1. EXT Tuning
13th ATF2 Project Meeting, January
M. Woodley

2. ATF / ATF2 Schematic Layout
Emittance
Measurement
5 × WS, 4 × OTR
10 μ W wires
(x/y/+10°/-10°)
Final
Doublet
Coupling
Correction
Final Focus
β-match
Dump
Inflector
Laserwire
EXT
Laserwire
INJ
PIP WS
10 μ W wires
(x/y/45°)
5 μ C wires
(y/+1.3°/-1.3°)
IPBSM
10 μ W wires
(x/y)
5 μ C wires
screen
Damping
Ring
Beam
Transport
FOBO
XSR e-
S-band
RF Gun
1.3 GeV S-band Linac
120 m
13th ATF2 Project Meeting, January
M. Woodley

3. Outline EXT tuning (a recipe) emittance measurements with the OTRs
calibration
cross-check with WS
4D reconstruction results
4D emittance measurements
lattices
building a coupled beam matrix
refresher on emittance growth
Summary and Continuing Work
13th ATF2 Project Meeting, January
M. Woodley

4. EXT Tuning Recipe load desired optics configuration
standardize FF magnets (FS package)
normally reset QS’s and QK’s to zero
normally reset FF movers to zero
check each shift that desired lattice is SET (FS “configCheck” function)
after (roughly) steering beam to dump, do lattice diagnostics check
verify BPM signs after calibration; look for focusing errors
ZH/ZV response (FS package)
“grid” scan (new FS package ... see Yves’ talk)
establish horizontal extraction trajectory
verify KEX1/KEX2 voltage (43.4 kV)
use BS1X/BS3X/BH1X/ZH1X to center orbit in QF1X/QD2X/QF3X by hand
steer EXT/FF using Yves’ code (FS package)
expect steered orbit < 200 um
DR orbit & extraction trajectory
measure and correct dispersion (FS package)
computer correction of DX/DPX using QF1X/QF6X
manual correction of DY using QS1X/QS2X
measure emittance and correct coupling
multi-OTR emittance measurement (FS package)
manually optimize projected vertical emittance with QK1X/QK2X/QK3X/QK4X
... or other (faster) techniques (see Javier’s and Glen’s talks)
move to IP region
check beta matching!
need IP C-wires, PIP W- and C-wires, MSPIP all working at the same time!
13th ATF2 Project Meeting, January
M. Woodley

5. Emittance Measurement with OTRs
13th ATF2 Project Meeting, January
M. Woodley

6. OTR2X beam tilt … is it real? Check measured response to ZH9X
13th ATF2 Project Meeting, January
M. Woodley

7. OTR Vertical Emittance Measurement
December 14, :44
name sigt sigd sig
OTR0X
OTR1X
OTR2X
OTR3X
Vertical emittance parameters at OTR0X
energy = GeV
emit = pm
emitn = nm
emitn*bmag = nm
bmag = ( )
bmag_cos = ( )
bmag_sin = ( )
beta = m ( )
alpha = ( )
chisq/N =
Propagated vertical spot sizes
OTR0X = um ( )
OTR1X = um ( )
OTR2X = um ( )
OTR3X = um ( )
13th ATF2 Project Meeting, January
M. Woodley

8. Wire Scanner Vertical Emittance Measurement
December 14, :30
(MW1X σy value ignored)
sigt sigd sigw sig
Vertical emittance parameters at MW0X
energy = GeV
emit = pm
emitn = nm
emitn*bmag = nm
bmag = ( )
bmag_cos = ( )
bmag_sin = ( )
beta = m ( )
alpha = ( )
chisq/N =
Propagated vertical spot sizes
MW0X = um ( )
MW2X = um ( )
MW3X = um ( )
MW4X = um ( )
13th ATF2 Project Meeting, January
M. Woodley

9. black circles = WS blue circles = OTR
OTR Vertical Emittance Measurement
December 14, :44
Wire Scanner Measured Vertical Beam Sizes
December 14, :30
(MW1X σy value ignored)
black circles = WS
blue circles = OTR
13th ATF2 Project Meeting, January
M. Woodley

10. 4D Coupling Measurement & Emittance Reconstruction
13th ATF2 Project Meeting, January
M. Woodley

11. simulation
13th ATF2 Project Meeting, January
M. Woodley

12. 2D projected (Gauss fit)
measurement:
2D projected (Gauss fit)
4D lsqnonlin analysis
13th ATF2 Project Meeting, January
M. Woodley

13. Ideal Coupling Correction with 4D Emittance MeasurementSQ WS
coupling
correction
measurement
emittance x y x' y'
setting σ13 to zero at first 4 WS using SQs is equivalent to minimizing εy with the SQs
ref: “Zeroth order design report for the Next Linear Collider: Volume 2”, section 11.3
13th ATF2 Project Meeting, January
M. Woodley

