By James Morgan, Run II Coordinator

The A0 abort kicker power supplies are located in the building that lost power. Kickers are essentially fast bending magnets that can reach peak bending strength between beam bunches. The abort kickers are normally synchronized with the beam to work properly. With the building losing power, the kickers would have spontaneously fired asynchronous to the beam. Some of the beam would have received a smaller bend during the rising edge, missing the abort and landing elsewhere in the ring. I believe most of the beam should still have ended up in the A0 region. The A48 collimator should have been in for this store; it is intended to offer some protection to CDF in the event of an abort kicker problem.

The store was lost at 6:15 a.m. on Saturday, December 20. Operations was unable to cool down the B-1 house, so cryogenic and vacuum experts came in to diagnose the problem. By late afternoon it was apparent that there was a leak in the cryostat vacuum that would require a warm-up to room temperature to repair. The original estimate was 12 days for the Tevatron to be cold again. About a two day beam tune-up period was expected following the repair before establishing a colliding beam store. Repairs and tune-up went faster than expected. Repairs were completed early on 12/28 and cryogenic cool-down began at 4:00 a.m.. The B-1 house was cold on the afternoon of 12/29 and power supply turn-on followed during the evening. Tevatron experts began their beam tune-up around 7:00 a.m. on 12/29, then required only two shifts (instead of two days) to have the Tevatron ready to resume collider operation. The first Collider store began at 2:10 a.m. on 12/31.