Nuclear Instrumentation Module: Difference between revisions

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{{refimprovemore citations needed|date=July 2011}}

[[File:Short Nuclear Instrumentation Crate - side view.jpg|thumb|A NIM Cratecrate with a variety of modules. ]]

The '''Nuclear Instrumentation Module''' (NIM) standard defines mechanical and electrical specifications for [[modular crate electronics|electronics modules]] used in experimental [[particle physics|particle]] and [[nuclear physics|nuclear]] physics. The concept of [[Modular design|modulemodules]]s in [[Electronics|electronic]] systems offers enormous advantages in flexibility, interchange of instruments, reduced design effort, ease in updating and maintaining the instruments.

The NIM standard is one of the first (and perhaps the simplest) such standardstandards. First defined by the [[United States Atomic Energy Commission|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, [[Analog-to-digital converter|ADCADCs]]s, [[Digital-to-analog converter|DACDACs]]s, discriminators[[Constant fraction discriminator|CFDs]], etc.), which plug into a larger chassis ('''[[modular crate electronics|NIM crate]]''', or '''NIM bin'''). The crate must supply ±12 and ±24 &nbsp;[[volt]]s [[Direct current|DC]] power to the modules via a [[backplane]]; the standard also specifies ±6&nbsp;V DC and 220&nbsp;V or 110&nbsp;V [[Alternating current|AC]] pins, but not all NIM bins provide them. Mechanically, NIM modules must have a minimum standard width of 1.35 &nbsp;in (34&nbsp;mm), a maximum faceplate height of 8.7 &nbsp;in (221&nbsp;mm) and depth of 9.7 &nbsp;in (246&nbsp;mm).<ref>[http://www.osti.gov/energycitations/servlets/purl/7120327-MV8wop/7120327.PDF Standard NIM Instrumentation System (DOE/ER-0457T).], p. &nbsp;19.</ref> They can, however, also be built in multiples of this standard width, that is, double-width, triple-width etc.<ref>W. R. Leo, ''Techniques for Nuclear and Particle Physics Experiments -&nbsp;– A How-to Approach''. 1994.</ref>

The NIM standard also specifies cabling, connectors, [[Electrical impedance|impedances]] and levels for [[Boolean logic|logic]] signals. The fast logic standard (commonly known as '''NIM logic''') is a current-based logic, negative "true" (at −16 &nbsp;mA into 50 &nbsp;ohms = −0.8 &nbsp;volts) and 0 &nbsp;mA for "false"; {{clarify span|an [[Emitter-Coupledcoupled Logiclogic|ECL]]-based logic|reason="RAS syndrome"?|date=June 2023}} 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 [[Computer Automated Measurement and Control|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.

==Standard pin assignments==