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Variation of Effective Atomic Numbers of some Thermoluminescence and Phantom Materials with Photon Energies

Author Affiliations

  • 1Department of Physics, Federal University of Technology, Minna, NIGERIA

Res.J.chem.sci., Volume 1, Issue (2), Pages 64-69, May,18 (2011)

Abstract

Effective atomic numbers (Zeff) of 15 materials (CaSO, nylon, methyl but-3-enoate, mylar, C4, Al, SiO, stearate, CH4, CaF2 water, Iron sulphate, polystyrene, polyvinyl, and potassium calcium sulphate) used in dosimetry and substitute materials were calculated using standard formula based on their mass attenuation coefficients (µm). The µm of the materials were obtained for photon energies of 0.01 KeV to 20 MeV using WinXCOM. Generally, Zeff for each of the substances considered is not a constant but varies with photon energy. Zeff varies from11-17 for CaSO, 3-6 for nylon, 6-7 for methyl but-3-enoate, 4-7 for mylar, 8-9 for C4, 10-12 for Al, 10-12 for SiO, 3-6 for stearate, 2-5 for CH4, 13-18 for CaF2 3-8 for water, 12-23 for Iron sulphate, 4-6 for polystyrene, 5-16 for polyvinyl, and 12-17 for potassium calcium sulphate. The variations of Zeff with photon energy for all the 15 substances follow similar pattern. The variations were dictated by photon interaction processes. The highest value of Zeff for all the materials was obtained at the lowest energy, while the lowest value was obtained between 0.1 and 1.5 MeV. The mean atomic number of each compound was also found to be equal to the eff obtained at intermediate energies of the energy spectrum considered (0.1 MeV -1.5 MeV). The upper and lower limit of Zeff for each of the considered materials was found to be dictated by the atomic numbers of the constituent elements of the materials.

References

  1. James E.M., Physics for Radiation Protection: A Handbook.Copyright WILEY- VCH Verlag GmbH and Co. KGaA, Weinheim, 822, (2006)
  2. Cevik U., Damla N. andCelik A., Effective Atomic Numbers and Electron Densities For Cdse and Cdte Semiconductors, Radiat. Meas.,43 1437-1442 (2008)
  3. Jackson D.F., Hawkes D.J., X-ray attenuation coefficients of elements and mixtures, Phys. Rep., 70, 169–233 (1981)
  4. Shivaramu V.R., Effective atomic numbers for photon energy absorption and energy dependence of some thermoluminescent dosimetric compounds, Nuclear Instruments and Meth. Phys Research B, 168, 294-304 (2000)
  5. Johns H.E. and Cunningham J.R., The Physics of Radiology, Charles C. Thomas, Springfield, IL, 796 (1983)
  6. Khan F.M., The physics of radiation therapy. Lippincot Williams and Wilkins, Philadephia, 542 (1984)
  7. Hine G.J., The effective atomic numbers of materials for various gammaray interactions,Phys. Rev.,85, 725 (1952)
  8. Siddappa K., Khayyom A., Parthasaradhi K. and Rao J.R., Effective Atomic Numbers for Photoelectric and Incoherent Scattering Processes for Gamma Rays., Nucl. Sci. Engng., 45, 96 (1971)
  9. Kiran K.T., Venkerteratnam S. and Venkata R. K., Effective Number Studies in Clay Minerals for Total Photon Interaction in the Energy Region 10 Kev to 10 Mev., Rad. Phys. Chem., 48, 70 (1996)
  10. Hubbell J.H., Seltzer S., Tables of X-ray mass attenuation coefficients and mass energy-absorption coefficients 1 keV–20MeV for elements Z=1 to 92 and 48 additional substances of dosimetric interest, NISTIR 5632, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA, (1995)
  11. Parthasaradhi K., Esposito A., Pelliccioni M., Photon attenuation coefficients in tissue equivalent compounds, Int. J. Appl. Radiat. Isot., 43, 1481–1484 (1992)
  12. Nowotny R., XMuDat: Photon attenuation data on PC. IAEA-NDS-195 International Atomic Energy Agency, Vienna, (1998)
  13. Berger M.J., Hubbell J.H., 1987/1999, XCOM: Photon cross sections database, web version 1.2, available at http://physics.nist.gov/xcom. National Institute of Standards and Technology, Gaithersburg, MD 20899, USA, Originally published as NBSIR 87-3597 XCOM: Photon cross sections on a personal computer (1999)
  14. Gerward L., Guilbert N., Jensen K.B., Levring H., WinXCom-a program for calculating X-ray attenuation coefficients, Radiat. Phys. Chem., 71, 653–654 (2004)
  15. Manohara S.R., Hanagodimatha S.M., Thind K.S. and Gerward L., On the effective atomic number and electron density: a comprehensive set of formulas for all types of materials and energies above 1 keV., Nucl. Instum. Meth. B,266, 3906 (2008)
  16. Manjunathaguru V., Umesh, T. K., Effective atomic numbers and electron densities of some biologically important compounds containing H,  \n  \r\n\r   \rC, N, and O in the energy range 145–1330 keV., J. Phys. B: At. Mol. Opt. Phys., 39, 3969 (2006)