emittance measurements and related experimental results 15th atf2 project meeting, january 24 2013m....
TRANSCRIPT
M. Woodley
Emittance Measurements and Related Experimental Results
15th ATF2 Project Meeting, January 24 2013 1/44
M. Woodley15th ATF2 Project Meeting, January 24 2013 2/44
Outline• emittance measurements
– charge dependence– coupling correction
• kicker issues• BS3X issues• vertical dispersion correction with correctors• beta matching in EXT upstream of OTRs
– in inflector– in coupling correction section
• other issues• Summary, Continuing Work, Mitigation
M. Woodley15th ATF2 Project Meeting, January 24 2013 3/44
Emittance MeasurementIssues:• do we believe the OTR measurements?• how stable/reproducible are the measurement results?• what about charge and bunch length correlations?
M. Woodley15th ATF2 Project Meeting, January 24 2013 4/44
QF
9X
QK
1X
Q
D10
X
QF
11X
QK
2X
Q
D12
X
QF
13X
QD
14X
QF
15X
QK
3X
Q
D16
X
QF
17X
QK
4X
QD
18X
QF
19X
QD
20X
QF
21X
EXT Diagnostics Section
165 170 175 180 185 1900
5
10
15
20
25
30
35
40
Ver
tical
Bea
m S
ize
(um
)
S (m)
OTR Vertical Emittance MeasurementDecember 14, 2011 07:44
Wire Scanner Measured Vertical Beam SizesDecember 14, 2011 09:30(MW1X σy value ignored)
black circles = WSblue circles = OTR
M. Woodley15th ATF2 Project Meeting, January 24 2013 5/44
0 2 4 6 8 10 12 14 16 18 200.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65ICT = 0.4446 +- 0.0051
ICT
Meas #
November 6, 2012
0 1 2 3 4 5 6 7 8 9 10 1120
21
22
23
24
25
26
27
28
29EmitY = 25.4122 +- 0.2439 pm
Em
itY (
pm)
Meas #0 1 2 3 4 5 6 7 8 9 10 11
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65ICT = 0.4967 +- 0.0082
ICT
Meas #
November 29, 2012
(e10
)(e
10)
M. Woodley15th ATF2 Project Meeting, January 24 2013 6/44
0 1 2 3 4 5 6 7 8 9 10 1123
23.5
24
24.5
25
25.5
26
26.5
27
ICT
Cor
rect
ed E
mitY
(pm
)
Meas #
EmitY = 25.2738 +- 0.1437 pm @ ICT = 0.45 (chisq=1)
0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.6520
21
22
23
24
25
26
27
28
29
30EmitY vs ICT
ICT (e10)
Em
itY (
pm)
p0= 16.4+- 1.261
p1= 19.73+- 2.707
RMS= 0.42 pm
NDF= 8 chisq/N = 0.391
rho = 1.001
EmitY = 16.4 ± 1.3 pm @ ICT = 0ΔEmitY/ΔICT ≈ 2 pm/109
November 29, 2012
0.35 0.4 0.45 0.5 0.5514
16
18
20
22
24
26
28
30EmitY vs ICT
ICT (e10)
Em
itY (
pm)
November 6, 2012
EmitY = 13.3 ± 3.5 pm @ ICT = 0ΔEmitY/ΔICT ≈ 3 pm/109
0 1 2 3 4 5 6 7 8 9 10 115
10
15
20
25
30EmitY = 26.9659 +- 0.5466 pm @ ICT = 0.45 (chisq=1)
ICT
Cor
rect
ed E
mitY
(pm
)
Meas #
~ 30 minutes
M. Woodley15th ATF2 Project Meeting, January 24 2013 7/44
6.25
9.76
14.06
3.51
σy (μm)
ICT (1010)
εy (pm)
βy = 2.56 m
DR XSR σy vs ICT
“by eye”linear fit:
0.07 pm / 109
in EXT:2 pm / 109
November 6, 2012
M. Woodley15th ATF2 Project Meeting, January 24 2013 8/44
ICT = 5x109
DR RF = 0.29 MV
εx = 1.87 nmBx = 1.05εBx = 1.96 nm
εy = 30.1 pmBy = 1.01εBy = 30.4 pm
ICT = 5x109
DR RF = 0.20 MV
εx = 1.77 nmBx = 1.08εBx = 1.93 nm
εy = 28.8 pmBy = 1.00εBy = 28.9 pm
Emittance vs Bunch Length (December 21 2012 owl)
M. Woodley15th ATF2 Project Meeting, January 24 2013 9/44
Coupling CorrectionIssues:• do we believe the OTR beam tilt measurements?• do measured beam tilts respond to coupling correction?
