022893   Cahill R T;Kerrigan D J (School of Chemical and Physical Sciences, Flinders Univ, Adelaide 5001, Australia) : Dynamical space: supermassive galactic black holes and cosmic filaments. Prog Phys 2011, 4, 79-82.

The unfolding revolution in observational astrophysics and cosmology has lead to numerous puzzles: "supermassive" galactic central black holes, galactic "dark matter" ha-los, relationships between these black hole "effective" masses and star dispersion speeds in galactic bulges, flat spiral galaxy rotation curves, cosmic filaments, and the need for "dark matter" and "dark energy" in fitting the Friedmann universe expansion equation to the supernovae and CMB data. Herein is reported the discovery of a dynamical theory for space which explains all these puzzles in terms of 3 constants; G, α - which experimental data reveals to be the fine structure constant α <126> 1/137, and δ which is a small scale distance, perhaps a Planck length. Jt is suggested that the dynamics for space arises as a derivative expansion of a deeper quantum foam phenomenon. This discovery amounts to the emergence of a unification of space, gravity and the quantum.

1 illus, 13 ref

022892   Bhantnagar S (NO, Dayalbagh Education Institute, Agra-282 005, Email: sonali.bhatnagar@yahoo.co.in) : Gamma ray astronomy at Pe V energies. Curr Sci 2009, 97(7), 1005-8.

The GRAPES-3 (Gamma Ray Astronomy at Pe V Energies Phase 3) experiment is a collaboration project amongst universities and institutes in our country along with Japan. The experiment employs a high density array of plastic scintillation detectors and a large area tracking muon telescope. The scintillation detectors detect the electrons in an air shower for getting information on the shower, particularly for generating trigger, determining arrival direction and estimating the energy of the primary particle. The muon telescope detects and measures the muon component in the extensive air shower (EAS). The muon telescope is an effective tool, in the study of the nuclear composition of primary cosmic rays. The tracking muon telescope has also proved to be an invaluable tool in the studies of the solar flares, coronal mass ejections and the subsequent Forbush decrease events observed at the Earth. The collaboration is being expanded with addition of several major facilities like Cherenkov telescope, low frequency dipole array for the measurement of shower energy, addition of several modules of muon telescopes to cover a large area and a neutron monitor. In this article we briefly describe the experiment from its beginning.

4 illus, 13 ref

022891   Assis Armando V D B (Departamento de Fisica, Universidade Federal de Santa Catarina-UFSC, Trindade 88040-900, Florianopolis, SC, Brazil, Email: armando.assis@pgfsc.ufsc.br) : Note on the quantization mechanism within the cold big bang cosmology. Prog Phys 2011, 4, 40-1.

Obtains a Cold Big Bang Cosmology, fitting the cosmological data, with an absolute zero primordial temperature, a natural cutoff for the cosmological data to a vanishingly small entropy at a singular microstate of a comoving domain of the cosmological fluid. This solution resides on a negative pressure solution from the general relativity field equation and on a postulate regarding a Heisenberg indeterminacy mechanism related to the energy fluctuation obtained from the solution of the field equations under the Robertson-Walker comoving elementar line element context in virtue of the adoption of the Cosmological Principle. In this paper, we see the, positive, differential energy fluctuation, purely obtained from the general relativity cosmological solution in [3], leads to the quantum mechanical argument of the postulate in [3], provided this energy fluctuation is quantized, strongly supporting the postulate in [3]. I discuss the postulate in [3], showing the result for the energy fluctuation follows from a discreteness hypothesis.

4 ref

022890   Assis A V D B (Departamento de Fisica, Universidade Federal de Santa Catarina-UFSC, Trindade 88040-900, Florianopolis, SC, Brazil, Email: armando.assis@pgfsc.ufsc.br) : On the neutrino opera in the CNGS beam. Prog Phys 2011, 4, 85-90.

