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Indian Journal of Pure and Applied Physics

 

 

 ISSN: 0019-5596

CODEN: IJOPAU 42 (6) 383-470

Volume 42

Number 6

June 2004

 

CONTENTS

  

Nuclear Physics

Determination of live-time efficiency for a photonuclear experiment

387

I Akkurt

 

 

 

Effect of gamma background on the neutron sensitivity of fission detectors

390

V Balagi, K R Prasad* & S K Kataria

 

 

 

Multi-pion production in hadron-nucleus interactions—self – similar or self–affine

      398

Dipak Ghosh*, Argha Deb, Prabhat Bandyopadhyay,  Mitali Mondal, Kanchan Kumar Patra, Jayita Ghosh & Madhumita Lihiri

 

 

 

Proton emission in asymmetric nuclear interactions at 14.5 AGeV : Evidence of strong dynamical fluctuations

403

Dipak Ghosh*, Argha Deb, Swarup Ranjan Sahoo, Prabir Kumar Halder, Kanchan Kumar Patra & Jayita Ghosh

 

 

 

Atomic and Molecular Physics

 

Molecular polarizabilities of some organic solvents

    407

A Radha Krishna Murthy* & M Rangacharyulu

 

 

 

Vibrational and normal coordinate analysis of xanthine and hypoxanthine

411

V Krishnakumar* & M Arivazhagan

 

 

 

Modification in photoluminescence spectra of porous silicon by changing the surrounding electric environment

419

Kiran Sehrawat & R M Mehra*

 

 

 

Determination of the rotational constants A and C for a slightly perturbed SiH3CCH molecule

423

Mohammad Al-Share

 

 

 

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

 

Excitation and ionization of laser-pumped potassium vapour

429

M A Mahmoud

 

                                                                                          

 

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

 

Studies on fluid structure and molecular interactions of amides

   435

T Thenappan* & U Sankar

 

 

Effect of doping on dynamical properties of diluted magnetic semiconductors

440

Mahendra Aynyas* & Sankar P Sanyal

 

 

 

Ac  electrical properties of  60B2O3-(40-x) PbO-xMCl2­  and  50B2O3-(50-x)PbO-xMCl2 (M=Pb, Cd) glasses 

445

Shajo Sebastian & M Abdul Khadar*                                           

 

 

 

Vibrating single crystal piezoelectric disc gyroscope

452

A K Singh* & Vrushali Deo

 

 

 

Interdisciplinary Physics and Related Areas of Science and Technology

 

High spectral purity cavity stabilized microwave oscillators

459

A Sen Gupta

 

 

 

Condensed Matter: Structure, Mechanical and Thermal Properties

Effect of capsicum annum on the inhibition of growth of cholesterol crystals

465

Thomas T George* & K Mohnan Pillai

 

 

 

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

 

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 42, June 2004, pp. 387-389

 

 

Determination of live-time efficiency of a photonuclear experiment

I Akkurt

The live-time efficiency has been calculated and corrected to obtain the absolute magnitude of the experimental yield. The percentage efficiency of the data acquisition system used in a photoneutron experiment at Maxlab in Lund (Sweden) has been determined.

 

IPC Code: G 01T

[Keywords: Data acquisition, Photonuclear experiment, Live-time]

 

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 390-397

 

 

Effect of high gamma background on neutron sensitivity of fission detectors

V Balagi, K R Prasad & S K Kataria

 

Tests were performed on two parallel plate and two cylindrical fission detectors in pulse and dc mode. The effect of gamma background on neutron sensitivity was studied in thermal neutron flux from 30nv to 60nv over which gamma field intensity ranging from 230kR/h to 3.7MR/h was superposed. In the case of one of the parallel plate detectors the fall in neutron sensitivity was observed to be 3.7% at 1MR/h and negligible below 1MR/h. In the case of one of the cylindrical counters the fall in neutron sensitivity was negligible below 500kR/h and 37% at 1MR/h. The data was used to derive the design parameters for a wide range fission detector to be procured for PFBR instrumentation for operation at 600ºC and gamma background of 1MR/h.

 

IPC Code: G 21 J 5/00

[Keywords: Fission detectors; Neutron sensitivity; Neutron flux]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 398-402

 
Multi-pion production in hadron-nucleus interactions—self-similar or self-affine

Dipak Ghosh, Argha Deb, Prabhat Bandyopadhyay, Mitali Mondal,

Kanchan Kumar Patra, Jayita Ghosh & Madhumita Lihiri

 

Two-dimensional factorial moments analysis of multi-particle production in    AgBr interactions at 350        GeV/c with real phase-space partition is performed by considering anisotropy of phase space. It is observed that multi-particle production process is self-affine rather than self-similar. The importance of two-dimensional analysis for the interpretation of data in terms of intermittency is also demonstrated.

