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Nuclear Instrumentation Module

NIM standard module connector pin assignments (required by DOE/ER-0457T)
Pin # Function Pin # Function
1 Reserved [+3 V] 2 Reserved [-3 V]
3 Spare Bus 4 Reserved Bus
5 Coaxial 6 Coaxial
7 Coaxial 8 200 V DC
9 Spare 10 +6 V
11 -6 V 12 Reserved Bus
13 Spare 14 Spare
15 Reserved 16 +12 V
17 -12 V 18 Spare Bus
19 Reserved Bus 20 Spare
21 Spare 22 Reserved
23 Reserved 24 Reserved
25 Reserved 26 Spare
27 Spare 28 +24 V
29 -24 V 30 Spare Bus
31 Spare 32 Spare
33 117 V AC (hot) 34 Power Return Gnd
35 Reset (scaler) 36 Gate
37 Reset (aux) 38 Coaxial
39 Coaxial 40 Coaxial
41 117 V AC (neutral) 42 High Quality Gnd
G Gnd Guide Pin

The Nuclear Instrumentation Module (NIM) 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 (and perhaps the simplest) 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 (DOE/ER-0457T). It provides a common footprint for electronic modules (amplifiers, ADCs, DACs, discriminators, etc.), which plug into a larger chassis (NIM crate, or NIM bin). 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 (34 mm), a maximum faceplate height of 8.7 in (221 mm) and depth of 9.7 in (246 mm)[1]. They can, however, also be built in multiples of this standard width, that is, double-width, triple-width etc.[2]

The NIM standard also specifies cabling, connectors, impedances and levels for logic signals. The fast logic standard (commonly known as NIM logic) is a current based logic, with negative true (at -16 mA into 50 ohms = -0.8 Volts); an ECL-based logic is also specified.

Apart from the above mentioned mechanical/physical and electrical specifications/restrictions, the individual is free to design his 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 which do not require digital data communication but benefit from a backplane connector that is better suited for high power use.

See also

BNC connectors for analog and logic signals
Computer Automated Measurement and Control (CAMAC)
Data acquisition
LEMO connectors, for higher density modules
Nuclear electronics
RG-58 50 ohm coaxial cable for timing and logic signals
RG-62 93 ohm coaxial cable for spectroscopy signals
[1] Examples of NIM bins, crates and pulse generators.
[2] Example of current NIM unit.


^ http://www.osti.gov/energycitations/servlets/purl/7120327-MV8wop/7120327.PDF Standard NIM Instrumentation System (DOE/ER-0457T). p. 19
^ W.R. Leo, Techniques for Nuclear and Particle Physics Experiments - A How-to Approach. 1994

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