Abstract: For compensating for the rate dependent change of charge-to-voltage conversion factor in a drift-type radiation detector there is detected a change in a momentary photon hit rate affecting said drift-type radiation detector. A drain current flowing through an integrated amplifier of said drift-type radiation detector is changed by an amount proportional to the detected change in said momentary photon hit rate.

Abstract: A drift detector produces an indication of an occurred hit of a quantum in the detector element. For neutralising accumulated charge in the detector element, indications of occurred hits are used to trigger pulses of deliberately increased neutralisation current into the drift detector for the duration of a limited time interval. Alternatively such triggering may be based on the operation of a timer.

Abstract: Disclosed is a method and an apparatus for analyzing pieces of ore for the purpose of sorting. Each piece falling by the analyzer is irradiated individually by means of two gamma radiation sources operating at different energy levels so selected that, as to the scattering effect, at one level the Compton effect is predominant and at the other level the Compton effect and the photoelectric effect compete with each other. The former effect is strongly dependent on the ordinal number of the element and, thus, by detecting with at least one detector the scattering intensities produced with the said two sources of radiation and comparing the scattering intensities with each other, the proportion of heavy elements in the ore piece can be determined and the ore piece can be classified on the basis thereof. For example, one energy dispersively operating scintillation detector can be used for detecting the scattered radiation.