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, Nov 21 2006» 9-8-9 scheme, Dec 28 2006

• Basic segmentations:

Main Linac

RF Unit

Cryogenic Unit

APD meeting March 7, 07

ML Lattice design

Nov. 21 revision (v.4) 8-8-8

5APD meeting March 7, 07

ML Lattice design

Lattice Revision HistoryDate Cav/

CMQ/CM Comments

1/06 12 1/2 USColdLC by PT, TESLA-like, straight

3/06 8 1/4 PT + curved

5/06 8 1/3 BCD-like, simple periodic lattice

5/06 8 1/3 Added cryo boxes and warm straights

6/06 8 1/3 May 31 (ver. 3) cryo layout

9/06 8 1/3 SBEND version *)

10/06 8 1/3 M.Woodley RTML-ML-BDS **)

1/07 8 1/3 “8-8-8” Nov 21. cryo layout (ver. 4)

2/07 9-8-9 1/3 “9-8-9” Dec 28. cryo layout

**) http://www.slac.stanford.edu/~mdw/ILC/2006e/

*) http://tdserver1.fnal.gov/project/ILC/ARCHIVE/ILC-ML-SbendCurvature.zip

6APD 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

7APD meeting March 7, 07

ML Lattice design

Curvature Implementation

• GKICK, Multipole

• SBEND

8APD 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

9APD meeting March 7, 07

ML Lattice design

ILC2006e (8-8-8) Lattice -functions

MAD

LIAR

Lucretia

10APD meeting March 7, 07

ML Lattice design

ILC2006e Orbit

MAD Lucretia

11APD meeting March 7, 07

ML Lattice design

ILC2006e Dispersion

MAD Lucretia

12APD 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

13APD 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

14APD meeting March 7, 07

ML Lattice design

TODO

• 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

» Angle of steering to the Earth’s curvature is 6e-6. Eloss=37keV, Ploss=1.6W

» One possible solution – make smooth transition from curved to straight beam line.

15APD meeting March 7, 07

ML Lattice design

Synchrotron Radiation in a Single Corrector

L

EB

3.0

L

EU SR

2441085.8

IavUP SRSR

E – particle energy [GeV]

– bending angle

L – corrector length [m]

B – corrector field [T]

USR – particle energy loss [eV]

Iav – average beam current [A]

PSR – average radiated power [W]

E=250L=0.335Iav=4e-5 for 1s beam at 5Hz

USR [keV] PSR [W]

5e-6 26 1.1

1e-5 100 4.5

5e-5 2600 110

1e-4 10300 450