In this brief paper, solve the relativistic kinematics related to the intersection between a relativistic beam of particles (neutrinos, e.g.) and consecutive detectors. The gravitational effects are neglected, but the effect of the Earth rotation is taken into consideration under a simple approach in which we consider two instantaneous inertial reference frames in relation to the fixed stars: an instantaneous inertial frame of reference having got the instantaneous velocity of rotation (about the Earth axis of rotation) of the Cern at one side, the lab system of reference in which the beam propagates, and another instantaneous inertial system of reference having got the instantaneous velocity of rotation of the detectors at Gran Sasso at the other side, this latter being the system of reference of the detectors. Einstein's relativity theory provides a velocity of intersection between the beam and the detectors greater than the velocity of light in the empty space as derived in this paper, in virtue of the Earth rotation. We provide a simple calculation for the discrepancy between a correct measure for the experiment and a measure arising due to the effect derived in this paper.

1 ref

022889   Assis A V D B (Departamento de Fisica, Universidade Federal de Santa Catarina-UFSC, Trindade 88040-900, Florianopolis, SC, Brazil, Email: armando.assic@pgfsc.ufsc.br) : Comments onthe statistical nature and on the irreversibility of the wave function collapse. Prog Phys 2011, 4, 42-6.

In a previous preprint, [2], reproduced here within the appendix in its revised version, we were confronted, to reach the validity of the second law of thermodynamics for an unique collapse of an unique quantum object, to the necessity of an ensemble of measures to be accomplished within copies of identical isolated systems. The validity of the second law of thermodynamics within the context of the wave function collapse was sustained by the large number of microstates related to a given collapsed state. Now, we will consider just one pure initial state containing just one initial state of the quantum subsystem, not an ensemble of identically prepared initial quantum subsystems, e.g., just one photon from a very low intensity beam prepared with an equiprobable eigenset containing two elements, an unique observation raising two likelihood outcomes. Again, we will show the statistical interpretation must prevail, albeit the quantum subsystem being a singular, unique, pure state element within its unitary quantum subsystem ensemble set. This feature leads to an inherent probabilistic character, even for a pure one-element quantum subsystem object.

4 ref

021917   Zendehnam A;Mirzaei M;Farashiani A;Horabadi Farahani L (Physics Dep, Thin Film Laboratory, Arak Univ, Arak-Iran, P.O. Box 38516-879, Iran, Email: A-zendehnam@araku.ac.ir) : Investigation of bending loss in a single-mode optical fibre. Pramana J Phys 2010, 74(4), 591-603.

Loss of optical power in a single-mode optical fibre due to bending has been investigated for a wavelength of 1550 nm. In this experiment, the effects of bending radius (4-15 mm, with steps of 1 mm), and wrapping turns (up to 40 turns) on loss have been studied. Twisting the optical fibre and its influence on power loss also have been investigated. Variations of bending loss with these two parameters have been measured, loss with number of turns and radius of curvature have been measured, and with the help of computer curve fitting method, semi-empirical relationships between bending loss and these two parameters have been found, which show good agreement with the obtained experimental results.

11 illus, 17 ref

021916   Yadav N;Bhatt P;Singh R;Subrahmanyam V S; Shanker R (Physics Dep, Atomic Physics Laboratory, Banaras Hindu Univ, Varanasi-221 005, Email: shankerorama@gmail.com) : Measurement of the bremsstrahlung spectra generated from thick targets with Z=2-78 under the impact of 10 Ke V electrons. Pramana J Phys 2010, 74(4), 563-74.

Presents new experimental data on thick target bremsstrahlung spectra generated from the interaction of energetic electrons with bulk matter. The 'photon yields' in terms of double differential cross-sections (DDCS) are measured for pure elements of thick targets: Ti (Z - 22), Ag (Z = 47), W (Z = 74) and Pt (Z = 78) under the impact of 10 keV electrons. Comparison of DDCS obtained from the experimental data is made with those predicted by Monte-Carlo (MC) calculations using PENELOPE code. A close agreement between the experimental data and the MC calculations is found for all the four targets within the experimental error of 16%. Furthermore, the ratios of DDCS of bremsstrahlung photons emitted from Ag, W and Pt with those from Ti as a function of photon energy are examined with a relatively lower uncertainty of about 10% and they are compared with MC calculations. A satisfactory agreement is found between the experiment and the calculations within some normalizing factors. The variations of DDCS as a function of Z and of photon energy are also studied which show that the DDCS vary closely with Z; however, some deviations are observed for 'tip' photons emitted from high Z targets.

