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Low temperature electron mobility in Ga0.5In0.5P/GaAs quantum well structures
No full textWe analyse the low temperature subband electron mobility in a
Ga0.5In0.5P/GaAs quantum well structure where the side barriers are delta-doped with
layers of Si. The electrons are transferred from both the sides into the well
forming two dimensional electron gas (2DEG). We consider the interface roughness
scattering in addition to ionised impurity scattering. The effect of screening of
the scattering potentials by 2DEG on the electron mobility is analysed by changing
well width. Although the ionized impurity scattering is a dominant mechanism, for
small well width the interface roughness scattering happens to be appreciable. Our
analysis can be utilized for low temperature device applications.Low temperature electron mobility in Ga0.5In0.5P/GaAs quantum well structures
T Sahu*, J N Patra1 and P K Subudhi2
Department of Electronic Science, Berhampur University, Berhampur-760 007, Orissa,
India
1Department of Physics, S B R Govt. (Auto) Women.s College, Berhampur, Orissa, India
2Department of ECE, IACR Degree Engineering College, Rayagada-765 002, Orissa, India
E-mail : [email protected] of Electronic Science, Berhampur University, Berhampur-760 007, Orissa,
India
1Department of Physics, S B R Govt. (Auto) Women.s College, Berhampur, Orissa, India
2Department of ECE, IACR Degree Engineering College, Rayagada-765 002, Orissa, Indi
Thoron in the environment and its related issues
No full textSince radon is internationally noted as the second cause of lung cancer,
many countries are trying about to solve the problem worldwide. In addition, a new
evidence of lung cancer risk has been recently found out with a low level below 200
Bq m–3. Thus the action level will have to be set lower than before. Importance of
radon exposure has been further recognized and accurate radon concentrations will be
required. Recently thoron has also been recognized from the viewpoint of accurate
radon measurements. The present paper describes specification of the NIRS radon and
thoron chambers, passive measurement technique of radon and thoron and thoron
interference on radon measurements from both experimental studies and field
experiences on epidemiological study area.Thoron in the environment and its related issues
Shinji Tokonami
National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba
263-8555, Japan
E-mail : [email protected] Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba
263-8555, Japa
Thoron in the environment and its related issues
No full textSince radon is internationally noted as the second cause of lung cancer,
many countries are trying about to solve the problem worldwide. In addition, a new
evidence of lung cancer risk has been recently found out with a low level below 200
Bq m–3. Thus the action level will have to be set lower than before. Importance of
radon exposure has been further recognized and accurate radon concentrations will be
required. Recently thoron has also been recognized from the viewpoint of accurate
radon measurements. The present paper describes specification of the NIRS radon and
thoron chambers, passive measurement technique of radon and thoron and thoron
interference on radon measurements from both experimental studies and field
experiences on epidemiological study area.Thoron in the environment and its related issues
Shinji Tokonami
National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba
263-8555, Japan
E-mail : [email protected] Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba
263-8555, Japa
Gamma and neutron dose measurements with solid state nucleartrack detectors
No full textAn attempt has been made to explore the possibility of using solid state
nuclear track detectors for the estimation of gamma and neutron doses based on the
use of changes in activation energy of degradation of these detectors, due to
irradiation (gamma.neutron), as a means of dosimetry. Thermogravimetry (TG) has been
applied as a tool for these studies carried out on Lexan and CR-39 track detectors.
A linear relationship observed between the decrease in activation energy and the
dose (gamma.neutron) received by the detectors suggests the possibility of the use
of these detectors as gamma and neutron dosimeters.Gamma and neutron dose measurements with solid state nucleartrack detectors
P C Kalsi
Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai-400 085, India
E-mail: [email protected] Division, Bhabha Atomic Research Centre, Mumbai-400 085, Indi
Oxygen (O6+) ion beam irradiation effects on etching parameter in lexan polymeric track detector
No full textThe polymer Lexan was irradiated to 80MeV O6+ ion beam using the 15UD pelletron at Inter
University Accelerator Centre, New Delhi. The ion fluence ranging from 1011 to 3 × 1012 ions/cm2 has been used
to study the dose effects of irradiation on Lexan. By using the etching technique, it is observed that the bulk etch
rate of the sample increases with increasing the ion influence, while the activation energy associated with it
show a decreasing trend which can be explained on the basis of polymer degradation.Neerja* and Surinder Singh
Department of Physics, Guru Nanak Dev University,
Amritsar-143 005, Punjab, India
E-mail : [email protected] of Physics, Guru Nanak Dev University,
Amritsar-143 005, Punjab, Indi
Spectroscopic studies of copper and carbon ion irradiated polypropylene
No full textThe samples of polypropylene (PP) have been irradiated with 120 MeV 64Cu9+ and 70 MeV 12C5+
ion beams, with the fluence ranging from 1 × 1013 to 1 × 1011 ions/-cm–2. UV-VIS and FTIR techniques have been
used to study the chemical and optical properties of these irradiated polymers. UV spectra revealed that the
optical-gap energy decreases by 54 % with copper ion irradiation at the fluence of 1 × 1013 ions/cm2, whereas
at the same fluence, carbon beam decreases the optical-gap energy by 20%. FTIR analysis of ion irradiated
samples revealed the presence of –OH, C = O and C = C bonds. Alkyne formation has been observed only in the
case of copper ion irradiation.Ravinder Singh, Kawaljeet Singh Samra, Ramneek Kumar and Lakhwant Singh*
Department of Physics, Guru Nanak Dev University,
Amritsar-143 005, Punjab, India
E-mail : [email protected] of Physics, Guru Nanak Dev University,
Amritsar-143 005, Punjab, Indi
Radon exhalation rate in Chhatrapur beach sand samples of high background radiation area and estimation of its radiological implications
No full textChhatrapur beach placer deposit, situated in a part of the eastern coast of Orissa, is a newly
discovered high natural background radiation area (HBRA) in India. The sand samples containing heavy minerals,
were collected from Chhatrapur region by the grab sampling method at an interval of ~ 1 Km. Radon exhalation
rates were measured by "Sealed Can Technique" using LR-115 type type II in the sand samples containing heavy
minerals collected from the beach. Radon activity is found to vary from 1177.1 to 4551.4 Bq m–3 whereas the
radon exhalation rate varies from 423.2 to 1636.3 mBq m–2h–1 with an average value of 763.9 mBq m–2h–1.
