, Govt. Narmada College, Hoshangabad-461 001, Email: bsarya13@yahoo.com) : High pressure behavior of alkaline earth tellurides. Indian J Phys 2009, 83(2), 153-61.

Authors have predicted high pressure structural behavior and elastic properties of alkaline earth tellurides (AETe; AE = Ca, Sr, Ba) by using two body interionic potential approach with modified ionic charge (Z_me). This method has been found quite satisfactory in case of the rare earth compounds. The equation of state curve, structural phase transition pressure from NaCI (B1) to CsCI (B2) phase and associated volume collapse at transition pressure of alkaline earth tellurides (AETe) obtained from this approach, so have been compared with experimentally measured data reveal good agreement. We have also investigated bulk modulus, second and third order elastic constants and pressure derivatives of second order elastic constants at ambient pressure which shows predominantly ionic nature of these compounds. First time, we have calculated the Poisson ratio, Young and Shear modulus of these compounds.

7 illus, 4 tables, 20 ref

023098   Alam M S;Chowdhury M D (Physics Dep, Shahjalal Univ of Science and Technology, Sylhet, Bangladesh, Email: shahalam032003@yahoo.com) : Reflection of light by a moving mirror. Indian J Phys 2009, 83(2), 233-40.

The law of reflection of light by.a moving mirror in the case of special Lorentz transformation is well known. We have derived the law of reflection of light by a moving mirror in the case of the most general Lorentz transformation. It has been observed that in the case of special Lorentz transformation, the law of reflection of light by a moving mirror is very simple but in the case of the most general Lorentz transformation, the law of reflection of light by a moving mirror is very complex.

2 ref

023097   Agrawal V;Dwivedi A;Sharma B (NO, BS Anangpuria Institute of Technology and Management, Faridabad, Haryana, Email: veenuag2@rediffmail.com) : On the limitations of the equation of state based on the Lennard-Jones potential. Indian J Phys 2009, 83(2), 227-32.

It is emphasized that any equation of state (EOS) based on the generalized Lennard-Jones potential or the Mie potential, suffers from two main shortcomings as pointed out by Stacey and Davis [2]. One of the shortcomings viz. the problem related to imaginary numbers for the exponents in the potential function, has been removed recently by Jiuxun [11] by using a relationship between the exponents. However, the modified EOS obtained by Jiuxun suffers from the second shortcoming viz. it gives lower values for -B₀B″₀, an important equation of state parameter related to the second pressure derivative of the bulk modulus. Values of B₀B″₀ obtained by Jiuxun are not consistent with those reported by Stacey and Davis.

1 table, 6 ref

023096   Acharya S;Das B K;Mohanty G C (Post-Graduate Dep of Physics, Ravenshaw College, Cuttack-753 003, Email: swaroop_acharya2000@yahoo.co.in) : Ultrasonic study of binary mixtures of acetylacetone with polar diluents at 303.16 K vis-a-vis molecular interaction. Indian J Phys 2009, 83(2), 185-91.

The ultrasonic velocity (C) and density (p) of binary mixture of acetylacetone with polar diluents have been measured at temperature 303.16 K and frequency of 2 MHz. The data of C and p have been used to evaluate, isentropic compressibility (β), acoustic impedence (Z) and intermolecular free length (L_f) to study the molecular interaction. The study reveals that interaction is maximum in bromo-benzene acetylacetone mixture.

3 illus, 1 table, 25 ref

022147   Zhao Y;Shen Z;Lu J;Ni X;Cul Y (School of Science, Nanijng Univ of Science & Technology, Nanjing-210 094, Email: zhaoyan7906@mail.njust.edu.cn) : Laser-induced circumferential waves on hollow cylinder and their interaction with defects by finite element method. Indian J Phys 2009, 83(11), 1583-92.

A three dimensional (3-D) finite element model for simulating laser induced circumferential wave on a hollow cylinder is developed based on the thermoelastical mechanism, which can take any laser source into account and simulate the interactions between circumferential wave and defects in the hollow cylinder. The model is verified by a control calculation. The results show that the waveforms of circumferential wave are in very good agreement with those available in literature, not only on the arrival time and shape but also on the amplitudes of A₀, S₀ and A₁ modes. Using the model, circumferential waves on the surfaces of two series hollow cylinders are simulated, one with same thickness but different outer radius, and the other with the same outer radius but different thickness. The results show that a new mode appears in circumferential wave, compared with Lamb wave in plate. With increase of thickness or radius, the amplitude of the new mode reduces. Another conclusion is that with increase of the thickness of the hollow cylinder, the circumferential wave evolves gradually to the cylindrical Rayleigh waveform, which results from the attenuation of the coupling effect between the outer and inner surface. Moreover, the circumferential waves generated on a hollow cylinder with a surface defect are also simulated, and the results indicate that in the circumferential waves obtained at the point beyond the defect, the amplitude of A₀ mode decreases and its dispersion enhances. More importantly, a new bipolar waveform corresponding to the interaction of S₀ mode with the defect appears, its amplitude is larger than three times of that of S₀ mode. As a result, we consider that the new bipolar waveform will be the optimal feature to nondestructively detect the surface defect on the hollow cylinder.

8 illus, 11 ref

022146   Yadav R A;Yadav T K;Yadav M K;Yadav D P;Singh N P (Physics Dep, Banaras Hindu Univ, Varanasi-221 002, Email: rayadav@bhu.ac.in) : Normal modes man quality factors of shielded composite dielectric spherical resonators. Indian J Phys 2009, 83(10), 1421-38.