4 illus, 25 ref

021915   Varma R K (NO, Physical Research Laboratory, Navrangpura, Ahmedabad-380 009, Email: ramkvarma@gmail.com) : Observability of the effects of curl-free magnetic vector potential on the macroscale and the nature of the 'transition amplitude wave'. Pramana J Phys 2010, 74(4), 491-511.

Discusses here the prediction, based on a formalism by the author, on the observable effects of a curl-free magnetic vector potential on the macroscale as against the microscale of the Aharonov-Bohm effect. A new quantum concept - the 'transition amplitude wave' - postulated in the formalism has already been shown to exhibit matter wave manifestations in the form of one-dimensional interference effects on the macroscale. It was predicted by the formalism that the same entity would lead to the detection of a curl-free magnetic vector potential on the macroscale. We describe here the manner of generation of this quantum entity in an inelastic scattering episode and work out an algorithm to observe this radically new phenomenon, the detection of a curl-free magnetic vector potential on the macroscale. We determine the various characteristic features of such an observation which can then be looked for experimentally so as to verify the predicted effect, establishing thereby the physical reality of the new quantum entity, and to fully validate the formalism predicting it. It is also shown that this 'transition amplitude wave' can be regarded as a novel kind of 'quasiparticle' excited in the charged particle trajectory as a consequence of the scattering episode.

2 tables, 16 ref

021914   Srivastava A;Paltani P P;Medhekar S (Applied Physics Dep, Birla Institute of Technology, Mesra, Ranchi-835 215, Email: sarangmedekar@rediffmail.com) : Switching behaviour of a nonlinear mach-zehnder interferometer. Pramana J Phys 2010, 74(4), 575-90.

In the present paper, a detailed investigation on the switching behaviour of a nonlinear Mach-Zehnder interferometer (NMZI) has been carried out using beam propagation method (BPM). A thorough investigation on input vs. output characteristic has been carried out by varying different parameters like length of the arms, refractive index of the linear/nonlinear arm, wavelength of the input beams and nonlinear coefficient of the material of the nonlinear arm. The input vs. output characteristic has also been investigated by shifting the balance point of the NMZI. The present paper provides a physically intuitive understanding of the effect of change in different parameters of the NMZI on its switching behaviour.

19 illus, 20 ref

021913   Sen P (NO, Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad-211 019, Email: prasen@hri.res.in) : Density functional study of ferromagnetism in alkali metal thin films. Pramana J Phys 2010, 74(4), 653-59.

Electronic and magnetic structures of (1 0 0) films of K and Cs, having thicknesses of one to seven layers, are calculated within the plane-wave projector augmented wave (PAW) formalism of the density functional theory (DFT), using both local spin density approximation (LSDA) and the PW91 generalized gradient approximation (GGA). Only a six-layer Cs film is found to have a ferromagnetic (FM) state which is degenerate with a paramagnetic (PM) state within the accuracy of these calculations. These results are compared with those obtained from calculations on a finite-thickness uniform jellium model (UJM), and it is argued that within LSDA or GGA, alkali metal thin films cannot be claimed to have an FM ground state. Relevance of these results to the experiments on transition metal-doped alkali metal thin films and bulk hosts are also discussed.

2 illus, 18 ref

021912   Prasanna Kumar S;Manjunathaguru V;Umesh T K (Studies Physics Dep, Manasagangothri, Mysore Univ, Mysore-570 006, Email: umeshtk@gmail.com) : Effective atomic numbers of some H-, C-, N- and O-based composite materials derived from differential incoherent scattering cross-sections. Pramana J Phys 2010, 74(4), 555-62.