Effective dose equivalent in sand samples estimated from exhalation rate varies from 49.9 to 193.0 μSv y–1 with
an average value of 90.1 μSv y–1. From the activity concentration of 238U, 232Th and 40K computed radium
equivalent is found to vary from 864.0 to 11471.5 Bq kg–1 with an average value of 3729.0 Bq kg–1. External
hazard index, Hex range from 2.3 to 31.0 with a mean value of 10.1, which is quite high. This value supports the
conclusion based on high mean absorbed gamma dose rate in air due to the naturally occurring radionuclides as
1627.5 nGy h–1. A positive correlation has been found between U concentration and radon exhalation rate in the
sand samples. The use of sand as construction material may pose a radiation risk to ambient environment.A K Mahur1*, Rajesh Kumar1, D Sengupta2 and Rajendra Prasad1
1Department of Applied Physics, Z. H. College of Engineering & Technology,
Aligarh Muslim University, Aligarh-202 002, Uttar Pradesh, India
2Department of Geology and Geophysics, Indian Institute of Technology,
Kharaghpur-721 302, West Bengal, India
E-mail : [email protected] of Applied Physics, Z. H. College of Engineering & Technology,
Aligarh Muslim University, Aligarh-202 002, Uttar Pradesh, India
Department of Geology and Geophysics, Indian Institute of Technology,
Kharaghpur-721 302, West Bengal, Indi
Effect of bond angle and dihedral angle disorder on diamagnetic susceptibility of tetrahedrally coordinated amorphous semiconductors
No full textWe study the effect of bond angle and dihedral angle disorder on the
diamagnetic susceptibility (.) of a model amorphous semiconductor by adopting a
linear combination of hybrids formalism. We have constructed orthormal basis states
for the disorder network by introducing distortion in bond angles and dihedral
angles. We have used the disorder basis states in the expression for . and adopted
suitable averaging techniques to obtain .in terms of disorder parameters, which
shows interesting results.Author Affiliation: P C Tripathy, R N Acharya and T Sahu
1.Department of Electronic Science, Berhampur University, Berhampur-760 007, Orissa,
India
2.Department of Physics, Rajendra College, Balangir-767 002, Orissa, India
3.Department of Physics, S B R Govt. Women.s (Auto) College, Berhampur, Orissa, India
E-mail : [email protected] of Electronic Science, Berhampur University, Berhampur-760 007, Orissa,
India
1Department of Physics, Rajendra College, Balangir-767 002, Orissa, India
2Department of Physics, S B R Govt. Women.s (Auto) College, Berhampur, Orissa, Indi
Kinetics of unusual photoinduced currents in the solid state of some ferrocene derivatives
No full textKinetics of change in photoinduced currents (during illumination and
after switching off light source) in the solid state of some ferrocene derivatives,
namely, ferrocenecarboxylic acid, acetylferrocene, ferrocenecarbaldehyde,
hydroxymethyl ferrocene have been studied in dry nitrogen gas atmosphere. Unusual/
anomalous photocurrent versus time profiles were observed in some ferrocene
derivatives at certain cell temperatures. The kinetics of current changes under
photoexcitation and after switching off the light source have been observed to be
complicated in nature. Temperature-dependent behavior of the studied kinetics
indicates that charge carrier trapping/ detrapping and recombination processes are
significantly temperature dependent. These processes have an important role in
causing the temperature dependent unusual/ anomalous photocurrent versus time
profiles in the ferrocene derivatives studied.Kinetics of unusual photoinduced currents in the solid state of some ferrocene
derivatives
Aloke Kumar Chakraborty and Biswanath Mallik*
Department of Spectroscopy, Indian Association for the Cultivation of Science,
2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata-700 032, India
E-mail : [email protected] of Spectroscopy, Indian Association for the Cultivation of Science,
2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata-700 032, Indi
Large amplitude double layers in a four component dusty plasma with non-thermal ions
No full textDust acoustic double layers are studied in a four component dusty plasma.
Positively and negatively charged mobile dust and Boltzmann distributed electrons
are considered. The ion distribution is taken as nonthermal. The existence of
compressive and rarefractive double layers is studied by pseudopotential approach.
The effect of non-thermal ions on small amplitude and arbitrary amplitude double
layers are also studied.Large amplitude double layers in a four component dusty plasma with non-thermal ions
Gurudas Mandal1, Kaushik Roy2 and Prasanta Chatterjee2*
1Department of APCE, East West University, Mohakhali, Dhaka
Bangladesh
2Department of Mathematics, Siksha Bhavana, Visva Bharati,
Santiniketan-731 235, West Bengal, India
E-mail : [email protected] of APCE, East West University, Mohakhali, Dhaka
Bangladesh
2Department of Mathematics, Siksha Bhavana, Visva Bharati,
Santiniketan-731 235, West Bengal, Indi