CAT Chat Minutes

May 9, 1997


Issues that require action and/or follow-up
1. We have received information from a vendor regarding the maintenance schedule and costs for the cryo-pumping systems. Is the APS planning to have someone here who will be trained to do this and, if so, will that person's skills will be made available to the users? This would be something many of us may be interested in even if we were required to pay for the service.

We will review the requirements and evaluate whether we have the resources to perform this maintenance.

2. During part of the last run, the XBPMs were down for 12-ID. Were they recalibrated after they began working again and can we use the information from them?

The XBPMs in the ID front ends are susceptible to errors from multiple sources including non-linearity with ID gap and varying contributions from bending-magnet contamination. We are in the process of incorporating digital processors to correct the errors. This work will continue over the next several months. In the meantime, the ID XBPM signals can be used for relative measurements at a single ID gap over short-term periods, but repeatability from fill to fill is highly dependent on the stability of the positron BPMs.

3. Why can't we fill many bunches as opposed to fewer? This would provide us with longer stored beam lifetimes.

When the storage-ring fault rate is high, the lifetime does not matter. As the availability has improved, the impact of stored-beam lifetime is now more evident. We will continue to try different fill patterns during user operations without jeopardizing beam stability. At the same time, we will also investigate whether we can refill the storage ring at lower currents than 65 mA. This will provide longer stored beam fills.

4. What about 20 bunches evenly spaced?

The requirements for stable triggering of the positron BPM system is the primary driving force for determining the filling pattern. As further studies are done, the requirements will be relaxed and more flexibility will be available in setting the filling pattern.

5. Where do we bring up issues about lifetime, the schedule, etc.?

CAT Chat is the forum for you to bring these issues to us.

6. What does the long-term schedule look like?

We are planning to provide 5000 users hours during FY 1998. The actual schedule will be determined after the requirements for longer shutdown periods (such as the resurvey of the storage ring) are determined.

7. Machine studies days scheduled late in the week are very inconvenient since the user beam is then resuming on Friday or Saturday. What are the plans for machine studies on the long-term schedule?

The machine studies are scheduled for the beginning of the week, usually Monday to Tuesday.

Next week the ACIS personnel will require access to the ratchet doors for testing the door limit switches. The FCs have been speaking to all of you to coordinate access for this.

The chilled water system will be shut down on May 13 beginning at 0500 hours for 8 hours.

The real-time feedback is expected to be operational during the next run. We will provide more information on the planned operating conditions as it becomes available.

We are starting to look at the long-term schedule beyond August and into next year. We would like some input from you on how best to schedule access to the storage ring during long running periods for emergency repairs, as well as for routine inspections.