MACRO-USA folk at LNGS : Alec Habig (shifter), Erik Katsavounidis,
Stefano Stalio, Ionnis Katsavounidis, Paolo Saggese, Massimo Orsini.
First, the MACRO-USA group welcomed to the team Massimo Orsini, a new
technician who will work onsite at LNGS.
The big project in Hall B since the Frascati meeting has been the
resetting of the gains of the PMTs in the whole detector. This year,
the gains are being set on a tube by tube basis and splitter boxes
reconstructed as needed. It has been two years since the last such
thorough checking, and many problems are being corrected. The gains are
being set by eye using the "calibrated eyeballs" technique to +/-5V.
uVAX#3 was the first section of MACRO to be subjected to the procedure,
with uVAX#2 nearing completion now. uVAX#1 will be completed by
Christmas. Some numbers for the statistically minded:
Tank End Interventions | Tubes Replaced
-----------------------------------------------------------
uVAX#3 14 | 3
uVAX#2 20 | 4
Most tank ends were opened to replace bases, to install HV bases and/or
to cure shady PMTs. Some PMTs were swapped around so as to better match
the operating voltages. Many splitter boxes were found to have problems
and were rebuilt. On uVAX#2, 20 such splitters were rebuilt. Four of
them were bad enough that one of their two tubes was dead due to lack of
voltage before the gain setting.
Also found and replaced were several noisy fanouts, and a bad TOHM
module from SM4's attico. MACRO is in the unusual and pleasant
condition of having no nutty TOHM channels.
The voltages on Top tubes was raised by an average of 15-20 volts. The
lower detector tubes seem to be leveling off in their gain loss, with
average changes of 0-5 volts. This of course does not include problem
tubes or tubes which had HV bases installed.
Other work done during this time has been limited due to the demands of
gaisetting. However, a change to the WFD's to prevent the positive
overshoot discussed at Frascati. One module was modified by Ed Kearns
soon after the meeting, and has been tested in SM1 since.
Ionnis Katsavounidis has taken over routine ERP calibration constant
calculation. This will once again take place onsite at LNGS, and will
hopefully keep pace with the data once the initial catchup is completed.
Ionnis will also have a hand in maintaining the MACRO group unix
machines (riscgs1 and rsgs04), which will help allow these machines to
be useful again.
Other important news from the Gran Sasso area - while the collaboration
mourns the conversion of Le Fontenelle into a vegetarian restaurant, the
overall balance of culinary karma in Paganica is not too far out of
kilter, due to the conversion of the old Bar Elvis into "The Wolf", a
pizzeria/spaghetteria/risottoria with decent prices and a wide range of
goodies. The lab mensa, now back in full swing after being limited for
a while due to water problems, is pretty good (although not up to the
incomparable Frascati mensa standards).
--
Alec Habig, Boston University Particle Astrophysics Group
habig@budoe.bu.edu
http://www.astro.indiana.edu/home/ahabig/