 

IPC Code: G 21

[Keywords:    AgBr interactions, Two-dimensional factorial moments, Hurst exponent, self-affinity]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 403-406

 

Proton emission in asymmetric nuclear interactions at 14.5 AGeV:
Evidence of strong dynamical fluctuation

Dipak Ghosh, Argha Deb, Swarup Ranjan Sahoo,

Prabir  Kumar Haldar, Kanchan Kumar Patra & Jayita Ghosh

 

An analysis of data of medium energy protons emitted in 28Si –AgBr interactions at 14.5 AGeV reveals the existence of strong emission asymmetry in the azimuthal plane which is found to depend on the target excitation. A comparison with the data of 32S-AgBr(at 200 AGeV) and 16O-AgBr (at 60 AGeV) interactions indicates that emission asymmetry depends on the projectile mass and energy.

 

IPC Code: G 01N 3/00

[Keywords: Protons emission, Nuclear interaction, Dynamical fluctuation, Nuclear track detector]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 407-410

 

Molecular polarizabilities of some organic solvents

A Radha Krishna Murthy &  M Rangacharyulu

 

The one-dimensional semi-empirical d-function potential of chemical binding proposed by Lippincott and Stuttman has been applied to calculate the average molecular polarizability of some important organic solvents. The calculated values are compared with the molecular polarizability values calculated using the Lorentz-Lorentz formula. Reasonable agreement between the theoretical and the experimental values is observed.

 

IPC Code: G 01J

[Keywords: Polarizability, Dispersion energy, Expectation value] 

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 411-418

 

Vibrational and normal coordinate analysis of xanthine and hypoxanthine

V Krishnakumar and M Arivazhagan

 

The FTIR and FT-Raman spectra of xanthine and hypoxanthine have been recorded in the region 4000-50 cm-1 and 100-3500 cm-1 respectively. The normal coordinate calculations were carried out using Wilson’s FG matrix mechanism on the basis of General Valence force field for both in-plane and out-of-plane vibrations. All the normal modes of vibrations were assigned and discussed. Potential energy constants obtained in this study were refined using numerical methods.

 

IPC Code: GO1J 3/44

[Keywords: FTIR, FT-Raman, Normal coordinate analysis, xanthine, hypoxanthine]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 419-422

 

Modification in photoluminescence spectra of porous silicon by changing the surrounding dielectric environment

Kiran Sehrawat & R M Mehra

 

A method to control porous silicon (PS) emission properties by changing the dielectric environment surrounding the Si-crystallites has been demonstrated by undertaking a systematic investigation of photoluminescence (PL) spectra from PS recorded in a chosen set of organic solvents. On increasing the dielectric constant of the embedding medium from 2 to 24, a drastic drop (about four orders of magnitude) in PL intensity (IPL) accompanied with a blue shift of about 230 nm has been observed. The results have been explained quantitatively in terms of geminate recombination of an isolated electron hole pair applying Onsager’s model that predicts variation of Onsager length (lo) with dielectric constant of the embedding medium. This approach leads to Onsager length of the order of the PS nanostructure size for dielectric constant greater than 24, beyond which no further quenching was observed. The results suggest use of materials with low dielectric constant for encapsulating porous silicon without compromising its PL properties.

 

IPC Code: G01J 3/30

[Keywords: Photoluminescence, Porous silicon, Dielectric environment, Dielectric constant]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 423-428

 

Determination of the rotational constants A and C for a slightly perturbed SiH3CCH molecule

Mohammad Al-Share

 

The rotational constant, A0, for the ground state of SiH3CCH molecule was calculated using a technique which was used earlier for CH3CCH [Tam H S & Roberts J A, Struct Chem, 1 (1990) 211] and CH3CN [Al-Share M, Hajsaleh J, Qian S W & Roberts J A, Struct Chem, 5 (1994) 109]. This technique is based on calculating the moment of inertia tensors in the bent configuration due to the v10 vibrational state, which is associated with the SiCC bending motion. These values of the moment of inertia were fitted with the values calculated from the rotational constant B, which is found by measuring the rotational frequencies in the microwave and infrared regions experimentally. From the fitting, the bending angle           and the asymmetry parameters were determined for v10=1, 2, 3, and 4 bending vibrational states.

 

IPC Code: G 01J 3/00

[Keywords: Rotational constants, SiH3CCH molecule, Moment of inertia, Vibrational states]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 429-434

 

Excitation and ionization of laser-pumped potassium vapour

M A  Mahmoud

 

The excitation and ionization of low dense K vapur (no@1014 cm-3) by resonant cw laser radiation (I @10        w. cm-2) have been studied theoretically and the processes responsible for the transfer of energy from the laser – excited atoms into ionization have been presented. It has been established that seed electrons created by collisional ionization processes were heated in superelastic collisions with laser excited atoms, and subsequent electron – impact excitation and ionization as well as Penning ionization of high lying levels lead to the creation of more electrons.

