How is the Floated connection technology/mode working?
There are two different methods for connecting ionization chambers to an electrometer: Floated
and Grounded input technology. The main difference between the two systems is the way in which the polarization voltage is supplied to the ionization chamber.
The floated input clamps the outer chamber wall on ground potential, and provides the polarization voltage through the inner (collecting) electrode. Therefore, the electrometer amplifier is on polarization potential, and needs an isolating amplifier to provide analogue output. The extremely low current, initiated inside the chamber by radiation, forces the use of high sophisticated guarding techniques, in order to make the entire system (chamber, cable, connectors and amplifier) usable in clinical routine.
Floated input technology allows a consistent triaxial conception of electrometer input, cable, and detector. The chamber wall is on ground, and therefore the entire chamber and cable system is properly shielded. No protective sleeve is needed. This consequent shielding system provides extremely low noise operation. The outer shield of the triaxial cable is on ground. Standard triaxial connectors (either bayonet or threaded) can be used.