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74
ST 1.2 –
Dosimetría externa
MASS ATTENUATION COEFFICIENTS OF X-RAYS IN DIFFERENT BARITE
CONCRETE USED IN RADIATION PROTECTION AS SHIELDING AGAINST
IONIZING RADIATION
Almeida Jr.; Airton T.
1*
; Rodrigues, Leticia L.C.
2
;
Nogueira Tavares, Maria S.
3
; Santos, Marcus A.P
.
4
1
Brazilian Institute for Safety and Health at Work – FUNDACENTRO. Brasil.
2
Institute for Research and Nuclear Energy– IPEN / CNEN. Brasil.
3
Development Center of Nuclear Technology - CDTN/CNEN. Brasil.
4
Regional Center for Nuclear Science – CRCN / CNEN. Brasil.
* Responsible author, email:
airton.almeida@fundacentro.gov.br
The attenuation coefficient depends on the incident photon energy and the nature of
materials. The barite concrete has been largely used as shielding material in installations
housing gamma radiation sources as well as x-ray generating equipment, in order to minimize
exposure to individuals. This study was conducted to evaluate the efficacy of different
mixtures of barite concrete for shielding of diagnostic x-ray rooms. The mass attenuation
coefficient (µ/ρ). The mass attenuation coefficients have been measured employing CdTe
detector, XR-100T model. The distance between the source and the exposed surface of all
samples was measured by SSD light indicator of machine which was 350 cm. The slope of
the linear plot of the intensity transmitted versus specimen thicknes would yield the
attenuation coefficient. The mass attenuation coefficients (µ/ρ) were compared with
tabulations based upon the results from the XCOM program. The rectangular barite concrete
blocks with different thicknesses from were used for radiation attenuation test. The
experimental values are compared with theoretical values WinXcom. The plots of the
logarithm of transmitted intensity versus specimen thickness were linear for all the samples
and the µ/ρ was obtained from the plots by linear regression over the 25% - 2% transmission
range, under the good geometrical condition geometrical. There is a good agreement
between theoretical and experimental value, within the 9%. In fact over the entire
transmission range of 25–2% the experimental and theoretical values agree well for both the
energies. The authors wish to thank the directors of the FUNDACENTRO, CRCN, CDTN and
IPEN, by supporting on the implementation of this work. The authors also thank the FAPEMIG
and Ministry of Science and Technology - MCT/Brazil, through the Brazilian Institute of
Science and Technology (INCT) for Radiation Metrology in Medicine.