NIM Scaler Questions

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Tom Dressel
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NIM Scaler Questions

Post by Tom Dressel »

For us NIM dummies, could someone elaborate on what a scaler does?

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Richard Hull
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Re: NIM Scaler Questions

Post by Richard Hull »

There are two ways to get at the counts from a detector.

1. Analog meter.....This integrates the incoming pulses and moves a needle up scale to indicate an INSTANTANEUOS RATE of incoming pulses. (pulses per unit time)

Traditionally, this is readout in CPM (counts per minute). In the words of NIM, this module is called a RATEMETER.

Most all geiger counters include a ratemeter, built in.

2. A digital counter.....A NIM SCALER module is digital in nature and integrates nothing. Every pulse is counted and increments a digital counter taking a precise and unambiguous count of the pulses it receives, saving them into a visible readout. The end user determines the counting period over which the device counts by opening and closing the count gate. The user is then free to divide the count by the time and arrive at an overall average rate for that period of radiation detection.

Many Scalers have a timer also built into the module. The user can then set the device to automatically stop counting after a precise interval of time (usually set by thumbwheel switches on the front of the module below the counter.

In short, a scaler is a simple digital counter.

The choice of which to use in what application is pivotal, of course.

The RATEMETER lets you track variations, if any, in the incident radiation. This is perceived instantly in moderate to high radiation fluxes on a ratemeter. The ratemeter gives an instant reading of generalized radiation conditions. adjustments in a setup can be made fast and with minimal exposure using a ratemeter.

The SCALER is much more desirable where very low radiation counting is a must and where precise background counting is required. The scaler is without the slop or ambiguity of the ratemeter, but you gotta' expose the system over a specified counting period. The data and, thus, the count rate is deduced or calculated POST EXPOSURE! You have no idea if the radiation was steady over that period or came in just a few intense bursts.

Obviously, for X-ray detection protection and handling of isotopes or radioactives, the ratemeter is the readout of choice.

For neutron counting, establishing a background level, etc. the scaler is best.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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