Indian Journal of Pure and Applied Physics

 Total visitors: 960  since 13-08-07

 

Volume 45

Number 8

AUGUST 2007

CODEN : IJOPAU 45 (8) 633-704

ISSN : 0019-5596

 

 

 

CONTENTS

 

Nuclear Physics

 

Two-dimensional void probability scaling of grey tracks emitted in 24Mg-AgBr interaction
at 4.5 AGeV/c

637

Dipak Ghosh*, Argha Deb, Madhumita Bannerjee Lahiri & Ishita Sen (Datta)

 

Atomic and Molecular Physics

 

x-ray production and ionisation cross-sections of k shell of argon by electron impact near threshold region

641

Mahmut Aydınol

 

Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics and Fluid Dynamics

 

Complex data mapping on a binary ferroelectric liquid crystal electrically addressed spatial light modulator for target recognition

647

Shilpi Goyal, Naveen K Nishchal, Vinod K Beri & Arun K Gupta*

 

Condensed Matter: Structure, Mechanical and Thermal Properties

 

Analysis of temperature dependence of thermal pressure of solids

654

S Digpratap*, K Rakesh & K Arunesh

 

Calculation of lattice specific heat of bcc NbZr dilute alloy

658

P D Semalty* & Kapil Dev

 

Single injection in a spherical insulator in CDMM mode

663

N K Sharma*, C Indra, T Radjakumar & G Meenakshi

 

Effect of coriolis force on a soret driven ferrothermohaline convection in a medium of sparse particle suspension

666

G Vaidyanathan*, R Sekar & R Hemalatha

 

Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties

 

Measurement of some physical parameters of a deformed Helix ferroelectric liquid crystal with an antiferroelectric phase

674

Amrita Mukherjee, M Rahman, S S Bhattacharyya & B K Chaudhuri*

 

Quantum Monte-Carlo simulation study of attractive Hubbard chain

679

Meenakshi S Khurana, Kamlesh Kumari & Ishwar Singh*

 

Electrical properties of thermally evaporated doped and undoped films of CdSe

687

M N Borah, S Chaliha , P C Sarmah* & A Rahman

 

Structural and low frequency dielectric studies of conducting polymer nanocomposites

692

D K Ray, A K Himanshu & T P Sinha*

 

 

___________

*The corresponding author has been indicated by (*) mark in case of papers with more than one author.


Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 637-640

 

 

Two-dimensional void probability scaling of grey tracks emitted in 24 Mg-AgBr interaction at 4.5 AGeV/c

Dipak Ghosh, Argha Deb, Madhumita Bannerjee Lahiri & Ishita Sen Datta

Nuclear and Particle Physics Research Centre, Department of Physics, Jadavpur University, Kolkata 700 032

Received 18 August 2006; revised 21 March 2007; accepted 30 May 2007

This paper presents a very rigorous study of two-dimensional void probability scaling of medium energy target protons emitted in 24Mg-AgBr interaction at 4.5 AGeV/c in terms of their emission angle (q ) and azimuthal angle f.The study indicates that the two-dimensional void probability scaling holds good for the total region of phase space.

Keywords: Protons, 24Mg-AgBr interaction, Multiparticle production, Particle density fluctuation

IPC Code: G09B23/00

 

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 641-646

x-ray production and ionisation cross-sections of k shell of argon by electron impact near threshold region*

Mahmut Aydınol

Atomic and Molecular Physics Section, Department of Physics, Faculty of Sciences &Arts, University of Dicle, Diyarbakir, Turkey

e-mail: aydinolm@dicle.edu.tr

Received 7 September 2006; revised 25 January 2007; accepted 3 May 2007

Excitation of argon by electron impact yielded characteristic X-rays and bremsstrahlung. They are simultaneously measured and analysed for several electron impact energy values. The X-ray yield ratio, Kβ1,3/Kα1,2, for the electron impact energy values of 7 < Ee < 11 keV is equal to (0.104 ± 0.016) and is in agreement with the given value by Salem et al., Atomic Data Tables, 14 (1974)91. Characteristic X-ray yields of Kα1,2 and Kβ1,3 lines of argon, increase rapidly as the electron impact energy values increase from 3,5 to 11 keV. The K shell ionisation cross-section results are compared with an earlier experimental results on argon K shell ionisation given by Dolgov-Savalev and Panchenko [Opt-spectro (1970) 575]. K shell ionisation cross-section dependency to the electron impact energies is found to be similar and shows rapid increase starting from near threshold energy to 11 keV. The effects of simultaneously produced competing radiationless yields on to the Kα1,2 and Kβ1,2 X-ray line yields of argon, have been investigated.

