ATF2 Beam Size Correction by Linear Knob

ATF2 Beam Size Correction by Linear Knob Making Linear Knob Mover of SX DXWaistX, WaistY, PEX DYPEY, Coupling R1 is used for the coupling index Orthogonal Knob WaistX: SF1_DX=-0.00043123 wx SD4_DX=0.00256159 wx SF6_DX=-0.0167073 wx WaistY: SF1_DX=-0.0121574 wy SD4_DX= 0.0721866 wy SF6_DX= -0.0243731 wy PEX: SF1_DX= 0.00539274 px SD4_DX= -0.000363894 px SF6_DX= 0.0122067 px PEY: SD4_DY= -0.279389 py SD0_DY= 0.353846 py R1: SD4_DY= -0.0584437 r1 SD0_DY= -0.0479828 r1 Response of Each Knob

Misalignment of Q DX Q dx is distributed according to Gaussian distribution. WaistY correction is done for sy. Correction step:1mm(sy>1mm) 100mm(sy>100nm) 20mm(sy<100nm) because of the resolution of the sy calculation by tracking(NP=1000) Before Cor. After Cor. dx=5e-5m  dx=4e-5m  95% CL values are plotted.

Misalignment of Q DY Q dy is distributed according to Gaussian distribution. R1,WaistY,PEY correction is done for sy in this order. Correction step:R1:1e-3 (sy>1mm) 1e-4(sy>100nm) 1e-5(sy<100nm) PEY: 10mm Example:dy=1e-5m  sy=60.5nm(95%CL) after correction Correction is not good enough

Redefinition of Linear Knob Vertical Beam Size with Coupling Redefinition of Knob PEY: SF6_DY= -0.231976 py SD4_DY= -0.186651 py SD0_DY= 0.429982 py R1: SF6_DY= 0.526463 r1 SD4_DY= -0.268909 r1 SD0_DY= -0.220771 r1 R2: SF6_DY= 0.387005 r1 SD4_DY= -0.154714 r1 SD0_DY= -0.127017 r1 Need for correction not only r1 but also r2 Response for R2 Correction gu=261,bu=0.004  r2 correction is important Order: R2,R1,WY,PEY Step: R1:1e-2 (sy>1mm) 1e-3(sy>100nm) 1e-4(sy<100nm) R2:1e-3 (sy>1mm) 1e-4(sy>100nm) 2e-5(sy<100nm) Performance Example:After correction for dy=1e-5 95%CL value 60.5nm  47.3nm  New Knob Old Knob

Misalignment of Q DY revised Misalignment of Q roll Iterative correction works well for the event that the 1st correction failed. e.g.) roll=1e-4 after one cor. sy=65.6nmcor. again sy=36.6nm 

# of iteration = 2 For only Q-dx error, iteration has no meaning because the correction is for WaistY only. Iterative Correction Misalignment of Q roll Misalignment of Q dy Field Error of Q dK1 Only WaistY correction No iteration

Errors (dK1/K1, dx, dy, roll)=a(5e-4, 40mm, 20mm,100mrad) sy Correction with All Errors of Q Correction # of iteration ≤ 5 Iteration stops if sy≤ 35nm For a<0.7, sy<40nm after correction Mover Spec. Requirement Minimum step min. coeff. knob min.step WY:2e-5 SF1_DX=-0.0121574 wy 2.4e-7 PEY:1e-5 SD4_DY= -0.186651 py 1.9e-6 R1:1e-4 SD0_DY= -0.220771 r1 2.2e-5 R2:2e-5 SD0_DY= -0.127017 r1 2.5e-6 Dynamic range For a=0.6 max. coeff. knob min.step maxWY:1.98e-3 SD4_DX= 0.0721866 wy 1.4e-4 maxPEY:3e-4 SD0_DY= 0.429982 py 1.3e-4 maxR1:1.3e-3 SF6_DY= 0.526463 r1 6.5e-4 maxR2:3.8e-3 SF6_DY= 0.387005 r1 1.5e-3

ATF2 Beam Size Correction by Linear Knob

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