007731   Suresh S;Ramanand A;Vasanthakumari R (Polymer Technology Dep, B.S.A. Abdur Rahman Univ, Seethakathi Estate, GST Road, Vandalur, Chennai-600 0048, Email: kumarirv@yahoo.co.in) : Structural, optical and photoconductivity studies on benzoyl glycine NLO single crystals. Asian J Chem 2011, 23(1), 37-40.

Single crystals of benzoyl glycine (BG) with high degree of transparency were grown by slow evaporation technique. Powder crystal X-ray diffraction analysis reveals that the crystal belongs to orthorhombic system with the space group P2₁2₁2₁. The physical parameters have been determined for the grown crystal. The optical absorption study reveals the transparency of the crystal in the entire visible region and the cut off wavelength was found to be 240 nm. The optical band gap was found to be 3.75 eV. The dependence of extinction coefficient (k) and refractive index (n) on the wavelength have also been reported. The dielectric constant was also studied as a function of frequency at room temperature. The photo conductivity study proves that benzoyl glycine crystal exhibits negative photoconductivity.

11 illus, 22 ref

007730   Sumathi T;Varalakshmi M (Physics Wing, DDE, Annamalai Univ, Chidambaram, Email: tsumathi92@yahoo.com) : Effect of LiCl, NaCl and KCl on aqueous phenylalanine at 303 K. Indian J pure appl Phys 2012, 50(2), 105-9.

Density, speed of sound and viscosity data for 2-amino 3-phenyl propanoic acid commonly known as phenylalanine in aqueous sodium chloride (NaCl), potassium chloride (KC1) and lithium chloride (LiCl) have been measured in the concentration range 0.00-0.10 mol.kg^-1 at 303 K. From these data, adiabatic compressibility (β), change (Δβ), relative change in adiabatic compressibility (Δβ/β₀), acoustic impedance (Z), limiting apparent molar compressibility (φ_k), limiting apparent molar volume (φ_v) and their constants 5_k and S_v have been computed. The observed variation of these parameters helps in understanding the nature of solute-solvent interactions present in the system. The structure-breaking capacity of phenylalanine has been inferred from aqueous electrolytes using Jones-Dole equation.

3 tables, 19 ref

007729   Singh P;Rao S V L S;Pande R (Ion Accelerator Development Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: psingh@barc.gov.in) : Role of beam dynamics studies for accelerator safety. Indian J pure appl Phys 2012, 50(7), 439-41.

Several accelerators are being designed for various applications ranging from research, medical applications to energy production. The beam dynamics studies are used to work out the configuration of these accelerators. One of the objectives of these studies is to optimize the size of the components and minimization of the beam losses in the system. The large beam losses will not only produce radioactivity in the accelerator components but also can melt them due to large beam energy deposition. This can lead to air rush in the system and hence the damage of the whole system. Optimization of the beam dynamics is of great importance particularly in high current accelerators where space charge forces play an important role. In the case of high intensity accelerators several new phenomena like resonances and beam halos formation take place which leads to large beam losses. For hands on maintenance of the accelerator components for ADS applications, it is estimated that the beam loss should be <60> 1 nA/m which requires a careful beam dynamics studies for the system. It is also useful to understand the beam loss mechanism and their minimization particularly in the case of high current accelerators.

2 illus, 6 ref

007728   Singh M P;Sharma A;Singh B;Sandhu B S (Physics Dep, Punjabi Univ, Patiala-147 002, Email: balvir@pbi.ac.in) : Experimental measurement of coherent to incoherent cross-section ratio of elements in the range 6 ≤ Z ≤ 82 for 59.54 ke V gamma photons. Indian J pure appl Phys 2012, 50(7), 490-3.

The coherent (Rayleigh) to incoherent (Compton) scattering cross-section ratio of elements in the range 6 ≤ Z ≤ 82 for 59.54 keV gamma photons, have been measured. An HPGe gamma detector, placed at 90° to the incident beam, detects gamma photons scattered from the target under investigation. The intensity ratio of Rayleigh to Compton scattered peaks observed in the recorded spectra, corrected for photo-peak efficiency of gamma detector and absorption of photons in the target and air, along with the other required parameters provides differential cross-sections ratio for Rayleigh to Compton scattering. The measured values of cross-section ratio are found to agree with theory for low Z elements, but deviate from theory for high Z elements.

3 illus, 1 table, 7 ref

007727   Sharma I D;Sharma V K;Dhawan S K;Saini P K (Physics Dep, S S V College, Hapur, Ghaziabad-245 101, Email: idsharma1974@gmail.com) : Modification and designing of electrodeposited polypyrrole film for optoelectronic applications. Indian J pure appl Phys 2012, 50(3), 184-7.

The electrodeposited polypyrrole (PPY) film over ITO coated glass substrate has been prepared and its current voltage response using Schottky emission theory has been analyzed. The electrodeposition of PPY has ben carried out by electrochemical polymerization of 0.2 M pyrrole monomer and cycling the potential between -0.2V to 0.8 V at a scan rate of 20mV/s using KC1 as supporting electrolyte. The formation of polymer has been confirmed by X-ray diffraction and FTIR measurements whereas the surface morphology has been observed using scanning electron microscope. The band gap of PPY film has been calculated using UV visible spectroscopy and found to be 2.4 eV. In addition, the current-voltage response of deposited film was also recorded to evaluate its electronic attributes such as barrier height (®_B) and constant factor (β). The results revealed the ®_Band β values of 0.314 eV and 1.72x10^-4, respectively. These films may have potential applications in electronic and optoelectronic sensing devices.

7 illus, 18 ref

007726   Shanbhag A A;Tripathy S P;Sahoo G S;Sunil C; Nandy M;Sarkar P K (Health Physics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: shanbhag@tifr.res.in) : Angular distribution of the ambient neutron dose equivalent from incidence of alpha particles on thick Al target. Indian J pure appl Phys 2012, 50(7), 531-3.

In this study, the measured data of angular distribution of neutron dose equivalent due to neutrons arising from the bombardment of 19.8 and 30 MeV alpha particles on a thick aluminium target has been reported. These measurements have been carried out at the BARC-TIFR Pelletron Linac Accelerator Facility using neutron dose equivalent meters popularly known as REM meters. The neutron dose equivalent values measured at a distance of 1 m from the target at various angles relative to the incident beam direction are presented here. The values are compared with those predicted by the empirical formulation of Clapier & Zaidins.

3 illus, 1 table, 5 ref

007725   Saran P K;Nandy M;Sarkar P K;Goyal S L (Applied Physics Dep, Guru Jambheshwar Science & Technology Univ, Hisar-125 001, Email: goyalsneh@yahoo.com) : Production of long-lived <. Indian J pure appl Phys 2012, 50(7), 509-12.

The excitation functions of (n, 2n) and (n, α) reactions for the production of long-lived radio nuclides ²⁶A1 and ²⁴Na from ²⁷A1 have been calculated for 1-20 MeV neutrons. The excitation functions of these reactions are calculated using the codes AL1CE-91, EMPIRE-2.19 and TALYS-1.0. The codes account for the major nuclear reaction mechanisms, including direct, pre-equilibrium and compound nuclear ones. The excitation functions of these isotopes have been compared graphically with the evaluated nuclear data file and available experimental data. The results are more or less agreeing up to which energy the experimental data are available whereas ALICE code largely under predicts the data in the energy range 1-20 MeV.