Electromagnetic field analysis of shielded composite dielectric spherical resonator in which the dielectric sphere is composed of two concentric spheres with different dielectric materials has been made. Characteristic equations for the TE_nml and TM_nml( modes have been derived. From these characteristic equations, the resonant frequencies and quality factors have been calculated using numerical method. Computations of the resonant frequencies and quality factors have been made for resonators with parameters suitable for the optical and microware regions.

14 illus, 14 tables, 24 ref

022145   Yadav J;Rafique S M;Shanti Kumari (Physics Univ Dep, T M Bhagalpur Univ, Bhagalpur-812 007, Email: dr.jp_yadav@yahoo.co.in) : Impact of eigenvalues on the pseudopotential calculation of superconducting parameters of metals Ga, Cd and In. Indian J Phys 2009, 83(10), 1487-93.

Some superconducting (SC) state parameters of metals Ga, Cd and In have been studied through Harrison's First Principle [HFP] pseudopotential technique using McMillan's formalism. The impact of choosing two different sets of core energy eigenvalues viz. Herman-Skillman and Clementi (or Experimental) has been studied. It has been observed that the choice of eigenvalues has appreciable impact on the form factor and consequently on the SC state transition parameter viz. electron-phonon coupling strength (A) and superconducting transition temperature Tc. Hence the choice of suitable eigenvalues is essential for these computations. Reasonable agreement with experimental and theoretical data have been obtained.

3 illus, 2tables, 14 ref

022144   Vijay Y K (Physics Dep, Rajasthan Univ, Jaipur-302 004, Email: yk_vijay@sancharnet.in) : SHI induced nano track polymer filters and characterization. Indian J Phys 2009, 83(7), 927-35.

Swift heavy ion irradiation produces damage in polymers in the form of latent tracks. Latent tracks can be enlarged by etching it in a suitable etchant and thus nuclear track etch membrane can be formed for gas permeation / purification in particular for hydrogen where the molecular size is very small. By applying suitable and controlled etching conditions well defined tracks can be formed for specific applications of the membranes. After etching gas permeation method is used for characterizing the tracks. In the present work polycarbonate (PC) of various thickness were irradiated with energetic ion beam at Inter University Accelerator Centre (IUAC), New Delhi. Nuclear tracks were modified by etching the PC in 6N NaOH at 60 (±1) °C from both sides for different times to produce track etch membranes. At critical etch time the etched pits from both the sides meet a rapid increase in gas permeation was observed. Permeability of hydrogen and carbon dioxide has been measured in samples etched for different times. The latent tracks produced by SHI irradiation in the track etch membranes show enhancement of free volume of the polymer. Nano filters are separation devices for the mixture of gases, different ions in the solution and isotopes and isobars separations. The polymer thin films with controlled porosity finding it self as best choice. However, the permeability and selectivity of these polymer based membrane filters are very important at the nano scale separation. The Swift Heavy Ion (SHI) induced nuclear track etched polymeric films with controlled etching have been attempted and characterized as nano scale filters.

5 illus, 1 table, 23 ref

022143   Varadwaj P R;Jaman A I (NO, Saha Institute of Nuclear Physics, Sector-1, Block-AF, Bidhannagar, Kolkata-700 064, Email: aismail.jaman@saha.ac.in) : Millimeterwave spectrum of DC discharge produced ICN in excited vibrational states. Indian J Phys 2009, 83(9), 1323-31.

An indigenously built 50 kHz source-modulated millimeter-wave spectrometer was used to produce cyanogen iodide (ICN) in the excited vibrational states (01^{10), (0330), (1000), (2000) and (0200) and record their corresponding rotational spectra. The analysis of the recorded spectra was carried out in the frequency range of 57.0 - 98.0 GHz. ICN was produced using a DC glow discharge through a mixture of methyl iodide (CH₃I) and benzyl cyanide (C₆H₅CH₂CN) vapor at low pressure. 127 nuclear quadrupole hyperfine structure and the Hype doublet spectra of (01₁0) state have been resolved. The observed and assigned rotational transition frequencies were used in a least-square fit to determine more accurate values of molecular constants. The agreement between the derived parameters and those reported earlier clearly indicate that the reported spectral lines belong to ICN in the excited vibrational states. It also indicates that ICN could be produced in selective excited vibrational states by DC glow discharge technique.}

5 tables, 16 ref

022142   Tripathi B;Vijay Y K;Singh F;Avasthi D K;Wate S (Physics Dep, Rajasthan Univ, Jaipur-302 067, Email: tripathi_balram@sify.com) : Structure and optical luminescence of C<. Indian J Phys 2009, 83(12), 1659-65.

Iron doped CdS nanocrystals have been synthesized by using aqueous solution precipitation method. Samples of CdS:Fe have been subjected to irradiation using C₊₆ (80 MeV) under of 1x10₁₃ ions/cm². For characterization, X -raydiffraction (XRD), Photoluminescence (PL) and Optical absorption studies have been performed. The system has been found in hexagonal phase having particle size distribution 18-20 nm. Photoluminescence intensity has been found to decrease, while optical band gap has been found to increase in irradiated samples.

3 illus, 2 tables, 14 ref

022141   Tayal V;Gupta G P;Tripathi A N (Physics Dep, S.D. (Postgraduate) College, Muzaffarnagar-251 001, Email: tayalvikas11@rediffmail.com) : Energy levels, oscillator strengths and lifetimes in Ar V. Indian J Phys 2009, 83(9), 1271-88.

