This Recommendation applies to cylindrical radiation probes containing a Geiger-Muller counter tube, or a proportional counter tube, or a scintillation detector, and possibly a pre-amplifier.
It need not be applicable to probes used in drill holes for mining and prospecting purposes, since drill hole diameters are determining factors in such applications.
SIS SS IEC 256:1983 history
1983SIS SS IEC 256:1983 Nuclear instrumentation - Externa! diameters of cylindrical radiation probes containing Geiger-Muller or proportional countertubes or scintillation detectors