From: Hans Jostlein (jostlein@fnal.gov)
Date: Wed Jun 01 2005 - 11:01:16 CDT
Thanks, Janet
Do we know what the maximum allowed wall reflectivity is?
We may be able to get black steel which would be just a thin oxide coating.
Hans
----- Original Message -----
From: "Janet Conrad" <conrad@nevis.columbia.edu>
To: "Josh R Klein" <jrk@mail.hep.utexas.edu>
Cc: "Matthew Worcester" <mworcest@hep.uchicago.edu>; "Joseph Formaggio"
<josephf@u.washington.edu>; <braidwood@hep.uchicago.edu>; "Paul Nienaber"
<nienaber@fnal.gov>
Sent: Wednesday, June 01, 2005 10:51 AM
Subject: Re: pmt glass radiation
> Hi,
>
> As long as we are testing materials: What paint are we using to blacken
> the
> inside of the tank?
>
> On MiniBooNE we chose the materials to assure that the oil would not be
> poisoned.
> 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
> contamination.
>
> We chose an epoxy to dip the tubes and a Sherwin-Williams paint for the
> light-tight
> 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
> later...
>
> -Janet
>
> Josh R Klein wrote:
>
> >Joe,
> > 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
> >this.
> >
> > 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.
> >>
> >>-Janet
> >>
> >>
> >>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.
> >>>
> >>>Cheers,
> >>>Matt
> >>>
> >>>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,
> >>>>Joe
> >>>>
> >>>>
> >>
> >>
>
>
>
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