14. Ideal Coupling Correction with 2D Emittance MeasurementSQ WS
coupling
correction
emittance
measurement x y x' y'
setting σ13 to zero at 4 WS using SQs is not equivalent to minimizing εy with the SQs
13th ATF2 Project Meeting, January
M. Woodley

15. ATF2 Coupling Correction with 2D Emittance MeasurementSQ
OTR
coupling
correction
emittance
measurement x y x' y'
setting σ13 to zero at 4 WS using SQs is not equivalent to minimizing εy with the SQs
13th ATF2 Project Meeting, January
M. Woodley

16. “Irwin” Coupling Parameters: Generating Coupled Beam Matrices
Lie algebra generator:
Define D:
Define g and h (two alternate forms):
Define β1,2 and α1,2 to be the uncoupled x,y Twiss parameters, and ε1,2 to be the uncoupled (intrinsic) x,y emittances.
Then can construct coupled beam matrix (σ) from arbitrary mixtures of the 4 coupling phases (a,b,c,d).
ref: “Expanded Studies of Linear Collider Final Focus System at the Final Focus Test Beam”, Appendix A, section A.3
13th ATF2 Project Meeting, January
M. Woodley

17. Matlab script for generating
function sig=e4d2sig(X) %
% sig=e4d2sig(X)
% Compute 4x4 beam matrix from 10 "4D" beam parameters
% (see SLAC-R (December 1995), pp )
% Input: X(10) = 4D beam parameters (emit1,emit2,beta1,beta2,alpha1,alpha2,a,b,c,d)
% Output: sig(4,4) = computed beam matrix
% download 4D beam parameters
e1=X(1);e2=X(2);
b1=X(3);b2=X(4);
a1=X(5);a2=X(6);
a=X(7);b=X(8);c=X(9);d=X(10);
sig=zeros(4,4);
% compute g and h
D=b*c-a*d;
t=sqrt(abs(D));
if (D>0)
g=cosh(t);
h=sinhc(t); % sinhc(t)=sinh(t)/t
else
g=cos(t);
h=sinc(t); % sinc(t)=sin(t)/t
end
% horizontal 2x2 sub matrix
sig(1,1)=b1*(g^2*e1+h^2*(c^2+d^2)*e2);
sig(2,1)=-g^2*a1*e1-h^2*(c*(a+a1*c)+d*(b+a1*d))*e2;
sig(2,2)=(g^2*(1+a1^2)*e1+h^2*((a+a1*c)^2+(b+a1*d)^2)*e2)/b1;
sig(1,2)=sig(2,1);
% vertical 2x2 sub matrix
sig(3,3)=b2*(g^2*e2+h^2*(b^2+d^2)*e1);
sig(4,3)=-g^2*a2*e2-h^2*(b*(a+a2*b)+d*(c+a2*d))*e1;
sig(4,4)=(g^2*(1+a2^2)*e2+h^2*((a+a2*b)^2+(c+a2*d)^2)*e1)/b2;
sig(3,4)=sig(4,3);
% coupling 2x2 sub matrix
sig(3,1)=sqrt(b1*b2)*g*h*(b*e1+c*e2);
sig(3,2)=sqrt(b2/b1)*g*h*((d-a1*b)*e1-(a+a1*c)*e2);
sig(4,1)=sqrt(b1/b2)*g*h*((d-a2*c)*e2-(a+a2*b)*e1);
sig(4,2)=g*h*((a*a1-d*a2+b*a1*a2-c)*e1+(a*a2-d*a1+c*a1*a2-b)*e2)/sqrt(b1*b2);
sig(1,3)=sig(3,1);
sig(2,3)=sig(3,2);
sig(1,4)=sig(4,1);
sig(2,4)=sig(4,2);
Matlab script for generating
coupled beam matrices
(I still need to figure out how to use
the coupled matrix (4x4) to populate
particle distributions for tracking … )
13th ATF2 Project Meeting, January
M. Woodley

18. DR Orbit & Extraction Trajectory
Emittance & Coupling
DR Orbit & Extraction Trajectory
13th ATF2 Project Meeting, January
M. Woodley

19. Combined EXT 4-wire Horizontal Emittance Measurement
(Nave=3, Nmeas=3, May )
sigt sigd sigw sig
Horizontal emittance parameters at MW1X
energy = GeV
emit = pm
emitn = nm
emitn*bmag = nm
bmag = ( )
bmag_cos = ( )
bmag_sin = ( )
beta = m ( )
alpha = ( )
chisq/N =
Propagated horizontal spot sizes
MW1X = um ( )
MW2X = um ( )
MW3X = um ( )
MW4X = um ( )
13th ATF2 Project Meeting, January
M. Woodley

