CAT Chat Minutes

August 22, 1997


Issues that require action and/or follow-up
1. During the past several shifts, a large number of orbit corrections have been done. What is the reason for all of these corrections?

One of the beamlines recently installed a pinhole aperture, which severely reduced the available flux. When the beamline was first set up during the shielding verification, the orbit was corrected only to the extent that the beam was transmitted through the effectively large apertures. We now attempted to optimize the orbit position to its final location. This has been completed, and there should be no need for further extensive corrections.

2. What is the smallest orbit correction that you can make reliably?

The smallest, reliably attainable orbit correction is dependent on the BPM noise level, which varies from BPM to BPM with time. Typically, the limit is 5 microrad, which is equivalent to about +/- 8 microns at the BPM. Smaller changes can be requested, but there is no guarantee that they can be achieved and repeated.

Information/Follow-up items
APS Operational Status Update:  The storage ring is running at about 90% availability. Some of the fills are lasting 14 hours. Two shifts of shielding verification were scheduled for next week. We will not use the shift we had scheduled for August 25. Machine Studies are scheduled to begin at 0800 hrs. on Monday August 25 and last for 24 hours. User Ops will resume Tuesday August 26 at 0800 hrs. The shielding verification shift scheduled for Thursday, August 28, may also be canceled. We will confirm the cancellation early next week by CATNET and update the schedule.

Other:  The APS picnic is occurring today at 5:00 p.m. at Argonne Park.