Indian Journal of Pure and Applied Physics

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Volume 46

Number 5

MAY 2008

CODEN: IJOPAU 46 (5) 291-362

ISSN: 0019-5596

 

 

 

CONTENTS

 

 

General

 

Rigorous treatment of scattering by quantum zero-range interactions

295

Ritesh Kumar Dubey, V J Menon* & D N Tripathi

 

The Physics of Elementary Particles and Fields

 

Effect of -mediated flavor-changing neutral currents on  decay

306

S Sahoo* & L Maharana

 

Nuclear Physics

 

Proton radioactivity with modified Coulomb potential

312

Indira Mehrotra & Shweta Prakash*

 

Atomic and Molecular Physics

 

Vibrational analysis of pyrazinamide

315

S Gunasekaran* & E Sailatha

 

Condensed Matter:Structural, Mechanical and Thermal Properties

 

Synthesis of CdIn2S4 by flux method

321

L A Patil* & M D Mahanubhav

 

Synthesis and characterization of sodium substituted lanthanum manganite

325

M P Sharma, S K Jain*, Anjali Krishnamurthy & Bipin K Srivastava

 

MREI-model calculations for layered mixed crystals of the series Hf S2-xTex (0 ≤ x ≤ 2)

330

Chanchal & A K Garg*

 

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

 

Cryogen-free low temperature and high magnetic field apparatus

334

S D Kaushik*, Anil K Singh, D Srikala & S Patnaik

 

Structural and optical studies of chemically prepared CdS nanocrystalline thin films

339

J Barman*, K C Sarma, M Sarma & K Sarma

 

Optical properties of polyaniline doped PVC-PMMA thin films

344

S H Deshmukh*, D K Burghate, S N Shilaskar, G N Chaudhari & P T Deshmukh

 

Interdisciplinary Physics and Related Areas of Science and Technology

 

Evaluation of performance of GPS controlled rubidium clocks

349

P Banerjee*, A K Suri, Suman, Arundhati Chatterjee & Amitabh Datta

 

High performance FGMOS-based low voltage current mirror

355

Parshotam S Manhas*, Susheel Sharma, K Pal, L K Mangotra & K K S Jamwal

 

 

 

___________

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

 

 


Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 295-305

Rigorous treatment of scattering by quantum zero-range interactions

 

Ritesh Kumar Dubey, V J Menon & D N Tripathi

Department of Physics, Banaras Hindu University, Varanasi 221 005

E-mail : jayaram_bhu@yahoo.co.in; dubeyrk@rediffmail.com

Received 14 October 2006; revised 5 March 2008; accepted 14 March 2008

A new rigorous treatment of solving the Schrödinger scattering equation for a general contact potential U(x) has been developed. It is proved that if U(x) is regarded as a distribution characterized by a tiny length scale b then the wave function y and its derivative y¢ become continuous across the apparent singular point x = 0. Hence, the reflection and transmission coefficients can be constructed for many cases namely usual d(x), controversial d¢(x) and entirely new quasi d¢(x) interactions.

Keywords : Contact potential, Scattering, Distributions, Schrödinger, Reflection, Transmission, Quantum zero

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 306-311

 

Effect of Z¢-mediated flavor-changing neutral currents on B→pK decay

S Sahoo1 & L Maharana2

1Department of Physics, National Institute of Technology, Durgapur 713 209

1E mail:sukadevsahoo@yahoo.com

2Department of Physics, Utkal University, Bhubaneswar 751 004.

2E mail:lmaharan@iopb.res.in

Received 31 January 2007; revised 8 March 2008; accepted 14 March 2008

The effect of a Z¢-mediated flavor-changing neutral current (FCNC) on the B→pK decay process has been studied. We find the branching ratio is enhanced from its standard model (SM) value and gives the possibility of new physics.

Keywords: Bottom mesons, Z¢ boson, Decays of bottom mesons, p  and K mesons

 

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 312-314

 

Proton radioactivity with modified Coulomb potential

 

Indira Mehrotra & Shweta Prakash

Department of Physics,University of Allahabad, Allahabad 211 001

Received 13 July 2007; accepted 10 March 2008

The phenomenon of proton decay is treated as the transmission of the proton across a potential barrier developed due to combined effects of the Coulomb potential, centrifugal potential and various renormalization processes. In the present paper, a microscopic approach has been used to calculate a Coulomb potential from Woods-Saxon charge density distribution function. Half-lives of proton emitters have been calculated in the framework of WKB method with modified Coulomb potential. Significant improvement in the values of half-lives is obtained as compared to those calculated with the Coulomb potential of a spherical charged core.

