Abstract: The invention relates to an instrument which uses an individual semi-conductive detector with special coverings as an essential sensor, and a method whereby the amplitude information of the signals from said semi-conductive detector are used to determine a person's dose in mixed neutron/photon-fields. Said instrument is highly sensitive and has a low energy dependency. It is possible for the dose to be read directly, and to emit a warning if the dose limit is exceeded. The inventive method enables a compact person's dose meter, which is immune to interference, to be produced with low power consumption.