M. Woodley15th ATF2 Project Meeting, January 24 2013 10/44
250 300 350 400 450 500 550 600 650 700250
300
350
400
450
500
550
600
650
700
750OTR2X X VS ZH9X Expected Pos
ZH9X Expected Pos /um
OT
R2X
X /
um
p0= 8.922+- 8.079p1= 0.9918+-0.01692
RMS= 7.75 umNDF= 9
chisq/N = 1.081rho = 1.010
OTR2X beam tilt … is it real? Check measured response to ZH9X
X
Y
OTR0X before corrections OTR0X after dispersion correction OTR0X after coupling correction
M. Woodley15th ATF2 Project Meeting, January 24 2013 11/44
Extraction KickerIssues:• multipole fields (quadrupole/sextupole): are they real?• what’s the correct voltage?• is the kicker rolled?• what’s inside? (field linearizer? metal or plastic electrode
restraint?)
M. Woodley15th ATF2 Project Meeting, January 24 2013 12/44
Field Simulation (May 26, 2005)C. Pappas, SLAC
1 2 3 4
0.75" Ф0.827" Ф
0.5"0.75" 1.3"1.0"
0.0625"
0.591" Ф
electrodeceramicchamber
scale: 1.14" (figure) ≈ 0.75" (actual)
±25σx
ceramic chamber
DIMAD SBEND parameters:
L = 0.4 m ANGLE = 5.0e-3 rad K1 = -1.846929e-1 m-2
K2 = -3.824591e+1 m-3
M. Woodley
0 10 20 30 40 50 60-5
-4
-3
-2
-1
0
1
2
3
4
5
X
(m
m)
S (m)
KE
X1
QM
6RQ
M7R
BS
1XB
S2X
BS
3X
BH
1X
BH
2X
BH
3X
KE
X2
QS
1X
Q
F1X
QD
2X
Q
F3X
QF
4X
Q
D5X
QF
6X
Q
S2X
QF
7X
QD
8X
QF
9X
QK
1X
Q
D10
X
Q
F11
X
Q
K2X
QD
12X
QF
13X
QD
14X
QF
15X
QK
3X
Q
D16
X
Q
F17
X
Q
K4X
QD
18X
QF
19X
QD
20X
QF
21X
QM
16F
F
Q
M15
FF
QM
14F
F
Q
M13
FF
QM
12F
F
Q
M11
FF
QD
10B
FF
Q
D10
AF
F
QF
9BF
F
Q
F9A
FF
QD
8FF
QF
7FF
SF
6FF
0 10 20 30 40 50 60-5
-4
-3
-2
-1
0
1
2
3
4
5
Y
(m
m)
S (m)
KE
X1
QM
6RQ
M7R
BS
1XB
S2X
BS
3X
BH
1X
BH
2X
BH
3X
KE
X2
QS
1X
Q
F1X
QD
2X
Q
F3X
QF
4X
Q
D5X
QF
6X
Q
S2X
QF
7X
QD
8X
QF
9X
QK
1X
Q
D10
X
Q
F11
X
Q
K2X
QD
12X
QF
13X
QD
14X
QF
15X
QK
3X
Q
D16
X
Q
F17
X
Q
K4X
QD
18X
QF
19X
QD
20X
QF
21X
QM
16F
F
Q
M15
FF
QM
14F
F
Q
M13
FF
QM
12F
F
Q
M11
FF
QD
10B
FF
Q
D10
AF
F
QF
9BF
F
Q
F9A
FF
QD
8FF
QF
7FF
SF
6FF
what we expected to see (no kicker multipoles) …
bad BPMs
… what we observed
15th ATF2 Project Meeting, January 24 2013 13/44
Orbit Bump Study (February 2010): bump vertically through KEX2
bad BPMs
M. Woodley
what we expected to see (with predicted kicker multipoles) …
… what we observed
0 10 20 30 40 50 60-5
-4
-3
-2
-1
0
1
2
3
4
5
Y
(m
m)
S (m)
KE
X1
QM
6RQ
M7R
BS
1XB
S2X
BS
3X
BH
1X
BH
2X
BH
3X
KE
X2
QS
1X
Q
F1X
QD
2X
Q
F3X
QF
4X
Q
D5X
QF
6X
Q
S2X
QF
7X
QD
8X
QF
9X
QK
1X
Q
D10
X
Q
F11
X
Q
K2X
QD
12X
QF
13X
QD
14X
QF
15X
QK
3X
Q
D16
X
Q
F17
X
Q
K4X
QD
18X
QF
19X
QD
20X
QF
21X
QM
16F
F
Q
M15
FF
QM
14F
F
Q
M13
FF
QM
12F
F
Q
M11
FF
QD
10B
FF
Q
D10
AF
F
QF
9BF
F
Q
F9A
FF
QD
8FF
QF
7FF
SF
6FF
0 10 20 30 40 50 60-4
-3
-2
-1
0
1
2
3
4
X
(m
m)
S (m)
KE
X1
QM
6RQ
M7R
BS
1XB
S2X
BS
3X
BH
1X
BH
2X
BH
3X
KE
