rhodium self powered neutron detectors (SPND) have been used for a long time in the experimental devices at the SILOE reactor.
In a time-dependant neutron flux, the rhodium SPND behaves as a first order linear system. Consequently, the response of the SPND is not similar to the incident flux evolution because time constants are involved. In order to draw-out the true flux variation, a convolution type method is to be used.
As a result of the time discretisation of the linear differential system that couples the SPND current to the neutron flux, one has to use differential equations. The resolution of these equations is equivalent to an approximate inversion of the initial system.
The numerical method described above has been applied in a microcomputer system, in order to treat the SPND signal by a computer-driven millivolmeter.
Nowadays, devices for transient experiments in the SILOE reactor are driven by a P.C. system, based on this numerical approach and using an independent data acquisition; the reliability and the ergonomics aspects have been taken into account. The modular conception of the system allows easy further developments for flux monitoring in various surroundings.