Keywords: x-ray production, Ionisation cross-sections, Threshold region

IPC Code: G01N23/00

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 647-653

 

Complex data mapping on a binary ferroelectric liquid crystal electrically addressed spatial light modulator for target recognition

 

Shilpi Goyal, Naveen K Nishchal, Vinod K Beri & Arun K Gupta*

Photonics Division, Instruments Research & Development Establishment, Raipur Road, Dehradun 248 008

*E-mail: akgupta@irde.res.in

Received 12 October 2006; revised 29 May 2007; accepted 1 June 2007

For displaying a complex valued function onto a binary amplitude-only or phase-only spatial light modulator, an encoding technique is required. In this paper, we implement an encoding scheme proposed by Davis et al. [Appl Opt, 42 (2003) 2003] for optical processing the complex product function in the hybrid digital-optical correlator. The output of this correlator consists of two autocorrelation peaks along with a strong dc. Out of these three terms, our interest is in capturing only one of the correlation peaks, while discarding the other correlation peak and strong dc. For capturing only one of the correlation peaks, we multiplied a chirp function with the rotation-invariant maximum average correlation height filter. The product function, that is basically a multiplied product of the input scene’s Fourier spectrum and the chirp-encoded filter, is inverse Fourier transformed to obtain the correlation peaks. Due to chirp encoding, the correlation signals are focused in three different planes. Thus, placing our peak capturing CCD camera at a particular plane we can capture only one autocorrelation peak. Results with almost similar tank images having different energy values have also been shown.

Keywords: Hybrid digital-optical correlator, Chirp encoding, MACH filter

IPC Code: C09K 19/00

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 654-657

Analysis of temperature dependence of thermal pressure of solids

 

S Digpratap, K Rakesh & K Arunesh

Department of Physics, Institute of Basic Sciences, Khandari, Agra 282 002

Received 21 September 2006; revised 13 February 2007; accepted 15 May 2007

Thermal pressure is an important physical quantity playing the central role in the evaluation of high temperature equations of state for solids. Recently, Kumar and Singh, [Indian J Phys, 78 (2004) 1225] have studied several formulations for the temperature dependence of thermal pressure demonstrating the inadequacies of the models developed by earlier researchers. It is emphasized in the present work that the method adopted by Kumar and Singh is seriously flawed and inconsistent with the recent findings. The Suzuki formulation for volume thermal expansion has been derived correctly in the present study and found to be in close agreement with the experimental data on thermal pressure for various solids considered by Kumar and Singh.

Keywords: Thermal pressure, Thermal expansivity, Equation of state

IPC Code: G01L; G01N25/04; B01J3

 

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp 658-662

 

 

Calculation of lattice specific heat of bcc NbZr dilute alloy

P D Semalty & Kapil Dev

Department of Physics H N B Garhwal University Campus, Badshahithaul Tehri-Garhwal 249 199

E-mail: psemalty@sancharnet.in

Received 24 June 2005; revised 8 September 2005; accepted 11 September 2006

The lattice specific heat at very low temperatures, using a perturbation model which includes the mass change and change in the nearest-neighbour force constants due to interaction between impurity and host atoms has been calculated. In addition to the local perturbation due to mass change and force-constant changes, the effect of volume change has also been taken into account. The calculated results have been compared with the experimental measurements and values of central and non-central force-constant changes have been obtained. The increase in lattice specific heat is explained on the basis of these force-constant changes. The possibility of occurrence of resonance and localized modes from the calculation of resonant denominator have been investigated.

Keywords: Lattice specific heat, Dilute alloys, Resonance modes, Localized modes, Green’s function, Force-constant change

 

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 663-665

 

 

 

Single injection in a spherical insulator in CDMM mode

 

N K Sharma, C Indra, T Radjakumar & G Meenakshi

Department of Physics, Kanchi Mamunivar Centre for Post Graduate Studies, Pondicherry 605 008

Received 2 February 2006; revised 21 August 2006; accepted15 May 2007

The electrical behaviour of an insulator has been studied for a single injection (electrons) current flow containing significant density of thermally generated free carriers under density dependent mobility mode. The current injection in CDDM mode with spherical geometry has been further studied. In this problem, it is found that at low current injection, the pure Ohm’s law for current-voltage characteristics has finally been converted into the half power law at high injection level under space charge regime.

Keywords : Spherical insulator, Electron injection, Point contact, Density

IPC Code: HOIB

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 666-673

 

Effect of coriolis force on soret driven ferrothermohaline convection in a medium of sparse particle suspension

 

G Vaidyanathana ,R Sekarb & R Hemalathac

aDepartment of Physics, bDepartment of Mathematics, Pondicherry Engineering college, Pondicherry 605014

cDepartment of Mathematics, Kanchi Mamunivar Centre for Post Graduate Studies, Pondicherry 605008

aE-mail: gvn_pec@yahoo.com

Received 9 May 2006; revised 10 November 2006; accepted 17 April 2007

In ferrofluids three components namely core, surfactant and carrier fluids coexist. Thermal convection in a multicomponent fluid has wide applications in industrial, ionospheric and geothermal systems. In this paper, the effect of magnetic fields along the vertical axis on a soret driven thermohaline convective instability in a ferrofluid saturating rotating porous medium has been examined using linear stability analysis. The infinitely spread fluid layer is assumed to be contained in between two free flat conducting boundaries. The exact solutions for stationary and oscillatory instabilities are obtained. It is found that the stationary instability is possible for Taylor numbers up to 100. When the values of Taylor number are greater than 100, the system is found to stabilize through oscillatory mode. The calculations made on this study are shown graphically.

