Re: pmt glass radiation

From: Janet Conrad (
Date: Wed Jun 01 2005 - 10:51:34 CDT


As long as we are testing materials: What paint are we using to blacken
inside of the tank?

On MiniBooNE we chose the materials to assure that the oil would not be
Andrew Bazarko did a really impressive range of studies and
it was quite striking what happened to the oil with many kinds of paints
and epoxies.

We must take care.

Note that on MiniBooNE, where events are >50 MeV, we didn't worry about

We chose an epoxy to dip the tubes and a Sherwin-Williams paint for the
panels. Joe, I may be able to get you some of the paint and the
epoxy and we
could test it. I'll contact Andrew.

Also, we have a facility here called "MiniMiniBooNE" which we may be
able to use
to do some tests. It is painted with MiniBooNE paint and has a
distance of about 40 cm
tube face to edge of tank. We might be able to use this to test the
rate from the tubes and
also the background rate from the paint. It isn't clear to me that we
will be allowed
to fill this with scintillator oil (MiniBooNE does not used doped oil,
so we would have to
be able to clean it out very very well before the next MiniBooNE
tests). But I can check.
Paul Nienaber will send out some dimensions and info on the test setup


Josh R Klein wrote:

> Just to add to Janet's note: the electronics components in the SNO tube bases
>are probably a larger contribution than the glass in terms of radioactivity. We
>might look into getting un-painted SMD's for our bases if we were worried about
> Josh
>On Wed, Jun 01, 2005 at 10:24:42AM -0500, Janet Conrad wrote:
>>Hi Joe,
>>If I gave you a tube, with base, dipped in the protective enamel, could
>>you send it to
>>your low backgorund counting facility and have them measure the rates
>>and what is coming out?
>>Because there is more than just the tube -- there is the basis, the
>>protective coating, etc.
>>It would be nice to know where we stand with the whole package.
>>Matthew Worcester wrote:
>>>Hi Joe,
>>>Thanks again for the talk. I think the background must scale much
>>>more like the amount of material. So if you assume equal density of
>>>the glass, we should scale by volume. Assuming the 5912 is a 5 mm
>>>thick sphere and that the 2" tube is also 5 mm thick I get about 6
>>>Bq/pmt for the 8" tube, which is ballpark.
>>>On Tue, 31 May 2005, Joseph Formaggio wrote:
>>>>Dear Matt,
>>>> Forgive me if I have sent you this talk before. It is a talk from
>>>>Moriyama from LRT2004. If you check out his slide 14, he quotes
>>>>~0.025 decays/sec/PMT, though these are much smaller PMTs (2").
>>>>However, scaling to an 8" tube, that means a rate of ~0.4 Hz/tube
>>>>(rather than 10). However, the background may not scale simply with
>>>>area. Hamamatsu does not list the R8778 in their catalog, so it
>>>>might be what we would expect to see in the future.
>>>>Hope it helps,

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