Keywords : Proton radioactivity, Coulomb potential, Charge density

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 315-320

 

 

Vibrational analysis of pyrazinamide

S Gunasekaran & E Sailatha

Spectro Physics Research Laboratory, Pachaiyappa’s College, Chennai 600 030

Received 11 August 2006; accepted 12 September 2007

Pyrazinamide (PZA) is an anti-tubercular drug, with molecular formula C5H5N3O. The FTIR and FT Raman spectra of PZA have been recorded in the region 4000-400cm-1 and 3500–50cm-1, respectively for molecular study. A detailed vibrational analysis has been made on the fundamental modes of vibration. A normal coordinate analysis has been carried out for PZA following the Wilson’s FG matrix method. A set of potential constants has been evaluated using the method of kinetic constants on the basis of C1 point group symmetry. The evaluated potential constants have been compared with those of related molecules and are in the expected range to confirm the correctness of the assignments made. To check whether the chosen set of vibrational frequencies contributes maximum to the potential energy associated with the normal coordinates of the molecule, potential energy distribution (PED) has been evaluated.

Keywords: Fourier transform infrared spectra, Fourier transform Raman spectra, Pyrazinamide, Vibrational band assignments, Normal coordinate analysis, Potential energy distribution.

Indian Journal of Pure & Applied Physics

Vol 46, May 2008, pp. 321-324

 

Synthesis of CdIn2S4 by flux method

L A Patil* & M D Mahanubhav

PG Department of Physics, Pratap College, Amalner 425 401

*E-mail: lapresearch@rediffmail.com

Received 12 December 2007; accepted 5 March 2008

Stoichiometric and non-stoichiometric powders of CdIn2S4 have been synthesized by flux method. X-ray diffraction (XRD) studies reveal that CdIn2S4 powders are polycrystalline in nature with spinel cubic structure. Thick films of CdIn2S4 powders have been prepared using screen printing technique on glass substrates. The films are characterized by energy dispersive X-ray analysis (EDAX) for quantitative elemental analysis, scanning electron microscopy (SEM) for microstructural studies and optical absorption studies for determination of band gap energies. The optical band gap energy for stoichiometric film is observed to be 2.38 eV while for nonstoichiometric films, it increases as the Cd/In ratio increases.

Keywords: CdIn2S4, Flux method, Screen printing, Thick films, Absorption spectra

 

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 325-329

 

Synthesis and characterization of sodium substituted lanthanum manganite

 

M P Sharma, S K Jain*, Anjali Krishnamurthy & Bipin K Srivastava

Department of Physics, University of Rajasthan, Jaipur 302 004

*Department of Physics, Apex Engineering College, Jaipur 302 022

E-mail: mps_45@yahoo.com

Received 22 August 2007, revised 3 January 2008; accepted 22 February 2008

Three compositions of sodium substituted lanthanum manganites La1-xNaxMnO3 (for x = 0.1, 0.2 and 0.5) have been prepared using sol-gel technique followed by two different thermal treatments. Attempts to prepare 50 atomic per cent Na (for La) substituted sample, which would be the maximum permissible amount of Na as per valence consideration, did not yield a compound of correct stoichiometry. Of the two stoichiometric samples, the one with 20 atomic% sodium shows an ordered ferromagnetic state and that with 10 atomic% sodium is disordered ferromagnet.

Keyword: Sol-gel technique, Lanthanum manganites, Ferromagnet, Mott insulator

 

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 330-333

 

MREI-model calculations for layered mixed crystals of
the series Hf S2
-xTex (0≤x≤2)

 

Chanchal & A K Garg*

Department of Physics, N A S College, Meerut 250 001

E-mail: chanchalakg05@rediffmail.com

Received 22 August 2007; revised 22 February 2008; accepted 4 March 2008

Optical phonon frequencies for IR active modes have been calculated for layered mixed crystals in the series Hf S2-xTex (0≤x≤2) using MREI-model. The model is simple and involves only two adjustable parameters. Various force constants and the values of local and gap modes have been reported. The model has been found to work reasonably well and the calculated values agree with the experimental values.

Keywords: MREI-model, Hf S2-xTex, Infrared, Phonon calculations, Layered compounds

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 334-338

 

Cryogen-free low temperature and high magnetic field apparatus

 

S D Kaushik, Anil K Singh, D Srikala & S Patnaik

School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067

Received 12 December 2007; accepted 15 January 2008

The importance of low temperature and high magnetic field measurements in pure and applied science research cannot be overstated. Traditionally these experiments have been carried out by evaporation of liquefied helium. This is a costly proposition, especially in our country, where maintaining liquid helium plants and the recovery lines has become persistent predicament. In this paper, the possibility of an alternative cost-effective technology based on two stage Gifford-McMahon closed cycle cryocoolers which is most ideally suited for small groups of researchers has been presented. The principle of operation and instrumentation details of a recently installed single compressor 1.6 K, 8 tesla cryocooler has been described.