X2
QS
1X
Q
F1X
QD
2X
Q
F3X
QF
4X
Q
D5X
QF
6X
Q
S2X
QF
7X
QD
8X
QF
9X
QK
1X
Q
D10
X
Q
F11
X
Q
K2X
QD
12X
QF
13X
QD
14X
QF
15X
QK
3X
Q
D16
X
Q
F17
X
Q
K4X
QD
18X
QF
19X
QD
20X
QF
21X
QM
16F
F
Q
M15
FF
QM
14F
F
Q
M13
FF
QM
12F
F
Q
M11
FF
QD
10B
FF
Q
D10
AF
F
QF
9BF
F
Q
F9A
FF
QD
8FF
QF
7FF
SF
6FF
bad BPMs
15th ATF2 Project Meeting, January 24 2013 14/44
Orbit Bump Study (February 2010): bump vertically through KEX2
M. Woodley
set ZH3X/ZH4X/ZH5X X-bump; scan ZV5X/ZV6X/ZV7X Y-bump; find X-bump setting where Y-bump closes
at this point the quadrupole field seen by the beam in KEX2 has the value predicted by POISSON for the vacuum chamber center
we observed that BSM background increased at X-bump = -1.5 mm, so we set X-bump back to zero … KEX2 horizontally misaligned?
should scan X-bump and observe BSM background to locate center of KEX2 vacuum chamber (in X)
ΔX ΔY
ΔX = +3 mm
ΔX = +1 mm
ΔX = 0
ΔX = -1.5 mm
15th ATF2 Project Meeting, January 24 2013 15/44
M. Woodley15th ATF2 Project Meeting, January 24 2013 16/44
Δεy/εy0 (%) ≈ 60.4 × [ΔYkicker1 (mm)]2
Vertical emittance growth (ηy corrected)
12 pm -> 20 pm @ +- 1 mm
M. Woodley15th ATF2 Project Meeting, January 24 2013 17/44
QK1X[K1]
QK2X[K1]
QK3X[K1]
QK4X[K1]
Simulation of vertical offset in KEX1
• coupling due to sextupole component blows up vertical emittance
• coupling corrected with QK skew quads (after vertical dispersion correction)
• pattern of QK strengths is not what we observe (QK1X is relatively weak)
• more in Edu Marin’s presentation …
-20 -10 0 10 200
50
100QK1X
-20 -10 0 10 200
50
100QK2X
-20 -10 0 10 200
20
40
60QK3X
I (A)-20 -10 0 10 200
20
40
60
80QK4X
I (A)
Nov/Dec 2012 QK*X SET-file values
simulations by Edu Marin
M. Woodley
-800 -700 -600 -500 -400 -300 -200 -100 00
50
100
150
200
250
300
350
400
450dX/dV = -0.5085 um/V
X BS
3X (
um)
KEX (V)
V
x
RcVcRx
1212
1,,
R12 = 4.7329 mm/mraddX/dV = -0.5085 mm/kV
dθ/dV = -0.1074 mrad/kVθ0 = -5 mrad V0 = 46.5 kV
(SLAC NDR KEX: 0.1158 mrad/kV)
Horizontal orbit position at BS3X center estimated by
back-propagation from EXT BPM measurements
(QF1X-QF4X) … courtesy of Yves Renier
8 μm
112 μm
215 μm
315 μm
415 μm
0 V
-200 V
-400 V
-600 V
-800 V
ΔX @ BS3X (from orbit fit) ΔVKEXΔX
ATF2 feedback
measurement: 2012/12/07 Owl Shift
15th ATF2 Project Meeting, January 24 2013 18/44
M. Woodley15th ATF2 Project Meeting, January 24 2013 19/44
EXT Orbit (Corrected) vs KEX VoltageDecember 13, 2012 Day Shift
40 45 501520
1540
1560
1580
1600
BS
1X (
A)
KEX (kV)40 45 50
2540
2560
2580
2600
BS
3X (
A)
KEX (kV)
40 45 50-1.5
-1
-0.5
0
0.5
ZV
1X (
A)
KEX (kV)40 45 50
-0.4
-0.2
0
0.2
0.4
ZV
2X (
A)
KEX (kV)
KEX1 steers vertically?inferred roll is ~100 mrad (!)
… or something else?