In this work, we have made an effort to determine whether the effective atomic numbers of H-, C-, N- and O-based composite materials would indeed remain a constant over the energy grid of 280-1200 keV wherein incoherent scattering dominates their interaction with photons. For this purpose, the differential incoherent scattering cross-sections of Be, C, Mg, Al, Ca and Ti were measured for three scattering angles 60°, 80° and 100° at 279.1, 661.6 and 1115.5 keV using which an expression for the effective atomic number was derived. The differential incoherent scattering cross-sections of the composite materials of interest measured at these three angles in the same set-up and substituted in this expression would yield their effective atomic number at the three energies. Results obtained in this manner for bakelite, nylon, epoxy, teflon, perspex and some sugars, fatty acids as well as amino acids agreed to within 2% of some of the other available values. It was also observed that for each of these samples, Z_eff was almost a constant at the three energies which unambiguously justified the conclusions drawn by other authors earlier [Manjunathaguru and Umesh, J. Phys. B: At. Mol. Opt. Phys. 39, 3969 (2006); Manohara et al, Nucl. Iustrum. Methods B266, 3906 (2008); Manohara et al Phys. Med. Biol. 53, M377 (2008)] based on total interaction cross-sections in the energy grid of interest.

3 illus, 2 tables, 7 ref

021911   Parihar M L (NO, Rajasthan State Centre of IEI, Rajasthan) : Energy conservation-a necessity for development. J Instn Engrs-Pt TN 2010, 91(Dec), 3-5.

Highlights the ways and means for conservation of energy for human survival. The awareness and participation by end users is most significant to conserve energy.

1 table, 4 ref

021910   Pakzad H R (Physics Dep, Islamic Azad Univ, Bojnourd Branch, Iran, Email: pakzad@bojnourdiau.ac.ir) : Kadomstev-Petviashvili equation in warm dusty plasma with variable dust charge two-temperature ion and nonthermal electron. Pramana J Phys 2010, 74(4), 605-14.

In this work, the propagation of nonlinear waves in warm dusty plasmas with variable dust charge, two-temperature ion and nonthermal electron is studied. By using the reductive perturbation theory, the Kadomstev-Petviashvili (KP) equation is derived. The energy of the soliton and the linear dispersion relation are obtained. The effects of variable dust charge on the energy of soliton and the angular frequency of linear wave are also discussed.

3 illus, 32 ref

021909   Nath P (Electronics Science Dep, Gauhati Univ, Guwahati-781 014, Email: pnath07@gmail.com) : Non-intrusive refractometer sensor. Pramana J Phys 2010, 74(4), 661-8.

An experimental realization of a simple non-intrusive refractometer sensor is demonstrated in this communication. The working principle of the sensor is based on intensity modulation of the back-reflected light when output light from an optical fibre end focusses onto air-medium interface. The change in the refractive index of the medium affects the reflectance of the incident light signal and thus modulates the back-reflected signal. Refractive index variation as small as 0.002 RIU can be measured using the present technique. The advantages of the technique are its simplicity, cost efficiency and usefulness in monitoring refractive indices of acidic solutions.

5 illus, 1 table, 11 ref

021908   Moungsrijun S;Srisuksawad K;Lorsirirat K; Nantawisarakul T (Department of Physics. Faculty of Science, King Mongkut's University of Technology, Thonburi, Bangkok 10140, Thailand, Email: sasiphy@hotmail.com) : Using fallout <. Curr Sci 2010, 98(4), 542-7.

The Lam Phra Phloeng dam was constructed in 1963 and is located in the Nakhon Ratchasima province. The dam has severely reduced water level caused by deforestation and agriculture at the upper land. Sediment cores were collected using a gravity corer. The ²¹⁰Pb activities were measured using alpha and gamma spectrometry and sedimentation rates were determined. The sedimentation rates decreased gradually from the upstream to the crest of the dam. The high sedimentation rate may be due to the inflow from the tributary as well as eroded materials that come from the upland area to the dam.

