Limits...
Efficiencies of Some Spherical Ion Chambers in Continuous and Pulsed Radiation: A Numerical Evaluation.

Maghraby AM - Pol J Radiol (2015)

Bottom Line: Evaluation of the collection efficiencies of ion chambers is a necessity for the proper evaluation of radiation quantities in different applications.Through current work there is an attempt of focusing on how the selection of ion chamber dimensions may affect the overall collection efficiency in addition to the proper selection of other influencing parameters.Also, collection efficiencies considering diffusion current values (fd) were evaluated for the five chambers, and plotted versus the applied polarizing potential.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Faculty of Science - Alzulfi - Almajmaah University, Almajmaah, Saudi Arabia ; Department of Radiation Dosimetry, National Institute of Standards (NIS), Ionizing Radiation Metrology Laboratory, Giza, Egypt.

ABSTRACT

Background: Evaluation of the collection efficiencies of ion chambers is a necessity for the proper evaluation of radiation quantities in different applications. Overall collection efficiency is the product of three different values: collection efficiencies considering contributions of, volume recombination, back-diffusion loss and initial recombination, the later may be neglected at low charge rates.

Material/methods: Five common spherical ion chambers of different volumes and specifications were included in this study for the evaluation of volume recombination collection efficiency and back diffusion collection efficiency for continuous and pulsed radiation and at different values of the applied polarizing potential. Through current work there is an attempt of focusing on how the selection of ion chamber dimensions may affect the overall collection efficiency in addition to the proper selection of other influencing parameters.

Results: Collection efficiencies considering volume recombination (fv) for five spherical ion chambers of common types were evaluated for continuous and pulsed radiation over a wide range of polarizing potential. The relation between the ion chamber volume and its evaluated collection efficiencies were studied for both continuous and pulsed radiation; transit time values for the ion chambers included in this study were evaluated at different values of applied potential. Also, collection efficiencies considering diffusion current values (fd) were evaluated for the five chambers, and plotted versus the applied polarizing potential.

Conclusions: Through this study it was feasible to evaluate numerically the collection efficiencies of some spherical ion chambers considering volume recombination and back diffusion effects; the affecting parameters were studied and highlighted.

No MeSH data available.


The relation between the change in applied voltage and the calculated collection efficiency considering diffusion current loss (fd)) for different spherical ion chambers.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4664224&req=5

f6-poljradiol-80-515: The relation between the change in applied voltage and the calculated collection efficiency considering diffusion current loss (fd)) for different spherical ion chambers.

Mentions: The collection efficiency corresponding to back diffusion loss (fd) for different ion chambers was evaluated according to the equation (8). As shown in Figure 6, fd increased non-linearly as the applied polarizing potential increased; according to the figure, the highest value of fd was achieved by two ion chambers, A5 followed by A3 and A4, while the lowest values of fd were those of A6 and A8, for example, at a value of the applied polarizing potential V=500 V, fd was 99.88% for A5, and 99.87% for A3 and A4, while for A6 and A8 it was 99.86% and 99.80%, respectively.


Efficiencies of Some Spherical Ion Chambers in Continuous and Pulsed Radiation: A Numerical Evaluation.

Maghraby AM - Pol J Radiol (2015)

The relation between the change in applied voltage and the calculated collection efficiency considering diffusion current loss (fd)) for different spherical ion chambers.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4664224&req=5

f6-poljradiol-80-515: The relation between the change in applied voltage and the calculated collection efficiency considering diffusion current loss (fd)) for different spherical ion chambers.
Mentions: The collection efficiency corresponding to back diffusion loss (fd) for different ion chambers was evaluated according to the equation (8). As shown in Figure 6, fd increased non-linearly as the applied polarizing potential increased; according to the figure, the highest value of fd was achieved by two ion chambers, A5 followed by A3 and A4, while the lowest values of fd were those of A6 and A8, for example, at a value of the applied polarizing potential V=500 V, fd was 99.88% for A5, and 99.87% for A3 and A4, while for A6 and A8 it was 99.86% and 99.80%, respectively.

Bottom Line: Evaluation of the collection efficiencies of ion chambers is a necessity for the proper evaluation of radiation quantities in different applications.Through current work there is an attempt of focusing on how the selection of ion chamber dimensions may affect the overall collection efficiency in addition to the proper selection of other influencing parameters.Also, collection efficiencies considering diffusion current values (fd) were evaluated for the five chambers, and plotted versus the applied polarizing potential.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Faculty of Science - Alzulfi - Almajmaah University, Almajmaah, Saudi Arabia ; Department of Radiation Dosimetry, National Institute of Standards (NIS), Ionizing Radiation Metrology Laboratory, Giza, Egypt.

ABSTRACT

Background: Evaluation of the collection efficiencies of ion chambers is a necessity for the proper evaluation of radiation quantities in different applications. Overall collection efficiency is the product of three different values: collection efficiencies considering contributions of, volume recombination, back-diffusion loss and initial recombination, the later may be neglected at low charge rates.

Material/methods: Five common spherical ion chambers of different volumes and specifications were included in this study for the evaluation of volume recombination collection efficiency and back diffusion collection efficiency for continuous and pulsed radiation and at different values of the applied polarizing potential. Through current work there is an attempt of focusing on how the selection of ion chamber dimensions may affect the overall collection efficiency in addition to the proper selection of other influencing parameters.

Results: Collection efficiencies considering volume recombination (fv) for five spherical ion chambers of common types were evaluated for continuous and pulsed radiation over a wide range of polarizing potential. The relation between the ion chamber volume and its evaluated collection efficiencies were studied for both continuous and pulsed radiation; transit time values for the ion chambers included in this study were evaluated at different values of applied potential. Also, collection efficiencies considering diffusion current values (fd) were evaluated for the five chambers, and plotted versus the applied polarizing potential.

Conclusions: Through this study it was feasible to evaluate numerically the collection efficiencies of some spherical ion chambers considering volume recombination and back diffusion effects; the affecting parameters were studied and highlighted.

No MeSH data available.