Marc Ross Saturday, June 5, 2004 nanometer BPM status and plans

Author Name Date Slide # 2 Nano-meter Beam Position Monitor RD Marc Ross – SLAC June 5, 2004 First Mini-workshop on Nano-project at ATF Parameter Thermal noise-174dBm/Hz IF bandwidth20MHz Noise in-band-101dBm System Componentsgain (dB)noise figure (dB) output noise (V) Cable x Limiter x C-band amplifier1071 x 10 –5 Mixer x filter x 10 –6 IF amplifier and anti- alias filter digitizer (10 counts) Estimates: Noise

Parameter Units Cavity Loss3.89 x Joules/Coulomb 2 /mm 2 Cavity internalQ5100(from V. Vogel) External Q3300 Coupling.35  Energy coupled out1.37 x Joules/Coulomb 2 /mm 2 Power out at 1 nm displacement over characteristic fall time 1.12 x (-99.5dBm)Watts (1 nm, 1 x ppb, 310 ns fall time) Gain used2.24 x 10 5 (53.5 dB)(June 2003) Signal strength after amplification 2.52 x 10 –8 (-46 dBm)Watts (1 nm, 1 x ppb, measured 310 ns fall time) Signal strength1.12mV (rms – 50 Ohm) Digitizer counts9Counts rms at beginning of decay Digitizer full scale913nm (8192 = 2 13 full scale) Estimates: Signal

beam jitter – y simple record of ~1500 pulses roughly in sequence –4 um rms, large thermal stability problems (not seen in winter)

Use two to predict 3rd estimated resolution of x 0.112um or 91 nm.

Correlation coefficients BPM1x BPM2yCorrelations indicate x y coupling in the BPMs not really surprising Also indicate calibration errors vs. channel code: x,y,x’,y’,I (13)

1x1x2x2x3x3x1y1y2y2y3y3y 1x’1x’ 2x’2x’ 3x’3x’ 1y’1y’ 2y’2y’ 3y’3y’ Linear fit with all... X: measurements matrix, 1 row/machine pulse, 13 cols including I, k is the column index A: coefficients (x is attenuated (20dB)) (nm) (~nm effective dipole size  ~0.1 urad)

Author Name Date Slide # 8 Nano-meter Beam Position Monitor RD Marc Ross – SLAC June 5, 2004 First Mini-workshop on Nano-project at ATF Plans cavity tuning (done today for 2 out of 3 BPM’s by V. Vogel) stabilization of ATF beam (!) –dispersion of 5mm (typical best) –( δ~ 1e-3; when energy jitter = δ, 5um jitter results); –typical uncorrected dispersion ~ 20-50um –energy jitter is usually < δ measure loss factor and coupling (β) bench test of noise is ok. –(new electronics)

Author Name Date Slide # 9 Nano-meter Beam Position Monitor RD Marc Ross – SLAC June 5, 2004 First Mini-workshop on Nano-project at ATF Recent tests better alignment than –dispersion correction readily achievable possibility of removing x attenuation calibration using new procedure still have: –temperature measurements (improved since March) –ATF extraction line and damping ring BPM’s (maybe more stable) resolution ? need ~ 8e9/pulse