Re: pmt glass radiation

From: Matthew Worcester (
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.


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

This archive was generated by hypermail 2.1.6 : Thu Jun 02 2005 - 03:10:13 CDT