4 illus, 25 ref

007724   Sahoo S;Middya T R;Sit S K (Electronics & Instrumentation Engineering Dep, Dr. Meghnad Saha Institute of Technology, P O Debhog, Haldia, Dist Purba Medinipore, West Bengal-721 657, Email: swapansit@yahoo.co.in) : Dielectric behaviour of aprotic polar liquid dissolved in non-polar solvent under static and high frequency electric field. Indian J pure appl Phys 2012, 50(3), 175-83.

Dielectric behaviour of aprotic polar liquids (j) like N,N dimethylformamide (DMF), N,N dimethylacetamide (DMA) and acetone (Ac) has been studied under static as well as 9.987, 9.88 and 9.174 GHz electric field employing Debye theory of polar-non polar liquid mixture in terms of measured ε_ij and imaginary ε_ij part of complex relative permittivity ε_ij*, static ε_0ij and high frequency ε_∞ij for different W_j's of solute dissolved in non polar solvent at 27°C temperature. Double relaxation times τ₂ and τ₁ due to whole molecule and part of the polar molecule have also been estimated analytically using the complex high frequency orientational susceptibility X_ij* (= ε_ij-ε_∞ij) from measured data for DMF and DMA in C₆H₆ and CC1₄ as well as acetone in C₆H₆ and CC1₄ solvent, respectively at 27°C. Out of the six systems, three systems show double relaxation time τ₂ and τ₁ and dipole moment μ₂ and μ₁. The estimated μ's and τ'S agree excellently well with the reported and measured values from ratio of slope and linear slope method. The dipole moments μ_0s'S in static electric field are also compared with μ_j's in hf method. The relative contributions c₁ and c₂ due to τ₁ and τ₂ have been calculated from Frohlich equation as well as graphical plot of χ_ij/χ_oij-W_jJ and χ_ij/χ_oij w_j curve at W_j → 0. Solute-solute and solute-solvent molecular associations are ascertained in different molecular environment.

6 illus, 3 tables, 19 ref

007723   Sahoo G S;Tripathy S P;Shanbhag A A;Sunil C; Joshi D S;Sarkar P K (Health Physics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: sahoo.gouri232@gmail.com) : Neutron measurement in <. Indian J pure appl Phys 2012, 50(7), 513-16.

In this work, neutron measurements were carried out for the interaction of 60 and 67.5 MeV ¹²C, 57.3 and 65 MeV ¹³C ions with thick aluminium target by using CR-39 detectors and neutron rem meter. Both the detector systems were irradiated at different angles viz. 0°, 30°, 60°, 90° with respect to the beam direction. The normalized track density (tracks cm^-2 projectile^-1 at 1 m) in CR-39 detectors was correlated with the normalized dose equivalent values (μSv projectile^-1 at 1 m) obtained using the neutron rem meter. The track density was found to be more in case of ¹³C than ¹²C. However in all the cases, the track density per incident projectile was found to decrease as the angle with respect to beam direction increases, indicating non-isotropic nature of neutron emission. The ratio between measured dose equivalent in rem meter to the measured track densities in CR-39 detectors was found to be (2.8±0.2) μSv cm², which remains constant irrespective of the change in angle with respect to the beaih direction as well as in neutron energy distribution, indicating a flat dose response of CR-39 detectors.

4 illus, 15 ref

007722   Rawat A;Mahavar H K;Chauhan S;Tanwar A;Singh P J (Physics Dep, M S J Govt. College, Bharatpur-321 001, Email: pjsingh.makkar@gmail.com) : Optical band gap of polyvinylpyrrolidone/polyacrilamide blend thin films. Indian J pure appl Phys 2012, 50(2), 100-4.

Thin films of polyvinylpyrrolidone, polyacrilamide and their blends were prepared using solution cast method and characterized using X-ray diffraction (XRD) technique. Optical absorption spectra of these thin films have been recorded in the wavelength range 190-600 nm using UV-visible spectrophotometer. Optical band gap of the films has been calculated by using Tauc's relation and variations in the values of optical band gap with the variation of composition in the blend films have been found from 4.77 to 5:10 eV. The tail width of the localized states has been calculated by using Urbach's relation. Absorption coefficient and extinction coefficient have been calculated at 220 nm wavelength in the region where the absorbance by the thin film is the maximum. The optical band gap has been correlated with the number of carbon atoms per molecule.

4 illus, 1 table, 28 ref

007721   Raju K;Rakkappan C (Physics (DDE) Dep, Annamalai Univ, Annamalai Nagar-608 002, Email: raju@svce.ac.in) : Ultrasonic studies on the molecular interaction of ethyl cellulose in n-alkanols. Asian J Chem 2011, 23(1), 19-22.

Ultrasonic velocity, viscosity and density for the solutions of ethyl cellulose in propan-1-ol, butan-1-ol, pentan-1-ol and hexan-1-ol mixtures were measured at 303, 313 and 323 K. From the experimental data, the various acoustical parameters such as adiabatic compressibility (β_ad), Rao number (R), free length (L_f), internal pressure (π) and solvation number (S_n) have been computed. The trends in acoustical parameters indicate that there are molecular interactions between the components.

4 tables, 19 ref

007720   Rai R K;Kher R S;Khan S A;Dhoble S J;Upadhyay A K (Physics Dep, Government Engineering College, Ujjain-456 010, Email: rakeshrai1900@gmail.com) : Device for mechanoluminescence excitation by applying gradually varying pressure on the sample. Indian J pure appl Phys 2012, 50(7), 534-7.

Low cost set-up has been designed and developed for producing mechanoluminescence (ML) by continuously varying pressure on the sample. The ML of γ-irradiated BaAl₂O₄:Eu phosphor has been studied. ML is excited impulsively by dropping a load through guiding cylinder and by applying continuously varying pressure on the sample. When BaAl₂O₄:Eu phosphor is deformed impulsively, a single peak with shoulder is observed in the time versus ML intensity curve, while number of peak is observed when continuously increasing pressure applied on to the sample. When pressure is continuously decreased less number of peaks is observed as compared to that of increasing pressure. The enhancement in ML intensity with γ-irradiation suggests that BaAl₂O₄ :Eu is a suitable candidate for ML dosimetry.

6 illus, 19 ref

007719   Pradhan S K;Dash S K;Moharana L;Swain B B (Physics Dep, Nayagarh Autonomous College, Nayagarh-752 069, Email: bb.swain@vivtech.co.in) : Molecular interaction parameters of binary mixtures of diethyl ether and apolar solvents using ultrasonic probe. Indian J pure appl Phys 2012, 50(3), 161-6.

Ultrasonic velocity (U), density (p) and co-efficient of viscosity (η) of pure and binary mixtures of diethyl ether with carbon tetrachloride, carbon disulphide and benzene have been measured at 303.15 K using an ultrasonic interferometer, pyknometer and Ostwald viscometer, respectively. Molecular interaction parameters i.e isentropic compressibility (β_s), intermolecular free length (L_f), molar volume (V_m), acoustic impedance (Z), available volume (V_a), free volume (V_f), internal pressure (π_i) and the relaxation time (τ) have been calculated and interpreted for the intra and intermolecular association among like and unlike molecules. Dipole-induced dipole type of interaction is found to be stronger in case of CC1₄ mixture.