Calculates the excitation energies, oscillator strengths and transition probabilities for electric-dipole-allowed and intercombination transitions among the 46 LS levels belonging to the configurations 3s^{23p2, 3s3p3, 3s23p3d, 3p4, 3s23p4s, 3s23p4p, 3s3p2(2S)4s, 3s3p2(2P)4s, 3s3p2(4P)4s, 3s3p2(2D)4s, 3s23p4d and 3s23p4f of Si-like Argon. These states are represented by extensive Configuration-Interaction (Cl) wavefunctions obtained using the CIV3 computer code of Hibbert. From our transition probabilities we have also calculated the radiative lifetimes of singlet and triplet states of Ar V. Our results are compared with other available theoretical calculations and experimental data. To assess the importance of relativistic effects on our calculated values, we have also carried out calculations in the intermediate-coupling scheme using the Breit-Pauli Hamiltonian. Small adjustments to the diagonal elements of the Hamiltonian matrices have been made so that the energy splittings are as close as possible to the experimentally compiled energy values of the National Institute for standards and Technology (NIST). The energy splitting of 85 fine-structure levels, the oscillator strengths and transition probabilities for electric-dipole-allowed and intercombination transitions and the lifetimes of some fine-structure levels are presented and compared with available experimental and other theoretical values. In this calculation, we also predict new data for several fine-structure levels where no other theoretical and experimental results are available.}

6 tables, 39 ref

022140   Subhash Chandra;Annapoorni S;Sonkawade R G; Kulriya P K;Singh F;Avasthi D K;Rana J M S;Ramola R C (Physics Dep, H N B Garhwal Univ, Badshahi Tahul Campus, Tehri Garhwal-249 199, Email: subhash.physics@gmail.com) : Interaction of oxygen (O<. Indian J Phys 2009, 83(7), 943-7.

High-energy ion beam irradiation of the polymers is a good technique to modify the properties such as electrical conductivity, structural behaviour and mechanial properties. Polyaniline thin films doped with hydrochloric acid (HCI) were prepared by oxidation of ammonium persulphate. The effect of Swift Heavy Ions irradiation on the electrical and structural properties of polyaniline has been measured in this study. Polyaniline films were irradiated by oxygen ions (energy 80 MeV, charge state O^{+7) with fluence varying from 1 x 1010 to 3 x 1012 ions/cm2. The studies on electrical and structural properties of the irradiated polymers were investigated by measuring V-l using four probe set-up and X-ray diffraction (XRD) using Bruker AXS, X-ray powder diffractometer. V-l measurements shows an increase in the conductivity of the film, XRD pattern of the polymer shows that the crystallinity improved after the irradiation with Swift Heavy Ions (SHI), which could be attributed to cross linking mechanism.}

2 illus, 1 table, 17 ref

022139   Singh R;Samra K S;Ramneek Kumar;Singh L (Physics Dep, Guru Nanak Dev Univ, Amritsar-143 005, Email: lakhwant@yahoo.com) : Spectroscopic studies of copper and carbon ion irradiated polypropylene. Indian J Phys 2009, 83(7), 955-61.

The samples of polypropylene (PP) have been irradiated with 120 MeV ^{64Cu9+ and 70 MeV 12C5+ ion beams, with the fluence ranging from 1 x 1013 to 1 x 1011 ions/-cnrr-2. UV-VIS and FTIR techniques have been used to study the chemical and optical properties of these irradiated polymers. UV spectra revealed that the optical-gap energy decreases by 54% with copper ion irradiation at the fluence of 1 x 1013 ions/cm2, whereas at the same fluence, carbon beam decreases the optical-gap energy by 20%. FTIR analysis of ion irradiated samples revealed the presence of-OH, C = 0 and C = C bonds. Alkyne formation has been observed only in the case of copper ion irradiation.}

5 illus, 1 table, 10 ref

022138   Singh M;Singh L;Singh B (Physics Dep, Guru Nanak Dev Univ, Amritsar-143 005, Email: lakhwant@yahoo.com) : Different shapes of tracks in phlogopite, biotite and soda lime glass. Indian J Phys 2009, 83(7), 977-83.

Etched track opening geometries in Biotite, Phlogopite and soda-lime glass irradiated with swift heavy ions [^{197Au(11.64 MeV/n), 136Xe(11.56 MeV/n), 58Ni(11.56 MeV/n)] at different angle of incidence have been studied using appropriate chemical etching technique. Different geometries (Hexagonal, irregular polygon, triangular in case of Biotite and Phlogopite, and circular & elliptical in case of soda lime glass detector) of heavy ion tracks are reported in the present investigations using optical microscope. The different shapes of these heavy ions track geometries are found to be related with various target-projectile parameters (viz : type of projectiles, energy, stopping power, angle of incidence of the projectile, density of defects and its reactivity with etchant, etching conditions and chemical structure of the detectors). The dependence of different shapes of heavy ion tracks in isotropic and anisotropic medium on the variation of radiation damage densities along the ion trajectories have also been discussed.}

6 illus, 17 ref

022137   Singh M;Singh B;Kaur N;Singh L (Physics Dep, Guru Nanak Dev Univ, Amritsar-143 005, Email: lakhwant@yahoo.com) : Reliability of stopping power tables and codes for heavy ions (8 ≤ Z ≤ 92) in gases. Indian J Phys 2009, 83(8), 1099-107.

