RADIATION MEASURING INSTRUMENT

PURPOSE:To enable highly accurate radiation measurement, by preventing as much as possible the occurrence of a peak shift in energy spectrum outputted from a signal processing section. CONSTITUTION:A peak shift correcting means (X) is provided between a linear amplifier section 4 and AD converter 5. When an analog output signal is inputted from a preamplifier section 2, the means (X) causes the amplifier section 4 to perform a series of signal processing operations. Then a switch SW is closed by the period of, for example, a time TM after a peaking time passes at the amplifier section 4. Therefore, a zero pulse vT outputted from the amplifier section 4 is supplied to the AD converter 5 through an amplifier AMP1 for subtraction and, simultaneously, amplified at another amplifier AMP2 for amplification at a gain A (R2/R1). Moreover, the pulse vT is inputted to an amplifier AMP3 for integration as a zero measure pulse va through the SW which is closed by the time TM. The pulse va is completely integrated by the amplifier AMP3 and fed back to the amplifier AMP1 as a signal vb for zero correction and subtracted from the output signal vT of the amplifier section 4.