Nuclear Instrumentation Standard

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The NIM standard , originally an acronym for Nuclear Instrumentation Module Standard , was developed in 1964 for nuclear and high-energy physics. Nuclear Instrumentation Standards (NIM) are modular systems with bus connections that are only used to power the built-in modules. Power is supplied via the bus (backplane). These standards are designed to be modular throughout, so that a kind of "modular system" is always available. The dimensions of the modules, the dimensions of the housing and superframes and the connections (backplane) are specified in accordance with the EUR 4100 and AEC NIM (TIS20893) standards. The concept of modules in electronic systems allows enormous advantages in flexibility, in changing instruments, in reduced design effort; they are easy to expand and maintain.

The NIM standard is the first (and probably the simplest) of such standards. It was defined by US Atomic Energy Commission's report TID-20893 in 1968–1969 and was largely revised in 1990 (DOE / ER-0457T). It provides a common connection surface for electronic modules that are plugged into a larger housing (NIM-crate or NIM-bin). The housing provides ± 12 and ± 24 volts DC for the modules via a backplane; the standard also requires ± 6V DC and 220V or 110V AC connections, but not all NIM packages have these. From a construction point of view, the NIM modules have a minimum width of 3.43 cm (1.35 in) and a height of 22.225 cm (8.75 in). The width can also be a multiple of this standard, so there are double-wide and triple-wide modules. The slots serve as a holding device and power supply for 12 NIM modules. NIM modules can e.g. B. analog / digital converters, analyzers, preamplifiers or high-voltage supplies. The NIM standard also defines the cabling, connections and plug connections, impedances and thresholds for logical signals.

The Nuclear Instrumentation Module ( NIM ) standard is a standard for negative logic levels .

Since photomultipliers, for example, supply negative levels, logic levels were defined for negative pulses in the NIM in 1964. This standard defines the logical "1" or "0" via currents, whereby voltages can be measured via terminating resistors of 50 Ω.

In contrast, the transistor-transistor logic (TTL) defines the logic "1" or "0" via positive voltage levels.

Comparison of NIM and TTL
default logical 0 logical 1
NIM 0mA (0V @ 50Ω) –12 mA to –32 mA (–0.6 V to –1.6 V @ 50Ω)
TTL 0V to 0.4V 3.3 V to 5 V (output) or 1.5 V to 5 V (input)