9 illus, 1 table, 19 ref

007718   Pomp S (Physics and Astronomy Dep, Uppsala Univ, Box 516, 75120 Uppsala, Sweden, Email: Stephan.Pomp@physics.uu.se) : Medley facilities past and future: fast neutron nuclear data for science and industry. Indian J pure appl Phys 2012, 50(7), 446-9.

The Medley facility has been installed at The Svedberg Laboratory (TSL) for more than 10 years. During that time double-differential cross-sections for neutron-induced light-ion production have been measured for a range of target nuclei at incoming neutron energies of up to 175 MeV. Now, Medley will move to a new home at the Neutrons For Science (NFS) facility at GANIL in France. This facility is currently under construction and should start operating 2014. The pulsed beam combined with time-of-flight measurements will allow for good neutron energy resolution. The paper briefly summarizes the motivation for the experiment, design concepts, results achieved at TSL, and the future plans at NFS.

1 illus 20 ref

007717   Paul S;Pandey M;Tripathy S P;Sarkar P K (Health Physics Div, Bhabha Atomic Research Centre, Mumbai-400 095, Email: spaul@barc.gov.in) : Grey level analysis of 2D images to determine length of α-tracks in CR-39 detectors. Indian J pure appl Phys 2012, 50(7), 486-9.

In this work, the 2-dimensional images of α-tracks in CR-39 detectors have been analyzed in terms of grey values to obtain the critical information such as track length and angle, which usually cannot be obtained by conventional optical microscopes. A user-interactive code has been developed for the automated track detection based on the average grey values and light intensity in the vicinity of individual tracks. The code automatically identifies the tracks, and determines the track density, length, major axis, minor axis, eccentricity, incidence angle, etc. and provides a 2-D cross-sectional view of the detected tracks. The algorithm efficiently segregates individual tracks from the overlapped multi-tracks present above a preset depth (threshold) provided by the user with the option of manual rejection of track like manufacturing defects in the detector. This method can eventually be applied for neutron spectrometric studies, where the length and angle information of the recoil tracks in solid polymeric track detectors are crucial.

3 illus, 2 tables, 4 ref

007716   Pant K;Arora P;Yadav S;Gupta A S (National Physical Laboratory, Council of Scientific and Industrial Research (CSIR), Dr K S Krishnan Marg, New Delhi-110 012, Email: pantk@mail.nplindia.ernet.in) : Design and development of atomic flux controller for cesium fountain clock at NPL, India. Indian J pure appl Phys 2012, 50(8), 593-9.

Development of an electronic module for controlling the atomic flux from Cesium (Cs) Source (Cs ampoule) to the cooling chamber of Physics package of Cs fountain clock being developed at National Physical Laboratory (NPL) India, is described. Cs source is integrated with octagonal cooling chamber and the amount of Cs diffusing into the chamber is controlled by controlling the temperature of Cs ampoule. The atomic flux controller is basically a temperature controller which is designed for maintaining the temperature from 10°C to 80°C. It is based on lock-in amplifier and proportional-integral-differential (PID) controller techniques for precise control of temperature. Thermoelectric Coolers (TECs) is used for cooling and heating the Cs ampoule.

15 illus, 13 ref

007715   Pande M;Patel N (TPD, Bhabha Atomic Research Centre, Mumbai-400 085, Email: manjiri@barc.gov.in) : Measurement and analysis of the radio frequency radiation (non-ionizing) in dc accelerator based 14 MeV neutron generator facility at BARC. Indian J pure appl Phys 2012, 50(7), 478-81.

Radio frequency (RF) driven ion sources are used in various scientific applications like neutral beam injection systems for fusion reactors, particle accelerators, neutron generator and neutron spallation source. In BARC, a dc accelerator based 14 MeV neutron generator uses RF type ion source. This ion source uses an indigenously developed RF amplifier system, which capacitively couples (via two external electrode rings) the RF power at 100 MHz to deuterium gas filled RF ion source assembly to generate deuterium plasma. The RF radiation (non- ionizing radiation) emanates from the capacitively coupling in addition to very minor RF radiations from the amplifier assembly itself. This radiation was measured at various locations within the neutron generator facility and was, then analyzed from safety point of view and compared with international standards for RF radiation. It was observed that the measured RF radiations are within the limit and do not pose any hazard for equipment or personal safety. This paper describes in detail the measurements and their analysis.

8 illus, 6 ref

007714   Nayak M K;Haridas G;Sahu T K;Dashora S; Nandedkar R V;Sarkar P K (Health Physics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: nayak@rrcat.gov.in) : Bremsstrahlung source term determination for 450MeV electrons. Indian J pure appl Phys 2012, 50(7), 494-7.

Bremsstrahlung X-ray source term at 450 MeV was experimentally determined at booster synchrotron of Indus-1 facility at Raja Ramanna Centre for Advanced Technology. Electron beam at 450 MeV extracted from booster synchrotron was allowed to fall on 25 mm lead target for the generation of the bremsstrahlung X-rays. The dose rate due to the X-rays in the forward direction was measured in 30 cm x 30 cm x 30 cm water phantom using CaSO₄:Dy thermoluminescent discs. The water phantom was placed at 1m from the target. Maximum dose rate obtained was 3.04 Gy/h at a depth of 5 cm in the phantom. The experiment was simulated using EGSnrc code and the value obtained is 3.10 Gy/h at 5 cm depth. The data is compared with the source term usually evaluated using the empirical relation suggested by W P Swanson, which gave 3.90 Gy/h. The experimental value is found to be in excellent agreement with the simulated dose rate. It is also found to be in good agreement with the value obtained from Swanson's empirical relation within °28%.

4 illus, 1 table, 6 ref

007713   Narendra K;Srinivasu C;Narayana Murthy P (Physics Dep, V.R. Siddhartha Engineering College, Vijayawada-520 007, Email: kollanarendra@rediff.com) : Ultrasonic study of cyclohexane with o-xylene at different temperatures. Asian J Chem 2011, 23(2), 752-4.

Molecular interactions have been studied in binary liquid mixtures of cyclohexane and o-xylene by ultrasonic velocity (u), density (ρ) and viscosity (η) measurements at 303.15, 308.15, 313.15 and 318.15 K and at different mole fractions. Acoustical parameters such as adiabatic compressibility (β), intermolecular free length (L_f), free volume (V_m), internal pressure (π) were calculated from the experimental data. The investigations on the binary mixture containing non-polar, non-polar liquids shows weak induced dipole-induced dipole attractions.

6 illus, 8 ref

007712   Nakamura T (NO, Tohoku Univ, Japan, Email: nakamura_takasi@nifty.com) : Neutron detector development and measurements around particle accelerators. Indian J pure appl Phys 2012, 50(7), 427-38.

