Criteria for the equivalence of spherical and cylindrical proportional counters in microdosimetry
The proximity functions, or the closely related geometric reduction factors, of cylinders and spheres are compared in order to assess the degree of equivalence that can be achieved if cylindrical microdosimetric detectors are substituted for spherical instruments. Equality of the dose mean energy imparted per event, anti epsilon/sub D/, is chosen as a criterion for equivalence. A cylinder of height and diameter equal to 0.895 d is found to be closely equivalent to the sphere of diameter d. The equivalence is largely preserved even if the radiation is unidirectional and perpendicular to the axis of the cylinder. The equivalence does not pertain to the frequency mean energy imparted per event, anti epsilon/sub F/, or to the event frequencies, PHI, per unit absorbed dose. Cubes are also considered, since they are occasionally invoked in microdosimetric computations. One finds that a cube of side length 0.837 d is most closely equivalent to a sphere of diameter d. The quantity anti epsilon/sub D/ for the cube cannot differ by more than 4% from the value of the sphere.
- Research Organization:
- Universitaet Wuerzburg, Germany
- OSTI ID:
- 6463424
- Journal Information:
- Radiat. Res.; (United States), Vol. 86:2
- Country of Publication:
- United States
- Language:
- English
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