ATF2 ultra-low betas and even more chromatic proposals R. Toms, S. - - PowerPoint PPT Presentation

ATF2 ultra-low betas and even more chromatic proposals

• R. Tomás, S. Bai, P. Bambade, Y. Kamiya, S. Kuroda,
• Y. Renier, A. Seryi and G. White

Thanks to H. Braun, A. Jeremie, A. Latina,

• D. Schulte, F. Zimmermann et al

ATF2 collaboration meeting, 2008

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.1/29

FFS problematics

Problem Scales with Radiation E3 Chromaticity (ξy) L∗/β∗ Imperfections, tuning time 1/σ∗?

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.2/29

Chromaticity

Project Status β∗

y [mm]

L∗ [m] L∗/β∗

y

ξy FFTB Measured 0.167 0.4 2400 10000 ATF2 Design 0.1 1.0 10000 19000 ATF2 ultra-low β Proposed 0.025 1.0 40000 76000 CLIC 3TeV Design 0.09 3.5 39000 63000 CLIC long L* Proposed† 0.1 8 80000 120000 ILC Design 0.4 3.5 8750 15000 ILC pushed Design 0.2 3.5 17500 30000

† Proposed by A. Seryi in CLIC08

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.3/29

CLIC FFS, 3.5m versus 4.3m L*

0.2 0.4 0.6 0.8 1

• 0.01
• 0.005

0.005 0.01 Peak luminosity (relative) dp/p L*=3.5m L*=3.5m (opt.) L*=4.3m

→ Larger peak-lumi-bandwidth for the 3.5m L* FFS

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.4/29

IP spot size: tuning

Project Status σ∗

y [nm]

FFTB Measured 70 ATF2 Design 37 ATF2 ultra-low β Proposed 20 ILC Design 6 CLIC Design 2

Does tuning difficulty scale as σ∗−1

y

? ATF2 offers the unique opportunity to study tuning versus σ∗

y.

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.5/29

ATF2 ultra-low β proposal

• !"
• !#$%! &

(

'!&# + "

• %

.

• 0/)

• 4 56

&76 88$" 3 ' 4 79:5

• 4 59&6

; .)<

• !4 9#"%
• =
• *4 85)

(- 4 5'%'()7")))

• "-
• ! " # $ !%&! ' ( ( $ ) )%# )!

*+!('',(%! (-'.#-%!'!%/0$ !#!-%##'!$(!%%#%+($!+!%$%%+/%(%!( '0

• 1

! '%/$2/#%0!30$

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.6/29

ATF2 β∗ scan (S. Bai)

0 .0 0 0 0 0 .0 0 0 2 0 .0 0 0 4 0 .0 0 0 6 0 .0 0 0 8 1 7 2 7 3 7 4 7 5 7 6 7 7 7 8 7 9 7

sig y (lo g s c a le ) b e ty n o m in a l b e tx h a lf b e tx s q rt(b e ty*e p sy ) b e ty

n o m in a l/4

V a ria b le A T F 2 b e a m s iz e

cacacacac cacacacac

• ←MAPCLASS optimization

So far the minimum ATF2 σ∗

y=20nm

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.7/29

Tuning simulations

• Realistic alignment and field errors are assigned

to the ideal model

• Tuning algorithm is the Simplex having:

variables:x, y, roll and magnet strength

• bservables:Luminosity (CLIC) or beam sizes

(ATF2)

• Ground motion is included in the simulation
• γǫx = 3µm, ǫx = 1.2nm

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.8/29

ATF2 ultra-low β tuning example

0.01 0.1 1 500 1000 1500 2000 2500 3000 3500 4000 IP beam sizes [µm] Iteration number (1 iteration=1 minute) ATF2 ultra-low βy tuning example (Simplex)

• vert. Gauss
• vert. rms
• hor. Gauss
• hor. rms

targets

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.9/29

CLIC tuning: 100 perturbed machines

1 2 3 4 5 6 7 8 9 0.5 1 1.5 2 2.5 3 3.5 4 Counts Initial σy [µm]

Initial CLIC beam sizes up to 4µm (to be tuned down to 1nm).

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.10/29

Luminosity after tuning

2 4 6 8 10 12 14 0.6 0.8 1 1.2 Counts Relative final luminosity [L0]

20% of the cases below 80% of the target luminosity!

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.11/29

How to fix this?

• Join the ATF2 collaboration

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.12/29

ATF Initial σy for 150 seeds

2 4 6 8 10 12 14 16 0.5 1 1.5 2 2.5 3 3.5 4 Counts Initial σy [µm]

Up to 4µm of initial σy (same as CLIC!).

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.13/29

ATF2 β∗

y=0.025mm

10 15 20 25 30 35 40 10 15 20 25 30 35 40 Gaussian σy [nm] RMS σy [nm]

Rising discrepancy between rms and Gaussian fit, what does the Shintake monitor do?

