Starting Friday, Oct 31, 1997 we have been having serious problems with
the quality of the electrical power provided to our MACRO detector.
This is primarily due to the failure of part (~10%) of the battery
elements that the laboratory has in order to backup transient lack of
electrical power as provided by the italian power company (ENEL).
This, in combination with the particularly *unstable* power supply given
to us by ENEL over the last 4 days has resulted in actually feeding this
bad quality power to all our electronics and PMTs. We have seen this
effect on NIM power supplies, electronics and most importantly our
PMTs. Power transients have been turning on and off PMTs in various places
in the detector (mostly SM4/5/6). In the risk of permanent damage of
our PMTs, we have kept only part of the scintillator system on over the
weekend, making sure that at least 2 SMs (the ones more stable) have
been taking data on all MACRO systems (US electronics, PHRASE, streamer tubes).
Today, the laboratory technicians have examined the battery system and
called the service company in order to restore at least one set of
batteries. This is expected to happen tomorrow; hopefully, at that
time we will be able to restore the full data taking.
At this very moment we collect scintillator data only with SM1/2/3 while
SM4/5/6 remain off. This was a compromise between keeping the detector on
for gravitational collapse and saving the most senstitive to power
transients parts of it.
Please feel free to contact me if you have any questions, comments of
suggestions.
--Erik Katsavounidis