A comparative study of various stopping power tables and codes for heavy ions in gases has been made through comparison of computed values and the corresponding experimental data. Ten gaseous media : five monatomic rare gases (He to Xe), two diatomic gases (H₂, N₂) and three polyatomic gaseous compounds (CH₄, CF₄ and CO₂) have been chosen to study the stopping power investigations of heavy ions (8 ≤Z≤ 92) having energy ranges of ~0.10-10.00 MeV/n and ~20.00-57.00 MeV/n. We compare the experimental data of stopping power to values calculated using various tables and computer codes by ICRU-73, Ziegler et al (SRIM2003.26), Grande and Schiwietz (CasP3.1), Paul and Schinner (MSTAR3.12), and Bazin and Tarasov (USE ++:2-ATIMA1.2). On the basis of statistical analysis, we estimate the reliability of these tables and codes. It has been observed that the MSTAR3.12 code shows the best agreement with the experimental data for projectile ions (8 ≤ Z ≤ 18) in the entire energy range. The SRIM2003.26 code provides good results except for some heavy projectiles (Xe, Pb and U). The values tabulated by CasP3.1 code underestimate especially at low energy region. No significant trend is observed in case of LISE++:2-ATIMA1.2 code and ICRU-73 report.

2 tables, 43 ref

022136   Singh L;Singh M;Singh B;Navjeet Kaur (Physics Dep, Guru Nanak Dev Univ, Amritsar-143 005, Email: lakhwant@yahoo.com) : Stopping power contribution due to target and projectile excitation/ionization : a comparative study. Indian J Phys 2009, 83(8), 1109-15.

Comparative study of stopping power codes for different ions in compounds has been made by comparing the computed stopping power values using different codes with the corresponding experimental data. Two computer codes, semiempirical SR1M2006.02 and theoretical CasP3.2 have been used to evaluate and compare the stopping powers of different compounds for protons (125 KeV), helium (500 KeV) and lithium ion (175 KeV) projectiles. The energy behaviour of stopping power of various compounds for helium ion in the energy range (0.3-2.0 MeV) has been studied. The merits and demerits of the adopted formulations are highlighted. It has been observed that the calculation based on SRIM2006.02 provides the best agreement with the experimental data as compared to CasP3.2 code. The stopping power contribution due to target and projectile excitation/ ionization at low energies has been evaluated and discussed with reference to CasP3.2 code. From these comparative studies it has been concluded that the target and projectile excitation/ionization increases the stopping power (>20%) at lower energies.

1 illus, 1 table, 58 ref

022135   Singh K K;Singh J;Altaf M;Singh A K; Shyampati;Ganai P A;Lalmani (Physics Dep, Banaras Hindu Univ, Varanasi-221 005) : Some unnsual high dispersion whistler triplets recorded at a low L-value (L=1.17). Indian J Phys 2009, 83(11), 1517-23.

A detailed analysis of the VLF data collected during January to December, 2003 at the low latitude station Jammu (geomag. lat., 22° 2& N; L = 1.17) has yielded some unusual VLF events like whistler triplets of very high dispersion D - 70 - 90 sec1/2. From the dispersion analysis of the whistler triplets, it is found that the individual whistlers of the triplets are one-hop high dispersion ducted whistlers having propagation path along higher and closely spaced L-values (L-4.0) than the L~ value of the recording station. The dispersion and occurrence characteristics of these high dispersion whistlers of the triplets are compared with those of the majority of low dispersion whistlers (D ~30-40 sec^{1/2) recorded during the same period. Generation and propagation mechanisms are briefly discussed.}

3 illus, 1 table, 15 ref

022134   Singh J;Singh H;Singh S;Bajwa B S (Physics Dep, Guru Nanak Dev Univ, Amritsar-143 005, Email: singhjoga@rediffmail.com) : Uranium, radium and radon exhalation studies in some soil samples using plastic track detectors. Indian J Phys 2009, 83(8), 1147-53.

Radium concentration and radon exhalation rate have been measured in soil samples collected from some areas belonging to upper Siwaliks of Kala Amb, Nahan and Morni Hills of Haryana and Himachal Pradesh states, India using LR-115 type II plastic track detectors. Uranium concentration has also been determined in these soil samples using fission track registration technique. Radium concentration has been found to vary from 5.30 to 31.71 Bq.kg^{-1, whereas uranium concentration varies from 33.21 to 76.26 Bq.kg-1. The radon exhalation rate in these samples varies from 216.87 to 1298.00 mBq.m-2hr-1 (6.15 to 36.80 mBq.kg-1.hr-1). Most of the samples have uranium concentration above the worldwide average concentration of 35 Bq.kg-1. A good correlation (R2 = 0.76) has been observed between uranium concentration and radon exhalation rate in soil. The values of uranium, radium and radon exhalation rate in soil are compared with that from the adjoining areas of Punjab.}

1 illus, 2 tables, 26 ref

022133   Singh H;Singh J;Singh S;Bajwa B S (Physics Dep, Guru Nanak Dev Univ, Amritsar-143 005, Email: harman_edu@rediffmail.com) : Uranium concentration in drinking water samples using the SSNTDs. Indian J Phys 2009, 83(7), 1039-44.

