COBRA Magnet Status W Ootani MEG collaboration meeting
COBRA Magnet Status W. Ootani MEG collaboration meeting, Feb. 8 th, 2007
COBRA in Run 2006 • COBRA was pretty stable except for two incidents. . . • Field stability ~ 0. 05%(FWHM) Monitored field BTS OFF BTS ON • We had two unexpected quenches during one week running. • Dec. 16 th, 21: 30: COBRA ON • Dec. 19 th, 19: 05: First quench (cooling water problem? ) • Dec. 21 st, 12: 00: Second quench • Dec. 22 nd, 7: 00: COBRA OFF
Quench Problem • We had two quenches during the beam time in last December. • No (fake) quench for 8 months before December since fixing the previous noise problem. . . • External noise was observed again in the quench detector signal line. • Much faster than the previous one • New noise source? inside the MEG system? • What measures can be taken? • Look for the noise source • Modify shielding and grounding scheme • A few good things to know. . . 100 m. V • Different method to detect quench? SQD? • Nothing was damaged by the quench. • Quick recovery (~2. 5 hrs) thanks to newly installed TMP 200 msec
Fringe Field Problem at πM 3 • Influence of the COBRA stray field on the πM 3 beam line. • Solutions • Permalloy shielding on the beam pipe (Jun. 2006) • Iron plates on the beam line wall (Dec. 2006) • Worked well. They can survive with this setup. • Complete the installation of the shielding wall during this shutdown period. • Ordering 30 standard iron sheets (2000 x 1000 xt 10) πM 3 beam line with Permalloy sheet Iron plates
Schedule • Feb. 13 Refrigerator maintenance • Feb. 23 COBRA will be cold. • - mid-Apr. Investigate quench problem • Look for noise source • Improve shielding and grounding
- Slides: 5