1. E CM bias in the presence of Beamstrahlung Arik Florimonte & Mike Woods, SLAC September 15, 2004

2. Wakefields + DisruptionY-Z Kink instability (larger for WARM) (larger for COLD)(comparable at WARM, COLD) E-Spread + E-Z correlation + Y-Z Kink instability E CM Bias (larger for WARM) (comparable at WARM, COLD)(larger for WARM) E 1 and E 2 are beam energies measured by the energy spectrometers. (ISR and beamstrahlung are turned off for this study.) LC Machine Design (  y = 0)  (E CM bias ) (  y = 0) Max(E CM bias ) vary  y,  y WARM-500+520 ppm170 ppm+1000 ppm COLD-500+50 ppm30 ppm+250 ppm Summary of E CM bias Summary of E CM Bias studies w/ Beamstrahlung OFF

3. LC Machine Design (  y = 0)  (E CM bias ) (  y = 0) Max(E CM bias ) vary  y,  y WARM-500+520 ppm170 ppm+1000 ppm COLD-500+50 ppm30 ppm+250 ppm NLC'-5000 ppm10 ppm+50 ppm Summary of E CM bias NLC TESLA NLC’

4. Definition of E CM bias (BSL OFF) E 1 and E 2 are beam energies measured by the energy spectrometers. (ISR and beamstrahlung are turned off for this study.) where Definitions of E CM bias (BSL ON) studied Vary cutoff energy from 480-495 GeV gives best results

5. Actually changes luminosity and hence beamstrahlung, due to waist focusing. So not ok for estimating E_bias!

8. NLC1 NLC NLC w/ random-ordered energy NLC NLC w/ random-ordered energy NLC NLC w/ random-ordered energy NLC NLC w/ random-ordered energy Tails are similar in both E1+E2 and E1-E2 distributions Clear difference in 2 distributions Negligible difference in 2 distributions

9. TESLA1 TESLA TESLA w/ random- ordered energy TESLA TESLA w/ random- ordered energy TESLA TESLA w/ random-ordered energy TESLA TESLA w/ random-ordered energy Tails are similar in both E1+E2 and E1-E2 distributions Negligible difference in 2 distributions Clear difference in 2 distributions

10. NLC’ NLC’ NLC’ w/ random-ordered energy NLC’ NLC’ w/ random-ordered energy NLC’ NLC’ w/ random-ordered energy NLC’ NLC’ w/ random-ordered energy Tails are similar in both E1+E2 and E1-E2 distributions Clear difference in 2 distributions Competing/cancelling ECM bias contributions

11. Offset scan, E CM bias vs. y-offset Beamstrahlung turned on E cutoff = 495 GeV Espread on- gaussian E

12. Offset scan, E CM bias vs. y dispersion Beamstrahlung turned on E cutoff = 495 GeV Espread on- gaussian E

13. NLC TESLA NLC’ LC Machine Design (  y = 0)  (E CM bias ) (  y = 0) Max(E CM bias ) vary  y,  y WARM-500 +970 ppm140 ppm+1120 ppm COLD-500 +170 ppm40 ppm+350 ppm NLC'-500 2 ppm23 ppm-190 ppm Summary of E CM bias in presence of BSL (uses gaussian E results w/ E cutoff = 495 GeV)

14. LC Machine Design (  y = 0)  (E CM bias ) (  y = 0) Max(E CM bias ) vary  y,  y WARM-500+970 ppm140 ppm+ 1120 ppm COLD-500+170 ppm40 ppm+350 ppm NLC'-5002 ppm23 ppm-190 ppm Summary of E CM bias in presence of BSL (uses gaussian E results w/ E cutoff = 495 GeV) Summary of E CM bias without BSL LC Machine Design (  y = 0)  (E CM bias ) (  y = 0) Max(E CM bias ) vary  y,  y WARM-500+520 ppm170 ppm+1000 ppm COLD-500+50 ppm30 ppm+250 ppm NLC'-5000 ppm20 ppm+50 ppm