Uranium concentrations in the drinking water samples collected mainly from hand pumps along the Amritsar to Bathinda track are presented. Uranium concentration values in these samples show a wide range of variation depending upon different factors like source, location, depth and local geology etc. The observed uranium content in water samples has been found to be varying from 0.9 ± 0.08 to 63± 0.21 ppb and even the radon activity in ground water observed in our earlier survey carried out in this area has been found to be increasing from Amritsar towards Bathinda. The higher values were observed from the ground water samples particularly of the areas falling in belt from Zira to Maur towards the Haryana border. The values observed at certain locations are found to be higher than the highest recommended value of 15 ppb [1]. The high uranium concentration observed particularly in certain areas along this track can be attributed due to interaction of ground water with the soil formation of this region and the local subsurface geology of the region.

1 table, 14 ref

022132   Shashikumar T S;Ragini N;Chandrashekara M S; Paramesh L (Studies in Physics Dep, Mysore Univ, Manasagangotri, Mysore-570 006, Email: lp@physics.uni-mysore.ac.in) : Radon in soil and its concentration in the atmosphere around Mysore city, India. Indian J Phys 2009, 83(8), 1163-9.

Radon concentration in soil-gas and in the atmospheric air has been studied around Mysore city (12°N and 76°E) using Solid State Nuclear Track Detectors. The radon in soil-gas is found to be higher at a depth of 1 m than at a depth of 0.5 m from the ground surface. The higher radon concentration in soil was observed near Chamundi Hills and Karigatta village with average values of 5.94 kBq.rrf3 and 5.32 kBq.rrT3 at 1 m depth from the ground surface. Seasonal variations in radon in soil gas shows that, the concentration is lower in summer with an average value of 0.60 kBq.rrf3 and higher in monsoon season with an average value of 4.70 kBq.m^{-3. Estimation of 226Ra in soil at these locations is also made using HPGe detector. The activity of 226Ra, varies from 4.82 to 74.23 Bq.kg-1 with an average value of 32.11 Bq.kg-1. Radon concentrations in soil-gas shows good correlation with the activity of 226Ra in soil with a correlation coefficient of 0.76}

2 illus, 2 tables, 22 ref

022131   Sharma V;Diwan P K;Pratibha;Sharma T;Shyam Kumar;Avasthi D K (Physics Dep, Chandigarh Engineering College, Landran, Mohali-140 307, Email: diwanpk@sify.com) : Energy loss of light ions in polypropylene absorber foils. Indian J Phys 2009, 83(7), 937-41.

The energy loss of Li, C and O ions in polypropylene absorber foils has been measured using 15 UD Pelletron Accelerator facility at Inter University Accelerator Centre (ILIAC), New Delhi, India. The actual experiment has been performed in low flux chamber attached to the General Purpose Scattering Chamber (GPSC). These experimental energy loss values have been compared with the computed values based on various empirical/semi-empirical formulations. Some interesting trends have been observed.

1 table, 12 ref

022130   Selvanayagam S;Velmurugan D;Yamane T;Suzuki A (Centre of Advanced Study in Crystallography and Biophysics, Madras Univ, Guindy Campus, Chennai-600 025, Email: d_velu@yahoo.com) : Use of iterative OASIS with low resolution SAD laboratory X-ray source (Cr Kα) data sets. Indian J Phys 2009, 83(12), 1671-79.

Anomalous scattering methods are widely used for phasing macromolecular structures. OASIS program works on a direct methods procedure and is used to break the phase ambiguity intrinsic in a single wavelength anomalous diffraction (SAD) experiment An iterative phasing/model-building procedure for processing SAD data includes the initial direct method phasing of SAD data, density modification, automatic model building and direct methods phasing of SAD data with feed back from partial structure information. This dual-space procedure has been tested on two experimental Cr Kα SAD data sets, 2.3 A for S-SAD and 2.4 A for I-SAD, of an enzyme glucose isomerase with an approximate molecular weight of 44 kDa (388 residues). HYSS in PHENIX was used to locate the anomalous scatterers for both the data sets (11 sulfurs for 2.3 A data and 9 iodines for 2.4 A data). Phasing and density modification were carried out using OASIS, DM and model building was then carried out using ARP/wARP. Two iterative cycles were necessary for the successful structure solution and refinement of the 2.3 A data set which built 384 residues out of 388. Regular ARP/wARP failed for the 2.4 A resolution data and hence the modified version of REFMAC5 was used in ARP/wARP. A successful model could be built after three iterative cycles of OASIS using this modified version which built 382 residues out of 388 residues. Minimal manual model building was required at this stage and the structure determination was completed using regular REFMAC5. All the computations mentioned here were carried out using Pentium IV PC.

3 illus, 1 table, 17 ref

022129   Sapna P;Jekendra Singh T (Physics Dep, Manipur Univ, Imphal-795 003, Email: sapna_potshangbam@yahoo.co.in) : Relaxation rate of a phonon due to interference. Indian J Phys 2009, 83(12), 1721-6.

A contribution to the relaxation rate of a phonon due to an interference term in the perturbation series is evaluated. This term is the product of quartic anharmonic Hamiltonian and defect Hamiltonian. Under certain conditions this contribution is not zero. At high temperatures it is found that the temperature dependence is similar to that of three-phonon processes although the frequency dependence is stronger than that of the three-phonon processes.

1 illus, 11 ref

022128   Sandhu A K;Singh S;Pandey O P (Physics Dep, Guru Nanak Dev Univ, Amritsar-143 005, Email: surinder_s1951@yahoo.co.in) : Effect of neutron-irradiation on optical properties of SiO₂-Na₂O-MgO-Al₂O₃ glasses. Indian J Phys 2009, 83(7), 985-91.