M. Woodley15th ATF2 Project Meeting, January 24 2013 20/44
BS3X Skew Quadrupole (?)Issues:• origin of observed anomalous vertical dispersion in EXT/FF?
– measured vertical dispersion in DR at extraction point is small• we have had problems with BS3X in the past
– BS3X had to be physically rolled ~ -4 mrad (March 17, 2010)
M. Woodley
140 150 160 170 180 190 200 210 220 230
-600
-400
-200
0
200
400
600
DY
(m
m)
S (m)
Modeledηy0 = -13.2 mmη′y0 = -14.2 mr
140 150 160 170 180 190 200 210 220 230
-600
-400
-200
0
200
400
600
DY
(m
m)
S (m)
ModeledBS3X skew quad
KL = -0.03 m-1
IIDX = -5.8 A
12 pm 39 pm
Measured
Δμy(BS3XIP) = 101.8°
15th ATF2 Project Meeting, January 24 2013 21/44
NOTE: ηx = 179 mm @ BS3X
M. Woodley
140 150 160 170 180 190 200 210 220 230-100
-50
0
50
100
DY
(m
m)
S (m)
Modeledηy0 = -13.2 mmη′y0 = -14.2 mr
140 150 160 170 180 190 200 210 220 230-100
-50
0
50
100
DY
(m
m)
S (m)
ModeledBS3X skew quad
KL = -0.03 m-1
IIDX = -5.8 A
12 pm 39 pm
Measured
Δμy(BS3XIP) = 101.8°
15th ATF2 Project Meeting, January 24 2013 22/44
zoom in …
M. Woodley15th ATF2 Project Meeting, January 24 2013 23/44
Measured
IQS = -0.951 A
140 150 160 170 180 190 200 210 220 230-100
-50
0
50
100
DY
(m
m)
S (m)
IQS = -0.834 A
ModeledBS3X skew quad
KL = -0.03 m-1
IIDX = -5.8 A
Measured
IQS = -0.474 A
140 150 160 170 180 190 200 210 220-200
-150
-100
-50
0
50
100
150
200
DY
(m
m)
S (m)
IQS = -0.500 A
ModeledBS3X skew quad
KL = -0.03 m-1
IIDX = -5.8 A
either use QS Σ-knob to correct EXT (IP-phase) …
… or use QS Σ-knob to correct FF (FD-phase)
M. Woodley15th ATF2 Project Meeting, January 24 2013 24/44
BS3X Skew Sextupole (?)Issues:• anomalous vertical dispersion amplitude depends on extraction
kicker voltage• X position dependent skew quadrupole field skew sextupole
M. Woodley
ΔKEX = -200 V
140 150 160 170 180 190 200 210 220-800
-600
-400
-200
0
200
400
600
DY
(m
m)
S (m)
KLBS3Xskew = -0.03215 m-1
Measured Modeled
ΔKEX = 0 (KEX = 50000 V)
140 150 160 170 180 190 200 210 220-800
-600
-400
-200
0
200
400
600
DY
(m
m)
S (m)
KLBS3Xskew = -0.03517 m-1
Measured Modeled
15th ATF2 Project Meeting, January 24 2013 25/44
M. Woodley
ΔKEX = -400 V KLBS3Xskew = -0.03094 m-1
140 150 160 170 180 190 200 210 220-800
-600
-400
-200
0
200
400
600
DY
(m
m)
S (m)
Measured Modeled
ΔKEX = -600 V KLBS3Xskew = -0.02913 m-1
140 150 160 170 180 190 200 210 220-800
-600
-400
-200
0
200
400
600
DY
(m
m)
S (m)
Measured Modeled
15th ATF2 Project Meeting, January 24 2013 26/44
M. Woodley
ΔKEX = -800 V KLBS3Xskew = -0.02610 m-1
140 150 160 170 180 190 200 210 220-800
-600
-400
-200
0
200
400
600
DY
(m
m)
S (m)
Measured Modeled
15th ATF2 Project Meeting, January 24 2013 27/44
-800 -700 -600 -500 -400 -300 -200 -100 0-0.036
-0.034
-0.032
-0.03
-0.028
-0.026
-0.024BS3Xskew VS dKEX
dKEX /V
BS
3Xsk
ew /
1/m
p0=-0.03493+-0.0004444p1=-1.058e-05+-9.071e-07
RMS=0.000444 1/mNDF= 3
rho = -0.989
BS3Xskew = 0 @ KEX = 46.7 kV
KEX lower voltage0 50 100 150 200 250 300 350 400 450
-0.036
-0.034
-0.032
-0.03
-0.028
-0.026
-0.024BS3Xskew VS BS3X X
BS3X X /um
BS
3Xsk
ew /
1/m
p0=-0.03513+-0.0004623p1=2.081e-05+-1.799e-06
RMS=0.000448 1/mNDF= 3
rho = 0.989
BS3Xskew = 0 @ BS3X X = +1.7 mm
toward DR (to the left)
M. Woodley
Set EXT Kicker Voltage to 46 kV
45.5 45.6 45.7 45.8 45.9 46 46.1 46.2 46.3 46.4 46.5350
400
450
500
550
600
650
700
750V0 = 45.936 +- 0.038
|DY
| (um
)
EXT_DKICKER (kV)
QD10B (FB off)
QD4A (FB off)QD10B (FB on)
QD4A (FB on)
49.1 49.2 49.3 49.4 49.5 49.6 49.7 49.8 49.9 50 50.1350
400
450
500
550
600V0 = 46.519 +- 0.046 (kV)
|DY
| (um
)
EXT_DKICKER (kV)
QD10B (FB on)
QD4A (FB on)