Various neutron detectors for spectrometry, environmental dosimetry and personal dosimetry have been developed by our group. For high energy neutron spectrometry, spallation detectors of C and Bi, large plastic and NE-213 scintillators, self TOF detector have been used for neutron production and shielding experiments at several high energy accelerator facilities, ISIS of Rutherford Appleton Laboratory, UK, Two-mile Linac of Stanford Linear Accelerator Center, USA, HIMAC of National Institute of Radiological Sciences, Japan, and RCNP of Osaka University, Japan. The response functions of these detectors have been obtained by measurements and calculations. Thick target neutron yields produced from high-energy particles from protons to Xe ions have been summarized, together with shielding benchmark experiments through concrete and iron at these facilities. Neutron measurements over wide energy range including cosmic neutron field were done with Phoswich detector and Bonner sphere spectrometer. For environmental neutron dosimetry, two types of dose equivalent dosimeters, so-called rem counters, high-sensitive type and light-weight type, have been developed and for personal dosimetry, silicon semiconductor dosimeter has been developed for use in nuclear facilities. These dosimeters have good quality to give ambient and personal dose equivalents for neutrons in the mixed radiation fields. The outline of these works will be reviewed in this paper.

12 illus, 26 ref

007711   Manjunatha H C;Chandrika B M;Rudraswamy B (NO, Bangalore Univ, Bangalore, Email: manjunathhc@rediffmail.com) : Bremsstrahlung data. Indian J pure appl Phys 2012, 50(7), 469-73.

Present work formulated the new method to evaluate the EB spectrum and hence Bremsstrahlung dose of beta nuclides (³²P, ⁸⁹Sr, ⁹⁰Sr/⁹⁰Y, ⁹⁰Y, ⁴⁰K, ⁶¹Co, ¹⁹⁹Pt, ¹⁶⁵Dy and ¹⁰¹Tc) in concrete. The Bremsstrahlung yield of these beta nuclides in concrete is also estimated. This estimated spectrum is accurate because it is based on more accurate modified atomic number (Z_mod) and seltzer's data where an electron-electron interaction is also included. Presented data in concrete provide a quick and convenient reference for radiation protection. The present methodology can be used to calculate the Bremsstrahlung dose in nuclear sheilding materials. It can be quickly employed to give a first pass dose estimate prior to a more detailed experimetal study.

5 illus, 4 tables, 8 ref

007710   Khem Chand;Rakesh Kumar (Mathematics and Statistics Dep, Himachal Pradesh Univ, Shimla-171 005) : Hall effect on heat and mass transfer in the flow of oscillating viscoelastic fluid through porous medium with wall slip conditions. Indian J pure appl Phys 2012, 50(3), 149-55.

The Hall current and slip conditions effects on heat and mass transfer of a general unsteady hydromagnetic, free convective flow of viscoelastic fluid (Walter's B-model) past an infinite vertical porous plate subjected to uniform suction through porous medium, have been investigated theoretically. The temperature and the concentration at the plate are assumed to be oscillating with time. The solutions of the governing equations for the velocity, temperature and the concentration fields are obtained in the closed form. The significant effects of the various parameters entering into the problem on the velocity and the skin friction fields have been evaluated numerically and expressed graphically. The rate of heat transfer and the mass transfer at the plate has been obtained and also discussed.

8 illus, 1 table, 16 ref

007709   Khanna V K (MEMS & microsensors Group, Central Electronics Engineering Research Institute (CEERI), Council o, Pilani-333 031, Email: vkk_ceeri@yahoo.com) : Fabrication of ISFET microsensor by diffusion-based Al gate NMOS process and determination of its pH sensitivity from transfer characteristics. Indian J pure appl Phys 2012, 50(3), 199-207.

The present paper describes the fabrication of ISFET (Ion-Sensitive Field-Effect Transistor) by a four-mask, thermal diffusion-based process. The sequence of physical and chemical processes for ISFET fabrication has been elaborated. In the first photomasking step, the regions for source and drain diffusion have been opened. The second photolithography defined the gate area. In the third photolithographic step, contact windows have been opened, and in the fourth photolithographic step, the metal pattern has been delineated. After completion of the fabrication process, the wafer has been diced into chips, which have been mounted on ceramic substrates to provide electrical connections for source, drain and substrate. Except for the gate region, the whole chip and wire bonds have been protected with insulating epoxy. For process characterization, current-voltage characteristics of MOSFET test devices simultaneously fabricated on the same wafer have been measured for gate-source voltages from -5 to +5 V. These were found to be N-channel, depletion-mode devices indicating similar behaviour for ISFETs. The pH-response of ISFET has been evaluated by drawing its I_DS-V_GS characteristics after immersion in standard buffer solutions and applying the gate-source voltage through Ag/AgCl reference electrode. From these transfer characteristics, pH-sensitivity of ISFET has been determined by finding the gate-source voltage necessary to ensure constant I_DS. V_DS condition. Technological shortcomings of this work have also been pointed out, and necessary remedial measures have been suggested.

11 illus, 32 ref

007708   Kavosh Tehrani M;Babazadeh A (Physics Dep, Maleke-ashtar Univ of Technology, Shahin shahr, Iran, Email: m_kavosh@mut-es.ac.ir) : Quantum size effect on band gap and effective mass of ZnS nano-particle. Asian J Chem 2011, 23(2), 871-4.

Calculate the band gap of ZnS nanoparticle and show that it increases with decreasing its size. The simplest way for discussing this phenomenon and finding the band gap for different sizes is to use effective mass approximation. That shows this method isn't useful for smaller sizes than 2.5 Angstrum because the effective mass of particles below 2.5 Angstrum also depends on the size. The density functional theory was used to obtain the band gap of ZnS nanoparticle. This theory also be used for determine the effective mass for various particle size. Finds equation that shown variation effective mass for various particle sizes of ZnS. This equation fit with experimental results.

9 illus, 1 table, 29 ref

007707   Kanjilal S (Center of Advanced Study in Geology, Banaras Hindu Univ, Varanasi-221 005, Email: kanjilalsushant@rediffmail.com) : 'Stereocidaris' keertii smith, 2010 vis-a-vis 'Stereocidaris' namadica (duncan, 1887) from the Bagh formation, Madhya Pradesh, India. J Palaeont Soc India 2011, 56(2), 237-40.

'Stereocidaris' keertii Smith, 2010 is the second cidaroid echinoid being reported 123 years after the first one, i.e. 'S.' namadica (Duncan, 1887), on the strength of a single specimen, picked loose, from an abandoned quarry at Karondia, assigning both of them a Turonian age. While keertii, at the first glance, looks very similar to 'S.' namadica, the former has been deemed differentiable from the latter for its wider perradial ambulacral zone filled with smaller, somewhat elongate granules, and the degree of coarseness of the extrascrobicular granulation of their interambulacral plates. In this note it has been argued (with an explanation on the likely reasons for the observed differences between namadica and keertii) that Smith's new taxon (the latter obne) is merely an ecophynotypic variant of namadica.

^ssc3 illus, 9 ref

007706   Hussain K M A;Podder J;Saha D K;Ichimura M (Materials Science Div, Atomic Energy Centre, Bangladesh Atomic Energy Commission, Dhaka-1000, Bangladesh, Email: kazi326@yahoo.com) : Structural, electrical and optical characterization of CuInS₂ thin films deposited by spray pyrolysis. Indian J pure appl Phys 2012, 50(2), 117-22.

