Microprocessor-controlled integrating read-out systems for photomultiplier tubes

Two types of wide dynamic range integrating read-out systems for photomultiplier tubes have been developed. One system is based on a voltage-to-frequency converter-counter system and the second is based on summing a large number of analogue-to-digital converter values. Both systems operate under microprocessor control. The microprocessor controls and sequences the acquisition of replicate integrated measurements and software is provided for calculation of background-corrected values, standard deviations for up to 32 replicate values and signal-to-noise ratios. Development and implementation of this software capability in a small system is greatly facilitated by use of a hardware floating-point package. All program software is stored in erasable programmable read-only memory. This system has been particularly useful for the acquisition of data from a single-channel inductively-coupled plasma atomic-emission spectrometer.