Re: pmt glass radiation

From: Matthew Worcester (mworcest@hep.uchicago.edu)
Date: Wed Jun 01 2005 - 09:58:42 CDT


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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