Short Nuclear Instrumentation Crate - side view

The Nuclear Instrumentation Module (NIM) standard defines mechanical and electrical specifications for electronics modules used in experimental

particle In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, fro ...

and

nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: *Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space * 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 one of 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

volt The volt (symbol: V) is the unit of electric potential, electric potential difference ( voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). D ...

s DC power to the modules via a

backplane A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backb ...

; 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). They can, however, also be built in multiples of this standard width, that is, double-width, triple-width etc.W. R. Leo, ''Techniques for Nuclear and Particle Physics Experiments - A How-to Approach''. 1994 The NIM standard also specifies cabling, connectors,

impedances In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit. Quantitatively, the impedance of a two-terminal circuit element is the ratio of the comp ...

and levels for

logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premis ...

signals. The fast logic standard (commonly known as NIM logic) is a current-based logic, negative "true" (at −16 mA into 50 ohms = −0.8 volts) and 0 mA for "false"; 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.

Standard Pin Assignments

{, class="wikitable" , + 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 , , , ,

References

Experimental particle physics

Standard Pin Assignments

See also

References