Total visitors:1,813 since 30-07-04

Indian Journal of Pure and Applied Physics

 

 

 

ISSN: 0019-5596

CODEN: IJOPAU 42 (7) 471-548

Volume 42

Number 7

July 2004

 

CONTENTS

Nuclear Physics

 

Simultaneous effect of collimator size and absorber thickness on the gamma ray build-up factor

Charanjeet Singh, Gurdeep S Sidhu, Ashok Kumar, Parjit S Singh & Gurmel S Mudahar*

475

Charge spectrum of ultra heavy cosmic ray ions (Z = 68-96) measured onboard long duration exposure facility

V Batra, A Dutta* & S Biswas

479

Atomic and Molecular Physics

 

Non-orthogonality of Lippmann-Schwinger ¾ Low states

V J Menon*, B K Patra & Ritesh Kumar Dubey

485

Critical evaluation of goodness of fit of computerised glow curve deconvolution

B Arunkumar Sharma, Th Basanta Singh & R K Gartia*

492

Mössbaur and infrared studies of some glasses and glass-ceramics from the XMnO(40-X)YFe2O3.10Al2O3.50B2O3 system

Roshan Lal, N D Sharma* & Kailash Chandra

 

498

Effect of couplings of the n = 2 states on excitation processes by protons and anti-protons impact on H(2s) atoms

Reda S Tantawi

506

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

 

Ultrasonic velocity and allied parameters in solutions of cypermethrin with xylene and ethanol

P Subramanyam Naidu & K Ravindra Prasad*

512

Physics of Gases , Plasmas and Electrical Discharges

 

Complex dielectric function and collective dynamics of one-dimensional weakly coupled quantum and classical hot plasmas

S P Tewari* & Jyoti Sood

518

Condensed Matter: Structure, Mechanical and Thermal Properties

 

Crystallographic analysis of 1H, 4H-tetrahydro-8-methyl-quinolizino-(9,9a,1gh) coumarin

Rajnikant*, Dinesh, Kamni & Bandhan Sharma

524

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

 

Effect of grain size on the mobility and transfer characteristics of polysilicon thin-film transistors

Navneet Gupta & B P Tyagi*

528

Electrical conduction of succinic acid doped glycine pellet

D K Burghate*, S H Deshmukh, Laxmi Joshi, V S Deogaonkar & P T Deshmukh

533

Dielectric relaxation studies of (Ge20Se80)0.90Sn0.10 glassy alloy

Pradeep S Chandel*, Anup Thakur, Vineet Sharma, N Goyal & S K Tripathi

539

*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, July 2004, pp 475-478

 

Simultaneous effect of collimator size and absorber thickness on
the gamma ray build-up factor

Charanjeet Singh, Gurdeep S Sidhu, Ashok Kumar, Parjit S Singh & Gurmel S Mudahar

 

The build-up factor values have been measured for 662 keV gamma rays in the extended media of bakelite and perspex under different collimation conditions. A correlation effect has been obtained in the measurements due to collimator size and absorber thickness to prevent the multiple scatter photons reaching the detector.

[Keywords: Gamma ray build-up factor, Photons]

IPC Code: G 01T 1/00

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 479-484

 

Charge spectrum of ultra heavy cosmic ray ions (Z=68-96) measured onboard
long duration exposure facility

V Batra1, A Dutta1 & S Biswas2

 

The results of the abundance of relativistic ultra heavy (UH) nuclei with charge Z > 65 from an analysis of detectors exposed in space by Ultra Heavy Cosmic Ray Experiment (UHCRE) conducted onboard NASA's Long Duration Exposure Facility (LDEF) are presented. A total of 72 events including two actinides (88 £ Z £ 100) have been identified from the scanning of ~0.21m2 detector area. A peak at = 78 and a smaller peak around = 85 could be seen. The charge fragmentation of the cosmic ray ions has also been seen within the detector stack. The detailed analysis of charge spectrum for the elements in the charge region, Z = 65-96, is presented. An enhancement of r-process elements relative to solar system is observed. The results suggest a mixed source of rapid (r) and slow (s) process nuclei with Z > 65 for cosmic rays in space.

