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Dielectric response of makrofol-KG polycarbonate irradiated with 145 MeV Ne6+ and 100 MeV Si8+ ions
No full textThe passage of heavy ions in a track detector polymeric material produces lattice deformations.
These deformations may be in the form of latent tracks or may vanish by self annealing in time. Heavy ion
irradiation produces modifications in polymers in their relevant electrical, chemical and optical properties in the
form of rearrangement of bonding, cross-linking, chain scission, formation of carbon rich clusters and changes
in dielectric properties etc. Modification depends on the ion, its energy and fluence and the polymeric material. In
the present work, a study of the dielectric response of pristine and heavy ion irradiated Makrofol-KG polycarbonate
is carried out. 40 μm thick Makrofol-KG polycarbonate films were irradiated to various fluences with Si8+ ions of
100 MeV energy from Pelletron at Inter University Accelerator Centre (IUAC), New Delhi and Ne6+ ions of 145 MeV
from Variable Energy Cyclotron Centre, Kolkata. On irradiation with heavy ions dielectric constant ( ) decreases
with frequency where increases with fluence for both the ions. Variation of loss factor (tan ) with frequency
for pristine and irradiated with Si ions reveals that tan increases as the frequency increases. Tan also
increases with fluence. While Ne irradiated samples tan shows slight variation with frequency as well as with
fluence. Tan has positive values indicating the dominance of inductive behavior.Author Affiliation: Rajesh Kumar, S Asad Ali, Udayan De, D K Avasthi and Rajendra Prasad
1.Department of Applied Physics, Z H College of Engineering & Technology,
Aligarh Muslim University, Aligarh-202 002, Uttar Pradesh, India
2.Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata-700 064, India
3.Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110 067, India
E-mail : [email protected] of Applied Physics, Z H College of Engineering & Technology,
Aligarh Muslim University, Aligarh-202 002, Uttar Pradesh, India
Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata-700 064, India
Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110 067, Indi
Seasonal variation on radon emission from soil and water
No full textRadon is being measured continuously in spring water and soil-gas at Badshahi Thaul Campus,
Tehri Garhwal in Himalayan region by using radon Emanometer since December 2002. An effort was made to
correlate the variance of radon concentrations in spring water and soil-gas with meteorological parameters at
the same location. The main meteorological parameters that affect the radon emanation from host material is
surrounding temperature, barometric pressure, wind velocity, rain fall and water level of the spring. The correlation
coefficient between radon concentration in spring water and different atmospheric parameters was computed.
The correlation coefficient between radon concentration in spring water and the maximum atmospheric temperature
was 0.3, while it was 0.4 for minimum atmospheric temperature at the monitoring site. The correlation coefficient
for radon concentration in spring water with minimum and maximum relative humidity was 0.4. Spring water
radon concentration was found positively correlated (0.6) with water discharge rate of the spring. A weak
correlation (0.09) was observed between the radon concentration in spring water and rain fall during the
measurement period. As temperature of near surface soil increases, the radon emanation coefficient from the
soil surface also increases. The possible effects due to global warming and other climatic changes on environment
radiation level were also discussed in detail.Yogesh Prasad1, Ganesh Prasad1, G S Gusain1, V M Choubey2 and R C Ramola1*
1Department of Physics, H N B Garhwal University, Badshahi Thaul Campus,
Tehri Garhwal-249 199, Uttarakhand, India
2Wadia Institute of Himalayan Geology, Dehradun-248 001,
Uttarakhand, India
E-mail : [email protected] of Physics, H N B Garhwal University, Badshahi Thaul Campus,
Tehri Garhwal-249 199, Uttarakhand, India
Wadia Institute of Himalayan Geology, Dehradun-248 001,
Uttarakhand, Indi
The role of CDW gap on the magnetic phase transition in CMR materials
No full textWe propose a model to study the magnetic phase transition in the
Colossal-Magneto-Resistance (CMR) material of general type R1–xAxMnO3(R = La, Sm,
Nd; A = Ca, Sr, Ba). The model Hamiltonian consists of a Charge Density Wave (CDW)
gap in the eg-band and the strong magnetic field due to the spin ordering in the
localized tgcore electrons. The Hamiltonian is solved by using Zubarev’s Green’s
function technique to calculate CDW gap (.) and magnetization (Md)in t2g band. Both
of them are solved self-consistently. Their combined effect on the temperature
dependent magnetization (Mc) due to the eg band electrons is investigated. Both the
magnitude and the transition temperature of (Mc) are strongly influenced by both .