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.14/29

ATF2 β∗

y=0.025: Shintake monitor

For beams with larger deviation from Gaussian made by Rogelio

y (micron)

• 65.1
• 65
• 64.9
• 64.8
• 64.7
• 64.6
• 64.5

1 10

10

10

beam size (nm) 18 20 22 24 26 28 30 32 34 36 38 entries 2 4 6 8 10

beam proÞle 23.7 nm (core beam size) 27.7 nm (measured) 29.8 nm (RMS beam size) The larger deviation cause bigger difference

29th Oct. 2008 ATF2 Weekly meeting 9/16

Measured size is between the core size and the RMS size

• Y. Kamiya

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.15/29

Final spot size for βy=0.025mm

5 10 15 20 25 30 35 20 25 30 35 40 45 50 55 60 Counts Final σy [nm]

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.16/29

Success versus time, βy=0.025mm

10 20 30 40 50 60 70 80 90 2000 4000 6000 8000 10000 12000 14000 Efficiency [%] Number of iterations

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.17/29

Summary table

case

• Max. tuning time

Ratio of success βy=0.1mm 5.5 days 100% βy=0.05mm 8 days 90% βy=0.025mm 10 days 80% Tuning time roughly scales with β−2

y

• r σ−1

y

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.18/29

The magnetic error crisis

• C. Spencer’s magnetic measurements.
• Impact on beam sizes for the nominal ATF2:
• Lucretia, σy =100nm
• SAD, σy =90nm
• MADX, σy =55nm
• Discrepancies among the codes for multipoles

above the sextupole.

• IP spot sizes no longer 37nm!
• Then? Rematch and fix bugs → ǫx

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.19/29

Rematching with MAPCLASS

20 25 30 35 40 45 50 55 1 2 3 4 5 6 7 8 IP σx,y [nm]

• rder

ATF2 IP beam sizes with multipoles σy (before rematch) σy (after rematch) σx/100 (before rematch) σx/100 (after rematch) σy OPT2

MAPCLASS manages to restore the effect of the mul- tipoles for the nominal ATF2 (ǫx = 1.2nm).

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.20/29

Glen’s simulation with MAPCLASS optics

(ǫx =1.2nm) MAPLCLASS optics better than ideal!

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.21/29

Fix bugs and rematch and rematch

35 40 45 50 55 60 65 70 75 80 85 3 3.5 4 4.5 5 5.5 6 Vertical IP beam size, σy [nm] Normalized horizontal emittance, εx [µm] ATF2 with multipolar errors and MAPCLASS rematching All multipoles (rematch 1) All multipoles (rematch 2) Only sextupoles

Need N more rematching to obtain: lim

N→∞ σy

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.22/29

Particle distribution at γǫx = 6µm

0.1 1 10 100 1000

• 3000
• 2000
• 1000

1000 2000 3000 counts Y [nm] 60000 particles, γεx=6µm, all multipoles σfit=35nm σrms=80nm MADX Gaussian fit

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.23/29

Impact on ATF2 ultra-low β

10 20 30 40 50 60 70 80 1 2 3 4 5 6 7 8 Vertical IP beam size [nm]

• rder

AT2 ultra-low beta (βy=0.025mm) σy (with errors) σy (after rematch) σy (no errors)

So far, minimum beam size with multipoles 27nm (ǫx = 1.2nm). What about tuning?

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.24/29

Impact on ATF2 ultra-low β

5 10 15 20 25 20 25 30 35 40 45 50 Counts Final σy [nm]

Maximum tuning time 10 days Ratio of success 70% Most likely σy=29nm

(ǫx = 1.2nm)

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.25/29

Summary table

case

• Max. tuning time

Success σy βy=0.1mm 5.5 days 100% 43nm βy=0.05mm 8 days 90% 33nm βy=0.025mm 10 days 80% 26nm including multipoles βy=0.025mm 10 days 70% 29nm

(ǫx = 1.2nm)

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.26/29

Andrei’s proposal for CLIC: double L∗

Advantages of moving QD0 out of detector:

• Easier design
• Easier stabilization
• Less or zero interplay with solenoid

Disadvantages:

• Higher chromaticity → tuning difficulty?
• ...

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.27/29

ATF2 tests for long L∗?

• Could ATF2 βy be further reduced to prove larger

chromaticity?

• Present limitation is aberrations, could
• ctupoles/decapoles be introduced in ATF2

lattice to compensate for them?

• Seems that tuning time scales with 1/σy, what

about L∗?

• Could L∗ be increased in ATF2 by displacing the

Shintake monitor? Synergy with ground motion correlation studies (A. Jeremie, B. Bolzon)

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.28/29

Summary & outlook

• CLIC and ATF2 have many similarities:
• Same initial distorted σy ≈ 4µm
• Same chromatic level (ATF2 ultra-low β)
• Similar tuning failure using the Simplex
• Magnetic errors crisis. Solutions: change optics?

add dodecapoles? low ǫx operation? Superconducting QF1?

• More colorful proposals to come
• Lots of work for 2009: CERN hired a PhD to

work ≈80% on ATF2

Thanks!

Rogelio Tom´ as Garc´ ıa ATF2 ultra-low betas and even more chromatic proposals – p.29/29