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

Modern electrometers
A modern electrometer is a highly sensitive electronic voltmeter whose input
impedance is so high that the current flowing into it can be considered, for
most practical purposes, to be zero. The actual value of input resistance for
modern electronic electrometers is around 10 14 Ω, compared to around 10 10 Ω
for nanovoltmeters. Owing to the extremely high input impedance, special
design considerations must be applied to avoid leakage current such as
driven shields and special insulation materials.
Among other applications, electrometers are used in nuclear physics
experiments as they are able to measure the tiny charges left in matter by the
passage of ionizing radiation. The most common use for modern
electrometers is the measurement of radiation with ionization chambers, in
instruments such as Geiger counters.
Charlie Chong/ Fion Zhang