06/18/97 Update

PEP-II Update June 18

PEP-II update as of noon June 18, 1997. Much has happened since the last update with several milestones being set:

HER: The HER commissioning group lowered the energy of the ring to 8.5 GeV to increase the RF quantum lifetime (only two of five RF stations are now installed). We are also running with the IR final quadrupole doublet set to half strength due to cooling water issues. Nevertheless, with tuning of injection parameters, RF phases, and orbits in the ring, the beam lifetime was increased to 1 minute by Monday June 16. Thus, we have officially "stored" a beam. At the same time we were able to stack multiple injection cycles into a single bucket and accumulate a stored beam. Injection remains at 1 Hz. Furthermore, we were able to inject seven bunches spaced equally around the ring. Finally, we phased the RF stations using the synchrotron tune and determined that we have about 6.1 MV of acceleration, very close the expected 6.3 MV.

Positrons: A week ago we obtained permission from the safety committees to transport positrons in the PEP-II low energy injection line. Starting Monday evening over a period of 12 hours (June 16-17), Dave Schultz, Rick Iverson and the injection group extracted a damped 3.1 GeV positron beam from the linac. With a little steering, the positrons were transported 2000 meters in the bypass line to the temporary tune-up dump at Sector 28 in the linac tunnel. The positrons are now only 300 m from the LER injection point. All are very pleased with this great progress.

Future: We will continue to commission the HER until the end of June. LER installation will be done in July and August. HER commissioning will resume in September. Injection line studies will continue throughout this time in parallel with the SLC linac program.

Thanks again for everyone's help. Cheers, John

Suggestions to: John Seeman

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