Indian Journal of Pure and Applied Physics

 

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VOLUME 40 NUMBER 7 JULY 2002

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CONTENTS

 

Nuclear Physics

Correlation among target fragments in muon-nucleus interactions at (42045) GeV

Dipak Ghosh*, Argha Deb, Syed Imtiaz Ahmed & Parthasarathi Ghosh

 

461

Atomic and Molecular Physics

Fluorescence quenching of 6-chloro-2-phenyl [benz (b) pyrrole]-1-carboxaldedhyde thiosemicarbazone

by CCl4 in different solvents

H M Suresh Kumar, M N Ravikanth, R S Kunabenchi*, S M Hangodimath, J S Biradar,

P Renuka, N N Math, J S Kadadevaramath & S R Inamdar

 

 

466

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

Opto-electronic properties of semiconductors and alkali halides

R R Reddy*, Y Nazeer Ahammed, K Rama Gopal, P Abdul Azeem & T V R Rao

 

471

Effect of Cu-site occupancy on superconducting order parameter dimensionality and related correlations

in low-disorder Fe and Zn doped YBCO

U C Upreti* & A V Narlikar

476

Resistivity studies on Al-Zn-Mg system

S K Joshi*, Lalit Mehta & A P Deshpande

482

Dielectric properties of electron beam deposited amorphous SiOx (0< x< 2) thin films

M J A Sarkar*, M A R Sarkar & M D Hossain

489

Evaluation of hysteresis loss for rubber-ferrite composites and estimation of magnetostrictive

constant (ls) from loop parameters

S Sindhu & M R Anantharaman*

 

495

Theoretical determination of electron impact ionization of Si+ and Si++ and CR7+ ions

M Alfaz Uddin* & M Golam Mortuza

501

Studies on Al-Si-X samples (where X=Mn, Fe)

Lalit Mehta*, S K Joshi & A P Deshpande

520

Interdisciplinary Physics and Related Areas of Science and Technology

Stabilityof unbroken super symmetry through equilibrium behaviour of RABAM of ANN

Manu Pratap Singh

 

508

Ultrasonic propagation in breast tissue with ductal carcinoma

Kirti Gandhi Bhatia, V R Singh*, M C Bansal & Sanjiv Bhatia

515

News Scan

Now blue jets videoed from ground

Tarun Banerjee

 

524

____________

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

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 461-465

Correlation among target fragments in muon-nucleus

interactions at (42045) GeV

Dipak Ghosh, Argha Deb, Syed Imtiaz Ahmed & Parthasarathi Ghosh

High Energy Physics Division, Department of Physics, Jadavpur University, Calcutta 700 032

Received 2 August 2001; revised 19 March 2002; accepted 8 April 2002

Two-particle short-range correlation among target fragments produced in muon-nucleus interactions at (42045) GeV has been investigated. The strong correlation is observed in both forward and backward hemispheres in cos θ phase space.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 466-470

Fluorescence quenching of 6-chloro-2-phenyl [benz (b) pyrrole] -1-carboxaldehyde thiosemicarbazone by CCl4 in different solvents

H M Suresh Kumar, M N Ravikanth, R S Kunabenchi, S M Hanagodimath*

J S Biradar, P Renuka**, N N Math, J S Kadadevaramath & S R Inamdar#

*Department of Physics, **Department of Chemistry, Gulbarga University, Gulbarga 585 106

#Department of Physics, Karnatak University, Dharwad 580 003

Received 26 November 2001; revised 27 February 2002; accepted 30 May 2002

The quenching of fluorescence of 6-chloro-2-phenyl [benz (b) pyrrole]-1-carboxaldehyde thiosemicarbazone by carbon tetrachloride has been studied in dioxan, acetonitrile, methanol and butanol solvents at room temperature to understand the quenching mechanism. The Stern-Volmer plot has been found to be non-linear with a positive deviation for all the solvents. Various rate constants for the quenching processes are determined using a modified S-V equation and have been found to be dependent on solvent polarity. The results suggest that both static and dynamic quenching processes are responsible for the observed positive deviation in the SV plot.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 471-475

Opto-electronic properties of semiconductors and alkali halides

R R Reddy*, Y Nazeer Ahammed, K Rama Gopal, P Abdul Azeem & T V R Rao

Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003

Received 24 July 2001; revised 1 April 2002

An attempt has been made to find out the dependence between optical susceptibility, refractive index, electronic polarizability and magnetic susceptibility on energy gap of the II-VI, III-V semiconductors and alkali halides. The estimated values of these parameters are in good agreement with the available experimental data. A good agreement between theory and experiment demonstrate the validity of the present work.

