Logarithmic count rate:

The discriminator excludes passage of pulses which are less than a predetermined level. A function of the discriminator is to exclude noise and gamma pulses which are lower in magnitude than neutron pulses.

A pulse is then sent to the pulse integrator where they are integrated to provide a signal that is proportional to the logarithm of the count rate.

The log count rate amplifier then amplifies the signal that varies straightly as the logarithm of the pulse rate, in the detector. The logarithmic count rate is then displayed on a meter with a logarithmic scale in counts per second.

The logarithmic count rate signal is differentiated to measure the rate of change within neutron flux. The differentiator outcome is proportional to reactor period. A value of reactor period is inversely proportional to the real rate of change of reactor power and relates to power changes through factors of e (2.718).  The power rate modified based on factors of 10, in decades per minute, is more useful to the reactor operator. Thus, the outcome of the differentiator is converted from reactor period to decades per minute through the meter scale used.