Reuter Stokes Proportional Counter

[9a3daa]

As far as I know - according to my calculations - a 60uCi AmBe give flux of 30n/s

Of course, I'll have a little look at the other threads.

[Carl Willis]

I don't see anyone disagreeing with you that this is a B-10 LINED tube filled with argon.

There is ample information about using these kinds of tubes in our archives. Based on your description of your testing so far I cannot conjecture about the tube's condition. I think Tyler gave you good advice about testing it, but I will add that an MCA is very helpful. There are example pulse-height spectra from neutron capture in B-lined tubes in this forum.

A 60-microcurie AmBe source of decent home construction probably emits about 10 n / sec. That's detectable over counting intervals of an hour or more perhaps, but extremely weak and not likely to be helpful in testing your tube.

-Carl

[Richard Hull]

Usually you would need a 300uCi source or better for easy, obvious counting. Using a 1mCi source would be just about ideal for "no statisitics" or long counting regimes. This is given that the boron lined tubes are not as efficient as a 3He tube which is capable of working with a god deal weaker source.

Richard Hull

[9a3daa]

One more question:
Why are you sure that the my tube is B-10 lined?
Why this does not written on the nameplate?

I want to be 100% sure that this neutron detector.

[Tyler Christensen]

Because GE told you it is...

"The part RS-P7-0805-127 would be a B-10 lined proportional counter, filled with ~0.8bar of Argon as quench gas. According to our files, this detector was made in 1976."

[Carl Willis]

Your first message quotes a response from GE Reuter Stokes to your own inquiry:

>"The part RS-P7-0805-127 would be a B-10 lined proportional counter."

That's the tube's manufacturer telling you what it is. There is no reason to suspect it's inaccurate, and there's nobody here who can be more authoritative on the subject.

-Carl

[9a3daa]

Thank you very much all!

Soon I'm going to institute in my town for the equipment- and I'll get you the results.

[9a3daa]

Why GE are we told me that is ~ 0.8bar - and on my tube writes Pressure: 23 cm Hg

And 23 cm Hg is 0.3bar
How?

[Chris Bradley]

Maybe they told you '-0.8bar', or that the label should've been marked as inches Hg??

...just errors...

Either way, are you saying you doubt all the information the manufacturer of the item then supplies you?

[Carl Willis]

Well, one possibility that's easy to think of is that the person who went to the filing cabinet to look up data on your tube saw a "0.3" on the spec sheet and thought it looked like "0.8". The numbers 3 and 8 look similar. You could always ask them to clarify, if it matters sufficiently to you. The label is more likely to be accurate.

On another matter...please follow the rules regarding an introduction if you intend to keep posting to our forums. We have this rule to cut down on "drive-by" posting and to promote community. Thanks in advance.

-Carl

[9a3daa]

How am I violate the rule?

I'm just politely asking questions.
I was a little confused, and do not know English very well - I use google translator - please have a little understanding.

[Carl Willis]

From the rules:

>2) New members are required to introduce themselves in the "Please Introduce Yourself" forum prior to posting elsewhere on the site.

Thanks,
Carl

[9a3daa]

Am Introduce Yourself

[9a3daa]

GE told me again by email:

Dear Arni,

I apologize for my answer. If the pressure written on the tube is 23cmHg, then it is 0.3bar of Argon. Which strengthen my position that this detector is not design for gamma radiation detection.

At Reuter Stokes, we have more than 56 years’ experience in making nuclear detectors. According to our numbering system, which I attach a copy to this e-mail: RS-P7-0805-127

- RS means that it is a Reuter Stokes detector,
- P7 is a B-10 lined proportional counter
- 08 is the diameter of the detector in 1/8 of an inches,
- 05 is the length of the detector in inches,
- 1 means that the body shell is made of aluminum, and
- 27 is the number of the detector in the series issued.

Now I'm 100% sure that it is a neutron detector.

[9a3daa]

How much thick should be moderator for my detector?
parafin moderator: ________inch
HDPE moderator: ________inch

[Carl Willis]

That depends on what you want to use it for.

[9a3daa]

They will be used to measure the neutron from AmBe source.
Not fusor neutrons.

[Richard Hull]

You have a couple of options

1. Thermalize the source's fast neutrons with polyethylene or parafin and measure with a naked tube
2. Place a moderator of polyethylene or parafin around the tube allowing it to count the fast neutrons from the source.
3.Place the tube and source in a neutron oven (special moderator arrangement)

In general, #3 will do the best job and give sligthly more counts, but #2 will create a nice fast neutron counter system.

3" of parafin or polyethylene or water all around the tube or source will suffice to thermalize the fast neutrons that you might encounter as an amateur.

I am rather stunned you haven't looked at the FAQs and seen Carl's fabulous videos! A lot comes from monkey-see-monkey-do.

Richard Hull

[Carl Willis]

About 6 cm thickness of either wax or HDPE will be close to optimum for the ~5 MeV-average AmBe spectrum if the source is distant from the detector.

If the source is close to the detector, the optimum thickness is smaller, perhaps decreasing to ~4 cm.

The most efficient geometry for counting a weak source is to place the detector and the source in contact with each other inside of a moderating reflector. In this case, the thicker the moderator the better--there is no optimum. Practically speaking, a 10-cm thickness is usually a good balance between efficiency and size/weight.

-Carl

[9a3daa]

If I understand correctly, it should look like this:

Yes thank you Carl and others.

[aka47]

I can't claim to be knowledgable on this one. Because I am not.

At the moment I am in a similar position building up a couple of detectors using a pair of ex russian CHM11 tubes.

When making things (Which I do a lot) I often go on the large size being as it is easier to cut more off than add it on.

In this case though I will be going on the smaller side and picking a moderator/tube assembly size that can fit in snugly in common rain water fall pipe. As it is then simple enough to make an add on sleave using rain water fall pipe and the next size of pipe up (Stench pipe is 110mm here in the UK). With the void between the two filled with something hydrogen rich and very, very cheap.

Domestic plastic rain & drain piping is inexpensive, easily worked and solvent welded and will withstand the inter wall void being filled with hot parafin wax or made into hollow sleaves to be filled with a liquid moderator of my choice.

My thinking is :-

1. If I make my moderator too big it is going to be painful and undesirable to try and (Turn on a lathe) trim it after the fact.

2. I can always make it bigger by adding sleeves over the top if I need it for another application that demands the moderator be thicker.

3. If I want it thinner after doing 2 above I can take the sleave off.

With anything I make I always want it to be some other size, if not right away, then some time thereafter. I guess it is the nature of experimentation. The trick is to design with later in mind.

The technique above will let me do this.

[Carl Willis]

Regarding drain pipe (presumably PVC), please read this 2006 thread about why that's a poor material:

viewtopic.php?f=13&t=5691#p38086

-Carl

[Chris Bradley]

Carl Willis wrote:
> Regarding drain pipe (presumably PVC)
I've seen it supplied in polypropylene here in UK. Polyprop plumbing is commonly marked 'PP' in matrix-ink writing on the side. If not, probably PVC. Underground waste pipes are usually PE.

[aka47]

Thanks for that Carl, much apreciated.

Looks like sleeving is in, PVC Material is out.

Fortunately there are other types of plastic pipe to use instead. Maybe not quite as cheap, but equaly as easily worked.

http://en.wikipedia.org/wiki/Plastic_pipework

[aka47]

Agreed, chris.

I will be making the initial case/moderator from HDPE Rod. There is a localish supplier I usualy use for feedstocks on projects I am working on. They are not the cheapest out there but are convenient and will cut to length.

http://www.directplasticsonline.co.uk/HDPERod/Natural/