NIM, or Nuclear Instrumentation Module, is a standardized specification that defines electronic modules that are used in nuclear and particle physics. It was first defined by the US Atomic Energy Commission in 1968. NIMs continue to be sold and used today, primarily in national and university physics laboratories.
A NIM is a vertical module 8.75“ (222mm) tall, 1.35” (34mm) wide, and 9.7“ (246mm) deep. Each NIM has a multi-pin connector on its rear that carries power and ground lines.
NIMs slide into slots in a NIM bin, which is a chassis designed to hold NIMs. NIM bins usually include a power supply for NIMs, with power provided on mating connectors in the rear of each slot. The most common form factor is 19” rack-mount, though smaller tabletop units are also common. On the rear of a NIM bin, the bottom section of each slot is occupied by the power connector, and the remaining space above it is usually open to the outside, for cabling purposes.
NIMs do not communicate with each other via bins; any desired connections between them must be explicitly made via connectors on the front or the rear of each NIM. The number and types of connectors on the front or rear of a NIM are entirely implementation-specific, i.e. they depend on what function the module is designed to perform.
Typical NIMs are pulse amplifiers, pulse height discriminators, single- or multi-channel analyzers, pulse counters, pulse digitizers, HV generators for PMT-based or other particle detectors, and many others.
NIMs and NIM bins are, or have been, manufactured by LeCroy, Canberra, Tennelec, Nuclear Data, and many other companies. Due to standardization, NIMs are interoperable between manufacturers, i.e. one can mix Canberra and Ortec NIMs in a bin made by Tennelec.
At the time of this writing (January, 2022), NIMs are commonly and inexpensively available via various auction venues.