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User name sarty
Log entry time 11:26:56 on June24,2000
Entry number 44800
keyword=look out for doglegs...slight energy changes
As RC, I've learned that when Ops do a "dogleg adjustment", they are actually changing the optical path length around the machine (via RF "kicks") on a pass-by-pass basis to ensure proper phasing at each pass. Although this may seem irrelevant to us, it turns out that this adjustment actually changes the beam energy
a little bit (according to J. Benesh, by "a couple 10^(-4)". This is then on the order of 1 MeV for us.
So, it may be useful for us to pay attention to when they do these doglegs when
trying to compare "ep" and "ARC" energy measurements.
Check ELOG. List of last dogleg adustments can be found by searching for "dogleg" or "path length adjustment":
ELOG 114854 - 06/23/00 at 13:57:11
ELOG 114621 - 06/20/00 at 21:00:46
ELOG 114501 - 06/19/00 at 17:44:47
From those ELOG entries, it is impossible for me to evaluate the magnitude of energy change from these adjustments. Will ask J. Benesh on Monday.