CAT Chat Minutes

February 28, 1997

 

Issues that require action and/or follow-up
1. When an orbit correction is requested, the response from the control room is difficult to understand. When the call is made to make the request, the Operator indicates that the beam is where it was requested to be. When we look at our XBPMs, this does not appear to be true. Why is this happening?

The XBPMs are not characterized over the entire ring. When the FCs are asked to make a correction, if the request is for 50 microradians or more they will call M. Ramanathan first. The XBPMs are very effective in monitoring the beam position when it is in the dynamic range but do not do very well outside of that range.

2. We should be able to look at our XBPMs and be able to use those numbers to make orbit correction requests to the Control Room.

We are working on a fix for this.

3. How does the Control Room decide which orbit to go back to?

There is a pre-established orbit during operations. When the beam is reinjected, it will go back to this orbit. Today the operator loaded a totally different file, which put the beam in a different orbit. This caused the many requests for corrections to be made. This was an error, and we hope it will not recur.

4. Would you suggest that we call the Control Room and tell them at the time we are making an orbit correction request?

No, please continue to call the FCs.

5. Sector 1 is doing some HHL studies that are very sensitive to these corrections. So that the collected data are not wasted, could we have prior notice of an orbit correction?

Yes, prior to any orbit correction, we will have an announcement made to the effect: "orbit correction in 10 minutes."

6. Because not all of the XBPMs are characterized, should we consider ours to be reliable?

The vertical relative accuracy of the BM front-end XBPMs is within 2 or 3 microns. The ID XBPMs required considerable work before they can be used routinely. The implementation is about six to eight months away.

7. Sector 5 personnel were doing some work on the shielding deficiencies. When they checked the roof, they got a reading of about 3000. Is this acceptable, and can we get some guidelines as to what is acceptable?

At 100 mA, the acceptable levels are 5000 cpm at walls, 25000 cpm on the roof and Ð1000 cpm at the back wall. If the numbers are greater, contact the FC. Note that the 5000 cpm compares to 0.25 mrems on contact.

Information
We have completed all shielding verification that we had scheduled for this week. We will not use March 5th, but we will use March 6 (the contingency).

There is something wrong with the machine this time. We hope to have this fixed before the next run and with this fix so many orbit corrections will not be necessary.