A.Kulikov SLAC MAC review October 2003 Electron Cloud Issues A.Kulikov SLAC MAC review October 2003

Electron multipacting in the LER straight sections. Feb. 2000 50 nTorr @ 1 A Feb. 2000 25 nTorr @ 1.1A Current, mA Current, mA Oct. 2003 5.5 nTorr @ 1.5 A Oct. 2003 1.2nTorr @ 1.5 A Current, mA Current, mA

Electrons in the HER. All HER holding vac. pumps HER distributed ion pumps

Electrons in the LER arcs VP4031 09_29_03 Elec4031 09-29-03 VP4031 (6-8)-Jul-01 Solenoid OFF VP4031 15-Aug-01 Solenoid ON 14-Aug-01

Electron multipacting and luminosity July 2000 29 sections ON 2-May-2000 Before 17:00: 10 sections of solenoids ON (Str. 12) After 18:15: 23 sections ON (Str. 12, Str. 4, Str. 8) The last section in the straights was energized 16-Mar-01 (54 total) Solenoids in the LER arcs: the first - 23-Apr-01, the last - 9-Feb-02

Positron beam sizes driven by the electron cloud effect 31-Jul-2000

Str. 12 solenoids effect on the beam sizes Str.12 solenoids effect on the beam sizes. All other solenoids in the ring are ON, single ring. Lifetime Horizontal beam size Vertical beam size ON OFF 1.46 A 450 mA 28-Aug-01

Solenoids Arc-3 effect on the beam sizes Solenoids Arc-3 effect on the beam sizes. All other solenoids are ON, single beam. Lifetime Horizontal beam size Vertical beam size 1.5 A ON OFF 0.5 A 28-Aug-01

Solenoid field scan (Bmax = 30Gauss) 4” round SS chamber, colliding beams Bunch pattern - by 3 LER current - (1.45 - 1.25) A Number of bunches - 1078

Summer 2003 improvements: Additional 50 Gauss solenoids for all straight sections drift chambers. Double the field at pumping T-s, transitions and small drift chambers for all LER straight sections. Additional solenoids for “no sexstupole” girders in all LER arcs.

50 Gauss solenoid section

Pumping T

Double the field at the pumping T-s

“No sextupole” chamber