From: Joseph Formaggio (email@example.com)
Date: Thu Jun 02 2005 - 03:21:17 CDT
I am not absolutely sure, but I believe it is difficult to take background counts of a large object such as a phototube. Parts of it are ok (base, pieces of glass, etc). But the whole thing assembled I think is difficult. It depends on how big the chamber where they do the counting is, and how big their Ge crystals are.
On Wed, 1 Jun 2005, 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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