S2E optics design and particles tracking for the ILC undulator based e+ source

S2E optics design and particles tracking for the ILC undulator

based e+ source

Feng ZhouSLAC

ILC e+ source meeting, Beijing, Jan. 31 – Feb. 2, 2007

Main parametersParameter Symbol Value Units

Positrons per bunch at IP nb 2 x 1010 (1 x 1010)† number

Bunches per pulse Nb 2820 (5600) † number

Pulse Repetition Rate frep 5 Hz

Positron Energy (DR injection) E0 5 GeV

DR Dynamic Aperture γ(Ax +Ay) <0.09 m-rad

DR Longitudinal Acceptance Al (3.46)x( 25) cm-MeV

Electron Drive Beam Energy Ee 150 GeV

Undulator Period 1.15 cm

Undulator Strength K 0.92 -

Undulator Type - Helical -

Photon Energy (1st harm cutoff) Ec10 10.06 MeV

Target Material - Ti-6%Al-4%V -

Target Thickness Lt 0.4 / 1.5 r.l. / cm

Incident Spot Size on Target i >0.75 mm, rms

Positron Polarization† P 60 %

Layout of the ILC e+ source

• Target to capture system (125 MeV)• Target hall: 125 MeV dogleg,125-400 MeV NC pre-

acceleration, and 400 MeV dogleg• 5.03 km 400 MeV transport• SC boost linac to 5 GeV• Linac-to-Ring: spin rotations, energy compression, and beam

collimation. • 5-GeV beam dump

Transport in Target hall

• OMD (6T-0.5T): to transform e+ with small spot size and large divergence at the target into large size and small divergence at the capture cavities.

• N.C. RF capture cavities system embedded in a 0.5 T of solenoid to accelerate e+ beam to 125 MeV.

• PCAP - 125 MeV e+ beam dogleg: to separate e+ from e- and photons using a dogleg with 2.5 m of horiz. offset (by Nosochkov).

• PPA - NC pre-accelerator consisting of L-band structures embedded in a 0.5 T of solenoid to accelerate e+ from 125 MeV to 400 MeV.

• PPATEL - a 400-MeV horiz. and vert. dogleg to deflect the beam by 5 m and 2 m in the horiz. and vert. planes, respectively (by Nosochkov).

PCAP

PPA

PPATEL

0 20 40 60 80 100 120 1403

2

1

0

1

2

3

surveynn 1

surveynn 2

surveynn 0

PCAP

PPA

PPATEL

X (m)

Y (m)

Z (m)

400 MeV 5-km Transport• PTRANa – to follow e- main linac tunnel for 4 km.• PTRANb – to bring e+ from e- main linac tunnel to e+ booster linac

tunnel.• PTRANc – 479 m of transport to connect with booster linac.

0 1000 2000 3000 4000 50000

2

4

6

8

10

12

surveynn 1

surveynn 2

surveynn 0

Y (m)

X (m)

Z (m)

PTRANa

PTRANb

PTRANc

5-GeV e+ booster linac• Accelerate e+ beam from 400 MeV to 5 GeV. • Have 3 sections: - 400 MeV to 1.083 GeV (4 non-standard ILC CM, each CM has 6 9-cell cavities and 6 quads) - 1.083 GeV to 2.626 GeV (6 ILC CM, each has 2 quads) - 2.626 GeV to 5 GeV (12 standard ILC CM, each has 1 quad )

LTR – Linac to Ring• Spin rotations to preserve polarization in DR: - Bending magnets: from longitudinal to horizontal plane

=n7.929 at 5 GeV; here n=7 to get reasonable R56. - Solenoid: from horizontal to vertical, parallel or anti-parallel to the magnetic field in the DR:

= 26.23 T.m at 5 GeV.• Energy compression: R56 and RF section• Collimations: to reduce beam loss in the DR• Emittance measurement, and 3 PPS stoppers• Matching section

bendbendspin

GeVE 44065.0

)(_

B

LB solezsolespin

_

solez LB

bend

collimation7X7.929

collimation

solenoidRF

solenoid

RF section7X7.929

Emitt. station

Emitt. station

5-GeV e+ beam dump• As a beam dump: for 0.1% and 10% of energy

spread, the half edge beam sizes x/y are 3.9cm/8.3cm and 14.3cm/8.3cm, respectively, which meet the dump window specifications (see D. Walz, Snowmass, 2005).

• As an energy spectrometer: 0.1% of resolution.1st Bend of PLTR arc, its power off for dump

Dump bend Monitor for energy spectrometer

Dump window

Overall e+ source optics

0 1000 2000 3000 4000 50005

5

15

25

35

45

55

65

75

85

95

105

surveynn 1

surveynn 2

surveynn 0

X (m)

Y (m)

Z (m)

PCAP, PPA, and PPATEL

PTRAN

PBSTR

LTR

Overall e+ source geometry

Multi-particle Tracking from the Target to the DR injection line

• Multi-particle tracking from the Target to the capture system (125 MeV) (by Y. Batygin).

• Elegant code is used to track the e+ beam through the rest of the beamline including the PCAP, PPA, PPATEL, PTRAN, PBSTR, and LTR.

• Energy compression is optimized to accommodate more e+ within the DR 6-D acceptance:

m, and

(25MeV)(3.46cm)

09.0 yx AA

zE

Components Half aperture in x/y (cm) Capture cavities 2.3/2.3

PCAP 7.5/7.5

PPA 2.3/2.3

PPATEL 7.5/7.5

PTRAN 7.5/7.5

PBSTR 3.7/3.7

LTR RF section

Solenoid Others

3.7/3.72.0/2.07.5/3.5

ILC e+ source physical apertures

• Undulator parameter: K=1, =1cm.• Target: 0.4 r.l., immersed B0=6T. • OMD: B=B0/(1+g.z), g=0.6/cm, z=18.3cm.

