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The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals R. Toms Thanks to P. Bambade, S. Bai, H. Braun, B. Dalena, S. Kuroda, A. Latina, D. Schulte, A. Seryi, Y. Renier, G. Rumolo, G. White, F. Zimmermann et al CLIC seminar,

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SLIDE 1

The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals

  • R. Tomás

Thanks to P. Bambade, S. Bai, H. Braun, B. Dalena,

  • S. Kuroda, A. Latina, D. Schulte, A. Seryi, Y. Renier,
  • G. Rumolo, G. White, F. Zimmermann et al

CLIC seminar, November 2008

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.1/31

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SLIDE 2

CLIC Final Focus System with L∗=3.5m

2300. 2450. 2600. 2750.

s (m) FFS with L*=3.5m

0.0 50. 100. 150. 200. 250. 300.

β

x (m), β y (m)

[*10**( 3)]

  • 0.045
  • 0.040
  • 0.035
  • 0.030
  • 0.025
  • 0.020
  • 0.015
  • 0.010
  • 0.005

0.0 0.005 0.010

D

x (m)

β x β y Dx

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.2/31

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SLIDE 3

FFS problematics

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

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.3/31

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SLIDE 4

Radiation in CLIC (B. Dalena, CLIC’08)

  • Radiation in dipoles: 14% luminosity loss
  • Radiation in final quad: 10% luminosity loss

20 40 60 80 100 120 140 160 180

β

✱ y [µm]

2 4 6 8 10 12

σ

✱ y [nm]

β

✱ y of minimum Oide effect Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.4/31

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SLIDE 5

ILC FFS

5 10 15 20 25 30 35 40 45 200 400 600 800 1000 1200 1400 1600

  • 0.2
  • 0.15
  • 0.1
  • 0.05

0.05 0.1 0.15 0.2 Betas [km] Dispersion [m] Longitudinal location [m] βx βy Dx

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.5/31

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SLIDE 6

ATF2 - the ILC scaled test machine

2 4 6 8 10 12 14 10 20 30 40 50 60 70 80 90 100

  • 0.8
  • 0.6
  • 0.4
  • 0.2

0.2 0.4 0.6 β[km] Dx[m] Longitudinal Location[m] βx βy Dx

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.6/31

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SLIDE 7

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 ILC Design 0.4 3.5 8750 15000 ILC pushed Design 0.2 3.5 17500 30000

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.7/31

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SLIDE 8

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.8/31

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SLIDE 9

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.9/31

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SLIDE 10

ATF2 ultra-low β proposal

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Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.10/31

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SLIDE 11

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.11/31

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SLIDE 12

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)

  • Other tuning algorithms use pre-computed knob

scans

  • Ground motion is included in the simulation (not

yer for CLIC)

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.12/31

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SLIDE 13

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.13/31

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SLIDE 14

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.14/31

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SLIDE 15

Luminosity after max of 18000 tuning iter

2 4 6 8 10 0.4 0.6 0.8 1 Counts Relative final luminosity [L0]

Bug in my PLACET-MAD converter

80% of the seeds give more than 80% of the design luminosity → 20% fail.

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.15/31

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SLIDE 16

Luminosity after tuning - No Bug

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

Still 20% of the cases below 80% but not so much be- low!

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.16/31

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SLIDE 17

How to fix this?

  • Reduce the complexity of the system by either

reducing performance or increasing the length (P. Raimondi’s proposal)

  • Devise more clever algorithms than the Simplex
  • Test in ATF2 with the possibility of a wide range
  • f β∗

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.17/31

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SLIDE 18

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.18/31

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SLIDE 19

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.19/31

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SLIDE 20

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.20/31

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SLIDE 21

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.21/31

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SLIDE 22

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 The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.22/31

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SLIDE 23

The magnetic error crisis

  • Inital design specs on multipoles ≈ 10−4.
  • C. Spencer’s magnetic measurements show larger

than specs.

  • Impact on beam sizes for the nominal ATF2:
  • Lucretia, σy =100nm
  • SAD, σy =90nm
  • MADX, σy =60nm
  • Discrepancies among the codes for multipoles

above the sextupole (still under investigation)

  • IP spot sizes no longer 37nm!
  • Then? Rematch and fix bugs (or vice-versa)

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.23/31

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SLIDE 24

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.

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.24/31

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SLIDE 25

Glen’s simulation with MAPCLASS optics

(Multipoles up to sextupolar order only) MAPLCLASS optics better than ideal!

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.25/31

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SLIDE 26

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. What about tuning?

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.26/31

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SLIDE 27

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

Disclaimer: MADX-PLACET converter not fully debugged for dodecapolar multipoles plus discrepancies with LUCRETIA are not understood

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.27/31

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SLIDE 28

Andrei’s proposal: double L∗

Advantages of moving QD0 out of detector:

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

Disadvantages:

  • Lower luminosity
  • Higher chromaticity (tuning difficulty?)
  • Longer FFS (≈400m longer than current)

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.28/31

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SLIDE 29

Comparing βy

100 200 300 400 500 600 700 800 900 100 200 300 400 500 600 700 800 βy [km] Longitudinal location [m] Andrei’s proposal CLIC nominal

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.29/31

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SLIDE 30

Andrei’s proposal: double L∗

lumi per Andrei’s Optimized CLIC CLIC crossing

  • riginal

(MAPCLASS) (3.5m) design lumi peak 1.2 1.3 1.8 1.65 lumi total 2.7 3.0 5.6 4 After optimizing Andrei’s FFS with our code MAPCLASS:

  • peak luminosity is 21% lower than CLIC design and

28% lower than our actual lattice.

  • 4 strong octupoles and 2 strong decapoles are needed
  • Lots of work on the lattice pending

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.30/31

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SLIDE 31

Conclusions

  • The CLIC FFS is a challenge in all aspects
  • ATF2 gives us now the unique opportunity to test

CLIC FFS problematics

  • Magnetic errors surprised ATF2 and may do the

same for CLIC (even at the computer modeling level)

  • The international collaboration proves extremely

fruitful for the CLIC FFS! (and also for the other projects, e.g. MAPCLASS, etc)

Thanks!

Rogelio Tom´ as Garc´ ıa The CLIC FFS, ATF2 ultra-low betas and even more chromatic proposals – p.31/31