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Kiran K.U.,Government Science College | Ravindraswami K.,St Aloysius College Autonomous | Eshwarappa K.M.,Government Science College | Somashekarappa H.M.,Mangalore University
Annals of Nuclear Energy | Year: 2015

In this paper, multiple scattering of 137Cs gamma photons from composite materials is studied experimentally. Photons scattered in backward direction of 90° to the incident beam are detected by a NaI (Tl) detector. Single scattered events are reconstructed analytically to extract multiple scattered photons from the measured spectrum. We observe that for an increase in target thickness, there is an increase in multiple backscattered photons. After a particular thickness called as saturation thickness, multiple backscattered photons becomes almost a constant. The saturation thickness of the multiple scattered photons is used to assign effective atomic number for HDPE, UHMW, Nylon, Bakelite, Glass-epoxy, local wood (Hopea parviflora) and Portland Cement (grade 43). Experimental results are compared with Monte Carlo simulation. The ratio of single scattering events to multiple scattering events decreases for an increase in target thickness. © 2015 Elsevier Ltd. Source


Kavitha R.,St Aloysius College Autonomous | Vijaya A.,Government of Tamilnadu | Saraswathi D.,Anna University
Advances in Intelligent and Soft Computing | Year: 2012

Due to the advancement in information technology and varied learner group, e-learning has become popular. Hence computer based assessment become a prevalent method of administering the tests. Randomization of test items here may produce unfair effect on test takers which is unproductive in the outcome of the test. There is a need to develop the Intelligent Tutoring System that assigns intelligent question depending on the student's response in the testing session. It will be more productive when the questions are assigned based on the ability in the early stage itself. Also, if only the standard multiple-choice questions are focused, then the real embedded nature of computer assessment is sacrificed. Items with different constrained constructs are included to bring out the complex skills, analytical and comprehensive ability of learners. So, this study focus on building up a framework to automatically assign intelligent question with different constructs based on the learner ability while entry. Using Norm Referencing, questions are classified based on item difficulty. Item discrimination is found and there by only the items which can discriminate the performers alone are accumulated in the item pool to have maximum effect of intelligence in tutoring system. The level of new learner is predicted by means of Naïve Bayesian classification and the consequent item is posed. Thereby the objective of Intelligent Tutoring System is achieved by using both adaptability and intelligence in testing. © 2012 Springer-Verlag GmbH. Source


Kiran K.U.,Government Science College | Ravindraswami K.,St Aloysius College Autonomous | Eshwarappa K.M.,Government Science College | Somashekarappa H.M.,Mangalore University
Radiation Physics and Chemistry | Year: 2014

Multiple back-scattering of gamma photons from carbon and aluminium targets is studied with a view to estimate energy dependence on saturation thickness. The number of multiple backscattered photons increases with an increase in the target thickness and then saturates at a particular thickness called the saturation thickness. An intense collimated beam, obtained from 241Am, 57Co, 203Hg, 133Ba, 22Na, 137Cs, 65Zn and 60Co sources, is allowed to impinge on rectangular carbon and aluminium targets of varying thickness. The scattered photons from the samples are detected by a 76mm×76mm NaI (Tl) scintillation detector placed at a backscattering angle of 135°. The measured saturation thickness for multiple backscattering of gamma photons is found to be increasing with an increase in the energy of incident gamma photons. The experimental results are compared with Monte Carlo calculations carried out using the Monte Carlo N-Particle (MCNP) simulation code. © 2013 Elsevier Ltd. Source


Ravindraswami K.,St Aloysius College Autonomous | Kiran K.U.,Government Science College | Eshwarappa K.M.,Government Science College | Somashekarappa H.M.,Mangalore University
Indian Journal of Physics | Year: 2013

In this paper the energy, intensity and angular distributions of multiple scattering of 662 keV gamma photons, emerging from targets of aluminium, copper, iron and glass samples are studied as a function of target thickness. An intense collimated beam obtained from a 137Cs source of 5.8 mCi is allowed to impinge on samples of varying thickness. The scattered photons are detected by a properly shielded 76 mm × 76 mm NaI (Tl) scintillation detector. In Compton scattering experiments, it is observed that the number of multiple backscattered photons increase with an increase in target thickness and become almost constant for particular target thickness called saturation thickness. The saturation thickness decreases with increasing atomic number. The multiple scattering, an interfering background noise in Compton profile, has been successfully used to assign effective atomic number (Z eff ) to composite materials. The experimental results are compared with the Monte Carlo calculations using Monte Carlo nuclear particle code. © 2013 Indian Association for the Cultivation of Science. Source


Kiran K.U.,Government Science College | Ravindraswami K.,St Aloysius College Autonomous | Eshwarappa K.M.,Government Science College | Somashekarappa H.M.,Mangalore University
Applied Radiation and Isotopes | Year: 2016

Response function of a widely used 3 in×3 in NaI(Tl) detector is constructed to correct the observed pulse height distribution. A 10×10 inverse matrix is constructed using 7 mono-energetic gamma sources (57Co, 203Hg, 133Ba, 22Na, 137Cs, 54Mn and 65Zn) which are evenly spaced in energy scale to unscramble the observed pulse height distribution. Bin widths of 0.01 (MeV)1/2 are used to construct the matrix. Backscattered photons for an angle of 110° are obtained from a well-collimated 0.2146 GBq (5.8 mCi) 137Cs gamma source for carbon, aluminium, iron, copper, granite and Portland cement. For each observed spectrum, single scattered spectrum is constructed analytically using detector parameters like FWHM, photo-peak efficiency and peak counts. Response corrected multiple scattered photons are extracted from the observed pulse height distribution by dividing the spectrum into a 10 ×1 matrix. Saturation thicknesses of carbon, aluminium, iron, copper, granite and Portland cement are found out. Variation of multiple scattered photons as a function of target thickness are simulated using MCNP code. A relationship between experimental and simulated saturation thicknesses of carbon, aluminium, iron and copper is obtained as a function of atomic number. Using this relation, effective atomic numbers of granite and Portland cement are obtained from interpolation method. Effective atomic numbers of granite and Portland cement are also obtained by theoretical equation using their elemental composition and comparing with the experimental and simulated results. © 2016 Elsevier Ltd. Source

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