and Md. Hence the hopping of the band electrons are strongly controlled by these two
long range interactions. The results are discussed by varying the model parameters
of the manganite system.The role of CDW gap on the magnetic phase transition in
CMR materials
S Panda and G C Rout1*
Trident Academy of Technology, F2/A, Chandaka Industrial Estate, Bhubaneswar-751
024, Orissa, India
1Condensed Matter Physics Group, Department of Applied Physics and Ballistics, Fakir
Mohan University,
Balasore-756 019, Orissa, India
E-mail : [email protected] Academy of Technology, F2/A, Chandaka Industrial Estate, Bhubaneswar-751
024, Orissa, India
1Condensed Matter Physics Group, Department of Applied Physics and Ballistics, Fakir
Mohan University,
Balasore-756 019, Orissa, Indi
Nanoparticle size characterization by laser light scattering
No full textSpherical semiconductor nanoparticles (ZnS) were specially fabricated by
an inexpensive chemical route. The scattering profile of the nanoparticles was
investigated by laser light scattering technique. A beam of polarized light from a
diode laser (.0˜ 630 nm) was allowed to fall on the nanospheres embedded in flexible
host matrix Polyvinyl Alcohol (PVA). The light scattered from the samples were
detected by means of analyzer mounted photodiode array from 10° to 170° in steps of
1°. Signals from the detectors were interfaced with a high resolution data
acquisition system and the whole experiment was carried out in differential mode.
Size of the nanoparticles was obtained by using Mie theory and verified by T-matrix
approach. The results obtained agree with the XRD and TEM results.Nanoparticle size characterization by laser light scattering
A Gogoi*, G A Ahmed and A Choudhury
Optoelectronics and Photonics Laboratory, Department of Physics,
Tezpur University, Tezpur-784 028, Assam, India
E-mail : [email protected] and Photonics Laboratory, Department of Physics,
Tezpur University, Tezpur-784 028, Assam, Indi
Electrical properties of thin films of Eu2O3 substituted compounds
No full textEuropium oxide (Eu2O3) substituted compound has been prepared by
solid-solid reaction of the powders of Eu2O3, BaCO3 and CuO at 950°C for 16 hours.
The thin films have been deposited by high vacuum evaporation technique (vacuum ˜
10–6 torr). The variation of current (I ) with voltage (V ) at room temperature (RT
) i.e. 294 K and in ice (273 K) are found to be linear. The variation of electrical
resistivity (.) with temperature
(T ) by heating the sample above RT has been determined. Resistivity is found to
decrease with increase in temperature. Further the variation of electrical
resistivity (.) with temperature (T) from 77 K, liquid nitrogen temperature (LNT),
to 270 K has also been determined. It is observed that resistivity suddenly becomes
zero at around 87 K. Thus the prepared material has superconducting properties with
superconducting transition temperature, Tc at 87 K.Electrical properties of thin films of Eu2O3 substituted compounds
S Bhattacharjee* and B Baishya
Department of Physics, Dibrugarh University Dibrugarh-786 004, Assam, India
E-mail : [email protected] of Physics, Dibrugarh University Dibrugarh-786 004, Assam, Indi
Use of chemical etching of CR-39 foils at elevated temperature for fast neutron personnel monitoring in India
No full textCR-39 Solid State Nuclear Track Detecting foils (SSNTD), along with 1 mm
thick polyethylene radiator, sealed in triple laminated pouches, are used for
country wide Fast Neutron Personnel Monitoring in India. With the present system of
processing by elevated temperature electrochemical etching (ETECE) and evaluation
using automatic image analysis, only 16 foils are processed at a time and it is
useful over the dose equivalent range 0.2 mSv to 10 mSv. It has been reported that,
by processing CR-39 of good detection efficiency by chemical etching at elevated
temperature, more numbers of foils can be processed simultaneously.
In the present study, CR-39 foils from Pershore Moulding (UK) have been chemically
etched using 7 N KOH under various conditions of temperature and etching durations
and evaluated using high magnification microscope. The duration of chemical etching,
has been optimized at a constant temperature of 60°C for chemical etching process.
The characteristics of the chemically etched CR-39 foils are compared with the
characteristics of the CR-39 foils processed by the existing system of ETECE and the
detailed results are presented in the full text of the paper. It has been observed
that by chemical etching process, the dose equivalent range of CR-39 foils can be
extended above 60 mSv.Use of chemical etching of CR-39 foils at elevated temperature for fast neutron
personnel monitoring in India
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1Personnel Monitoring Section, Radiological Physics and Advisory Division, Bhabha
Atomic Research Centre,
Mumbai-400 094, India
2Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai-400 094,
India
E mail : [email protected] Monitoring Section, Radiological Physics and Advisory Division, Bhabha
Atomic Research Centre,
Mumbai-400 094, India
2Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai-400 094,
Indi
Review of Library & Information Services: Its Progressive Metamorphosis from Paper Library to a New Paradigm of Knowledge Hub
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