* Put here the phone calls you've received and how you fix the problem. *

High rates in EE-05 or EE+07

Problem description

Occasionally (roughly once per month, but can occur in bursts), high trigger rates are observed in all EG triggers for 4 adjacent towers in one of the following 2 regions:

EE-05 TCC 15 - towers 7,8,11,12

(ELOG entry)

EE+07 TCC 91 - towers 1,2,5,6

(ELOG entry)

Solution

  • Ask for ECAL to be recycled, then reconfigured. Try this at least twice
  • If this doesn't work, request for the appropriate VME crate to be power-cycled. The ECAL DCS expert-on-call can do this. First contact the ECAL RFM to request that this be done. He/she may then contact the ECAL DCS expert on your behalf, or do it themselves. They will need to know the offending sector (i.e. EE-05 or EE+07) to determine which crate to power-cycle
  • If this doesn't work, the last resort is to mask the towers. In collisions, mask the towers on the fly, and contact the ECAL RFM + other trigger experts to see if the problem can be fixed with further power-cycles when the run ends.

Further details

See this e-mail from Alex describing the source of the problem, and why a power-cycle helps.

High rates in EE+03 during UXC access

Problem description

Fluctuating high rates in EG2 and EG5, corresponding to two regions close to the outside edge of EE+03. See the ELOG below for a typical example.

ELOG entry

This has been observed to occur whenever there is an access in the underground cavern (UXC) and the cavern lights are turned on. This induces noise in the regions shown, which produces large rates at the lower EG thresholds. After 20-30 minutes, the problem disappears.

Solution

  • First verify that this is indeed the source of the problem. Check the Shift leader ELOGs to determine if there is an access underground. Also check the DQM plots which should show exactly the regions referred to in the above ELOG with high pedestal RMS and TP occupancy.
  • If this is confirmed, do nothing. The high rates should go away after ~20 minutes. There will be no underground access during collisions runs.

-- PascalPaganini - 03-Jun-2010

Topic attachments
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Texttxt ee_high_rate_problem.txt r1 manage 1.0 K 2010-11-04 - 19:09 DavidPetyt Description of high rate problem in EE-05, EE+07
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Topic revision: r2 - 2010-11-04 - DavidPetyt
 
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