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Secondary charged particle equilibrium in 137Cs and 60Co reference radiation fields.
- Source :
-
Radiation protection dosimetry [Radiat Prot Dosimetry] 2009 Sep; Vol. 136 (3), pp. 168-75. Date of Electronic Publication: 2009 Sep 15. - Publication Year :
- 2009
-
Abstract
- During the calibration or irradiation of dosemeters, typical irradiation geometries (collimated beams) and source-to-detector distances (1-5 m) lead to the fact that for photon energies above a few hundred keV, the secondary charged particle equilibrium is usually not ensured. The reason is that the effective beam radius at the detector position is smaller than the range of the secondary electrons produced in air whose maximum particle energy is as large as the maximum photon energy. Therefore, the International Organization for Standardization (ISO) recommends putting a build-up plate (BUP) made of polymethyl methacrylate in front of the dosemeter to be calibrated in ISO 4037-3. In this paper, the effect of the thickness of the BUP and its distance from the dosemeter at different source-to-dosemeter distances were investigated by means of measurement and calculation. It turned out that the geometrical arrangement of the source, dosemeter and BUP recommended by ISO mostly does not ensure secondary charged particle equilibrium. The consequence is to always place the BUP directly in front of the dosemeter to be calibrated or irradiated.
- Subjects :
- Cesium Radioisotopes standards
Cobalt Radioisotopes standards
Computer Simulation
Internationality
Radiation Dosage
Reference Values
Static Electricity
Cesium Radioisotopes analysis
Cesium Radioisotopes chemistry
Cobalt Radioisotopes analysis
Cobalt Radioisotopes chemistry
Models, Chemical
Radiometry methods
Radiometry standards
Subjects
Details
- Language :
- English
- ISSN :
- 1742-3406
- Volume :
- 136
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Radiation protection dosimetry
- Publication Type :
- Academic Journal
- Accession number :
- 19755433
- Full Text :
- https://doi.org/10.1093/rpd/ncp173