Keywords: Liquid helium, Gifford-McMahon cycle, Regenerator, Cryocooler


Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 339-343

 

Structural and optical studies of chemically prepared CdS nanocrystalline
thin films

 

J Barman1*, K C Sarma1, M Sarma2 & K Sarma3

1Department of Instrumentation & USIC, 2Department of Chemistry, Gauhati University, Guwahati

3Department of Physics, Cotton College, Guwahati 781 014

*E-mail: jayanta_barman2006@ yahoo.com

Received 22 August 2007: revised 3 March 2008; accepted 12 March 2008

Chemical bath deposition (CBD) technique has been used to prepare cadmium sulphide (CdS) thin films for various applications. Structural analysis of the films has been done by using Philips X-Pert PRO system analytical diffractrometer. Data collected by X-pert graphics software are used to identify the crystal structure, phase, grain size and lattice constant of films. XRD data have been obtained for optimizing the growth conditions for deposition. Ultra violet visible (UV-VIS) spectroscopy and scanning electron microscopy (SEM) are used to characterize the sample.

Keywords: Cadmium sulphide, Nanocrystalline, Structural properties, Optical properties

 

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 344-348

 

Optical properties of polyaniline doped PVC-PMMA thin films

S H Deshmukh, D K Burghate, S N Shilaskar*, G N Chaudhari** & P T Deshmukh***.

Postgraduate Department of Physics and **Chemistry, Shri Shivaji Science College, Amravati 444 603

*Department of Electronics, VIT, Pune

***Dr Panjabrao Deshmukh Polytechnic, Amravati 444 603

Received 13 October 2006; revised 18 December 2007; accepted 3 January 2008

The optical transmission and UV-VIS absorption spectra have been recorded in the wavelength range 450-1000 nm for different compositions of polyaniline doped PVC-PMMA thin films. The absorption coefficient (a), optical energy gap (Eopt), refractive index (n0), optical dielectric constant (e’), constant B and ratio of carrier concentration to the effective mass (N/m*) have been evaluated. The effects of doping percentage of polyaniline on these parameters have been discussed and the nonlinear behaviour for all the parameters are investigated.

Keywords: Optical properties, PVC-PMMA thin films, Non-linear behaviour

 

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 349-354

 

Evaluation of performance of GPS controlled rubidium clocks

P Banerjee, A K Suri, Suman, Arundhati Chatterjee & Amitabh Datta

Time and Frequency Section, National Physical Laboratory, New Delhi 110 012

Received 10 July 2007; revised 8 March 2008; accepted 14 March 2008

Global Positioning System (GPS) controlled rubidium clock systems are now being used widely for many precise timing applications. They also play the role of the reference time and frequency source in many laboratories. This demands the evaluation of performance of such clocks to assess their reliability. For this purpose, a special experimental campaign has been planned. The epoch time has been found to be reliable within 60 ns and frequency offset does not exceed few parts in 10-12. But the receiver takes few hours to achieve initial lock. Short-term stability in locked condition has been poorer than that of the rubidium clock in free running condition.

Keywords: Rubidium clock, GPS

 

Indian Journal of Pure & Applied Physics

Vol. 46, May 2008, pp. 355-358

 

High performance FGMOS-based low voltage current mirror

Parshotam S Manhas, Susheel Sharma, K Pal*, L K Mangotra & K K S Jamwal**

Department of Physics and Electronics, University of Jammu, Jammu 180 006

*Department of Earth Quake Engineering, IIT Roorkee, Roorkee

**Department of Physics, University of Kashmir, Srinagar 190 006

Received 29 August 2006; accepted 11 December 2007

Current mirror (CM) is the basic building block in analog and mixed mode circuit design. For high performance analog circuit applications, the current transfer ratio, output impedance and output swing are the most important parameters to determine the performance of the current mirror. CM’s are important for analog integrated circuits because of their wide use as constant sources or active loads in amplifier stages. Their application is increasing continuously due to the developments in current-mode integrated circuit design. This paper describes a new Current Mirror proposed and optimized to provide high accuracy, very high impedance and output swing at very low voltages using floating gate MOSFET’s (FGMOS). The new mirror-High Performance Low Voltage Current Mirror (HPLVCM)- based on FGMOS has output current range of ~2µA to 500µA, high output impedance (785.4GΩ at 100µA and 64M Ω at 500µA), comparatively high bandwidth (631MHz) and low input compliance voltage (0.18V at 50µA and 0.45V at 500µA input current). The new design has been verified using PSpice simulations for 0.5µm CMOS technology at a supply voltage of ±0.75V. The error in current transfer is observed to be less than ±0.1%.

Keywords: Floating gate, MOSFET, Low voltage analog circuits, Current mode circuits, Current mirrors