[Key Words: Ultra heavy nuclei, Galactic cosmic rays-abundance, Nucleosynthesis, Anomalons]

IPC Code: G01T 1/00

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 42, July 2004, pp 485-491

 

Non-orthogonality of Lippmann-Schwinger-Low states

V J Menon1, B K Patra2 & Ritesh Kumar Dubey1

 

For the general short-ranged potential the Lippmann-Schwinger-Low (LSL) scattering formalism by taking the limit  at the end of the analysis, with e being an infinitesimal adiabatic parameter has been re-examined. It is found that the LSL state  does not strictly satisfy the Schrodinger eigen equation, and the pair ,  is mutually non-orthogonal if En = Ek, n ¹ k. For this purpose a new type of projection operator , a non-linear relation among transition amplitudes, and a separable interaction as illustration have been used.

[Keywords: Scattering theory, Hamiltonian, Schrodinger, Resolvent, Lippmann-Schwinger-Low, Orthogonality]

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 492-497

 

Critical evaluation of goodness of fit of computerised glow curve deconvolution

B Arunkumar Sharma, Th Basanta Singh & R K Gartia

 

Computerised glow curve deconvolution (CGCD) technique is a powerful tool for evaluation of trapping parameters of the thermoluminescence glow curve. A difficulty in the outcome is the level of confidence in accepting the values of the parameters that the technique yields. At this juncture the importance of goodness of fit test arises to compare the deviations of experimental from the expected values obtained from the model. As far as dosimetric application is concerned the leaders of the field have propagated the Figure of Merit (FOM) as criteria to test the goodness of fit. In this paper, three well accepted conventional methods of goodness of fit statistics namely Discrepancies (DIS), Reduced Chi-square and Chi-square (c2) test are used with FOM to critically evaluate the potentialities of the statistical tests. Glow curves of iodised salt are taken as reference glow curves.

 

[Keywords: Computerised glow curve deconvolution, Thermoluminescence, Trapping parameters]

IPC Code: F 21K 2/00

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 498-505

 

Mössbauer and infrared studies of some glasses and glass-ceramics from
the XMnO(40-X)YFe2O3.10Al2O3.50B2O3 system

Roshan Lal & N D Sharma and Kailash Chandra

 

The 57Fe Mössbauer technique has been used to investigate the behaviour of glasses and their corresponding glass ceramic derivatives obtained from the system XMnO(40-X)YFe2O3.10Al2O3.50B2O3,  along with the effect of Al and Mn doping at the Fe-site for all the samples. MnO was introduced gradually to replace Fe2O3 in the series such that X=0,5,10,15,20 and 25 mol% of MnO containing 50% B2O3. The structural changes observed are consistent with Mn2O3 formulation and inferred by monitoring the infrared absorption spectra in the range 500-4000cm–1 by KBr technique. The Mössbauer technique is used for identification of crystalline material and the results are compared with that obtained from X-ray diffraction.

 

[Keywords: 57Fe Mössbauer technique, Infrared absorption, Glass-ceramics, X-ray diffraction]

IPC Code: G 01 J 3/00

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 506-511

 

Effect of couplings of the n=2 states on excitation processes by protons
and anti-protons impact on H(2s) atoms

Reda S Tantawi

 

Effect of couplings of the n = 2 states on the n = 3 excitation cross-sections in scattering of protons and antiprotons by hydrogen atoms being initially in the 2s state has been investigated by means of the impact parameter approximation. The calculations take into account the n = 1, 2, 3, and 4 states of the target and cover energy range from 3 - 2500 keV. The study of the influence of the electric charge of the projectile is a target of this investigation. Therefore, the exchange effects in the case of proton-induced reactions are ignored. The results of calculations for protons are in reasonable agreement with a previous work.

 

[Keywords: Coupling, Proton scattering, Anti-proton scattering, Impact parameter approximation]

IPC Code: C 01B 3/00

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 512-517

 

Ultrasonic velocity and allied parameters in solutions of cypermethrin
with xylene and ethanol

P Subramanyam Naidu & K Ravindra Prasad

 

Ultrasonic velocity, density and viscosity have been measured at different temperatures in the binary mixtures ¾ (1) cypermethrin + xylene and (2) cypermethrin + ethanol. Various acoustical and allied parameters have been computed and the results have been presented in the light of the molecular interactions between the like and unlike molecules. Solvation numbers, apparent molar compressibility etc., have also been evaluated which in turn are employed in the study and confirmation of molecular interactions (solute-solute and solute-solvent). Solute-solvent interactions have been suggested to be dominant in both the mixtures.

