Attendance : Rui Kang, Gerard Willering, A Foussat

Record of meeting 06/06/25:

The meeting focused on the findings during the last warm up of CB26 aperture on IHEP cold test station.

• Main failures identified occurred in the feedthrough connector where several pin to pins short was found with trace of burning
• The voltage taps test connector which is installed on dewar was apparently deteriorating in time and lead to last short issues on both CB25 and CB26

Action items:

•  IHEP will perform the QA HV test ( test value post He test) and continuity on CB26 coil to exclude or not its integrity
• The assessement of the failurre mode should check by calculation the current as function of time going through the short (I_short = I_magnet-I_dump, with I_dump is V_dump/Rdump). Using the calculated current and assuming all this current goes into a single instrumentation wire, the maximum hotspot temperature in a wire can be calculated as sort of a worst case scenario. This can remove doubts that wires in magnet C26 could have overheated, to be reported into the NC actions outcomes
• The re assembly of new connector should be planned and IHEP will confirm impact on schedule
• During the recommissionning of test station, CERN suggested to test only the insert ( no magnet) with connector installed in He gas at around around 300 K the connector pin to pin to check the insulation level.
• QA CERN is expecting latest inputs in the CB26 NC for its review shortly next week