Silica based glasses are used as nuclear shielding materials. The effect of radiation on these glasses varies as per the constituents used in these glasses. Glasses of different composition of SiO₂-Na₂O-MgO-AI₂O₃ were made by melt casting techniques. These glasses were irradiated with neutrons of different fluences. Optical absorption measurements of neutron-irradiated silica based glasses were performed at room temperature (RT) to detect and characterize the induced radiation damage in these materials. The absorption band found for neutron-irradiated glasses are induced by hole type color centers related to non-bridging oxygen ions (NBO) located in different surroundings of glass matrix. Decrease in the transmittance indicates the formation of color-center defects. Values for band gap energy and the width of the energy tail above the mobility gap have been measured before and after irradiation. The band gap energy has been found to decrease with increasing fluence while the Urbach energy shows an increase. The effects of the composition of the glasses on these parameters have been discussed in detail.

3 illus, 3 tables, 16 ref

022127   Samuel Selvaraj R;Muthuchami A;Nancharaiah M (Physics Dep, Presidency College, Chennai-600 005, Email: samuelselvaraj.r@rediffmail.com) : Influence of sunspot activity on the annual rainfall of Tamil Nadu, India. Indian J Phys 2009, 83(9), 1251-8.

An attempt is made to understand the existence of any relationship between the sunspot activity and Tamil Nadu annual rainfall from the 100 years data (1901-2000). It is found that the linear correlation between sunspot activity and Tamil Nadu annual rainfall is - 0.21 which is significant at 1% level. When the data is smoothed for eliminating small period oscillations such as El-nino and quasi -Biennial oscillation it is found that for 10 point smoothed values the linear correlation coefficient is - 0.75 and that for 20 point smoothed values is -0.86. A regression estimate is made for Tamil Nadu annual rainfall using sunspot activity by a quadratic regression equation. The excess rainfall period during 1996 to 1998 and deficient rainfall period during 2000 to 2003 can be explained from the sunspot activity.

7 illus, 9 ref

022126   Saini R S;Nain M;Chauhan R P;Nawal Kishore; Chakravarti S K (Physics Dep, Radha Krishan Sanatan Dharm College, Kaithal-136 027, Email: chauhanrp@hotmail.com) : Radon, thoron and their progeny levels in some dwellings of northern Haryana, India using SSNTDs. Indian J Phys 2009, 83(8), 1197-200.

Radon pollution is an important global problem of radiation hygiene. Radon and its progeny are the major contributors in the radiation dose received by general population of the world. Keeping this in mind the environmental monitoring of radon, thoron and their progeny in some dwellings of northern part of Haryana state of India has been carried out. The radon-thoron twin dosimeter cups were used for the study. The aim of the study is the possible health risk assessment in the dwellings under consideration.

1 table, 10 ref

022125   Sabharwal A D;Singh M;Singh B;Sandhu B S (Physics Dep, Punjabi Univ, Patiala-147 002, Email: arvingdeepaksabharwal@yahoo.com) : Experimental evaluation of multiple compton backscattering of gamma rays in copper. Indian J Phys 2009, 83(8), 1141-6.

The gamma ray photons continue to soften in energy as the number of scatterings increases in thick target, and results in the generation of singly and multiply scattered events. The number of these multiply scattered events increases with an increase in target thickness and saturates beyond a particular target thickness known as saturation depth. The present experiment is undertaken to study the saturation depth for 279 and 320 keV incident gamma ray photons multiply backscattered from copper targets of varying thickness. The backscattered photons are detected by a Nal(TI) gamma detector whose pulse-height distribution is converted into a photon spectrum with the help of an inverse matrix approach. To extract the contribution of multiply backscattered photons only, the spectrum of singly scattered photon is reconstructed analytically. We observe that the numbers of multiply scattered events increases with an increase in target thickness and then saturate. The saturation depth is found to be decreasing with increase in incident gamma energy.

3 illus, 1 table, 5 ref

022124   Roy U (Information Technology Dep, School of Technology (SOT), Assam Univ, Silcher-788 011, Email: utpal.roy@visva-bharati.ac.in) : Computation of resonance energies and widths in e<. Indian J Phys 2009, 83(12), 1637-45.

Reports calculation of S-wave resonances (energies and widths) in positron-hydrogen scattering below the N=2 hydrogen and the N=2 positronium excitation thresholds with the stabilization method using Hylleraas-type wavefunctions. Three resonances have been extracted out of which one is associated with the hydrogen n=2 threshold and the other two are found lying below the Ps(n=2) formation threshold. The present results agree with the most accurate calculations obtained by other methods.

5 illus, 1 table, 28 ref

022123   Ravichandran V;Chinnathambi V;Rajasekar S (Physics Dep, Sri K G S Arts College, Srivikuntam-628 619) : Effect of rectified and modulated sine forces on chaos in duffing oscillator. Indian J Phys 2009, 83(11), 1593-1603.

