Well, I just received my new PNC-1 neutron counter from an E-bay purchase. I paid $51.00 plus $10.00 shipping and handling.
The ad on e-bay had the usual disclaimers, "No way to test"........."Should be OK, but sold as is"........"Can be used for prospecting" (WRONGO)............ Oh well, the beat goes on.
Any way, it arrived and, thankfully, had the batteries removed. A huge piece of tape on it stated that they had been removed 4/3/68! Thus, giving an idea of its age. It has an old AEC (Atomic Energy Commission) property tag on it and a cal tag date of 5/21/66!
It was filthy, having been stored since the above dates, I am sure. It had lots of tape, labels, goofy property dots and garbage on it which had fused with the paint and took a lot of WD-40 to clean off over a 3 hour period. After a long tidy up and cleaning, plus some sanding of battery contacts which were not corroded, but just tarnished, it was ready to check.
With 5 new alkaline D cells in the unit, it thankfully read zero when turned on, but did have the required 1500 volts or so on the BF3 tube. A speaker, when attached, indicated about the normal click every minute or so. A very nasty 5 roentgen mixed radiation radium source I have read zero sitting right next to the unit. (That's cool and proper also)
Fusor III is down and the new lab area is not even nearly ready, so without a formal neutron source and knowing what I know about my other PNC-1, (I have two now), I would say this puppy works well! Calibration is next on the list.
Keep your eyes peeled guys........
For your reference, on the Eberline PNC-1 with the tube in the moderator base, there is .006 mrem per event per minute for fast neutrons. example: A reading of 166 events per minute represents a dosage of 1mrem of a fast flux. This, inturn, equals a flux of approx. 8 neutrons/sqcm/sec (the dial on the PNC-1 reads in events/min). At a range of 40cm from the poissor of a working fusor, this would work out to a total emission of about 1.6e105 neutrons/second
Richard Hull
Update: The above stated fast neutron calibration would be for 10mev or faster neutrons. According to Eberline 40-60 events/min is 1 mrem. Their counter goes very non-linear above 5mev and that is why the original professional user had attached special fast neutron to mrem cal stickers on the units.
Richard Hull
Created on Monday, March 26, 2001 11:54 AM EDT by Richard Hull Last Modified on Wednesday, April 11, 2001 3:29 PM EDT by Richard Hull