Current to Frequency Converter for Digitization of Millisecond Beam Signals

Beam-intensity monitoring in the Fermilab Neutrino Area requires sensitive and fast processing for beam signals (with four or five decade amplitude variations for a typcial detector) which are digitized with a current-to-frequency converter (IFC). The converter digitizes the input charge at a 1 pC/Hz rate with a processing limit at 10 MHz for a 10 nC charge input or a 10 ¿A current input. For a 1 ms beam pulse, the IFC can generate a 1 to 10,000 count output. The digitizer is two to three decades more sensitive than the fastest commercial V to F converters and the upper frequency limit is two or three decades higher than the present laboratory built IFC´s. The resolution over the 0 to 50°C temperature range and the linearity from 1 Hz to 1 MHz is held to ± 1% with a linearity deviation of + 5% at 10 MHz.