Copper indium disulphide (CuInS₂) thin films have been deposited on glass substrates by varying Cu:In and S:Cu ratios using spray pyrolysis deposition. The structural, compositional and electrical characterizations of the thin films have been analyzed by Energy Dispersive X-ray Analysis (EDAX), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), dc conductivity measurement and UV-VIS-NIR Spectrophotometry. The surface morphology has beenn studied by SEM. From XRD spectrum, the fundamental peaks of CuInS₂ (CIS) thin films have been identified as (112), (004)/(200), (204)/(220), (116)/(312) and (224) which indicate the chalcopyrite structure and showed an improvement of crystallinity of CuInS₂ thin films for Cu:In:S ratio of 1.14:1:1.88. The temperature variation of dc conductivity showed its semiconducting nature in all the films and the highest conductivity was estimated as 11.1786 (Ω-cm)^-1 and the corresponding band gap of 1.48eV.

8 illus, 2 tables, 10 ref

007705   Haridas G;Verma D;Sahani P K;Nayak M K; Thakkar K K;Sarkar P K (Health Physics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: nayak@rracat.gov.in) : Experimental determination of bremsstrahlung dose rate due to accidental beam loss in Indus-1 storage ring. Indian J pure appl Phys 2012, 50(7), 462-4.

During the operation of an electron storage ring where electron beam is stored for the production of synchrotron radiation, probability of accidental beam loss exists. In the present paper, Bremsstrahlung dose due to accidental beam loss in the storage ring Indus-1 has experimentally been measured. Stored electron beam current ranging from -10 to 100 mA was killed using a beam viewer (destructive) and the Bremsstrahlung dose per event of killing in the forward direction was measured using an ion chamber, made in house, along with an electrometer. Measurement was carried out within the shielded enclosure of the storage ring. Measured dose per event showed linearity up to 99.3 mA. The dose per event of beam killing at 99.3 mA was found to be 5.69 mGy after applying high energy correction factor. The paper describes the experiment and discusses the results.

3 illus, 1 table, 4 ref

007704   Haldar P K;Manna S K;Saha P;Ghosh D (Physics Dep, Jadavpur Univ, Kolkata-700 032, Email: prabirkrhaldar@yahoo.com) : Pecularities in the distribution of produced particles emission in <. Indian J pure appl Phys 2012, 50(3), 156-60.

The angular sub-structures of particle produced within dense and dilute groups along the rapidity axis in ²⁴Mg induced interaction of Ag/Br nuclei in an emulsion detector at 4.5 A GeV/c have been investigated. The experimental results have been compared with the results simulated by Monte Carlo method. Non-statistical jet-like sub-structures have been found in the data. However, when the parameter S₂ is used in the analysis there seems to be definite jet-structure for the dilute groups which cannot be accounted for independent emission model (MC). The average behaviour of the S parameters strongly favours the presence of jet-like sub-structures.

6 illus, 25 ref

007703   Gogoi R;Roy choudhury R;Khan M (Instrumentation Science & Centre for Plasma Studies Dep, Jadavpur Univ, Kolkata-700 032, Email: runmoni@gmail.com) : Arbitrary amplitude dust ion acoustic solitary waves and double layers in a plasma with non-thermal electrons. Indian J pure appl Phys 2012, 50(2), 110-16.

Sagdee's pseudo potential method is employed to study dust ion-acoustic solitary waves in an unmagnetized plasma with non-thermal electrons. An exact analytical expression is obtained for the pseudo potential. The range of parameters for the existence of solitary waves and double layers using the analytical expression of the Sagdeev potential has been found. It is observed that, depending on the values of the plasma parameters like ion temperature σ, non-thermal electron parameter β and the value of the dust grain charge μZ_d, both rarefactive and compressive solitary waves may exist. Critical values of these parameters, beyond which solitary waves would cease to exist, are obtained for some particular cases. Double layer solutions are also obtained for certain parametric values. Exact numerical results are obtained for arbitrary amplitude solitons and double layers.

7 illus, 35 ref

007702   Ghoshal S K;Sahar M R;Dousti M R;Sharma S; Rohani M S;Arifin R;Hamzah K (Advanced Optical Material Research Group, Physics Dep, Faculty of Science, Teknologi Malaysia Univ, 81310 UTM Skudai, Johor, Malaysia, Email: sibkrishna@utm.my) : Model for up-conversion luminescence in silver nanoparticles embedded erbium-doped tellurite glass. Indian J pure appl Phys 2012, 50(8), 555-65.

Nanoparticles (NPs) size dependent enhancement of the infrared-to-visible frequency up-conversion (UC) and absorption coefficient in silver NPs embedded Er³⁺ doped tellurite glasses on pumping with the 976 nm radiation have been investigated. The rate equations derived from the 4-level model developed by the authors earlier to discuss temperature dependent UC have now been extended to study the role played by NPs. The effects of quantum confinement and local field of silver NPs have been incorporated. Considering the spherical NPs size distribution as Gaussian, an analytical expression for the luminescence intensity and absorption coefficient has been obtained for the first time, is further exploited to examine the enhancement of UC emission intensity due to the presence of silver NPs. Furthermore, an enhancement in UC emission intensity of the green bands (²H_11/2→⁴I_15/2 and ⁴S_3/2→⁴I_15/2) and red band (⁴F_9/2→⁴I_15/2) emission of Er³⁺ ion at temperature 250 K and optimized Er³⁺ concentration 1.0 mol% have been observed up to few times in the presence of silver NPs in the glass. The green emission showed larger enhancement than the red emission. The observed of Er³⁺ luminescence is mainly attributed to the local field effects namely the surface plasmon resonance of silver NPs which causes an intensified electromagnetic field around NPs, resulting in enhanced optical transitions of Er³⁺ ions in the vicinity. The model is quite general and can be applied to other rare earth doped glasses containing metallic NPs. Our results on NPs size dependent emission intensity and absorption coefficient are in conformity with other findings. The present systematic study provides useful information for further development of UC lasers and sensors.

4 illus, 40 ref

007701   Dighe P M;Kamble L P;Das D;Pithawa C K (Electronics Div, Bhabha Atomic Research Center, Mumbai-400 085, Email: pmdighe@barc.gov.in) : Low energy pulsed X-ray ion chamber monitor for accelerator safety. Indian J pure appl Phys 2012, 50(7), 458-61.

Ion chamber sensitive to low energy pulsed X-rays has been developed for area monitoring at the electron accelerators Indus 1 and 2 of Raja Ramanna Centre for Advanced Technology, Indore. Conventional monitors available commercially underestimate the X-ray background because of pulsed nature of the radiation and are not sensitive to X-rays below 100 keV. For this purpose, a high pressure ion chamber made of aluminium with all welded construction has been developed and tested for use in pulsed X-ray background. The chamber has 25 litre sensitive volume, filled with nitrogen at 85 psi and current sensitivity is 12 nA/R/h. The chamber can measure exposure levels from 20 μR/h to 100 mR/h and has uniform energy response within ±12% from 35 keV to 1.25 MeV of X-ray energy. The ion chamber gave more than 86% collection efficiency at 100 mR/h average pulsed X-ray background for 500 V operating voltage. Theoretically evaluated collection efficiency values closely match with the experimentally observed values. The design details and characterisation of the ion chamber under different X-ray energy exposures and collection efficiency estimation for pulsed X-ray background have been studied.

