NukeWorker Forum
Reference, Questions and Help => Nuke Q&A => Instrument Q&A => Topic started by: Boilermaker on Jul 12, 2007, 03:18
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Hello everyone. Any feedback is appreciated. How is it better than using friskers like RM-25s, RM14s and PRM-6s? Thanks. In regards to scaler, how is it important?
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Boilermaker,
Depending on your particular needs it may or may not be better. I've only used it for table top sample counting (smears, A/S filters). You can attach a variety of detectors depending on your contaminant; you can adjust the high voltage depending on the detector. It provides the ability to perform timed counts on your samples for like up to 99 mins if I remember correctly. You've also got the ability to do electronic discrimination. I guess you could also use it as a portable ratemeter but its probably not the most rugged or practical instrument for that application.
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How is it better than using friskers like RM-25s, RM14s and PRM-6s? Thanks. In regards to scaler, how is it important?
Did you go to a museum and now have to write a report? ;D
All except the PRM-6 are designed to mainly be stationary devices. The Ludlum 2200 is designed mainly to be a scaler, one shot counting instrument. Along with the timer for scaler functions, it also has an energy discriminator circuit, so if coupled with an energy dependent detector (i.e. gas proportional or gamma sodium iodide) you can use it as a single channel analyzer, to reemphasize Laning's points. Since it has an analog meter, it could be used just like a RM-14 or RM-25, but you are wasting the money that you paid for the timing circuit and discriminator. It is not practical to replace a PRM-6 with a 2200 because the 2200 has no battery, is cumbersome, therefore not portable.
The main advantage of scaler over frisker is accuracy in significant digits and a lower minimum detectable contamination (MDC aka MDA). If you counted a smear with an analog frisker and held it there for 3 seconds, your LLD would be 80 net cpm with an 80 cpm background. A one minute scaler count of the same smear, same background would yield a LLD of 44 net cpm. With a scaler, you can also put the detector in a shield pig to lower the background and MDC/MDA/LLD.
If you are counting a hot smear, say 50,000 dpm, there is no advantage to a scaler over a frisker. If you are releasing say a large empty toolbox, for the total activity reading, an analog frisker is the right tool. Scanning at a slow frisk speed is more practical than doing 50 stationary 10 second scaler counts.