 

Indian J Pure & Applied Physics

Vol. 40, July 2002, pp. 476-481

Effect of Cu-site occupancy on superconducting order parameter dimensionality and related correlations in low-disorder Fe and Zn doped YBCO

U C Upreti & A V Narlikar

National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110 012

Received 1 March 2002; accepted 13 May 2002

The preliminary investigations, on fluctuation effects due to low chemical disorders in planes and chains in Y123 system as a comparative study. The possible effects of changing the low concentration planar Cu-site substituent Zn(0.33%) by a chainer Cu-site substituent Fe of almost the same concentration (0.30%) on the order parameter dimensionality in YBCO epitaxial thin films have been investigated. Related correlations have also been discussed. In c-axis oriented laser ablated epitaxial thin films of pure and doped YBCO superconductor samples the order parameter fluctuation effects observed in the mean-field-region, are correlated with the mean field critical temperature (Tcmf), the resistivity, and the excess conductivity (Ds). Aslamazov-Larkin (AL) theory with Anderson-Zou (AZ) model for background resistivity shows an order parameter dimensionality (OPD) cross-over in the pure film which changes to 3-dimensional (2-dimensional) superconducting behaviour by substituting low disorder of Fe (Zn). Compared to Fe doping, the dimensionality behaviour at such low-level doping of Zn suggests fast suppression of superconductivity. The sample parameters suggest correlations such that, the dimensionality is directly proportional to Tcmf, and Ds has weak dependence on the resistivity of a system and it (or the fluctuation) has slow suppression to low disorder of Fe.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 482-488

Resistivity studies on Al-Zn-Mg system

S K Joshi*, Lalit Mehta* & A P Deshpande**

*Department of Physics, Government Post-Graduate Arts & Science College, Ratlam 457 001

**Department of Physics, Amolakchand College, Yavatmal 445 001

Received 24 July 2001; revised 1 February 2002; accepted 28 May 2002

The preparation, characterisation and resistivity studies of Al-Zn-Mg system have been reported. The samples included in the present paper are: (i) Al21Zn42Mg37, (ii) Al21Zn41Mg38, (iii) Al21Zn40Mg39, (iv) Al21Zn39Mg40 and (v) Al21Zn38Mg41. The X-ray diffraction (XRD) studies indicate the presence of the icosahedral phase in these samples. Measurements of resistivity (r) of the samples and its variation with temperature have been carried out. The plot of (r) versus T indicate negative slope. The mechanism of transport for the icosahedral phase of Al-Zn-Mg samples over the temperature range 25-300 K is explained on the basis of mechanism of hopping through the critical states.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 489-494

Dielectric properties of electron beam deposited

amorphous SiOX (0 < x < 2) thin films

M J A Sarkar

Department of Physics, University of Rajshahi, Rajshahi-6205, Bangladesh

and

M A R Sarkar & M D Hossain

Department of Applied Physics and Electronics, University of Rajshahi, Rajshahi-6205, Bangladesh

Received 27 November 2001; revised 18 March 2002; accepted 6 May 2002

Dielectric properties of electron beam evaporated SiOX (0 < x < 2) thin films with thickness of 140-300 nm were studied in the frequency range 102-105 Hz and temperature range 300-580 K. Effects of SiOX film thickness, frequency and temperature on conductance and capacitance were studied for Al-SiOX-Al capacitors. The frequency dependence of conductance Gp was found to obey an equation of the form Gp= Af S where A is a constant and S is a temperature dependent quantity whose value is close to unity. Values of thermal activation energy were determined in different temperature ranges for different applied frequencies and results are discussed.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 495-500

Evaluation of hysteresis loss for rubber-ferrite composites and estimation of magnetostrictive constant (ls) from loop parameters

S Sindhu & M R Anantharaman*

Department of Physics, Cochin University of Science and Technology, Cochin 682 022

Received 12 August 2001; revised 8 March 2002; accepted 29 May 2002

Rubber ferrite composites (RFCs) are flexible elastomer magnets. The flexibility and mouldability of these magnets are an added attraction as far as applications are considered. They are also potential microwave absorbers. RFCs can be prepared by the incorporation of ferrite fillers in rubber matrices. The evaluation of saturation magnetostrictive constant (ls) for RFCs poses always a problem since they are flexible and elastic in nature. So, alternate methods for the estimation of ls is necessary. This paper discusses the estimation of ls for ferrite fillers as well as for RFCs from hysteresis loop parameters by employing a simple relationship. The magnetostrictive constant (ls) for the ceramic fillers as well as the RFCs are estimated and are presented here. The results are compared.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 501-507

