1. 1 H. Hayano for the ATF collaboration Low Emittance Beam Generation in ATF H. Hayano for the ATF collaboration BPM electronics improvement emittance tuning Laser wire beam size monitor emittance measurement results APAC2004 3/25/2004

2. 2 E=1.28GeV Ne=1x10 10 e - /bunch 1 ~ 20 bunches Rep=1.5Hz X emit=2.5E-6 ( at 0 intensity) (1nm) Y emit=2.5E-8 ( at 0 intensity) (10pm) Accelerator Test Facility for e - source development of LC Damping ring Linac

3. 3 Low Emittance tuning Optics modeling by beam based way Q-magnet strength correction in model Beam based BPM offset measurement Q, SX trim excitation & bump orbit to orbit response COD correction Dispersion correction Coupling correction horizontal kick to vertical response, then skew corrector

4. 4 ATF Damping Ring BPM Electronics: single pass detection for 96 BPMs DC-50MHz BW, base line clip & charge ADC, min. resolution ~20µm

5. 5 Spectrum of DR BPM Signal peak at ~ 1GHz

6. 6 BPM electronics improvement Electronics: 40MHz - 1GHz BW, base line clip & low noise LF amp min. resolution ~2µm

7. 7 Resolution Improvement Min. resolution ~ 2µm

8. 8 Vertical orbit Improvement

9. 9 Vertical dispersion Improvement

10. 10 X to Y coupling Improvement

11. 11 Laser wire beam size monitor in DR 14.7µm laser wire for X scan 5.7µm for Y scan (whole scan: 15min for X, 6min for Y) 300mW 532nm Solid-state Laser Fed into optical cavity

12. 12 Laser wire block diagram optical cavity resonance is kept by piezo actuator

13. 13 Beam profile by Laser wire  e 2 =  meas 2 -  lw 2  =  e 2 – [  (  p/p)] 2  measured by Q-trim excitation

14. 14 Bunch Length by SR monitor streak camera

15. 15 Energy Spread by beam size monitor at EXT dispersive point

16. 16 Transverse Emittance by Laser wire < 0.4% y/x emittance ratio Y emittance =4pm at small intensity

17. 17 Conclusion BPM resolution improvement by new electronics by extending band width minimum resolution is 2µm. Fine beam tuning using improved BPM Optics model and BPM offset were refined. Beam parameters were improved. Laser wire beam size monitor development Precise beam size measurement in DR with non-destructive way. Low vertical emittance beam was generated and confirmed.  y n = 1.0x10 -8 (4pm at 1.28GeV) vertical emittance at small intensity