NaI(Tl) Scintillator's Response Functions for Point-like and Distributed Gamma-ray Sources

H. R. Vega-Carrillo; J. L. Benites-Rengifo; V. M. Hernandez-Davila; J. M.  Ortiz-Rotriguez; H. A.  De Leon-Martinez

doi:10.15415/jnp.2016.41013

Authors

H. R. Vega-Carrillo Unidad Academica de Estudios Nucleares de la Universidad Autonoma de Zacatecas C. Cipres 10, Fracc. La Peñuela. 98068 Zacatecas, Zac. Mexico
J. L. Benites-Rengifo Centro Estatal de Cancerologia de Nayarit Calzada de la Cruz 118 Sur, Tepic, Nay. Mexico
V. M. Hernandez-Davila Unidad Academica de Estudios Nucleares de la Universidad Autonoma de Zacatecas C. Cipres 10, Fracc. La Peñuela. 98068 Zacatecas, Zac. Mexico.
J. M. Ortiz-Rotriguez Unidad Academica de Ingenieria Electrica de la Universidad Autonoma de Zacatecas Av. Ramon Lopez Velarde 801. Col. Centro, 98000 Zacatecas, Zac. Mexico
H. A. De Leon-Martinez Instituto Tecnológico de Aguascalientes Av. Adolfo López Mateos 1801 Ote. Fracc. Bona Gens, 20155 Aguascalientes, Ags. Mexico

DOI:

https://doi.org/10.15415/jnp.2016.41013

Keywords:

Gamma- ray, Point-like source, Distributed source, NaI(Tl) response, Monte Carlo

Abstract

The response functions of a NaI(Tl) detectors have been estimated using Monte Carlo methods. Response functions were calculated for monoenergetic photon sources (0.05 to 3 MeV). Responses were calculated for point-like sources and for sources distributed in Portland cement cylinders. Calculated responses were used to estimate the detector efficiency for point-like and distributed sources. Samples of cylindrical Portland cement were prepared and exposed to the photoneutron field produced by a 15 MV linac used for radiotherapy. Short half-life radioisotopes were induced and the activity was determined by measuring the pulse-height spectra with a NaI(Tl) g-ray spectrometer that was calibrated using point-like sources. Instead of doing corrections due to differences between the geometry, material and solid angle of point-like sources used for calibration, and the Portland cement cylinders, the detection efficiency was determined using the ratio between the efficiencies for the point-like and the distributed sources estimated with the Monte Carlo calculations, and the activity of the induced isotopes in cement was obtained.

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