 

IPC Code: H 01S 3/09

[Keywords: Collisional ionization, Superelastic collisions, Electron energy distribution function, Energy pooling collisions]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 435-439

 

Studies on fluid structure and molecular interactions of amides

T Thenappan & U Sankar*

 

Fluid structure in amides could be readily studied by dielectric measurements by virtue of the influence of local order and the overall dipole moment. The short-range interactions between permanent dipoles could be described by the Kirkwood–Frohlich correlation factor. In dilute solutions of amides with inert solvents, the interaction between the solute species among themselves may be given by the modified form of the correlation factor (g’) by taking care of solvent-solvent interaction.  The  dielectric constants of the binary mixtures of acrylamide, acetamide, benzamide and pthalimide in 1,4-dioxan were measured at 298, 308 and 318 K. The results were interpreted in the light of the theory. The nature of interaction was identified in all systems.

 

IPC Code: G 01R 27/26

[Keywords: Dielectric constant, Kirkwood correlation factor, H-bond, Multimers]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 440-444

 

Effect of doping on dynamical properties of diluted magnetic semiconductors

Mahendra Aynyas & Sankar P Sanyal*

 

The effect of  doping of Mn2+ impurity on vibrational properties of IV-VI compounds using three body force rigid ion model has been investigated . Pb-Mn-Te and Sn-Mn-Te systemic with different Mn+  ion concentrations have been considered. Our results show faster softening of TA mode at L point in the Brillouin zone due to Mn2+ substitution.

 

IPC Code: H 01F 1/40

[Keywords: Magnetic semiconductors, Doping, Mn2+ impurity]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 445-451

 

Ac electrical properties of 60B2O3-(40-x) PbO-xMCland
50B2O3-(50-x)PbO-xMCl2 (M=Pb, Cd) glasses

Shajo Sebastian & M Abdul Khadar* 

 

The glasses 60B2O3-(40-x) PbO-xMCland 50B2O3-(50-x)PbO-xMCl2 (M = Pb, Cd) containing different concentrations of PbCl2 and CdCl2 were prepared. The ionic transference number of the glass samples was determined using dc polarization technique. The ionic transference number obtained is nearly 1 indicating that the electrical conduction in the glass samples is purely ionic. The dependence of ac conductivity and dielectric constant on temperature and frequency was investigated and the electrical moduli were analyzed. The variation of dielectric constant and ac conductivity with increase in mole percentage of PbCl2 or CdCl2 has been investigated on the basis of structural changes occurring in the glass samples.

 

IPC Code: G 01N 33/38

[Keywords: Borate glass, Dielectric constant, Ac conductivity, Modulus analysis]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, June 2004, pp. 452-458

 

Vibrating single crystal piezoelectric disc gyroscope

A K Singh & Vrushali Deo

 

This paper deals with a single crystal piezoelectric disc gyro sensor. The principle of basic operation and the practical structure of the disc vibrating gyro has been described along with the experimental results for a prototype of the gyro sensor. The results obtained show that the proposed disc resonator operates as a gyro sensor, having sensitivity of about 0.9 mV/ °/s, and behaves almost linear in the range of upto 180 °/s .

 

IPC Code: G 01C 19/00

[Keywords: Piezoelectric, Gyroscope, Coriolis force, Vibrating mode, Resonance frequency]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol 42, June 2004, pp. 459-464

 

High spectral purity cavity stabilized microwave oscillators

A Sen Gupta

 

Low noise microwave oscillators and novel techniques of reducing the close in noise in these oscillators by using a high Q cavity as a frequency discriminator have been presented. In essence the discriminator converts noise-induced frequency fluctuations into corresponding phase variations of a signal reflected from it. An accurate model for the noise floor of the cavity discriminator has been described. The noise cancellation depends on factors such as—the cavity Q, microwave power into the cavity, the input coupling coefficient and the level of carrier suppression. Experimental results indicate reasonably good agreement with the model.

 

IPC Code: H 03 B

[Keywords: Data acquisition, Photonuclear experiment, Live-time]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol 42, June 2004, pp. 465-466

 

Note

 

Effect of capsicum annum on the inhibition of growth of cholesterol crystals

Thomas T George and K Mohanan Pillai+

 

Cholesterol is a well-known lipid found in atherosclerotic plaques. Crystals of cholesterol were grown by single diffusion gel growth technique. The inhibitory role of capsicum annum on the growth of cholesterol crystals is reported. The extract incorporated in the gel has considerable role in the reduction of nucleation centers and in inhibiting the growth of cholesterol crystals.

 

IPC Code: B O1D 9/00

[Keywords: Cholesterol crystals, Crystallization]