Extended Coupling Correction and Emittance Diagnostic Section for “optimal” ATF2

June 7, 2005 ILC BDS Meeting 1

Extended Coupling Correction and Emittance Diagnostic Section for “optimal” ATF2

nBPM (SLAC)nBPM (KEK)

FONT

Compton / laserwire

ODR

Existing ATF Extraction Line

Coupling Correction /Emittance Diagnostics

June 7, 2005 ILC BDS Meeting 2

June 7, 2005 ILC BDS Meeting 3

FF Optics ModificationsFrom Tauchi-san’s email ([bds 117] June 2, 2005):

5. Optics modifications:

(1) concentrate on "optimal" design (straight) … done (2) change bends from sector bends to rectangular … done (3) use 0.8 m bends (as used in ATF) instead of 1 m for better field

stability and more space … done (4) remove octupoles (do not use them, and they are tight) … done (OC0

removed; OC1 moved away from SF1) (5) extend diagnostics section (use up to ~10 m additional space) … done (6) QM14 is the strongest quad, and is close to max field of BT quads,

need to check if its strength can be reduced by reoptimizing the matching section … done (QM14[K1L] = -1.1 m-1)

June 7, 2005 ILC BDS Meeting 4

30 cm offset

ΔL = 7.1 m (w.r.t. baseline)

β*x,y = 4,0.1 mm

June 7, 2005 ILC BDS Meeting 5

baseline

optimal

Assembly Hall

June 7, 2005 ILC BDS Meeting 6

-1% +1%

June 7, 2005 ILC BDS Meeting 7

• ideally

–correction section with 4 independent skew quadrupoles, followed by

–2D (4 wire scanner) emittance measurement section–optics for orthogonal control of the 4 coupling phases–minimize εy once with each skew quadrupole

• in present ATF extraction line

–non-optimal optics in EXT straight section–wire scanners and skew quads interspersed–each wire scanner has x, y, and “u/v” (small angle, ~10°) wires

• one attempt at full 4D beam matrix measurement and correction was inconclusive1

Coupling Correction

1 See http://atfweb.kek.jp/atf/Reports/ATF-99-01.pdf

June 7, 2005 ILC BDS Meeting 8

“Ideal” skew correction / ε diagnostic sectionSQ SQ SQ SQ

WS WS WS WS

90°90°

180°90°

90°90°

45°45°

45°45°

45°45°

– x– y

See http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-8581.pdf

June 7, 2005 ILC BDS Meeting 9

90°90°

180°90°

90°90°

– x– y

33°57°

57°33°

33°57°

57°33°

SQ SQ SQ SQ

WS WS WS WS WS

59.210.8

108.05.9

59.210.8

108.05.9

59.210.8σ (μm)

2.0 2.0 2.0 2.0 2.0

2.0 2.0 2.0 2.0

1.3 1.3 1.3 1.3

For MAD files see http://www.slac.stanford.edu/~mdw/ATF2/optimal

June 7, 2005 ILC BDS Meeting 10

new quadrupole (between QF3X and BH1X.3)

1 2

-1 0 0 0

-0.52 -1 0 0

0 0 -1 0

0 0 1.37 -1

K KR

June 7, 2005 ILC BDS Meeting 11

sL

w1 w2 w3

N

L 2

min02

nnc 1cot

cc 120

0

00 2

1 2

L

3n

A ‘Drift’ A ‘Drift’ -Diagnostic Section-Diagnostic Section

3 wire scanners (or profile monitors)

00 ,

20

0min

1

00 ,

from Paul Emma …

June 7, 2005 ILC BDS Meeting 12

– x– y

σmin = 3 μm

June 7, 2005 ILC BDS Meeting 13

Continuing Work

• optimize system bandwidth and performance

• add BPMs and dipole correctors• simulate steering and dispersion/coupling

correction with machine/diagnostic errors• verify what space is needed for diagnostic

equipment in chicane• investigate drift ε–diagnostic section• writeup for ATF2 proposal document