[Halld-cal] FCAL radiation damage (fwd from Lubomir)

[Elton Smith]

---------- Forwarded message ----------
Date: Tue, 30 Nov 2010 17:56:43 -0500 (EST)
From: Lubomir Pentchev <pentchev at jlab.org>
To: Elton Smith <elton at jlab.org>
Subject: FCAL radiation damage


Hi Elton,

As we talked on the last calorimetry meeting, I was looking in the
literature to find examples of radiation damage that can be compared to
the Brad's results for FCAL. The RCS experiment at JLab used the same
type of lead glass (TF-1), although produced in Yerevan. They estimated a
total dose of 3-6kRad for the whole experiment. At the end they measured
the glass transparency. Look at:

http://www1.jlab.org/Ul/Publications/documents/ACF6D6.pdf

Fig.22 at page 13. So, they had ~85% transparency at the front of the
glass. Comparing this to the Brad's numbers for ~10kRad/year (at 10^8
gammas/sec), at:

http://argus.phys.uregina.ca/gluex/DocDB/0016/001641/002/RHG-Fall2010.pdf

pages 10 and 11, one concludes that the Bard's calculations underestimate
the radiation effects. Or maybe these plots are for 10^7 gammas/sec?

In any case, it will be useful to compare the Brad's calculations to
the results of the above paper.

Lubomir