7 illus, 4 ref

007700   Dhoble S J;Puppalwar S P;Dhoble N S;Mohanty A K (Physics Dep, RTM Nagar Univ, Nagpur-440 033, Email: sjdhoble@rediffmail.com) : One step synthesis of Cu<. Indian J pure appl Phys 2012, 50(7), 520-3.

Cu⁺ activated Li₂BPO₅ phosphor is synthesized by one step wet chemical technique and exposed to gamma-rays of ⁶⁰Co source for their thermolurninescence (TL) properties. The XRD technique shows the crystalline nature of the prepared material. Photoluminescence (PL) emission spectra of Li₂BPO₅:Cu phosphor show the strong prominent peak at 368 nm in the violet region of the visible spectrum assigned to the transition of 3d⁹4s¹ ↔ 3d¹⁰ of Cu⁺ ion. Thermolurninescence characterization of prepared Li₂BPO₅:Cu is low Z (Z_eff = 10.29) phosphor shows the prominent TL glow peak at 143°C at higher temperature and intensity is 2.6 times less than that of standard TLD CaSO₄:Dy (Z_eff = 15.3) phosphor, but almost 7.8 times more than that of well known LiF: Mg, Ti low Z phosphor. It may be one of the candidates for thermoluminescence dosimetry (TLD) of ionization radiations.

4 illus, 1 table, 15 ref

007699   Deore A V;Patil B J;Bhoraskar V N;Dhole S D (Physics Dep, Pune Univ, Pune-411 007, Email: sanjay@physics.unipune.ac.in ) : Design, development and characterization of tetrode type electron gun system for generation of low energy electrons. Indian J pure appl Phys 2012, 50(7), 482-5.

A tetrode type electron gun system for the generation of low energy electrons has been designed, developed and characterized. The electron gun, designed for irradiation experiments, has four electrodes namely, cathode, focusing electrode, control electrode and anode. This electron gun is capable to provide electrons of energy over the range of 1 keV to 20 keV, with current maximum 100 μA. The electron gun and a Faraday cup are mounted in the evacuated cylindrical chamber. The samples are fixed on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber and irradiated with low energy electrons at a pressure around 10^-6 mbar. In this electron gun system, at any electron energy over the entire range, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup. Also, the circular shape of the beam spot was maintained, even though the beam current and beam diameter are varied. The uniformity of the electron beam over the entire beam area was measured with a multi-electrode assembly and found to be 15%. This system is being used for the synthesis and diffusion of metal and semiconductor nanoparticles in polymeric and glass materials.

5 illus, 8 ref

007698   Cunha P D;Narayana Y (Studies in Physics Dep, Mangalore Univ, Mangalagangotri-574 199, Email: naryanay@yahoo.com) : Comparison of methodologies of gamma ray spectrometer and X-ray fluorescence. Indian J pure appl Phys 2012, 50(7), 524-6.

Gamma-ray spectrometric analysis is often considered as an ideal method for thorium analysis, which would otherwise require the use of more tedious, time consuming and often less precise chemical methods. With the development of rare earth research, X-ray fluorescence spectrometry analysis has become an important means of rare earth elements analysis and has been playing an increasingly important role. In the present study, the XRF-spectrometry and gamma-spectrometric techniques Have been carried out in determining the concentration of thorium in monazite bearing sand samples. Monazite is the principal source of thorium and the rare earth elements but its composition and the distribution may vary within very wide limits. Both XRF and Gamma-ray spectrometry techniques use uncharged radiation, although of different in origin, to identify and estimate concentrations of elements present in the sample. However, the XRF method is much quicker and the amount of sample needed for analysis is much less compared to gamma spectrometry analysis. The correlation study of the results obtained by these two methods was analysed and compared.

1 illus, 1 table, 8 ref

007697   Chen H P (Electronic Engineering Dep, Ming Chi Technology Univ, Taishan, Taiwan, R O C, Email: hpchen@mail.mcut.edu.tw) : Versatile current-mode universal biquadratic filter using plus-type dual-output ICCIIs. Indian J pure appl Phys 2012, 50(3), 188-98.

In this paper, a versatile three-input and three-output universal current-mode biquadratic filter is proposed. The circuit employs three plus-type dual-output inverting second-generation current conveyors (DO-ICCIIs) as active elements together with three grounded resistors and two grounded capacitors. The proposed configuration exhibits high-output impedance which is important for easy cascading in the current-mode operations. It can be used as either a single-input three-output or three-input two-output circuit. In the operation of single-input and three-output circuit, the lowpass, bandpass and bandreject can be realized simultaneously while the highpass filtering response can be easily obtained by connecting appropriate output current directly without using additional stages. In the operation of three-input and two-output circuit, all five generic filtering functions can be easily realized by selecting different three input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency and no component matching conditions or inverting-type input current signals are imposed. All the passive and active sensitivities are low. Post-layout simulations are based on using TSMC 0.18μm 1P6M CMOS process technology and supply voltages °0.9V to verify the theoretical analysis.

18 illus, 42 ref

007696   Chaudhary N;Bhattacharjee D;Yadav Y;Sharma S D;Acharya S;Dixit K P;Mittal K C (Accelerator & Pulse Power Div, Bhabha Atomic Research Centre (BARC), Mumbai-400 085, Email: nishantchaudhary06@gmail.com) : Monte Carlo simulation and measurement of X-ray dose from 9 Me V RF electron LINAC for cargov scanning. Indian J pure appl Phys 2012, 50(7), 517-19.

The 9 MeV RF Electron Linear Accelerator (Linac) is operational at Electronic Corporation of India Limited (ECIL), Hyderabad to demonstrate cargo-scanning applications to prevent the transport of contraband objects. The interrogation is done by a fanned X-ray beam produced by impinging an energetic electron beam on tantalum (Ta) target. The desired dose rate for this purpose is 22 Gy/min at 1 m from the X-ray source. It is required to determine the X-ray dose rate at one meter distance from the X-ray converter for a given set of beam parameters. Monte Carlo simulations have been done for the X-ray dose rate measurement by using Geant4 software toolkit. X-ray dose rate values at 1 m distance from X-ray target have been estimated at various polar angles with respect to the direction of the incident beam. The plot shows angular distribution of significant X-ray intensity in a cone of 15° half-angle. The maximum X-ray emission is in the forward direction of the beam and the dose-rate is estimated to be 19.40 Gy/min when the beam parameters are (i) 9 MeV energy (ii) 60 mA peak beam current and (iii) 250 Hz pulse repetition frequency (PRF). Experiments have also been carried out using air ionization chamber to obtain X-ray dose-rate at 1 m distance from target. The measured value without an electron-stopper after the target is 20.63 Gy/min at 1 m distance which is close to the required dose rate for the actual cargo scanning purpose. The simulated results also closely match with the experimental observations, implying that the present simulation model is suitable for the characterization of an X-ray source for cargo scanning applications.

3 illus, 2 ref

007695   Chatterjee S;Bandyopadhyay T (TLD Unit, RP&AD, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085, Email: sujoy@vecc.gov.in) : Estimation of induced activity in superconducting cyclotron at VECC: Monte Carlo calculations. Indian J pure appl Phys 2012, 50(7), 498-500.

