O. Presler

Off-center efficiency of HPGe detectors

The gamma ray detection efficiency of two HPGe detectors for off-center points was measured both on the detectors cap and outside the detectors cap. It was found that similar to measurements on the detector symmetry axis, for off-center measurements including those outside the detector cap also, the detector could be treated as an effective point detector. The virtual point detector was found to be almost at the same position for vertical and horizontal source displacements.

Determination of a source in a box with two detectors. I. non-absorbing media

It was found that the activity and the position of a radioactive point source (hot spot) in a large box containing low absorbing material can be measured accurately using two NaI(Tl) gamma-ray detectors at the opposite sides of the box i.e. at 180° one to another. The harmonic mean of the count rates square roots measured with the two detectors was found to be independent of the hot spot position and depends only on the source activity, the box size and the gamma-rays energy. The activity of the radioactive point source can be calculated from the above-mentioned mean. The position of the point source can be calculated from the ratio of the two detectors count rates.