Understanding Neutron Radiography Post Exam Reading VIII-Part 2a of 2A

Vibrating Reed Electrometers
An alternative approach to ion current measurement is to convert the signal
from direct current to alternating current at an early stage. This allows a more
stable amplification of the alternating current signal in subsequent operations.
The conversion is accomplished in a dynamic capacitor or vibrating reed
electrometer, by collecting the ion current across a resistive capacitive circuit.
The capacitance is then changed rapidly, compared to the time constant of
the circuit. The induced alternating current voltage is proportional to the
ionization current (Fig. 6).
Charlie Chong/ Fion Zhang