This; study has been carried out for the estimation of the induced activity in different parts of the accelerator and in the radiation shield constructed around the accelerator and the dose rate after various cooling times to estimate the dose to the radiation workers during the shutdown and maintenance of the cyclotron. An effort has also been made to estimate the residual activity for 80 MeV protons bombarded on Stainless Steel thereon activity produced on different materials like Cu, Al, Concrete and SS of different thickness. Cu, Al, SS are among many other materials which are widely used for fabrication of any accelerator.

6 illus, 3 ref

007694   Chatterjee A (Nuclear Physics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: amber@barc.gov.in) : Nuclear physics experiments using accelerators. Indian J pure appl Phys 2012, 50(7), 454-7.

In this paper, we present safety aspects for nuclear physics experiments from an accelerator user's perspective. An overview of the BARC-TIFR Pelletron and LINAC accelerators is given, followed by a description of the common experimental set-ups. In these experiments, detectors are used both online and offline to collect information. Detectors signals are processed by suitable electronics and data is gathered in data acquisition systems. Studies of nuclear reactions are often carried out in a scattering chamber. Description of the experiments and safety aspects are presented. Data acquisition systems are described. Aspects of data safety are discussed.

5 illus, 4 ref

007693   Biju K;Sunil C;Sarkar P K (Health Physics Div, Bhabha Atomic Research Centre, Trombay, Mumbai-400 094, Email: bijuk@barc.gov.in) : Scattering of neutrons in a high energy proton accelerator enclosure and the production of <. Indian J pure appl Phys 2012, 50(7), 465-8.

The neutron field inside high energy and high intensity proton accelerators can produce activation of air. The neutrons backscattered by the concrete walls contribute largely to production of argon-41 and carbon-14 concentration. Detailed knowledge on the neutron spectrum is necessary for the accurate estimation as the neutrons lying above thermal energy up to around 1.5 MeV, can also produce the ⁴¹Ar considerably large amount in addition to the thermal neutrons. Hence, the reflection of neutrons in a typical proton accelerator facility for proton energies in the range 100-500 MeV by concrete walls and the concentration of ⁴¹Ar and ¹⁴C has been studied in detail in using FLUKA Monte Carlo code. The neutron spectra inside the facility clearly indicate the dominance of the neutrons of energies within 1.5 MeV. The estimated neutron albedo/backscatter factors for the secondary generated by the 100 MeV proton beam falling on the copper target have been estimated around 11%. The build up of ⁴¹Ar and ¹⁴C concentration for a 24 hr proton beam irradiation and the decay of the activity for the next 24 hours after the beam shut down are estimated. The Monte Carlo computed saturated ⁴¹Ar concentration values are 2.5 times higher than that of the estimations based on analytical calculations, which assume the activation only by thermal neutrons.

6 illus, 4 tables, 7 ref

007692   Behrens R (Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany, Email: Rolf.Behrans@PTB.de) : Spectrometer for pulsed and continuous electron and photon radiation. Indian J pure appl Phys 2012, 50(7), 450-3.

A few-channel spectrometer for the determination of absolute fluence and energy distributions (spectra) of electrons and photons was developed. This spectrometer consists of thermo-luminescence detectors (TLDs) placed in a stack of 30 different absorbers. From the measured depth dose curve, the impinging particle spectra can be derived via unfolding methods (data evaluation). In mixed radiation fields, it is necessary to take information into account in addition to the measured depth dose curve (additional pre-information) for the data evaluation. The spectrometer was successfully applied in different areas.

7 illus, 11 ref

007691   Bafna M K;Sen P;Sen P K (Applied Physics Dep, Mandsaur Institute of Technology, Indore, Email: mkbafna@gmail.com) : Theoretical study of spin splitting in parabolic semiconductor quantum dots. Indian J pure appl Phys 2012, 50(8), 571-5.

The spin splitting in a lens shaped quantum dot in the absence of the externally applied magnetic field has been studied. Considering the parabolic confinement potential, the eigenfunctions and energy eigenvalues have been obtained. The analytical results have been applied to a II-VI, III-V semiconductor viz, CdSe/Znse, In_xGa_1-x. As quantum dot and the effect of dot size on the splitting energy has been calculated and the results have been compared with the experimental observations.

1 table, 19 ref

007690   Anbarasu P;Arivazhagan M;Balachandran V (Electronics Dep, Government Arts College, Paramakudi-623 707, Email: jjmarivu@yahoo.co.in) : Scaled quantum mechanical study of 2-acetyfluorene. Indian J pure appl Phys 2012, 50(2), 91-9.

The FTIR and FT-Raman spectra of 2-acetylfluorene have been measured in the range 4000-50 cm and 3500-50 cm, respectively. Utilising the observed FTIR and FT-Raman data, complete vibrational assignment and analysis of the fundamental modes of the compound have been carried out by employing the B3LYP/6-31 l++G(d,p) method for optimized geometries. The Total Energy Distribution (TED) values obtained reflect the correctness of the vibrational assignments.

3 illus, 4 tables, 22 ref

007689   Anand S;Singh K D;Sharma V K (Safety Studies Section, Health Physics Dep, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085, Email: sanand@barc.gov.in) : Shield design for a hull neutron monitor using Monte Carlo techniques. Indian J pure appl Phys 2012, 50(7), 527-30.

In the head-end process of a reprocessing plant, the spent fuel is chopped using a mechanical chopper into small pieces and the heavy metal oxide is leached in nitric acid leaving behind the undissolved zircaloy clad (hull) in the basket. The hull mass needs to be estimated for the residual actinides and fission products to check for the completion of dissolution and also for the purpose of nuclear material accounting. This is normally carried out by gamma spectroscopy for the residual fission products. A new method is proposed based on active/passive neutron measurements of the residual actinides. The basket along with the hull is moved to a corner of the dissolution cell using remote tools, where the hull monitoring exercise will be carried out. Hence, shielding around this basket is required in this area to limit the dose rate to a value acceptable (i) for the operating personnel engaged in monitoring, and (ii) for He detectors used to measure neutrons. It has been proposed that the acceptable dose rate criteria at this detector location should be less than 1.74 mGy/hr (200 mR/hr). ORIGEN2 code is used to calculate the gamma and neutron emission rate from the residual spent fuel and the clad material in the hulls. Shielding code based on Monte Carlo technique is used for the gamma and neutron shielding calculations. In this paper, calculations are carried out for each oMhe shield material considered, and it is found that the shielding thickness required to bring down the dose rate to 1.74 mGy/hr is 12.5 cm for lead or 21 cm for iron.

5 illus, 5 tables, 5 ref

007688   Acharya S;Joseph P;Bhat N N;Sanjeev G; Narayana Y (Engineering Physics Dep, Alva's Institute of Engineering and Technology, Moodbirdi-574 225, Email: narayanay@yahoo.com ) : Assessment of cell damages induced by gamma rays and pulsed electron beam at different dose rates. Indian J pure appl Phys 2012, 50(7), 474-7.