6 illus, 1 table, 14 ref

021907   Milani Moghaddam H (Physics Dep, Faculty of Basic Sciences, Mazandaran Univ, 47415 Babolsar, Iran, Email: hossainmilani@yahoo.com) : On the excited state wave functions of dirac fermions in the random gauge potential. Pramana J Phys 2010, 74(4), 633-41.

In the last decade, it was shown that the Liouville field theory is an effective theory of Dirac fermions in the random gauge potential (FRGP). We show that the Dirac wave functions in FRGP can be written in terms of descendents of the Liouville vertex operator. In the quasiclassical approximation of the Liouville theory, our model predicts that the localization length ξ scales with the energy E as ξ <126> E^-b2/(^{1+b>2)2, where b is the strength of the disorder. The self-duality of the theory under the transformation b → 1/b is discussed. We also calculate the distribution functions of to = |ψ0(x)|2, (i.e. p(t₀); ψ(x) is the ground state wave function), which behaves as the log-normal distribution function. It is also shown that in small to, p(t₀) behaves as a chi-square distribution.}

38 ref

021906   Katore S D;Rane R S;Wankhade K S;Sarkate N K (Mathematics Dep, SGB Amravati Univ, Amravati-444 602, Email: wankhade.kishor@rediffmail.com) : Einstein-Rosen inflationary universe in general relativity. Pramana J Phys 2010, 74(4), 669-73.

Einstein-Rosen inflationary Universe is investigated in the presence of mass-less scalar field with a flat potential. To get an inflationary Universe, we have considered a flat region in which the potential V is constant. Some physical properties of the model are discussed.

18 ref

021905   Hu Y X;Wu S Y;Wang X F;Xu P (Applied Physics Dep, Univ of Electronic Science and Technology of China, Chengdu 610 054, People's Republic of China, Email: wushaoyi@netease.com) : Theoretical study of the electron paramagnetic resonance parameters and local structure for the tetragonal Ir<. Pramana J Phys 2010, 74(4), 643-51.

The electron paramagnetic resonance (EPR) parameters (the g factors, hy-perfine structure constants and the superhyperfine parameters) for the tetragonal Ir²⁺ centre in NaCl are theoretically investigated from the perturbation formulas of these parameters for a 5d⁷ ion in tetragonally elongated octahedra. This impurity centre is attributed to the substitutional [IrCl₆]^4- cluster on host Na⁺ site, associated with the 4% relative elongation along the C₄-axis due to the Jahn-Teller effect. Despite the ionicity of host NaCl, the [IrCl₆]^4- cluster still exhibits moderate covalency and then the ligand orbital and spin-orbit coupling contributions should be taken into account. In addition, the theoretical EPR parameters based on the Jahn-Teller elongation show good agreement with the observed values.

1 table, 35 ref

021904   Dharmadhikari N P;Meshram D C;Kulkarni S D; Hambarde S M;Rao A P;Pimplikar S S;Kharat A G;Patil P T (Applied Physics Dep, JSPM'S Jayawantrao Sawant College of Engineering, Hadapsar, Pune-411 028, Email: sejalrohit2007@gmail.com) : Geopathic stress: a study to understand its nature using light interference technique. Curr Sci 2010, 98(5), 695-7.

The energy emitted by the earth at a specific location on the surface, which affects the normal human body function, is termed as geopathic stress (GS). Studies of the exact nature and characteristic of GS are sparse. Some studies indicate that GS may be of electromagnetic nature or subtle energy (Jane Thurnell-Read). The archaic method to identify GS is by dowsing. This communication attempts to make use of 'Light Interference Technique' to study the nature of GS in and around the pre-detected GS location on the Mumbai-Pune expressway and some residential areas of Pune. The results indicate that this stress may be due to concentrated low energy at the respective locations.

