Provided is an apparatus including a pulse generation device and a memory. The pulse generation device includes: an emitter, which includes a radioisotope containing a number of atoms greater than a total number of identification targets; and a detector, which is configured to detect an α particle and others emitted from the emitter due to spontaneous decay of an atomic nucleus to generate electric pulses. The memory stores a number of electric pulses obtained by measuring, in advance, for a given period of time, the electric pulses that are generated in the pulse generation device (initial pulse count), a date of the measurement, and an identification numerical value obtained by digitizing a pulse interval between the electric pulses (initial identification numerical value).