The analysis of radiation induced micronuclei frequency in a binucleated cell (MN/BNC) is a standard biological end point to determine the cell damage as well as absorbed dose. In the present study, biological end points such as binucleated cells with micronuclei (BNC with MN) and the number of micronuclei per micro-nucleated binucleated cell (MN/(BNC with MN)) have been used to assess the cell damage. Further, the results of BNC with MN and MN/BNC with MN have been compared with those of previously obtained MN/BNC results. Cell damages have been assessed in human blood lymphocytes, exposed to ⁶⁰Co γ-rays at a dose rate of 0.033 Gy s^-1 and 8 MeV pulsed electron beam at a mean instantaneous dose rate of 2.6 x 10⁵ Gy s^-1. The relative biological effectiveness (RBE) for electrons in comparison with γ-rays, has been studied. Dosimeters such as fricke and ferrous ammonium benzoic acid and xylenol orange have been used for the dose measurements. The linear-quadratic dose response curves have been observed for both gamma and electrons. However, the relative effectiveness of 8 MeV electrons with that of gamma radiation for MN yield was found to be more than unity for all the biological endpoints studied at a given dose. Present study suggests that the quantification of BNC with MN and MN/(BNC with MN) along with MN/BNC provides additional information, while assessing radiation induced cell damage.

4 illus, 3 tables, 10 ref

006682   Xavier S;Binu P J;Thankachan S (Physics Dep, Maharajas College, Ernakulam-682 011, Email: emmohammed_2005@yahoo.com ) : Dielectric properties of Co_1-xZn_xFe₂O₄ nanoparticles. Sci Soc 2011, 9(2), 175-82.

Series of polycrystalline spinel ferrites with composition Co_1-x Zn_XFe₂O₄ (x =0, 0.1, 0.3 and 0.5) have been synthesized by co-precipitation method. X-ray diffraction analysis showed that the samples were cubic spinel. The average crystallite size of the particles determined from the XRD was found to vary from 9 to 17 nm. The dielectric properties were studied as a function of frequency in the range 20Hz to 100MHz. The variation of dielectric properties and ac conductivity with frequency reveals that the dispersion is due to Maxwell - Wagner type of interfacial polarization. The Fourier Transform Infrared Spectroscopic analysis of the samples corroborates the spinel structure characteristics of Co_1-XZn_XFe₂O₄.

7 illus, 1 table, 23 ref

006681   vidya C;Ramamurthy P C;Joseph C M (Physics Dep, Dayananda Sagar College of Engineering, Bangalore-560 078, Email: cmjoseph@rediffmail.com) : Optical and structural studies on spin coated copper phthalocyanine (CuPc) thin films. Sci Soc 2011, 9(2), 193-6.

Thin films of CuPc were deposited using a spin coating method onto glass substrates. CuPc solution was prepared in acetonitrile and the deposition was done with a spin coater and then the films were annealed in vacuum (10^-3 Torr) at 70° C for 24hr. Uniform films were obtained for different rotor speeds. Optical, structural and microstructural characterizations were done and the results are discussed. The optical band gap for the film as obtained from the graph is around 1.66 eV. X ray diffraction studies on CuPc film deposited showed crystallinity and two major peaks with preferred orientation for CuPc. The grain size for the CuPc films is found to favor larger grain size for the annealed thin films.

4 illus, 20 ref

006680   Thankappan A;Joseph S A;Nampoori V P N (International School of Photonics, Cochin Science and Technology Univ, Cochin-682 022, Email: aparna.subhash@gmail.com) : Enhancement of UV emission of ZnO microrods on changing the excitation wavelength. Sci Soc 2011, 9(2), 151-4.

Presents excitation wavelength dependent spectroscopic observations of micro colloids of ZnO. The rods are synthesized by hydrothermal method; under prolonged treatment of zinc nitrate for 22 hrs in low temperature (80° C) with hexamine. The synthesized rods have an average length of 5 μm with hexagonal cross section. On changing the excitation wavelength from 266nm to 316nm, it can be seen that the UV emission is enhanced and visible emission is suppressed. This is proved by changing the concentration of the sample solution from 0.5m mol to 3m mol.

6 illus, 7 ref

006679   Thankachan S;Binu P J;Xavier S;Mohammed E M (Physics Dep, Maharajas College, Ernakulam-682 011, Email: emmohammed_2005@yahoo.com) : Dielectric studies of magnesium ferrite nanoparticles. Sci Soc 2011, 9(2), 163-8.

Magnesium ferrite nano particles were prepared using sol-gel technique which is one of the novel techniques to prepare nanosized particles. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. XRD analysis reveals the prepared samples are single phasic till with the spinel structure. Particle size calculation shows the prepared samples are of 10nm in size. FTIR analysis confirmed spinel structure of the prepared samples. Composition analysis was done using XRF. XRF result satisfies the expected composition of the prepared samples. The frequency dependence of the dielectric constant in the range 20 Hz -120MHz was also studied in the temperature range 300K-533K. Dielectric dispersion of nano ferrite can be explained using Maxwell-Wagner theory in consonance with Koops theory.

2 tables, 19 ref

006678   Sutradhar S;Pal M (NO, CSIR-Central Mechanical Engineering Research Institute, Durgapur-713 209, Email: m_pal@cmeri.res.in) : Nanocrystelline multiferroic materials. Sci Soc 2011, 9(2), 9-12.

Recently, great attention has been paid to multiferroics, which simultaneously show spontaneous electric and magnetic ordering in the same phase, due to the potential application for new electronic devices as well as the fascinating fundamental physics. Perovskite BiFeO₃, is one of the well known multiferroics with simultaneous ferroelectric (T_c → 1103 K), G-type antiferromagnetic (T_N → 643 K) and exhibit very weak magnetism at room temperature due to a residual moment from a canted spin structure². A major problem generally encountered in transport measurements is the high leakage current due to the low resistivity of the sample, which creates difficulties in the observation of the ferroelectric hysteresis loops. The high leakage current in bulk is attributed to defects and nonstoichiometry. So, improvement in magnetic properties and reduction of leakage current is essential for its real use in device applications.

4 illus, 10 ref

006677   Sumod S G;Pant T K;Nayar S R P (Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum-695 022, Email: sgsumodh@gmail.com) : On the variability of the observed HF doppler derived equatorial F-region plasma drifts during evening and morning hours and the chemical corrections therein. Indian J Radio Space Phys 2012, 41(2), 130-40.

Radar derived F-region vertical plasma drift measurements, especially during evening/morning hours are apparent mainly because of the additional contribution from photochemical loss and/or production. As a consequence, it is very important to delineate the role of chemistry from these drift measurements in order to have a meaningful/realistic interpretation of the actual movement of the plasma in the ionosphere. In this paper, two chemical schemes have been employed separately for evening and morning hours to estimate the apparent drifts produced solely due to the chemistry. This study has been carried out by taking into account the important chemical reactions over equator during these times and for the computation, the neutral density of N₂, O₂, and neutral temperature T_n have been obtained from the Mass Spectrometer and Incoherent Scatter (MSIS) model. The temporal, altitudinal and seasonal variations of the chemical contributions have been theoretically estimated. The observed F-region vertical plasma drift measurements obtained from a multi-frequency HF Doppler radar over Trivandrum (8.5°N, 77°E, 0.5°N dip latitude) are then corrected, by taking into account the reflection height variation. The study reveals that (i) the apparent drift due to chemistry is strongly altitude dependent and can indeed be as high as 10-15 m s^-1; (ii) there is a clear cut seasonal pattern for these correction factors with a northern hemispheric (NH) summer (lune) minima and a maxima during the NH winter solstice (December).

9 illus 2 tables, 30 ref