Present: Chris Orth, Erik Katsavounidis, Ioannis Katsavounidis, Lori
Gray, Fabrizio Cei, Sophia Kyriazopoulou, Massimo Orsini, Nikola
Zaccheo (2nd week)
During the first week we had a few problem counters. On
Wednesday Ioannis investigated 6w07-0 which was not firing
during LED-TDC calibrations yet gives apparently good muon data
during the week. Further investigation showed that the phototube
seems to "give up" on LED for a duration of several seconds,
then recovers. No droop in the LeCroy supplied voltage or current as
reported through the HV program were observed while the phototupe was
quiet.
Another tube behaved similarly during LaMoSsKa calibrations -
6E01-1, with the exception that this tank end never fully recovered.
This tank end remained very noisy. The phototube showed a bright but
distinct spe band when viewed with a scope. There is either an
undetected light leak, or a problem with the tube/base.
Yet another tank-end acted up this week, 2c04-1. This tank-end
gradually increased in brightness following Wednesday maintenance and
showed signs that one of the tubes may be becoming a flasher (the
trace on an analog scope would occasionally flicker in brightness).
Tohm rates increased for this box at the end of the week. Over the
weekend some spectacular waveforms were collected further supporting
the flasher diagnosis. Several 2 usec FWHM, 4V pulses were recorded on
end 0 of this tank, with coincident spe-chains of 11-15 in 10usec on
the end 1 side. Following this display of two extreme expected modes
of monopole interaction with our scintillator, it was agreed to shut
this tank-end off (Monday, Mar 2, 4:00PM)
These tank end problems were addressed the second week by
Massimo Orsini, Fabrizio Cei, and our shiny new technician Nikola
Zaccheo (welcome Nikola!). Both 6E01-1 and 2C04-1 were replaced.
6E01 has a slight oil leak at the connector on the tank end, and the
Tohm still triggers constantly there, but Massimo says that there
doesn't seem to be a light leak. Also Fabrizio says that the PHRASE
sees a lower-than normal rate on the new 2C04-1.
Other hardware problems included the SM6 attico tohm, and the
SM 4 Stop Master. Both are giving many no Q's during runs. The Tohm
appears to be misbehaving during the beginning of runs - so we suspect
that the initializing of the TOHM/LI thresholds is not successful. On
my second Wednesday on shift, Erik found that adding another fan near
the crate elminated the no Q problem for the Tohm during a mini-acq.
But after leaving the fans in place we found that we still do get
no-Qs during the start of run, but the number of errors at least seems
reduced.
The Stop Master appears to be giving no Q responses for fake
(not local to microvax 2) CSPAM triggers - at least this was the
common thread found in three problem events flagged in Erik's summary
files. Unfortunately, during further investigation via a mini-acq on
maintenace day Erik and I could not reproduce these no-Qs, even while
generating false cross CSPAM triggers with a pulser through the SPU.
We looked into this problem again the following Wednesday, again
without a successful repair.
The highlight of the second week was another attempt to
install the 3rd Harmonic (as in 150Hz) Filter on Wednesday. In order
to not repeat the incident a couple weeks before of blowing out a 5V
WFD power supply, the WFDs were shut off during power on of the
filters. (The filters have a large inductive load that causes very
large spikes when turned on). Immediately following turn on we did
blow a modified CAMAC supply on SM3, but this was easy to replace. We
found that the 3rd Harmonic filter on SM1 was noisy enough to
constantly trigger the North face tohm, and so SM1's filter was shut
off. The other 5 were left on overnight, but were shut off the next
morning after Ed Kearns' WFD monitor alerted us to an actual
enhancement (not filtering) of 150 HZ noise on the PMT fanouts,
especially on SM5. The noise was enough to wildly affect the WFD
pedestals (which are calculated by Ed's monitor on an event by event
basis).
Following the installation of the filters, Lori Gray found
that the LaMoSsKa and Slow Monopole calibrations were missing the
North face. It is still not clear whether this was just a coincidence
or if some other hardware (the N face LED switchbox) was also harmed
by the initial spike from the 3rd Harmonic Filter.
Other work during this period: Ioannis was very pleased to
announce that calibration constants are complete up to January gain
resetting! Fabrizio has been working full time testing all of the
phototubes that were moved from the tech house (which has now been
claimed by our LNGS Electrical staff). Many of these tubes have
manufacturing defects and have never been online in MACRO, but
Fabrizio expects that on the order of 10 or more working tubes will be
salvaged.
Changes at the lab: while not current to this shift period, I
thought the MACRO community should be aware of some changes at the
lab. First, the administration is quite serious about the new
paperwork required for lab-ID renewal. There are two forms in
question - one from the University as a whole, and the other for the
individual. Ask Ersilia if you haven't seen these forms and have no
idea what I am talking about.
I am told that eventually the new IDs will have magnetic
(shoplift-proof) strips which will be used to monitor people as they
pass through the underground labs. Keep an eye for electronic boxes
labelled "Confident". Also be aware of the many new security cameras
(one of them is in the bottom floor of the counting house, another 2
or 3 on top of MACRO. Big Brother is watching you.
There are also several large screen TVs installed (3 in the
MACRO hall alone!) that receive among other channels, CNN and BBC
news.
Apologies in advance if I left anything out,
Your humble shiftworker,
Chris Orth