Cavern intervention, disconnection of BML1C13.CO.Ly1 HV cable on rack on 30/10 [e-log]

• This cable has been disconnected due to the presence of a sparking connector on the HV line.

• The test excluded that the problem is in the patch panels, so it is on the BML1C13 cable or in the chamber.

• The first recovery attempt will consist of changing the cable connectors.

• The HV channel is now restored except for the BML1C13.CO.Ly, which remains disconnected.

LV:

• BML6_GC15 LV Vpd OVC on 27/10 [e-log]. BML6C15.CO.Ly1.PHI Vth changed from 1.0V to 0.8V.
• RPC BML4A03 LV Vpd OVC on 03/11 [e-log]. BML4A03.CO.Ly1.PHI Vth changed from 0.9V to 0.8V.
• RPC BMS4C02 LV Vpd OVC on 03/11 [e-log]. BMS4C02.CO.Ly0.ETA Vth from 1.0 to 0.8 and (most impacting) BMS4C02.PI.Ly0.ETA.DZ2 Vth from 1.0 to 0.75.

Power cut on Halloween night

• The RPC DAQ was not affected by the power cut. The LVL1 RPC trigger pads were kept ON [e-log].
• The RPC detector was not affected by the power cut from the point of view of the powering system. Alarms on the stop of the gas system triggered the automatic safety protection scripts of the RPC DCS, lowering the HV of the RPC HV channels (Legacy/BIS78/HVREC). For Legacy, in particular, they were lowered to 5000V (instead of the usual standby at 8500V). The RPC LV was not affected by the power cut. Brought back to STANDBY the following morning [e-log].

• From Alessandro: 

  • RPC Gas Monitoring, relying on an RPC flowmeter showing if flow is above threshold, went off, triggering the GAS FATAL signal, which triggers the safety script for ramping down RPC HV channels through SoftVmax that is set to 5000V for RPC legacy and to 3000V for BME+BIS78.
  • Several sensors (ATLAS/USA-15 and RPC) went off.

RPC inter-layer test during Run 509797

• Description: RPC test with either Ly0 or Ly1 ON, while the other is OFF. The test will be useful to detect possible layer inversions (with respect to the RPC DCS) by analysing the hit coincidences.

• Run 509797.  Stable Beams, LBs: 76-217.

• For analysis: Ly0 ON and Ly1 OFF, LBs: 80 - 146. Ly0 OFF and Ly1 ON, LBs: 172 - 217.
• HV recovery channels switched OFF for the whole test, BIS78 left ON for the whole test.