The effect of rectified and modulated sine forces on the onset of horseshoe chaos is studied both analytically and numerically in the Duffing oscillator. With single force analytical threshold condition for the onset of horseshoe chaos is obtained using the Melnikov method. The Melnikov threshold curve is drawn in a parameter space. For the rectified sine wave, onset of cross-well asymptotic chaos is observed just above the Melnikov threshold curve. For the modulus of sine wave long time transient motion followed by a periodic attractor is realized. The possibility of controlling of chaos by the addition of second modulated force is then analyzed. Parametric regimes where suppression of horseshoe chaos occurs are predicted analytically and verified numerically. Interestingly, suppression of chaos is found in the parametric regimes where the Melnikov function does not change sign.

9 illus, 17 ref

022122   Ramasamy V;Rajkumar P;Ponnusamy V (Physics Dep, Annamalai Univ, Annamalai Nagar-608 002) : Depth wise analysis of recently excavated Vellar river sediments through FTIR and XRD studies. Indian J Phys 2009, 83(9), 1295-1308.

The Fourier transform infrared (FTIR) spectral analysis has been carried out for sediments of Vellar river, Tamilnadu collected at various depths from twenty seven different locations. The minerals such as quartz, feldspar (miorocline and orthoclase), kaolinite, palygorskite, calcite, aragonite, montmorillonite, cerussite, hematite, sepiolite, magnesium oxalate and organic carbon are identified. Among these, quartz, feldspar and kaolinite are the major minerals and palygorskite, calcite, aragonite, montmorillonite, cerussite, hematite, sepiolite, magnesium oxalate and organic carbon are minor and traces. The relative distribution of these three major minerals was determined by computing the extinction co-efficient. The crystalline nature of quartz is judged by calculating crystallinity index which shows that the crystalline nature decreases with increase of depth. The observation made through relative distribution, shows that the amount of quartz and feldspar are relatively reduced and that of kaolinite is increased from upper to inner depth. As the depth increases the bands of kaolinite progressively broaden and shift to higher wave number side which suggests that the content of kaolinite increases with disorderedness. From XRD analysis, the minerals such as monazite, zircon and kyanite are additionally identified. The crystalline nature of quartz is also confirmed.

3 illus, 3 tables, 35 ref

022121   Rajsesh Kumar;Ali S A;De U;Avasthi D K;Prasad R (Applied Physics Dep, Z H College of Engineering & Technology, Aligarh Muslim Univ, Aligarh-202 002, Email: drrajesh04@rediffmail.com) : Dielectric response of makrofol-KG polycarbonate irradiated with 145 MeV Ne<. Indian J Phys 2009, 83(7), 963-8.

The passage of heavy ions in a track detector polymeric material produces lattice deformations. These deformations may be in the form of latent tracks or may vanish by self annealing in time. Heavy ion irradiation produces modifications in polymers in their relevant electrical, chemical and optical properties in the form of rearrangement of bonding, cross-linking, chain scission, formation of carbon rich clusters and changes in dielectric properties etc. Modification depends on the ion, its energy and fluence and the polymeric material. In the present work, a study of the dielectric response of pristine and heavy ion irradiated Makrofol-KG polycarbonate is carried out. 40 μm thick Makrofol-KG polycarbonate films were irradiated to various fluences with Si^{8+ ions of 100 MeV energy from Pelletron at Inter University Accelerator Centre (ILIAC), New Delhi and Ne6+ ions of 145 MeV from Variable Energy Cyclotron Centre, Kolkata. On irradiation with heavy ions dielectric constant (ε'') decreases with frequency where ε' increases with fluence for both the ions. Variation of loss factor (tan δ) with frequency for pristine and irradiated with Si ions reveals that tan S increases as the frequency increases. Tan 5 also increases with fluence. While Ne irradiated samples tan δ shows slight variation with frequency as well as with fluence. Tan S has positive values indicating the dominance of inductive behavior.}

4 illus, 1 table, 18 ref

022120   Rajprakash H G;Ganesh Sanjeev;Vijaykumar K B; Siddappa K;Nayak B K;Saxena A (Physics Dep, Microtron Center, Mangalore Univ, Mangalagangothri-574 199, Email: prakashraj06@rediffmail.com) : Angular distribution of photofission fragment of even-even and odd mass nuclei studies using SSNTD technique. Indian J Phys 2009, 83(8), 1135-40.

Fission fragment angular distribution measurements of even-even (^{232Th) and odd mass (237Np) nuclei were carried out using bremsstrahlung radiation in the energy range 7.4 to 9.2 MeV from variable energy microtron at Mangalore University. In the present work SSNTD lexan polycarbonate films were used to detect the fission tracks from both even-even (232Th) and odd mass (237Np) nuclei. From the knowledge of track density formed from photofission reaction of 232Th and 237Np, angular distribution of fission fragments was measured. The results obtained are discussed on the basis of Age Bohr theory in this paper.}

5 illus, 12 ref

022119   Rajkhowa M (Physics Dep, Govt. Science College, Jorhat-785 010, Email: rajkhowa_05@yahoo.com) : New parametrisation of tri-bimaximal mixings. Indian J Phys 2009, 83(9), 1343-51.

Recent neutrino oscillation data indicates tri-bimaximal mixings. In this communication author propose degenerate, inverted hierarchical and normal hierarchical structures of neutrino mass matrices in terms of two input parameters. These mass matrices not only predict tri-bimaximal mixings but also neutrino oscillation mass parameters comparable with experimental data. Considers contribution of Type-ll seesaw formula and observe possible deviations from tri-bimaximal mixings.

