Simplified electronic signal processing in the small nuclear physics laboratory

Abstract

Small nuclear physics laboratories of all kinds traditionally have processed the signals from radiation detectors with a variety of discrete NIM- or CAMAC-based electronic modules. The logic signals associated with signal processing are often passed through gate generators, coincidence modules, fan-in/fan-out modules, delay units, counters, and other assorted logic modules. These multi-component systems generate gates for acquisition systems, gates for specific linear electronics modules (ADCs and TDCs), or measure count rates and dead times. This can involve a significant number of individual modules each of which can be quite costly and each of which provides only limited functions. We describe here an upgrade to our acquisition system where all the needed logic functions are performed in just a single unit: a Universal Logic Module based on a Field Programmable Gate Array (FPGA) from JTEC Corporation. This module also contains flash memory that holds three separate configurations allowing for rapid changes from one electronics configuration to a different one. Both CAMAC and VME versions of the unit are available. The system described here is just one example of the huge variety of functionality that can be programmed into this single module. It can accommodate very complicated circuits and is easily reprogrammed. In the small nuclear physics laboratory the Universal Logic Module can save cost when upgrading systems and reduce the number of instances where one has an insufficient number of channels of a particular function.