Comparing the Measurement Value of Photon Contamination Absorbed Dose in Electron Beam Field for Varian Clinical Accelerator

-- M Mahdavi, S R M Mahdavi, H Alijanzadeh and M Zabihzadeh

Sometimes in electron radiotherapy, Bremsstrahlung photon is produced in accelerator head. This photon contamination creates various doses in electron beams. In this study, varian accelerator in electron mode has been simulated and the photon contamination depth dose for three energies 6, 9 and 12 MeV in Monte Carlo method was calculated. Also, electron depth dose curves in simulation and measurement were compared. The discrepancies between measurement and simulation of depth dose curves were calculated in high accuracy by a program that was written in FORTRAN language. The error average is less than 1.5% in semi-linear region for these three energies. Results show that the simulation has a good accuracy. Also, the graphs demonstrate that the dose of photon contamination is trivial versus electron dose. In phantom surface percentage photon contamination dose for these three energies ranged between 0.284% and 0.340% of maximum dose.

© 2011 IUP. All Rights Reserved.

A Simple Model to Evaluate Force Constants of Para-Disubstituted Benzenes

-- N Jigeesh and M Rangacharyulu

Evaluation of various force constants for the disubstituted benzenes is difficult and for complex sulpha drug molecules, it is very difficult. This paper assumes a simple force field model for the sulpha drug molecule by treating it as a para-disubstituted benzene molecule. The four C-C, two C-H and one C-N and C-S stretching force constants have been derived from that model using the reported experimental vibrational frequencies connected to the model. The derived values of stretching force constants are in good agreement with the reported values.

© 2011 IUP. All Rights Reserved.

An Approach to the Understanding of Structure and Stability of Atom

-- Seikh Hannan Mandal

The objective of this article is to show how experimental discoveries in atomic physics are logically connected, and we land up with the consistent theoretical explanation to the structure and stability of the atom. It is also shown that Bohr’s correspondence principle and Erhenfest’s adiabatic invariant hypothesis act as a guiding rules to this route. As a generalization to Bohr’s quantum condition, the Wilson-Sommerfeld quantization condition for multi-periodic system is presented with a derivation.

© 2011 IUP. All Rights Reserved.

Analysis of Cosmic Rays and Their Composition with Reference to Energy Spectrum

-- Dhirendra Kumar Tiwari and Richa Dixit

This paper determines the high energy cosmic rays and their composition. It gives a brief information about the source of origin, flux generation, composition and energy distribution of cosmic rays. It also explains the interactions and particle production of the cosmic ray air showers. The paper also analyzes the energy spectrum which relates to the source of cosmic rays and their propagation to earth over many orders of magnitude in energy. Research also discusses the correlation and interpretation of different observatories. The main analysis is based on the Pierre auger observatory analysis and highest energy cosmic rays with nearby extra galactic matters.

© 2011 IUP. All Rights Reserved.

Optical Properties of Rare-Earth Doped Magnesium Borax Glasses

-- Sujeet Jain and Ragini Singh

The paper aims to investigate the optical and spectroscopic properties of magnesium borax glasses doped with rare-earths. The optical absorption spectra were recorded at room temperature in the UV-Vis region. From the absorption edge studies, different radiative and optical properties have been evaluated to develop the fabrication processes for the implementation of integrated optical amplifiers and lasers to be used in optical communication systems as well as in medical systems and instrumentation.

© 2011 IUP. All Rights Reserved.

Theoretical Investigation of the Optical Properties of (Ge _0.17 Se _0.83 )_100–x In _x Glass System

-- Saurabh Tiwari, Ashish Kumar Saxena and Dinesh Saxena

The effect on the optical and physical properties with the addition of In content: constraint, heat of atomization, optical energy gap and the energetic parameter of (Ge0.17Se0.83)100–xInx (x = 0, 5, 10, 15, at %) glassy alloy were examined theoretically. Optical gap was determined from the heat of atomization data by Balkanski procedure and the energetic distribution of the gap. The introduction of a third element increases the disorder in the system and decreases the optical band gap values.

© 2011 IUP. All Rights Reserved.

Radio Refractive Index Variation with Related Weather Parameters at Surface Level in Ilorin, North Central Nigeria

-- K C Igwe, I A Adimula, O A Falaiye and O D Oyedum

Statistical analysis of surface radio refractive index and related atmospheric parameters over Ilorin (8o 32" N, 4o 34" E), North Central Nigeria, is presented. One minute interval measurement of temperature, pressure and relative humidity for a period of five years was obtained from the Baseline Surface Radiation Network (BSRN) of the University of Ilorin observatory. The diurnal and seasonal variations of these meteorological parameters especially in the tropics contribute to the analysis of refractivity variations and are needed for the design of efficient radio communication systems. Apart from the conventional deduction of low refractivity values in the dry season and high values in the wet season, the interrelationship of surface refractivity and related weather parameters were explored. The regression analysis carried out shows that mean monthly humidity and refractivity are well correlated with a correlation coefficient of 0.97 while the regression equation for predicting mean monthly refractivity N from the mean monthly relative humidity h is N = 0.881 h + 279.

© 2011 IUP. All Rights Reserved.