DocDB 8816


	February 2013 Muon Operations


Water Systems

General: O2 sensors need to be calibrated.  They may
be faulty, and not giving reliable readings.
Random system stops continue, and are not understood.
EH1: Pool resistivity holding at 1.5 Mohm-cm, though a new
sensor at a different point indicates 5.0.  The system 
continues to operate well.  Last filter change: 25jan2013.
Last resin change: 5jul12, though that is uncertain.
EH2: Resistivity about 1.1 Mohm-cm, down from 2.6 in early
February.  Early in February, the vacuum tank imploded and
shut down the water system.  Resistivity is slowing
improving following the repair.
Last filter change: 25jan2013.  Last resin change: 5nov2012
EH3: Level sensors have failed, including backups.
Until the level sensors are replaced (sometime in March),
the level is being maintained "manually", with a short
fill once per week, and the O2 sensors have been valved off
to minimize water loss.  Pool resistivity remains good,
above 6 Mohm-cm, and the water system is otherwise working
well.  EH3 is operating with 1 and 0.2 micron filters.
Last filter change: 25jan2013. Last resin change: 25nov2012.
EH4: Working well.  Frequent alarms do not indicate
serious problems, and are distracting to shifters.
DocDB 8752 is a draft proposal for replacing the level sensors.



Muon PMTs

We would like to replace some EH3 PMTs, though the improvements
from replacing the FEE cards may have made this less important.
This is still being studied.
See DocDB 8805.
Dead PMTs as of 20feb13:
DVIF42  DVIB32  DVIB41
LCIG72  LVIA44  LVOEF2
FCIA61  FVIA43  FVIE41  FVOC43  FVOA43  FVOG31  FVOE32  
See DocDB 8752 for a draft proposal for replacing PMTs.




Muon Calibration

No news


RPC Performance

There is a dead module in the middle of EH3.
Around middle of week of 2/14, the trigger rate efficiency and
noise rate of EH1 RPCs went down, in coincidence with total
gas flow rate going up by 25%.
The total flow rate went back down to 13% above normal after
about 10 days. This is being investigated.



RPC Gas System

All three RPC gas systems are running quite smoothly.
On 1/28/2013 there was a minor interruption for the EH2 
gas system due to a blown fuse in the gas pressure control
crate.  Zhijian Zhang from DGUT replaced the fuse the next
day; the system immediately returned to normal operation.
C. Lu is remotely monitoring the gas chromatograph
systems and digital bubbler systems from time to time.


RPC HV

No news


Overall Muon Performance

There are no firm indications of changes in performance
of the muon system in its primary role as a veto.
However, improvements in muon reconstruction efficiency in EH3
have been documented in DocDB 8805.  These are attributed to
the "touching" of FEE cables during the investigation of
noise on Dec 15, followed by further improvements with
the replacement of FEE boards on Jan 13 and 15.