 

[Keywords: Ultrasonic velocity, Binary mixtures, Solvation number, Molar compressibility]

IPC Code: B 01J 19/10

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 518-523

 

Complex dielectric function and collective dynamics of one-dimensional
weakly coupled quantum and classical hot plasmas

S P Tewari and Jyoti Sood

 

The complete expressions for the wave vector and frequency dependent complex dielectric function for one-dimensional weakly coupled one component quantum and classical hot plasmas have been derived. These expressions, which are valid for the entire domain of frequency and wave vector, are used to obtain the knowledge about the collective dynamics of the plasma by computing the dynamical structure factor at different temperatures and wave vector. The results obtained are quite different from those in three- and two-dimensional cases.

 

[Keywords: Plasma, Dielectric function, Collective modes]

IPC Code: G 06

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 42, July 2004, pp 524-527

 

 Crystallographic analysis of 1H, 4H-tetrahydro-8-methyl-quinolizino-(9,9a,1gh)coumarin

Rajnikant*, Dinesh, Kamni & Bandhan Sharma

 

The crystal structure of 1H,4H-tetrahydro-8-methyl-quinolizino-(9,9a,1gh)coumarin (C16H17NO2) has been determined by X-ray crystallographic techniques. The compound crystallizes in monoclinic space group P21/n with unit cell parameters:


a = 8.657(5) Å, b = 10.251(5) Å, c = 14.508(5) Å, b = 96.61(1)°, Z = 4, V = 1278.91(11) Å3. The structure has been solved by direct methods and refined upto reliability index of 4.8%. The fused benzene and pyrone rings are planar. Both the piperidine rings exist in distorted sofa conformation. The crystal structure is stabilized by C-H...O hydrogen bonds.

 

[Keywords: Crystal structure, Coumarin]

IPC Code: G01 J 3/00

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 528-532

 

 Effect of grain size on the mobility and transfer characteristics
of polysilicon thin-film transistors

Navneet Gupta* & B P Tyagi**

 

The effect of the grain size on the effective carrier mobility (meff) and transfer characteristics of a polycrystalline silicon thin-film transistor (poly-Si TFT) have been theoretically investigated by developing an analytical model. The dependence of meff is studied as a function of doping concentrations and gate voltage for different values of grain size. It is observed that at low as well as at high doping concentrations, the effective carrier mobility (meff) increases with increase in grain size, whereas the observed dip at the intermediate doping concentration is getting confirmed. The effect of the grain size on transfer characteristics of poly-Si TFT in its linear region is also presented. It is found that at low gate voltages, meff and ID increase rapidly with the increase in VG for all values of grain sizes due to the grain boundary barrier lowering effect. At high gate voltage the grain boundary barrier lowering effect becomes insignificant and causes the saturation of meff and ID. The model was found to account correctly for the experimentally observed mobility variation and yield a reasonably good agreement.

 

[Keywords: Mobility, Polysilicon thin-film transistors, Grain size]

IPC Code: H01L 27/00

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 533-538

 

Electrical conduction of succinic acid doped glycine pellet

D K Burghate, S H Deshmukh, Laxmi Joshi, V S Deogaonkar & P T Deshmukh

 

The electrical conduction of succinic acid doped glycine pellet has been measured by studying the I-V characteristics at various temperatures in the range 313-353 K. The results are presented in the form of I-V characteristics, and analysis has been made in the light of Poole-Frenkel, Fowler-Nordheim, Schottky, log(J) versus T plots, Richardson and Arrehenius plots. Results analysed suggest that, Schottky-Richardson mechanism is primarily responsible for observed conduction.

 

[Keywords: Succinic acid glycine pellet, Conductivity]

IPC Code: G 01 R

 

 

 

Indian Journal of Pure & Applied Physics

 Vol. 42, July 2004, pp 539-543

  

Dielectric relaxation studies of (Ge20Se80)0.90Sn0.10 glassy alloy

Pradeep S Chandel, Anup Thakur, Vineet Sharma, N Goyal & S K Tripathi

 

The frequency and temperature dependence of ac conductivity measurements have been made on (Ge20Se80)0.90Sn0.10 glassy alloy in the frequency range 2-50 kHz and in the temperature range 273-373K. Dielectric constant (΢) has been calculated using this data. The results indicate that dielectric dispersion occurs in this temperature and frequency range. The dielectric loss (΢¢) and loss angle (tand) have been calculated using Gever’s relation. The temperature dependence of dielectric loss (΢¢) shows relaxation peaks as a function of temperature. These relaxation peaks shift towards the higher temperature as the frequency is increased. A detailed analysis of the data shows that the results can be explained in terms of dipolar relaxation with a distribution of relaxation times, which is quite expected in case of chalcogenide glasses.

 

[Keywords: Dielectric relaxation, Glassy alloy, AC conductivity]

IPC Code: C 22 C