A method for determining the points of origin of radiation signals in a measurement zone , wherein - a number n = 2, 3, ..., i of radiation detectors for receiving radiation signals from the measurement zone and for providing measured values on the basis of received radiation signals are arranged in a known relative spatial arrangement to one another in a measuring head , in that front radiation detectors (2.1, 2.3, 2.5) are located at the entrance window of the measuring head and, alternatingly thereto, in gaps between the front radiation detectors (2.1, 2.3, 2.5), rear radiation detectors (2.2, 2.4) are arranged further away from the entrance window, so that each of the radiation detectors has a mutually different geometric efficiency with respect to the detection of a radiation signal from a specific point of origin , - radiation signals from the measurement zone are detected by means of the number of radiation detectors at a measurement time and measured values assigned to the measurement time are provided on the basis of the detected radiation signals , - the determination of the points of origin of the radiation signals is carried out taking into account the measured values of all radiation detectors and the known relative positional relationships of the radiation detectors to one another, and - the determination of the points of origin is carried out using a reference data set, said reference data set consisting of a number of partial reference data sets and each partial reference data set being formed by specific data of one of the points of origin in each case and the specific data being formed by relationships of measured values of the radiation detectors to one another. - a number n = 2, 3, ..., i of radiation detectors for receiving radiation signals from the measurement zone and for providing measured values on the basis of received radiation signals are arranged in a known relative spatial arrangement to one another in a measuring head , in that front radiation detectors (2.1, 2.3, 2.5) are located at the entrance window of the measuring head and, alternatingly thereto, in gaps between the front radiation detectors (2.1, 2.3, 2.5), rear radiation detectors (2.2, 2.4) are arranged further away from the entrance window, so that each of the radiation detectors has a mutually different geometric efficiency with respect to the detection of a radiation signal from a specific point of origin , - radiation signals from the measurement zone are detected by means of the number of radiation detectors at a measurement time and measured values assigned to the measurement time are provided on the basis of the detected radiation signals , - the determination of the points of origin of the radiation signals is carried out taking into account the measured values of all radiation detectors and the known relative positional relationships of the radiation detectors to one another, and - the determination of the points of origin is carried out using a reference data set, said reference data set consisting of a number of partial reference data sets and each partial reference data set being formed by specific data of one of the points of origin in each case and the specific data being formed by relationships of measured values of the radiation detectors to one another. <EOS>