20. Combined EXT 5-wire Vertical Emittance Measurement
(Nave=3, Nmeas=3, May )
sigt sigd sigw sig
Vertical emittance parameters at MW0X
energy = GeV
emit = pm
emitn = nm
emitn*bmag = nm
bmag = ( )
bmag_cos = ( )
bmag_sin = ( )
beta = m ( )
alpha = ( )
chisq/N =
Propagated vertical spot sizes
MW0X = um ( )
MW1X = um ( )
MW2X = um ( )
MW3X = um ( )
MW4X = um ( )
13th ATF2 Project Meeting, January
M. Woodley

21. Observed that first 2 EXT vertical correctors (ZV1X and ZV2X) needed to be strong to properly launch into EXT (since before EXT rebuild for ATF2 … )
hypothesize that correctors are compensating for a kick error in extraction channel
simulate error kick by rolling individual elements; use ZV1X and ZV2X to correct orbit
find error that gives best fit to actual ZV1X/ZV2X values → BS3X septum magnet roll
BS3X was physically rolled ~ -4 mrad (March 17, 2010) to relieve ZV1X and ZV2X
projected vertical emittance in EXT before coupling correction was improved (~20-40 pm before → ~10-20 pm after)
BS3X roll = mrad
Izv = (-6.976) amp
Izv = ( 0.965) amp
chi =
13th ATF2 Project Meeting, January
M. Woodley

22. Horizontal EXT Emittance Measurements
Vertical EXT Emittance Measurements
Date
Nwire
Emit (nm)
BMAG
Dec 4
1.784 ± 0.130
1.10 ± 0.04
Dec
1.686 ± 0.102
1.08 ± 0.05
Nov 2010 (?)
EXT kicker controller replaced
May
1.905 ± 0.078
1.08 ± 0.03
Apr
1.212 ± 0.065
1.26 ± 0.03
Mar
BS3X rolled ~4 mrad (CCW)
Feb
1.868 ± 0.336
1.15 ± 0.12
Feb
negative
Feb
1.626 ± 0.095
1.10 ± 0.06
Jan
Date
Nwire
Emit (pm)
BMAG
Dec 5
27.6 ± 1.8
1.09 ± 0.04
Dec 4
29.3 ± 3.1
1.05 ± 0.02
Nov 2010 (?)
EXT kicker controller replaced
May
11.7 ± 2.3
1.43 ± 0.25
Apr
15.4 ± 2.0
1.78 ± 0.17
Mar
BS3X rolled ~4 mrad (CCW)
Feb
22.08 ±0.9
1.19 ± 0.03
38.33 ± 1.1
1.10 ± 0.02
Feb
22.6 ± 1.4
1.15 ± 0.04
Feb
16.1 ± 0.7
1.06 ± 0.03
Jan
31.6 ± 1.2
1.03 ± 0.01
13th ATF2 Project Meeting, January
M. Woodley

23. SET-file History (Apr-Dec, 2010)
εy = 27.6 pm
Apr 21
εy = 15.4 pm
May 18
εy = 11.7 pm
KEX controller
replaced
Dec 9
εy = 29.3 pm
fast
kicker
fast
kicker
13th ATF2 Project Meeting, January
M. Woodley

24. 2010 Result 13th ATF2 Project Meeting, January 12 2012 M. Woodley
septum
2010 Result
13th ATF2 Project Meeting, January
M. Woodley

25. Summary & Continuing Work 13th ATF2 Project Meeting, January 12 2012
M. Woodley

26. Summary
more time is needed for analysis of existing data and simulations (MDW)
EXT setup and maintenance is well understood, relatively fast, and stable
mostly automated procedures … “recipe” for the rest
we have good BBA offset values for most quadrupoles and sextupoles
BPM system (striplines, C-band cavities, S-band cavities, IPBPMs) is working well
multi-OTR system is working well
we’re still plagued with vertical emittance growth between DR and EXT diagnostics section
up to a factor of 10!
appears to be strong x-y coupling ... maybe (at least partly) nonlinear
we have seen emittance measurements (May 2010) from the WS that show virtually no vertical emittance growth from DR to EXT diagnostics section (and no coupling correction required)
no empirical fudge factors required
need to figure out:
how to optimally correct the vertical emittance that we have (QK scan or “quick” methods)
what is causing the observed emittance growth and where does it happen?
are there other coupling sources between EXT diagnostics section and IP?
13th ATF2 Project Meeting, January
M. Woodley

27. Continuing Work coupling measurement / 4D beam reconstruction and ...
revisit emittance measurement and 4D reconstruction simulations
generate coupled beams at all phases (adjust coupling magnitude for εy = pm)
simulate QK scans … can we deduce ε2?
OTR and MSPIP tilt angles vs coupling phase … what should we expect to see?
simulate coupling correction schemes … what works? under what conditions?
and ...
13th ATF2 Project Meeting, January
M. Woodley