RE: pmt glass radiation

From: Matthew Worcester (
Date: Thu Jun 02 2005 - 09:37:26 CDT

Before anyone smashes anything, we have a sample of crushed borosilicate
from Hamamatsu at Chicago.


On Thu, 2 Jun 2005, Horton-Smith, Glenn wrote:

> Hi all,
> Indeed, the approach followed at KamLAND and Palo Verde was to
sacrifice a tube: specifically, smash it into little bits and pack the
pieces of glass into a bottle. Besides the practicalities of fitting the
thing into the shielded counting chamber, one generally wants a MC
simulation to get the detector efficiency for a given sample geometry and
to correct for Compton scattering in the sample itself, with the MC
validated using a known activity sample in each standard sample shape
(e.g., a 250 mL bottle). That's another reason it is convenient to
reshape the sample into a standard shape.
> I once shipped a large piece of quite solid, fractureless granite from
the KamLAND site to Caltech for counting, back in late 1998 or early 1999.
It was an odd shape and much too big to fit in the counter, and the person
who manually reduced it to gravel before counting (Andreas Piepke)
explained these facts of life to me later. :-)
> -Glenn.
> Joseph Formaggio wrote:
> 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.
> Joe

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