Theoretical determination of electron impact ionization

of Si+, Si++ and Cr7+ ions

M Alfaz Uddin & M Golam Mortuza

Department of Physics, University of Rajshahi, Rajshahi 6205, Bangladesh

Received 20 September 2001; revised 18 January 2002; accepted 10 April 2002

Semi-empirical formulae BEBA, BEB and Pattard-Rost models are employed to compute the total cross-section of single ionization of Si+, Si++ and Cr7+ ions by electron impact. The parameters of the semi-empirical formulae are obtained by fitting with the experimental data over a wide range of energy. It is found that, the semi-empirical formulae provide excellent fit, while the BEBA and BEB models give qualitative fit to the experimental data. The parameter-free Pattard-Rost model is in fairly good agreement with the data.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 520-523

NOTE

Studies on Al-Si-X samples (where X = Mn, Fe)

Lalit Mehta*, S K Joshi* & A P Deshpande

*Department of Physics, Government PG Arts & Science College, Ratlam 457 001

Department of Physics, Amolakchand College,

Yavatmal 445 001

Received 24 July 2001; revised 26 December 2001;

accepted 28 February 2002

The discovery of five-fold and ten-fold rotational symmetry in the Al-Mn alloys has given impetus to search for icosahedral phase in new samples. There has been much recent interest in the structures and physical properties of the newly discovered icosahedral phase of Al-Mn-Si and Al-Si-Fe alloys. In the present paper, the preparation , characterization and magnetic susceptibility measurements for the following samples: (i) Al74Si1Mn25 (ii) Al74Si5Mn21 (iii) Al74Si10Mn16 (iv) Al74Si1Fe25 (v) Al74Si5Fe21 and (vi) Al74Si10Fe16 have been reported. The studies reveal that the icosahedral phase seems to be more pronounced in the case of Al74Si1Mn25 while Al74Si5Mn21 shows the minimum content of the icosahedral phase. Studies by the authors indicate paramagnetic nature in these samples. Further, these materials have a tendency of retaining the magnetic field and that they give rise to the power loss.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 508-514

Stability of unbroken super symmetry through equilibrium behaviour of RABAM of ANN

Manu Pratap Singh

Department of Computer Science, Institute of Basic Science, Dr BRA University, Agra

Received 10 January 2001; revised 28 December 2001; accepted 13 May 2002

The behaviour of feedback unsupervised random adaptive bi-directional associative memory model (RABAM) dynamics of Artificial Neural Networks (ANN) has been used to explore the possibility of restoration and stability of super symmetry at finite temperature. It has been shown that, no finite temperature value, however large, can destabilize RABAM and that the unbroken super symmetry may be made stable through RABAM annealing model of dynamically states of ANN.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 515-519

Ultrasonic propagation in breast tissue with ductal carcinoma

Kirti Gandhi Bhatia, V R Singh, M C Bansal* & Sanjiv Bhatia

National Physical Laboratory, New Delhi 110 012

*MMH College, Ghaziabad, UP

Plastic Surgery Clinic, Chowk, Lucknow, UP

Received 20 May 2002; accepted 30 May 2002

Ultrasonic parameters of soft tissue tumours are still not known accurately. Breast tissues with diagnosis of ductal carcinoma are studied. A double-probe through-transmission technique is used. Ultrasonic velocity in abnormal breast tissue samples is found between 1438 ms-1 and 1514 ms-1and attenuation between 741 dBm-1 and 892 dBm-1. Other parameters like acoustic impedance and dynamic modulus of elasticity are also determined. Data may be used as an index in the identification and characterization of particular type of tumours after proper standardization.

 

Indian Journal of Pure & Applied Physics

Vol. 40, July 2002, pp. 524-524

News Scan

Now blue jets videoed from ground

For the first time ground based video recordings of blue jets have been made, spreading from the top of thunderclouds to the lower reaches of the ionosphere. The current in the blue jets constitutes an important component of the global electric circuit, which has not yet been accounted for by scientists. The study assumes significance as it is directly related to global convective activity and therefore to global warming, about which there is a serious concern world over.