A mathematical model of semiconductor detector gamma-efficiency calibration for rectangular cuboid (brick-shape) sources
Rectangular cuboid (rectangular parallelepiped), i. e., brick-shape sources are not really common in general gamma-spectrometry practice with semiconductor detectors, where axially symmetrical sources prevail. However, in some particular applications, like radioactivity control of food or...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
VINCA Institute of Nuclear Sciences
2018-01-01
|
| Series: | Nuclear Technology and Radiation Protection |
| Subjects: | |
| Online Access: | http://www.doiserbia.nb.rs/img/doi/1451-3994/2018/1451-39941802139M.pdf |
| Summary: | Rectangular cuboid (rectangular parallelepiped), i. e., brick-shape sources
are not really common in general gamma-spectrometry practice with
semiconductor detectors, where axially symmetrical sources prevail. However,
in some particular applications, like radioactivity control of food or
construction materials (for monitoring and regulatory purposes, radiological
emergency preparedness, or in the aftermath of nuclear accidents), brick
shapes may come to significance. In order to simplify routine/repetitive low
activity measurements, it is easier and more practical to measure the
radioactivity of these sources as such, i. e., without transforming them
into “regular” (cylindrical or Marinelli) shapes. This saves considerably on
laboratory time, workforce and consumables-thus eventually cutting the
cost of analysis and improving laboratory performance. In addition,
the accuracy of the analytical results is enhanced, as the
possibilities for systematic errors are reduced. To that aim, in the present
work a mathematical model for brick-source efficiency calibration is
developed. The well known, accurate and widely used efficiency transfer
principle is applied, together with detector efficiency calculations based
on the effective solid angle W concept. For testing purposes, comparisons
are made with previously developed and well established mathematical models
for detector calibration involving axially symmetrical sources
(point, disc, and cylinder). Namely, brick sources were regarded as a
sort of interpolation between the outer and inner cylinder of the same
height, for which efficiencies could be accurately determined by numerical
calculations (software ANGLE). For the sake of completeness, the
equivoluminous cylinders were taken into account as well. Brick shape
sources of various sizes and proportions were examined; when approaching
zero dimensions, results were obtained for point and disc sources. All
calculations were performed in gamma energy range 50-3000 keV. The results
are consistent and logical, with no discrepancies indicating bugs or
systematic errors-thus convincingly confirming the fundamentality and
reliability of the model. The model is about to be incorporated into ANGLE
software as a new functionality, so as to make it available to gamma
spectrometry community. |
|---|---|
| ISSN: | 1451-3994 1452-8185 |