Dec 7 (KEX @ 50 kV) Dec 12 (KEX @ 46 kV)
15th ATF2 Project Meeting, January 24 2013 28/44
M. Woodley15th ATF2 Project Meeting, January 24 2013 29/44
Vertical Dispersion CorrectionIssues:• can’t simultaneously correct vertical dispersion in EXT (at OTRs …
IP-phase) and in FF (FD-phase) using the QS Σ-knob• presence of KEX2 prevented use of vertical dipole correctors for
“other phase” vertical dispersion correction– emittance growth when off axis vertically in KEX2 (sextupole)– but … KEX2 is now gone (using BKX dipole instead)
• can now use both QS Σ-knob and vertical dipole correctors for vertical dispersion correction
M. Woodley
140 150 160 170 180 190 200 210 220-5000
-4000
-3000
-2000
-1000
0
1000
2000
3000
4000
Orb
it (u
m)
S (m)
ZV3X: ΔI = +0.096 A
140 150 160 170 180 190 200 210 220-250
-200
-150
-100
-50
0
50
100
150
200
250
DY
(m
m)
S (m)
ZV3X: ΔI = +0.096 A
140 150 160 170 180 190 200 210 220-5000
-4000
-3000
-2000
-1000
0
1000
2000
3000
4000
Orb
it (u
m)
S (m)
ZV11X: ΔI = +0.049 A
140 150 160 170 180 190 200 210 220-250
-200
-150
-100
-50
0
50
100
150
200
250
DY
(m
m)
S (m)
ZV11X: ΔI = +0.049 A
15th ATF2 Project Meeting, January 24 2013 30/44
Simulation
M. Woodley
Monday Day Shift, December 17, 2012
before correction after correction
QS*X : -1.050 A -0.113 A (ΔI = +0.937 A) … correct IP-phase ηy
ZV3X : +0.172 A +0.047 A (ΔI = -0.125 A) … correct FD-phase ηy
ZV11X : +0.201 A +0.229 A (ΔI = +0.028 A) … correct FF orbit
15th ATF2 Project Meeting, January 24 2013 31/44
M. Woodley15th ATF2 Project Meeting, January 24 2013 32/44
Beta MatchingIssues:• beta matching to FF using FF matching quads can’t be verified
easily (QMs are downstream of OTRs)• changing the matching quad strengths can be painful (steering, … )• matching in EXT inflector wasn’t possible given the constraints of
the double kicker system– but … KEX2 is now gone (using BKX dipole instead)– still need to hold dispersion fixed
• matching between inflector and OTRs means changing optics of coupling correction system– maybe not so bad given coupling correction algorithm (see
following presentation by Edu Marin … )
M. Woodley15th ATF2 Project Meeting, January 24 2013 33/44
before β-match
εx = 1.37 nmBx = 2.26εBx = 3.11 nm
εy = 36.1 pmBy = 1.52 εBy = 55.1 pm
(set12dec11_1908)
after β-matchεx = 1.60 nmBx = 1.24εBx = 1.99 nm
εy = 40.6 pmBy = 1.05 εBy = 42.6 pm
QF9X : 36.027 32.936 ( -8.6%)QD10X : 56.860 66.116 ( +16.3%)QF11X : 46.638 35.836 ( -23.2%)QD12X : 46.230 48.314 ( +4.5%)
(set12dec11_2012)
Beta Matching (December 11 2012 swing)
M. Woodley
name match0 match1 match2 match3 design
file 054152 061717 080625 084346
EmitX 1.7894 1.8228 1.7587 1.5860
BmagX 1.1946 1.0013 1.0026 1.0076 1.0000
EmBmX 2.1376 1.8251 1.7633 1.5981
BetaX 4.7239 6.0386 6.4327 6.2257 6.3052
AlphaX -2.8890 -4.2795 -4.6550 -4.5596 -4.4943
EmitY 28.4846 25.7572 30.8175 28.2300
BmagY 1.2000 1.3489 1.0554 1.0034 1.0000
EmBmY 34.1808 34.7439 32.5253 28.3262
BetaY 9.1308 9.4923 7.1151 6.0766 6.1903
AlphaY 4.4037 4.8369 3.2854 2.6087 2.5763
QF1X 50.682 50.947 50.812 50.812 49.024
QD2X 42.865 43.035 43.312 43.312 42.865
QF3X 30.497 30.724 30.800 30.800 30.498
QF4X 30.863 30.710 30.636 30.636 30.864
QD5X 41.940 42.083 41.995 41.995 41.940
QF6X 52.983 52.753 52.692 52.692 51.556
QF7X 54.600 54.524 57.931 57.931 54.601
QD8X 26.862 26.850 27.005 27.005 26.863
QF9X 34.701 36.133 36.027 36.027 34.702
QD10X 52.965 51.764 56.860 56.860 52.964
15th ATF2 Project Meeting, January 24 2013 34/44
Beta Matching (December 12 2012 owl)
0
1
2
3
X Y
M. Woodley15th ATF2 Project Meeting, January 24 2013 35/44
