Nuclear Instrumentation Module


Pin #FunctionPin #Function
1Reserved 2Reserved
3Spare bus4Reserved bus
5Coaxial6Coaxial
7Coaxial8200 V DC
9Spare10+6 V
11−6 V12Reserved bus
13Spare14Spare
15Reserved16+12 V
17−12 V18Spare bus
19Reserved bus20Spare
21Spare22Reserved
23Reserved24Reserved
25Reserved26Spare
27Spare28+24 V
29−24 V30Spare bus
31Spare32Spare
33117 V AC 34Power return Gnd
35Reset 36Gate
37Reset 38Coaxial
39Coaxial40Coaxial
41117 V AC 42High-quality Gnd
GGnd guide pin

The Nuclear Instrumentation Module standard defines mechanical and electrical specifications for electronics modules used in experimental particle and nuclear physics. The concept of modules in electronic systems offers enormous advantages in flexibility, interchange of instruments, reduced design effort, ease in updating and maintaining the instruments.
The NIM standard is the first such standard. First defined by the U.S. Atomic Energy Commission's report TID-20893 in 1968–1969, NIM was most recently revised in 1990. It provides a common footprint for electronic modules, which plug into a larger chassis. The crate must supply ±12 and ±24 volts DC power to the modules via a backplane; the standard also specifies ±6 V DC and 220 V or 110 V AC pins, but not all NIM bins provide them. Mechanically, NIM modules must have a minimum standard width of 1.35 in, a maximum faceplate height of 8.7 in and depth of 9.7 in. They can, however, also be built in multiples of this standard width, that is, double-width, triple-width etc.
The NIM standard also specifies cabling, connectors, impedances and levels for logic signals. The fast logic standard is a current-based logic, with negative true ; an ECL-based logic is also specified.
Apart from the above mentioned mechanical/physical and electrical specifications/restrictions, the individual is free to design their module in any way desired, thus allowing for new developments and improvements for efficiency or looks/aesthetics.
NIM modules cannot communicate with each other through the crate backplane; this is a feature of later standards such as CAMAC and VMEbus. As a consequence, NIM-based ADC modules are nowadays uncommon in nuclear and particle physics. NIM is still widely used for amplifiers, discriminators, nuclear pulse generators and other logic modules that do not require digital data communication but benefit from a backplane connector that is better suited for high power use.