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COBRA Status

W. Ootani

MEG Review Meeting

Jul. 18th, 2007

Quench Problem (slide from last meeting)

We had two quenches during the beam time in last December.

Dec.16th, 21:30: COBRA ON
Dec.19th, 19:05: First quench (cooling water problem?)
Dec.21st, 12:00: Second quench
Dec.22nd, 7:00: COBRA OFF

No (fake) quench for the past 8 months!
External noise was observed in the quench detector
signal line.

Much faster than the previous one
New noise source? inside the MEG system?

What measures can be taken?

Modify shielding and grounding scheme
Different method to detect quench? SQD?

A few good things to know...

Nothing was damaged by the quench.
Quick recovery (~2.5hrs) thanks to newly installed
TMP

200msec

100mV

The shielding and grounding scheme was improved after
the December run.
There hasnt been no unexpected shutdown since then.

No shutdown for ~10 days with SC+NC+Bypass during
shutdown period.
No shutdown for ~10 days with SC + (BTS) after accelerator
started to run.

The problem by the external noise seems fixed.

Quench Problem Status