The photomultiplier tubes (PMTs)of the DIRC of
BaBar are sitting in ultra pure water. Their
front window, made out of borosilicate glass, is
affected by water corrosion. We report here the
results of measurements of glass corrosion
performed by the PMT manufacturer and at Saclay.
It is found that there should be no problem, risk
of implosion or degradation of PMT performance,
in the short term (a few years). In the long term,
the 50 PMTs with a front window made out of a
wrong glass, less resistant to pure water, should
probabaly be replaced.
|