0 5 10 15 20 25 30 35 40 45 500
2
4
6
8
10
12
14
16
sqrt
(Bet
a)
S (m)
fit
0 5 10 15 20 25 30 35 40 45 500
2
4
6
8
10
12
14
16sq
rt(B
eta)
S (m)
fit
25 30 35 40 45 500
1
2
3
4
5
6
7
sqrt
(Bet
a)
S (m)
SQ
207.6°87.1°
89.9°90.0°
SQ SQ SQ
56.7°112.5°
25 30 35 40 45 500.5
1
1.5
2
2.5
3
3.5
4
4.5
sqrt
(Bet
a)
S (m)
SQ
180.0°90.0°
89.9°90.0°
SQ SQ SQ
90.2°90.0°
M. Woodley15th ATF2 Project Meeting, January 24 2013 36/44
MB2XIssues:• we were blind to the extraction trajectory between KEX1 and QF1X• two special button-type BPMs exist in this area
– MB1X at location of DR BPM 20 (between QM6R1 and QM7AR)– MB2X between septa BS2X and BS3X
• Glen hooked MB2X up to a spare channel in the stripline BPM DAQ system
M. Woodley15th ATF2 Project Meeting, January 24 2013 37/44
DRextraction
kicker
extractionsepta
MB1X(button)
MB2X(button)
MQF1X(stripline)
MB2X: top left button(stripline BPM system)
Y
X
~ ICT
M. Woodley15th ATF2 Project Meeting, January 24 2013 38/44
Additional Issues
M. Woodley15th ATF2 Project Meeting, January 24 2013 39/44
Effect of DR orbit feedback
DR FB ON
DR FB OFF and DR correctors were reset.
emittance increasedue to orbit feedback?
M. Woodley15th ATF2 Project Meeting, January 24 2013 40/44
Summary,Continuing Work,
Mitigation
M. Woodley15th ATF2 Project Meeting, January 24 2013
Summary (1)• multi-OTR EXT emittance measurements are reliable and stable
– measured beam tilt (coupling) values are believable and correspond to real X-Y coupling
• extracted vertical emittance is strongly dependent on bunch charge– 2-3 pm per 109 … much larger than observed in DR ( < 0.1 pm per 109 … IBS prediction?)– OTR camera gains were adjusted for low charge … optimized? other OTR systematics?– best vertical emittance observed during November-December running was 21 pm @ 109 e-/bunch
• extracted vertical emittance appears to be independent of DR RF voltage (bunch length)
• measured beam tilt (coupling) values are believable and correspond to real X-Y coupling– zeroing all 4 measured beam tilts minimizes projected vertical emittance
• observed KEX1 quadrupole/sextupole field components agree with (a) POISSON field simulation– tracking simulations indicate that vertical beam offset in KEX1 might not be a source of emittance growth– not sure exactly what’s inside either SLAC kicker
• KEX1 calibration measured with two independent methods– for 5 mrad (nominal) kick at 1.269 GeV: 46.5 kV (from orbit dependence); 46.7 kV (from vertical dispersion)
41/44
M. Woodley15th ATF2 Project Meeting, January 24 2013
Summary (2)• anomalous vertical dispersion in EXT/FF is well modeled by a skew quadrupole field at BS3X
– strength of inferred skew quadrupole depends on horizontal beam position in BS3X, consistent with a skew sextupole field there with strength K2L = 16 m-2 … for comparison, K2L for SD4FF is ~ 15 m-2
• both phases of vertical dispersion (IP and FD) can be corrected with a combination of QS Σ-knob and vertical dipole correctors ZV3X and ZV11X beta matching can be done more reliably using EXT inflector quads and/or coupling correction section quads– leave FF matching quads alone
• button-type BPM MB2X (between extraction septa BS2X and BS3X) is now reading out through the stripline BPM DAQ system– still needs to be calibrated– could imagine setting KEX1 to nominal voltage and using X reading as “gold” value
42/44
M. Woodley15th ATF2 Project Meeting, January 24 2013
• model horizontal orbit sensitivity of vertical emittance due to assumed BS3X skew sextupole field– after coupling correction, does pattern of QK strengths match observations?
