Parjit S. Singh

A study of photon interaction parameters in some commonly used solvents

Various parameters of dosimetric interest such as mass attenuation coefficients, effective atomic numbers and electron densities of some commonly used solvents such as acetonitrile (C(4)H(3)N), butanol (C(4)H(9)OH), chlorobenzene (C(6)H(5)Cl), diethylether (C(4)H(10)O), ethanol (C(2)H(5)OH), methanol (CH(3)OH), propanol (C(3)H(7)OH) and water (H(2)O) were computed in the wide energy range of 10 keV-100 GeV. A comparative study of two different methods used to compute effective atomic numbers has been done. It is observed that in the intermediate energy region (0.1-5 MeV), the mass attenuation coefficient values becomes almost the same for all the solvents, and the effective atomic number and electron density show almost constant values, whereas significant variation is observed in both lower (10-100 keV) and higher (5 MeV-100 GeV) energy regions for all the solvents, which may be due to the dominance of different partial interaction processes in different energy regions.

A study of energy and effective atomic number dependence of the exposure build-up factors in biological samples

A theoretical method is presented to determine the gamma-radiation build-up factors in various biological materials. The gamma energy range is 0.015-15.0 MeV, with penetration depths up to 40 mean free paths considered. The dependence of the exposure build-up factor on incident photon energy and the effective atomic number (Zeff) has also been assessed. In a practical analysis of dose burden to gamma-irradiated biological materials, the sophistication of Monte Carlo computer techniques would be applied, with associated detailed modelling. However, a feature of the theoretical method presented is its ability to make the consequences of the physics of the scattering process in biological materials more transparent. In addition, it can be quickly employed to give a first-pass dose estimate prior to a more detailed computer study.

Effect of collimator size and absorber thickness on gamma ray attenuation measurements

Mass attenuation coefficients have been measured in extended media of soil and water for 662 keV gamma rays under different collimation conditions. A correlation effect due to absorber thickness and collimator size has been observed.

Comparative studies of different concretes on the basis of some photon interaction parameters

Different photon interaction parameters viz. linear attenuation coefficient, mass attenuation coefficient, penetration depth, equivalent atomic number, exposure buildup factor have been computed for seven different concretes (ordinary, hematite-serpentine, ilmenite-limonite, basalt-magnetite, ilmenite, steel-scrap and steel magnetite) in the energy region of 0.015-15.0MeV. The computed parameters were studied as a function of incident photon energy, chemical composition and penetration depth of the selected concretes. It has been observed that among the selected concretes, steel magnetite offers maximum value for linear attenuation coefficient, mass attenuation coefficient, equivalent atomic number and least values in terms of penetration depth equivalent to mean free path and exposure buildup factors. Hence, it is concluded that it offers better shielding among the selected concretes. It is expected that in case of any nuclear accident, the presented buildup factor data may be helpful in estimating the effective dose given to people living in buildings constructed from one of the selected concretes.

Study of Gamma Ray Exposure Buildup Factor for Some Ceramics with Photon Energy, Penetration Depth and Chemical Composition

Gamma ray exposure buildup factor for some ceramics such as boron nitride (BN), magnesium diboride (MgB2), silicon carbide (SiC), titanium carbide (TiC) and ferrite (Fe3O4) has been computed using five parametric geometric progression (G.P.) fitting method in the energy range of 0.015 to 15.0 MeV, up to the penetration of 40 mean free path (mfp). The variation of exposure buildup factors for all the selected ceramics with incident photon energy, penetration depth, and chemical composition has been studied.

Variation of mass attenuation coefficient, effective atomic number, and electron density with incident photon energy of some organic acids

Abstract Mass attenuation coefficient, effective atomic number, and electron density of 12 organic acids, acetic acid (C2H4O2), acrylic acid (C3H4O2), benzoic acid (C7H6O2), butyric acid (C4H8O2), citric acid (C6H8O7), formic acid (CH2O2), lactic acid (C3H6O3), malic acid (C4H6O5), oxalic acid (C2H2O4), salicylic acid (C7H6O3), tartaric acid (C4H6O6), and valeric acid (C5H10O2), were computed in the wide energy range of incident photon energies from 1 keV to 100 GeV. The variation of these parameters has been studied as a function of incident photon energy. Further, a comparative study of two different methods used to compute effective atomic number is completed.

Buildup factor studies of HCO-materials as a function of weight fraction of constituent elements

Abstract The effects of fractional abundance of constituent elements have been investigated on the energy absorption buildup factors of HCO-materials for some incident photon energies at a fixed penetration depth of 20 mfp. At low incident photon energies, a change in buildup factor is seen whereas buildup factor values of HCO-materials are independent of fractional abundances of H, C and O for high energies.

Proton induced L-shell X-ray production cross-sections for Pb in the energy range 225–400 KeV

Abstract The L-shell X-ray production cross-sections in lead (Pb) by proton impact over the energy range 225–400 keV, with an interval of 25 keV, have been measured. The thick target X-ray yields have been obtained using a HPGe detector. The experimental results for σL1, σLα, σLβ and σLγ have been compared with perturbed stationary state theory with relativistic (R), energy loss (E) and Coulomb (C) corrections (ECPSSR theory). The comparison of Lα, Lβ and Lγ, X-ray production cross-sections shows a fairly good agreement, except at the lowest energy. The L1 X-ray production cross-sections are higher by ≈ 20–30% than their theoretical estimates.

Proton-induced L X-ray production cross sections and intensity ratios for Gd and Tb in the energy range 250-400 keV

The L X-ray production cross sections. sigma L alpha , sigma L beta and sigma L gamma for Gd and Tb obtained by proton impact in the energy range 250-400 keV have been measured using an HPGe detector. The theoretical calculations for these X-ray production cross sections have been performed by perturbed stationary state (PSS) theory with relativistic (R), energy loss (E) and Coulomb deflection (C) corrections (ECPSSR theory) using the theoretical values for X-ray emission rates, subshell fluorescence yields and Coster-Kronig transition probabilities. Due to the lack of other experimental data, the present results have been compared with the theoretical predictions and are found to be in reasonable agreement. The intensity ratios IL beta /IL alpha and IL gamma /IL alpha are also presented.

Experimental investigation of the multiple scatter peak of gamma rays in portland cement in the energy range 279–1332 keV

The pulse height spectra for different thicknesses of portland cement in the reflected geometry has been recorded with the help of a NaI(Tl) scintillator detector and 2 K MCA card using different gamma-ray sources such as Hg203 (279 keV), Cs137 (662 keV) and Co60 (1173 and 1332 keV). It has been observed that the multiple scatter peak for portland cement appears at 110 (±7) keV in all the spectra irrespective of different incident photon energies in the range 279–1332 keV from different gamma-ray sources. Further, the variation in the intensity of the multiple scatter peak with the thickness of portland cement in the backward semi-cylinders has been investigated.