Update on ILC ML Lattice Design

Alexander Valishev,for the FNAL LET group

FNAL

AP Dept. Meeting March 7, 2007

2APD meeting March 7, 07

ML Lattice design

Outline

• Basic layout• Curvature implementation• Matching• Summary and problems

3APD meeting March 7, 07

ML Lattice design

Lattice Design

• Defined by cryo segmentation• Versions of segmentation

» 8-8-8 scheme, May 31 2006» 9-8-9 scheme, Dec 28 2006

• Basic segmentations:

Main Linac

RF Unit

Cryogenic Unit

APD meeting March 7, 07

ML Lattice design

May 31 revision (v.3) 8-8-8

5APD meeting March 7, 07

ML Lattice design

Curvature Implementation

• Beam line geometry definition differs for MatLIAR/Lucretia and MAD.

• A method to have one set of decks and still be able to work with two codes was proposed by M.Woodley:» One common XSIF file, defining beam line, all common

elements, and ‘KINK’ elements at the ends of cryomodules.

» Two different files defining KINK elements to be used in MatLIAR and MAD. One of the files is called from the main file depending on the software used.

» Beam trajectory in both cases is changed by VKICK elements

• Another approach is to use vertical SBENDs» In this case one deck is compatible with both codes

6APD meeting March 7, 07

ML Lattice design

Curvature Implementation

• GKICK, Multipole

• SBEND

7APD meeting March 7, 07

ML Lattice design

Implementation of ‘KINKs’

• MatLIAR/Lucretia: Thin ‘dispersion-free kick’ GKICK, which pitches the coordinate system.

• MAD: Combination of» General thin multipole n=0, changes both

the beam trajectory and the coordinate system

» VKICK of the opposite sign

8APD meeting March 7, 07

ML Lattice design

ILC2006e (8-8-8) Lattice -functions

9APD meeting March 7, 07

ML Lattice design

ILC2006e Orbit

10APD meeting March 7, 07

ML Lattice design

ILC2006e Dispersion

11APD meeting March 7, 07

ML Lattice design

Emittance Preservation LIAR Simulation: CURVED LINAC: ILC BCD-Like LATTICE

Orb

it a

t th

e Y

CO

Rs

(m

)

Perfect Lattice - No misalignments

Zoom

No

rma

lize

d E

mit

tan

ce

(n

m)

Static Tuning: Dispersion Matched Steering (DMS) - Misalign the beamline components and perform the steering

Average of 50 machines

Straight

Curved

Co

rre

cte

d n

orm

ali

zed

em

itta

nc

e

(nm

)

Mean: 5.0 ± 0.4 nm

90%: 8.7 nm

Laser Straight

Mean: 5.3 ± 0.5 nm

90%: 9.5 nm

Curved

Distribution of emittance growth for 50 seeds

BPM index

BPM index

12APD meeting March 7, 07

ML Lattice design

Summary

• ML lattices based on two cryogenic layouts have been developed

• Two versions of ILC2006e (8-8-8) ML lattice (GKICK/MULT and SBEND) were studied» Both versions work well in Lucretia and show similar

emittance growth» It was decided at the Daresbury meeting in January

that only GKICK/MULT lattice will be supported

• Static alignment simulations show acceptable emittance growth in the curved ML lattice

• Dynamic simulations in progress

13APD meeting March 7, 07

ML Lattice design

Problems

• Create set of decks suitable for simulations of bunch propagation from RTML to the end

• Improve dispersion matching between curved and straight sections» The way it was implemented in ILC2006e

suggests large orbit kinks with angles of ~3e-4» At 250 GeV, this leads to energy losses of

100MeV and synchrotron radiation power of 4kW» One possible solution – make smooth transition

from curved to straight beam line.