• model horizontal orbit sensitivity of vertical kick due to assumed BS3X skew sextupole field– can we reproduce Okugi-san’s vertical steering (ZV1X and ZV2X) vs KEX1 voltage measurement?
• model the propagation of projected vertical emittance around the (coupled) Damping Ring– if εy = 12 pm at XSR source point (mid-store), is it 12 pm at the extraction kicker (last turn)?
• put KEX1 on a mover and try to measure vertical emittance vs KEX1 Y position?
43/44
Continuing Work
M. Woodley15th ATF2 Project Meeting, January 24 2013
• reduce Damping Ring vertical emittance– use new DR laserwire to confirm XSR measurements
• run at low charge … 109 e-/bunch or less– performance of diagnostics?
• understand charge dependence of vertical emittance– why is charge dependence of εy at OTRs > 20 times what is observed in DR?
– is this a wakefield? why doesn’t εy depend on DR RF voltage?
• we’ve been measuring vertical emittance blowup in EXT since before ATF2 was proposed– the only part of the system common to both ATF and ATF2 is the DR extraction system (6 m of beamline starting at
KEX1 and ending at BS3X)– maybe we should rip open the entire system and physically look for anything wrong?
• fix the slow DR circumference (energy) drift– should be better now that DR air conditioner is working again– install a small 4 dipole chicane for circumference adjustment (controlled by an energy feedback)?
44/44
Mitigation?
M. Woodley15th ATF2 Project Meeting, January 24 2013 45/44
Extra Slides
M. Woodley15th ATF2 Project Meeting, January 24 2013
Date Nwire Emit (nm) BMAG
Dec 14 2010 4 1.784 ± 0.130 1.10 ± 0.04
Dec 9 2010 4 1.686 ± 0.102 1.08 ± 0.05
Nov 2010 (?) EXT kicker controller replaced
May 18 2010 4 1.905 ± 0.078 1.08 ± 0.03
Apr 21 2010 4 1.212 ± 0.065 1.26 ± 0.03
Mar 17 2010 BS3X rolled ~4 mrad (CCW)
Feb 25 2010 4 1.868 ± 0.336 1.15 ± 0.12
Feb 17 2010 4 negative
Feb 3 2010 4 1.626 ± 0.095 1.10 ± 0.06
Jan 28 2010
Date Nwire Emit (pm) BMAG
Dec 14 2010 5 27.6 ± 1.8 1.09 ± 0.04
Dec 9 2010 4 29.3 ± 3.1 1.05 ± 0.02
Nov 2010 (?) EXT kicker controller replaced
May 18 2010 5 11.7 ± 2.3 1.43 ± 0.25
Apr 21 2010 5 15.4 ± 2.0 1.78 ± 0.17
Mar 17 2010 BS3X rolled ~4 mrad (CCW)
Feb 25 2010 5 22.08 ±0.9 1.19 ± 0.03
Feb 25 2010 5 38.33 ± 1.1 1.10 ± 0.02
Feb 17 2010 5 22.6 ± 1.4 1.15 ± 0.04
Feb 3 2010 5 16.1 ± 0.7 1.06 ± 0.03
Jan 28 2010 5 31.6 ± 1.2 1.03 ± 0.01
Horizontal EXT Emittance Measurements Vertical EXT Emittance Measurements
46/44
M. Woodley15th ATF2 Project Meeting, January 24 2013 47/44
OTR Vertical Emittance MeasurementDecember 14, 2011 07:44
