Boron-10 Tube

[Tom McCarthy]

Hi all,
Just found a Boron-10 lined tube on eBay for $16 (At this moment, a days bidding left), from the seller's description he says that it can detect d-d fusion neutrons, but only thermal ones. I understand that this means I would need a moderator to detect any neutrons I would be producing. There is also something about needing a portable survey meter or NIM to use the tube properly. From a quick look on eBay the portable survey meters seem relatively expensive at first glance, offsetting the gain of the tube itself's price. My question is is there some cheaper alternative that the tube can be used with or is it actually applicable in the first place?

Tom

[Carl Willis]

Hi Tom,

You need electronics to provide the tube with stable high voltage, to amplify and shape the signal, and to process the signal. All proportional tube detectors (BF3, boron-lined, He-3) have nearly identical requirements. There are some Russian corona counters on the market that work a bit differently.

Some, but not all, survey meters are usable with proportional tubes. Ludlum Model 3 and 12 are generally suitable, with the 12 being preferable. Bicron Surveyors and Eberline ASP-1s are also suitable. A NIM bin and modules can be used to build the most capable and versatile nuclear instruments around all kinds of detectors. You want at a minimum a NIM bin (crate), a HV power supply, a nuclear preamplifier, a shaping amplifier, and either an SCA and counter / timer or an ADC and MCA.

You are correct that survey instruments and NIM modules will cost much more than $16.

-Carl

[Tom McCarthy]

Thanks for the help Carl,
From your advice, I think my best buy would be to find a BTI bubble counter. As far as I know you only need the counter/detector itself and after that you only need to count the bubbles and do a few calculations based on distance from center of vacuum chamber, area, etc. Would you agree with this? Taking in the fact that I'm not looking to spend large amounts, keeping spending to a minimum.

Tom

[Carl Willis]

The BTI wins on cost, at least in the short term (although their limited life makes them costly for maintaining a continuous year-after-year detection capability). There's a lot of information about successful use of the BTI-PND detector in our archives.

-Carl

[Tom McCarthy]

At most I'll be buying two I think, as my main goal is to have my Fusor built before November, (Going a bit off-topic here) then I'll probably try to make it look a bit nicer, more efficient etc.
I'll try and read a few of those posts you mentioned over the weekend.
Tom

[Chris Bradley]

Almost certainly a Corona type tube from Russia, at those sorts of prices. The small ones are not particularly sensitive, but should pick up a half-decent fusor output. But be warned that they may well require you to built and perfect a pre-amp so that they can be used with standard scalers. That is no small mean feat with a small B-10 tube because the signal response to background neutrons will be one or two counts per several minutes, yet you are going to have to create a pre-amp circuit without really having a neutron signal with which you can check if it is working.

[Brian McDermott]

Tom,

I am the seller of the B10 tube in question. There are some archived posts here from circa 2005 that show how I and others set up and run the tube with various electronics. In short, all you need is a system where you set the lower level discriminator to a few mV and be able to adjust the bias voltage on the detector to somewhere around 650-750 volts (it varies depending on the tube). I used a Ludlum survey meter since I had one on hand at the time, but you can use any comparable circuit without the expense.

[Tom McCarthy]

Great to actually get in touch with a seller! EBay doesn't offer much in that way of things.

I think I'll stay at just a BTI bubble detector for now Brian, if I decide to expand on my neutron detection, I'll give you a message.

Tom