Keywords: Ferrofluids, Linear stability, Soret effect, Taylor number, Porous medium

IPC Code:H01F1/44

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 674-678

 

Measurement of some physical parameters of deformed helix ferroelectric liquid crystal with an antiferroelectric phase

Amrita Mukherjee*, M Rahman, S S Bhattacharyya & B K Chaudhuri

Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata 700 032

Received 24 April 2007; accepted 13 June 2007

The temperature dependent static dielectric constant of a deformed helix ferroelectric liquid crystal (DHFLC) material MOPBIC with antiferroelectric (AF) phase having very high value of spontaneous polarization (PS) and ultra short pitch have been measured for two different cell thickness. The static dielectric constant (e ˘ ) of this material is found to be extremely large and increases with increasing cell thickness. The behaviour of electrical switching time, optical response time and rotational viscosity has also been measured as a function of temperature showing very fast response time over a broad temperature range. Besides tristable switching property in the AF phase, additional advantages like high response speed in electro optic effects and low threshold voltage corresponding to their large spontaneous polarization demand great technological implications of this type of liquid crystals.

Keywords: Liquid crystals, Dielectric constants, Polarization

IPC Code: G 02 F 1/13

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 679-686

 

Quantum Monte-Carlo simulation study of attractive Hubbard chain

Meenakshi S Khurana*, Kamlesh Kumari & Ishwar Singh

Department of Physics, Indian Institute of Technology, Roorkee 247 667

Received 14 October 2006; accepted 10 April 2007

Quantum Monte-Carlo simulations of one-dimensional narrow band systems with attractive interactions (U < 0) have been reported. Using Hubbard model, local squared magnetic moments, probability of double occupancy, spin magnetic susceptibility and various spin pairing correlation functions as a function of Coulomb interactions for different band fillings have been studied.

Keywords: Quantum Monte-Carlo simulation, Hubbard chain, Coulomb interactions

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 687-691

Electrical properties of thermally evaporated doped and undoped films of CdSe

M N Borah, S Chaliha, P C Sarmah * & A Rahman

Department of Physics, Gauhati University, Guwahati 781014

*Electronics Department, Regional Research Laboratory, Jorhat 785006

*E-mail : pratap_sarmah@yahoo.com

Received 21 August 2006 ; revised 21 May 2007; accepted 5 June 2007

Electrical characteristics of Ag-doped and undoped films of CdSe have been reported. The activation energies at lower and elevated temperatures have been found to be 0.22 and 0.6eV, respectively. The Sn/CdSe junction exhibits Schottky barrier characteristics with diode ideality factor deviating from unity. Barrier height obtained from C-V plot and J-V plot are 0.8 and 0.72eV, respectively. The junction has been endowed with high series resistance.

Keywords: Electrical properties, Activation energy, Schottky barrier, Cadmium selenide

IPC Code: H0L

 

 

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 45, August 2007, pp. 692-699

 

Structural and low frequency dielectric studies of conducting polymer nanocomposites

D K Ray* , A K Himanshu# & T P Sinha+

+ Department of Physics, Bose Institute, 93/1, Acharya Prafulla Chandra Road, Kolkata 700 009

# Variable Energy Cyclotron Centre, Material Science Section, DAE, 1/AF Bidhan Nagar Kolkata 700 064

*Department of Radiotherapy, Chittaranjan National Cancer Institute, 37, S P Mukherjee Road, Kolkata 700 026

Received 14 June 2006; accepted 18 May 2007

The intrinsically conducting polymer (ICP), polyaniline (PANI) has been synthesized by chemical polymerization process with the help of water soluble support polymer poly (vinyl pyrrolidone) (PVP). The X-ray diffraction of synthesized PANI-PVP polymer reveals that the polymeric nanocomposites are partially crystalline with orthorhombic phase at room temperature. The morphology of these composite polymers has been studied by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The dielectric measurement of the sample is performed in the frequency range 100 Hz – 1MHz and temperature range 213-313 K. An analysis of real and imaginary parts of dielectric permittivity and the electric modulus indicate the polydispersive nature of relaxation time as confirmed by Cole-Cole plot of the complex permittivity. The frequency dependence of modulus spectra is found to obey an Arrhenius law with activation energy of 0.07 eV. The frequency dependent electrical data has been analyzed in the framework of the conductivity. These results elucidate that there is an increased coupling among the local dipolar motions (short range order localized motion).

Keywords: Polyaniline, Polyvinyl pyrrolidone, Polaron, Bipolaron, Emeraldine-salt, Nanocomposites

IPC Code: B82B