ISG – Damping Ring Physics and Design Group ATF – 2003// focus on the TRC challenge Marc Ross – 1.Instability about which little is known: Fast ion, 2.Instability about which little is known: CSR 3.Emittance tuning 4.Kicker stabilization 5.Diagnostics (not grouped with DR)

RF gun beam at 80MeV Beam Intensity ~1x10 10 /bunch Normalized Emittance  y= 28x10 -6 rad.m Bunch length  z= 6.4 ~ 7.9 ps Energy spread dE/E = 4.9% full-width Q.E. of CsTe cathode 16% initial, 2~3% with RF ON & constant over a week

New Laser wire : X & Y scan X profile Y profile Two wire chamber

Author Name Date Slide # 4 ISG 9 at KEK Marc Ross/SLAC Deflection cavity on I/Q cavity response with deflection cavity at full voltage Axes show directions of pure displacement (black) and pure angle (bluish) (green is 90 from pure displacement) –Tilter motion is not quite orthogonal Ellipticity is the ellipse aspect ratio (jiyouou) This plot shows equivalent ‘angle trajectory’

Author Name Date Slide # 5 ISG 9 at KEK Marc Ross/SLAC ATF goals 2003 Emittance tuning with precision laserwire / XSR beam size monitors –Alignment, skew, dispersion, procedure, stability –Low current y emittance  < 5pm-rad –Extraction line optics Commission new ring BPM system –Resolution about 8 times improved (3-4 um) Beam based alignment –Sextupole alignment to 20 um (present quad limit) –Dipole vertical positioning (problems with 2 magnet sources) Instability studies –Fast ion  laserwire / XSR studies (need detailed planning) –CSR – (evaluation of 50GHz emission)

Author Name Date Slide # 6 ISG 9 at KEK Marc Ross/SLAC ATF goals 2003 (2) Beam intensity / stability / repetition rate –Increase permitted stored beam 3 x (210mA) –Linac intensity 2 x (24e10) –RF Photocathode: stable, uniform multi-bunch beam Beam diagnostics work –position monitors –size monitors –correlation monitors –Stabilization Extraction kicker stability test ? – evaluation of existing study

Author Name Date Slide # 7 ISG 9 at KEK Marc Ross/SLAC ATF 2003 timeline Detailed schedule available to –3 weeks + 5 weeks of operation –New BPM’s; first round of BBA and laserwire/XSR beam size tests; nanoBPM triplet first resolution test –‘Pure’ single bunch operation –Attempt to cure coupled bunch instability to  ~ 7 weeks of operation probable –New power limit –Instability studies; BBA (2 nd round)

Author Name Date Slide # 8 ISG 9 at KEK Marc Ross/SLAC ATF weeks of operation (9.03  7.04) Speculation: 3e10 single bunch with short pulse laser –Impedance, IBS, single bunch collective effects beam stabilization using nanoBPMs (extraction line)