09/11/97 Update
09/11/97 Update
September 11, 1997
PEP-II commissioning restarted September 2nd after a productive two month installation period in which, among many things, 87 LER quadrupole-dipole magnet rafts were installed.
On September 2 the ring was locked and searched. RF processing started shortly thereafter. By day shift of September 3rd a beam at one Hz from the linac was established to the e- ring ready for injection (which was compatible with SLC/SLD running). By the evening of the same day 50 turns were obtained in the High Energy Ring (HER). Work on magnet power supplies and RF processing were done on Sept. 4.
By late evening on the 4th the newly installed current sheet septum (Bruce Feerick, Cherrill Spencer, Ed Daly, and others) was tuned and the injection rate maximized. An 8 mA beam was quickly stored. By early morning on the 5th a new record current101 mA in 32 bunches was stored surpassing the old record of 60 mA in June. At 70mA in 32 bunches the beam lifetime was 45 min. With 873 bunches at 60 mA the lifetime was 25 min. The reduced filling rate at 20 to 60 mA (depending on the number and spacing of bunches) as observed in June was again observed. We were happy that this effect did not change noticeably after we installed 12 more HER RF cavities during the down.
Starting on day shift Sept. 5 the longitudinal and transverse bunch-by-bunch feedbacks were tuned and adjusted ( John Corlett, Walter Barry, John Fox, et. al.). Both systems were made fully functional by Sept. 8. Much excitement was generated by using both feedbacks to selectively excite and damping beam modes and to look at the beam position spectra.
During this time the recently installed HER synchrotron light monitor (Alan Fisher, Ed Daly, Eric Bong, Doug McCormick, and others) saw first light and the focussed beam image showed the effects of the feedback systems.
From Sept 9 until now we took advantage of an upstream linac down time and retuning period to replace the last unshielded vacuum bellows module in the HER (Curt Belser, Ed Daly, Nadine Kurita, Dan Wright, Dave Bostic,...) and to tune the fundamental RF feedback loops (Paul Corredoura, Stephanie Allison, Rich Tighe, ...). Also the first of the three new RF stations in the HER (Matt Allen, Heinz Schwarz, Bob Rimmer, Mark Franks, Allan Hill, ...) was successfully processed to full power. We are now ready for higher currents.
Our September-October beam run will stop October 13. Until then we hope to reach at least 200 mA stored beam, demonstrate RF, longitudinal and transverse feedbacks, commission the three new RF stations, and to study beam backgrounds at the interaction point.
More news in 10 days time.
Thanks to all and cheers, John Seeman
Suggestions to: John Seeman
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