DocDB 8816


	March 2013 Muon Operations


Water Systems

EH3: water level sensors were replaced. It is now believed
that the mode of failure was the presure equalization
ports at the top of the sensor lines, which are under the
pool cover and subject to condensation rain from the pool
cover getting into the port.
Curiously, after at least a week, the water level sensor continues
to read a single value, with no variation whatsoever, leading us
to suspect that it may not be actually working.
EH2: The imploded vacuum tank was replaced, and operations
are returning to normal.
EH1: Continues to operate within specifications.
EH4: Continues to operate within specifications.
See DocDB 8891 for more details.



Muon PMTs

We would like to replace some EH3 PMTs, but it is unlikely
that there will be any opportunities for this.  There is
a visible reduction in pool veto efficiency at the location
corresponding to two dead, face-to-face PMTs.  See DocDB 8858.
Dead PMTs as of March, 2013:
EH1: DVIF42  DVIB32  DVIB41
EH2: LCIG72  LVIA44  LVOEF2
EH3: FCIA61  FVOE32  FVIE41  FVOA43  FVIA43  FVOC43  FVOG31  FVIG41
We have had one new failure in the last two days: FVIG41,
a Macro.  All of the failures are Macros.




Muon Calibration

From Jo Ellen of VT:
The MuCal system was working normally until yesterday (technically April 1 in China).
Now, In EH3 there seems to be some issue with a hot PMT channel which our PMT reference
was plugged in.  Dawei claims that noise is coming from our system, but we don't yet
understand what the issue is or how our system could be causing it.  I believe Meng has
asked [Hackenburg] about a dead channel that we could use to help trouble-shoot this issue.
According to Dawei there are no other channels (or dead PMTs) that we can use.  

Information about this past month's calibrations runs are:
http://web.dyb.ihep.ac.cn:8099/Calibration/89
http://web.dyb.ihep.ac.cn:8099/Calibration/91
http://web.dyb.ihep.ac.cn:8099/Calibration/93
http://web.dyb.ihep.ac.cn:8099/Calibration/94


RPC Performance

From Kwong Lau of UH:
According to Dawei who is on site, the RPCs are running fine with no outstanding problem.


RPC Gas System

From Changguo Lu of Princeton
There seems to be some problem with a performance degradation in EH1,
attributed to a R134A gas impurity.  See DocDB 8890 for details.


RPC HV

From Jo Ellen of VT:
The RPC HV system is still running as expected. 
There has been a trip or so, but once the channel has been restarted there has been no re-occurrence.


Overall Muon Performance

Performance continues unchanged.