5 illus, 28 ref

021903   Chattopadhyay P K;Paul B C (Physics Dep, Alipurduar College, P.O. Alipurduar Court, Dist. Jalpaiguri-736 122, Email: bcpaul@iucaa.ernet.in) : Relativistic star solutions in higher-dimensional pseudospheroidal space-time. Pramana J Phys 2010, 74(4), 513-23.

Obtains relativistic solutions of a class of compact stars in hydrostatic equilibrium in higher dimensions by assuming a pseudospheroidal geometry for the space-time. The space-time geometry is assumed to be (D - 1) pseudospheroid immersed in a D-dimensional Euclidean space. The spheroidicity parameter (A) plays an important role in determining the equation of state of the matter content and the maximum radius of such stars. It is found that the core density of compact objects is approximately proportional to the square of the space-time dimensions (D), i.e., core of the star is denser in higher dimensions than that in conventional four dimensions. The central density of a compact star is also found to depend on the parameter A. One obtains a physically interesting solution satisfying the acoustic condition when A lies in the range λ <62> (D + 1)/(D - 3) for the space-time dimensions ranging from D = 4 to 8 and (D + 1)/(D - 3) <60> λ <60> (D₂ - 4D + 3)/(D² - 8D - 1) for space-time dimensions ≥. The non-negativity of the energy density (p) constrains the parameter with a lower limit (A <62> 1). We note that in the case of a superdense compact object the number of space-time dimensions cannot be taken infinitely large, which is a different result from the braneworld model.

5 illus, 2 tables, 24 ref

021902   Cakmak N;Manisa K;Unlu S;Selam C (Physics Dep, Karabuk Univ, Karabuk, Turkey, Email: neclac@karabuk.edu.tr) : The investigation of O<. Pramana J Phys 2010, 74(4), 541-53.

The O⁺↔O^- first-forbidden β decay transitions have been investigated for some spherical nuclei. The theoretical framework is based on a proton-neutron quasipar-ticle random phase approximation (pnQRPA). The Woods-Saxon potential basis has been used in our calculations. The transition probabilities have been calculated within the ξ approximation. The relativistic β moment matrix element has been calculated both di-rectly without any assumption and assuming that it is proportional to the non-relativistic one.

4 illus, 6 tables, 22 ref

021901   Bharti A;Singh S;Khosa S K (Physics and Electronics Dep, Jammu Univ, Jammu-180 006, Email: arunbharti_2003@yahoo.co.in) : Structure of negative pairty yrast bands in odd mass<. Pramana J Phys 2010, 74(4), 525-39.

The negative parity yrast bands of neutron-deficient ^125-131Ce nuclei are studied by using the projected shell model approach. Energy levels, transition energies and B(M1)/B(E2) ratios are calculated and compared with the available experimental data. The calculations reproduce the band-head spins of negative parity yrast bands and indicate the multi-quasiparticle structure for these bands.

3 illus, 1 table, 27 ref

021900   Arulsamy A D (Physics School, The Univ of Sydney, Sydney, New South Wales 2006, Australia, Email: andrew@physics.usyd.edu.au) : Many-body hamiltonian with screening parameter and ionization energy. Pramana J Phys 2010, 74(4), 615-31.

Proves the existence of a Hamiltonian with ionization energy as part of the eigenvalue, which can be used to study strongly correlated matter. This eigenvalue consists of total energy at zero temperature (E₀) and the ionization energy (ξ). Shows that the existence of this total energy eigenvalue, E₀±ξ, does not violate the Coulombian atomic system. Since there is no equivalent known Hamilton operator that corresponds quantitatively to ξ, employ the screened Coulomb potential operator (Yukawa-type), which is a function of this ionization energy to analytically calculate the screening parameter (a) of a neutral helium atom in the ground state. In addition, we also show that the energy level splitting due to spin-orbit coupling is inversely proportional to ξ eigenvalue, which is also important in the field of spintronics.