4 tables, 11 ref

022118   Rajesh Kumar;Ali S A;Naqvi A H;Virk H S;De U; Avasthi D K;Rajendra Prasad (Applied Physics Dep, Z H College of Engineering & Technology, Aligarh Muslim Univ, Aligarh-202 002, Email: drrajesh04@rediffmail.com) : Optical band gap and carbon cluster sizes formed in 100 MeV Si<. Indian J Phys 2009, 83(7), 969-76.

A wide variety of material modifications in polymers have been studied by using ion irradiation techniques. Extensive research has focused on to Swift Heavy Ions (MeV's energy), probably because of good controllability and the large penetration length in polymers. High energy ion irradiation tends to damage polymers significantly by electronic excitation and ionization. It may result into the creation of latent tracks and can also cause formation of radicals such as ablation, sputtering, chain scission and intermolecular cross-linking, creation of triple bonds and unsaturated bonds and loss volatile fragments. Polypropylene polymer films of thickness 50 μrn were irradiated to the fluences of 1 x 10V^{10, 3 x 1010,1 x 1011, 3 x 1011, 6 x 1011 and 1 x 1012 ions/cm2 with Si8+ ions of 100 MeV energy from Pelletron accelerator at Inter University Accelerator Centre (ILIAC), New Delhi and Ne6+ ions of 145 MeV to the fluences of 108, 1010, 1011, 1012 and 1013 ions/cm3 from Variable Energy Cyclotron Centre, Kolkata. Optical modifications were characterized by UV towards the red end of the spectrum with the increase of the fluence. Value of optical band gap E_g shows a decreasing trend with ion fluence irradiated with both kinds of ions. Cluster size N, the number of carbon atoms per conjugation length increases with increasing ion dose. Cluster size also increases with the increase of electronic stopping power.}

4 illus, 2 tables, 3 ref

022117   Qureshi A;Shah S;Singh D;Singh N L;Singh K P (Physics Dep, M S Univ of Baroda, Vadodara-390 002, Email: singhnl_msu@yahoo.com) : AC electrical properties of proton irradiated EVA films. Indian J Phys 2009, 83(8), 1117-22.

MeV ions passing through polymeric films modify their electrical, optical and thermal properties and these changes are related to changes in the chemical structure of the polymers. Ethylene vinyl acetate (EVA) films were irradiated with 3 MeV proton beam at different fluences of 10^{13, 1014 and 1015 ions/cm2. AC electrical properties of pristine and irradiated samples were studied in the frequency range 100 Hz to 100 kHz by means of an LCR meter. There is an exponential increase in conductivity with log frequency and conductivity increases as fluence increases. The dielectric loss/constant is observed to change with the fluence. FTIR spectra reveals significant change in intensities of functional groups at a fluence of 1015 ions/cm2 due to scissioning of polymer chains.}

4 illus, 15 ref

022116   Prasad Y;Prasad G;Gusain G S;Choubey V M; Ramola R C (Physics Dep, H N B Garhwal Univ, Badshahi Thaul Campus, Tehri Grahwal-249 199, Email: rcramola@bsnl.in) : Seasonal variation on radon emission from soil and water. Indian J Phys 2009, 83(7), 1001-10.

Radon is being measured continuously in spring water and soil-gas at Badshahi Thaul Campus, Tehri Garhwal in Himalayan region by using radon Emanometer since December 2002. An effort was made to correlate the variance of radon concentrations in spring water and soil-gas with meteorological parameters at the same location. The main meteorological parameters that affect the radon emanation from host material is surrounding temperature, barometric pressure, wind velocity, rain fall and water level of the spring. The correlation coefficient between radon concentration in spring water and different atmospheric parameters was computed. The correlation coefficient between radon concentration in spring water and the maximum atmospheric temperature was 0.3, while it was 0.4 for minimum atmospheric temperature at the monitoring site. The correlation coefficient for radon concentration in spring water with minimum and maximum relative humidity was 0.4. Spring water radon concentration was found positively correlated (0.6) with water discharge rate of the spring. A weak correlation (0.09) was observed between the radon concentration in spring water and rain fall during the measurement period. As temperature of near surface soil increases, the radon emanation coefficient from the soil surface also increases. The possible effects due to global warming and other climatic changes on environment radiation level were also discussed in detail.

1 illus, 3 tables, 17 ref

022115   Pathak M;Gupta S;Bhattacharya D;Rao M K; Bhaumik B K (Atomic Energy Dep, Atomic Minerals Directorate for Exploration and Research, West Block VII, R K Puram, New Delhi-110 066, Email: bidhan_bhaumik@yahoo.co.in) : Mapping the inhomogeneity of the U and Th distributions-using sample size concept in the field conditions. Indian J Phys 2009, 83(7), 993-1000.

Indigenously fabricated portable gamma-ray spectrometer (PGRS) is used for the measurement of gamma activity of ^{214Bi (1.76 MeV) and 208TI (2.62 MeV), under field conditions in Mohar area, Shivpuri Distt. (MP). The energies are discriminated by using a Nal (Tl) crystal of size 1.75" x 2" PGRS used to map the primordial elemental distributions shows reversals of concentration of thorium and uranium (represented by radium group) in field and lab analysis in many samples, which is attributed to the inhomogenity of distribution of these elements in the area. The concept of difference in the volume of dish shaped field sample and the randomly picked up sample from the field grid point (400 gm in lab analysis) is utilized to interpret the inhomogenity of these elements. However interpretations are based on the assumption that these primordial elements (U, Th) are in secular equilibrium and the terrain has low topographic relief.}

4 illus, 2 tables, 9 ref