name sigt sigd sig----- ------- ------- -------OTR0X 17.00 2.54 16.80OTR1X 13.44 2.90 13.12OTR2X 19.18 5.77 18.29OTR3X 17.53 3.26 17.22 Vertical emittance parameters at OTR0X-------------------------------------------------------energy = 1.2817 GeVemit = 49.7560 +- 3.8167 pmemitn = 124.7989 +- 9.5732 nmemitn*bmag = 139.1183 +- 14.3102 nmbmag = 1.1147 +- 0.0582 ( 1.0000)bmag_cos = -0.0976 +- 0.0000 ( 0.0000)bmag_sin = 0.4310 +- 0.0000 ( 0.0000)beta = 6.2274 +- 0.6272 m ( 6.1903)alpha = 3.0722 +- 0.3470 ( 2.5763)chisq/N = 1.0000 Propagated vertical spot sizes-----------------------------------OTR0X = 17.6 um ( 16.8 +- 1.4)OTR1X = 12.5 um ( 13.1 +- 0.9)OTR2X = 18.8 um ( 18.3 +- 1.3)OTR3X = 16.9 um ( 17.2 +- 1.3)
165 170 175 180 185 1900
5
10
15
20
25
30
35
40
Ver
tical
Bea
m S
ize
(um
)
S (m)
QF
9X
QK
1X
Q
D10
X
QF
11X
QK
2X
Q
D12
X
QF
13X
QD
14X
QF
15X
QK
3X
Q
D16
X
QF
17X
QK
4X
QD
18X
QF
19X
QD
20X
QF
21X
EXT Diagnostics Section
M. Woodley15th ATF2 Project Meeting, January 24 2013 48/44
sigt sigd sigw sig------- ------- ------- ------- 19.50 2.76 2.50 19.14 19.40 5.81 2.50 18.34 13.60 3.18 2.50 12.98 29.50 3.70 2.50 29.16 Vertical emittance parameters at MW0X-------------------------------------------------------energy = 1.2817 GeVemit = 42.9533 +- 3.4254 pmemitn = 107.7395 +- 8.5918 nmemitn*bmag = 114.9045 +- 10.4024 nmbmag = 1.0665 +- 0.0409 ( 1.0000)bmag_cos = 0.3468 +- 0.0000 ( 0.0000)bmag_sin = -0.0229 +- 0.0000 ( 0.0000)beta = 8.8918 +- 0.9843 m ( 6.1903)alpha = 3.6762 +- 0.4276 ( 2.5763)chisq/N = 1.0000 Propagated vertical spot sizes-----------------------------------MW0X = 19.5 um ( 19.1 +- 1.4)MW2X = 18.0 um ( 18.3 +- 1.4)MW3X = 13.5 um ( 13.0 +- 1.0)MW4X = 27.5 um ( 29.2 +- 2.2)
165 170 175 180 185 1900
5
10
15
20
25
30
35
Ver
tical
Bea
m S
ize
(um
)
S (m)
QF
9X
QK
1X
Q
D10
X
QF
11X
QK
2X
Q
D12
X
QF
13X
QD
14X
QF
15X
QK
3X
Q
D16
X
QF
17X
QK
4X
QD
18X
QF
19X
QD
20X
QF
21X
EXT Diagnostics Section
Wire Scanner Vertical Emittance MeasurementDecember 14, 2011 09:30(MW1X σy value ignored)
M. Woodley15th ATF2 Project Meeting, January 24 2013 49/44
0 2 4 6 8 10 12 14-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
Y
(m
m)
S (m)
KE
X1
QM
6R
QM
7R
BS
1X
BS
2X
BS
3X
BH
1X
QS
1X
Q
F1X
QD
2X
QF
3X
ZV
100R
X
ZV
1X
ZV
2X
ZV
3X
BS3X roll = 4.66 mrad
BS3X roll = 4.66 mradIzv1 = -6.918 (-6.976) ampIzv2 = 1.270 ( 0.965) ampchi2 = 0.3102
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)
-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4SET-file values (April 2009 - May 2010)
ZV
2X C
urre
nt (
A)
ZV1X Current (A)
before March 17, 2010
after March 17, 2010
M. Woodley15th ATF2 Project Meeting, January 24 2013 50/44
3
4
5x 10
4
DK
ICK
ER
1500
1600
BS
1X
2500
2550
2600
2650
BS
3X
-2
-1
0
ZH
9R
Apr May Jun Jul0
5
10
BK
X
Oct Nov Dec Jan
Apr 21εy = 15.4 pm
May 18εy = 11.7 pm
SET-file History (Apr-Dec, 2010)
KEX controllerreplaced
fastkicker
fastkicker
Dec 9εy = 29.3 pm
Dec 14εy = 27.6 pm
M. Woodley15th ATF2 Project Meeting, January 24 2013 51/44
2010 2011 2012 201335
40
45
50
Time
EX
T-D
KIC
KE
R (
kV)
DR Extraction Kicker Historic Setpoint Data (from SET-files)
εy = 12 pmMay 18 2010
εy = 15 pmApril 21 2010