1 table, 27 ref

021899   Ananthanarayan B;Chakbrabarti R;Patra M (High Energy Physics, Indian Institute of Science, Bangalore-560 012, Email: anant@cts.iisc.ernet.in) : Single top quark events at fermilab. Curr Sci 2009, 97(1), 16-17.

^ssc

020880   Zendehnam A;Mirzaei M;Farashiani A;Horabadi Farahani L (Physics Dep, Thin Film Laboratory, Arak Univ, Arak-Iran, P.O. Box 38516-879, Iran, Email: A-zendehnam@araku.ac.ir) : Investigation of bending loss in a single-mode optical fibre. Pramana J Phys 2010, 74(4), 591-603.

Loss of optical power in a single-mode optical fibre due to bending has been investigated for a wavelength of 1550 nm. In this experiment, the effects of bending radius (4-15 mm, with steps of 1 mm), and wrapping turns (up to 40 turns) on loss have been studied. Twisting the optical fibre and its influence on power loss also have been investigated. Variations of bending loss with these two parameters have been measured, loss with number of turns and radius of curvature have been measured, and with the help of computer curve fitting method, semi-empirical relationships between bending loss and these two parameters have been found, which show good agreement with the obtained experimental results.

11 illus, 17 ref

020879   Yadav N;Bhatt P;Singh R;Subrahmanyam V S; Shanker R (Physics Dep, Atomic Physics Laboratory, Banaras Hindu Univ, Varanasi-221 005, Email: shankerorama@gmail.com) : Measurement of the bremsstrahlung spectra generated from thick targets with Z=2-78 under the impact of 10 Ke V electrons. Pramana J Phys 2010, 74(4), 563-74.

Presents new experimental data on thick target bremsstrahlung spectra generated from the interaction of energetic electrons with bulk matter. The 'photon yields' in terms of double differential cross-sections (DDCS) are measured for pure elements of thick targets: Ti (Z = 22), Ag (Z = 47), W (Z = 74) and Pt (Z - 78) under the impact of 10 keV electrons. Comparison of DDCS obtained from the experimental data is made with those predicted by Monte-Carlo (MC) calculations using PENELOPE code. A close agreement between the experimental data and the MC calculations is found for all the four targets within the experimental error of 16%. Furthermore, the ratios of DDCS of bremsstrahlung photons emitted from Ag, W and Pt with those from Ti as a function of photon energy are examined with a relatively lower uncertainty of about 10% and they are compared with MC calculations. A satisfactory agreement is found between the experiment and the calculations within some normalizing factors. The variations of DDCS as a function of Z and of photon energy are also studied which show that the DDCS vary closely with Z; however, some deviations are observed for 'tip' photons emitted from high Z targets.

4 illus, 25 ref

020878   Vishwakarma S R;Verma A K;Tripathi R N;Rahul; Maurya S K (Physics & Electronics Dep, Dr. R. M. L. Avadh University, Faizabad, Uttar Pradesh, Email: dr.rsnt@gmail.com) : Study of structural properties of starting material for n-type cadmium selenide thin films prepared in vacuum. Ultra Scient phys Sci 2010, 22(3), 607-12.

Since last two decades in the area of electronics group II-VI compounds have drowned considerable interest due to various applications of cadmium selenide (CdSe), a member of this group, is one of the promising semi conducting material from its applications point of view. The present investigation have directed the preparation and characterizations of n-type cadmium selenide thin films as starting materials of various composition of cadmium and selenium. For the preparation of starting material, definite amount of elementary materials (Cd and Se), are mixed together with pestle mortar and heated in the temperature range 200°C to 290°C for 3 to 6 hours under the vacuum of 10<^>-4 torr. Process was repeated five times. The structural characterization has been carried by using X- Ray powder diffraction measurements with the help of XRD data. We analyzed the effect of composition of cadmium and selenium on the lattice parameter 'c' and grain size 'D' of starting polycrystalline semiconducting materials.