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Bubble vs. Quantrad Ranger Plus

Posted: Thu May 28, 2015 7:42 pm
by David Kunkle
No neutron detector yet, but I had been assuming I'd get a bubble detector. They're only good for 6 mos., and at this point, my project could easily go on for over a year- meaning $500+ worth of bubble detectors with nothing but paperweights at the end.

I have the chance to get a 2007 Quantrad Ranger Plus for about $1500. Uses a He3 proportional counter- 4" long and 1/2" diameter. Gives cps readout among lots of other things. Needs a Bi207 source for calibration. A chunk of money, but since it's already used, should be worth what I paid for it at the end making it far cheaper than bubble detectors.

Any comments before I do something I'll regret, and how hard to find a Bi calibration source?

Re: Bubble vs. Quantrad Ranger Plus

Posted: Fri May 29, 2015 12:27 am
by Richard Hull
A true, radioactive neutron source can't be readily purchased by an individual. Period. They are limited to special NRC licensed users only.

Richard Hull

Re: Bubble vs. Quantrad Ranger Plus

Posted: Fri May 29, 2015 1:42 am
by Rich Feldman
David,

The $1500 is not an expense, it's a capital equipment cost. On the books of a business, it would have to be depreciated over some number of years.

Will you be able to get most of your money back by selling the detector some day, if nothing bad happens while it's in your custody?

Re: Bubble vs. Quantrad Ranger Plus

Posted: Fri May 29, 2015 2:29 am
by Bob Reite
You can send it to a calibration lab that has the necessary source. It should not cost more than $200.00 plus shipping both ways. The calibration should be good for several years as long as the instrument is treated gently.

Re: Bubble vs. Quantrad Ranger Plus

Posted: Fri May 29, 2015 3:23 am
by David Kunkle
Richard Hull wrote:A true, radioactive neutron source can't be readily purchased by an individual. Period. They are limited to special NRC licensed users only.

Richard Hull
Forgot about that. Must have been thinking about radioactive ores that people collect.

Re: Bubble vs. Quantrad Ranger Plus

Posted: Fri May 29, 2015 3:27 am
by David Kunkle
Rich Feldman wrote:David,

The $1500 is not an expense, it's a capital equipment cost. On the books of a business, it would have to be depreciated over some number of years.

Will you be able to get most of your money back by selling the detector some day, if nothing bad happens while it's in your custody?
Not really a business expense in my case. But as usual, I'd be taking a chance it doesn't implode on me. Kinda like that first turbo I got that is now a high tech doorstop. Other than that, I imagine it'd still be worth close to what I paid for it.

Re: Bubble vs. Quantrad Ranger Plus

Posted: Fri May 29, 2015 3:32 am
by David Kunkle
Bob Reite wrote:You can send it to a calibration lab that has the necessary source. It should not cost more than $200.00 plus shipping both ways. The calibration should be good for several years as long as the instrument is treated gently.
Assuming there's no actual damage to the unit (it appears to be functioning properly), it has a factory calibration stored in memory. Maybe use it as is, until I start registering neutrons, then I would want to send it off for calibration. What might the odds be that it would be so far off, it would not even register any neutron count from a fusor?

Re: Bubble vs. Quantrad Ranger Plus

Posted: Fri May 29, 2015 4:25 pm
by Richard Hull
As reported many times here, absolute neutron numbers are not a must have and are nearly impossible to obtain to within 10-20% with even the best gear in amateur hands.

A good detector or detection method is the key. Relative measurements with good detection gear are the very best the raw beginner might hope for. Run-to-run improvement in operational performance are easily obtained to within 5% or better.

Factory calibration is OK, but in many instances, a needless expense. A very, very old instrument might benefit from a modern calibration. I sent off an old Eberline counter some years ago that was new in the late 60's or early 70's and spent the big bucks. When it came back the numbers from a local source were not statistially different than when I sent it off.

Richard Hull

Re: Bubble vs. Quantrad Ranger Plus

Posted: Fri May 29, 2015 6:45 pm
by David Kunkle
Richard,

Thank you for several good points in there. Well taken here- mostly as good news. No real point in tracking down a calibration source or paying someone to do it then. I take it form your post that, except in some sort of extreme case, true counts would be off by a percentage and not orders of magnitude which is what I would be most concerned about. Am I assuming too much?

Re: Bubble vs. Quantrad Ranger Plus

Posted: Sat May 30, 2015 5:51 am
by Richard Hull
The trick to measuring neutrons is to be sure you are measuring them and not some other radiation. We have discussed at length how to show yourself that you are measuring neutrons. Tricks that can help you to be sure. Too many people just never read the FAQs on how to do this.

Richard Hull