Target Target

5 1011

1.5 1010

3.5 1010

0

150

300

datai 5

datai 4Time (s)

0.03 0 0.030.03

0

0.03

datai 1

datai 0

y’ (

rad)

y (m)

125 MeV 125 MeV

Y. Batygin, www.slac.stanford.edu/~batygin/

ILC e+ loss distribution along the beamline

0

5

10

15

20

25

30

35

40

Pos

itron

loss

rat

ed t

o ta

rget

(%

)

1.875816 105

1.875827 105

1.875839 105

9500

9575

9650

9725

9800

datai 5

datai 4

Time (s)

With LTR, but w/o collimation

2X3.46cm 50 M

eV

1.875816 105

1.875827 105

1.875839 105

9500

9575

9650

9725

9800

datai 5

datai 4Time (s)

With LTR and collimation

2X3.46cm 50 M

eV

1.823975 105

1.82398 105

1.823985 105

8000

8360

8720

9080

9440

98009800

8000

datai 5

1.823985 1051.823975 10

5 datai 4

Time (s)

W/o LTR

RMS values of magnet errors for tracking

Misalignment in x and y

plane

Field error Rotation error

Quad x = 200 my = 200 m

0.1%

Sextupole x = 200 my = 200 m

0.1%

Bend x = 200 my = 200 m

0.1% 0.3 mrad

0.015 0 0.015

0.0015

0

0.0015

datai 1

datai 0

test x 0

xp 0

y 0

yp 0

x datai 0 x

xp datai 1 xp

y datai 2 y

yp datai 3 yp

i 0 nfor

axx

n 1

axpxp

n 1

ayy

n 1

aypyp

n 1

x2 0

xp2 0

xpx 0

y2 0

yp2 0

ypy 0

x2 x2 datai 0 ax 2

xp2 xp2 datai 1 axp 2

y2 y2 datai 2 ay 2

yp2 yp2 datai 3 ayp 2

xpx xpx datai 0 ax datai 1 axp

ypy ypy datai 2 ay datai 3 ayp

i 0 nfor

ax2x2

n 1

axp2xp2

n 1

axpxxpx

n 1

ay2y2

n 1

ayp2yp2

n 1

aypyypy

n 1

test0 0 ax2

test0 1 axp2

test0 2 axpx

test0 3 ay2

test0 4 ayp2

test0 5 aypy

emit_x ax2axp2 axpx2

emit_y ay2 ayp2 aypy2

test0 6 emit_x

test0 7 emit_y

alfa_xaxpx

emit_x

alfa_yaypy

emit_y

beta_xax2

emit_x

beta_yay2

emit_y

gamma_x1 alfa_x2

beta_x

gamma_y1 alfa_y2

beta_y

test1 0 alfa_x

test1 1 alfa_y

test1 2 beta_x

test1 3 beta_y

test1 4 gamma_x

test1 5 gamma_y

m 0

accxi gamma_x datai 0 2 2 alfa_x datai 0 datai 1 beta_x datai 1 2

accyi gamma_y datai 2 2 2 alfa_y datai 2 datai 3 beta_y datai 3 2

m m 1 accxi datai 5 accyi datai 5 0.09if

test0 m 0 datai 0 accxi datai 5 accyi datai 5 0.09if






i 0 nfor

test0

No error

x (m)

x (

rad)

data

0.015 0 0.0150.0015

0

0.0015

datai 3

datai 2

No error

y (m)

y (

rad)

0.015 0 0.0150.0015

0

0.0015

datai 1

datai 0

test x 0

xp 0

y 0

yp 0

x datai 0 x

xp datai 1 xp

y datai 2 y

yp datai 3 yp

i 0 nfor

axx

n 1

axpxp

n 1

ayy

n 1

aypyp

n 1

x2 0

xp2 0

xpx 0

y2 0

yp2 0

ypy 0

x2 x2 datai 0 ax 2


y2 y2 datai 2 ay 2




i 0 nfor

ax2x2

n 1

axp2xp2

n 1

axpxxpx

n 1

ay2y2

n 1

ayp2yp2

n 1

aypyypy

n 1

test 0 0 ax2

test 0 1 axp2

test 0 2 axpx

test 0 3 ay2

test 0 4 ayp2

test 0 5 aypy



test 0 6 emit_x

test 0 7 emit_y

alfa_xaxpx

emit_x

alfa_yaypy

emit_y

beta_xax2

emit_x

beta_yay2

emit_y

gamma_x1 alfa_x2

beta_x

gamma_y1 alfa_y2

beta_y

test 1 0 alfa_x

test 1 1 alfa_y

test 1 2 beta_x

test 1 3 beta_y

test 1 4 gamma_x

test 1 5 gamma_y

m 0










i 0 nfor

test0

data

0.015 0 0.0150.0015

0

0.0015

datai 3

datai 2

with errors butno correction

x (m) y (m)

with errors butno correction

0.015 0 0.0150.0015

0

0.0015

datai 1

datai 0

test x 0

xp 0

y 0

yp 0

x datai 0 x

xp datai 1 xp

y datai 2 y

yp datai 3 yp

i 0 nfor

axx

n 1

axpxp

n 1

ayy

n 1

aypyp

n 1

x2 0

xp2 0

xpx 0

y2 0

yp2 0

ypy 0

x2 x2 datai 0 ax 2


y2 y2 datai 2 ay 2




i 0 nfor

ax2x2

n 1

axp2xp2

n 1

axpxxpx

n 1

ay2y2

n 1

ayp2yp2

n 1

aypyypy

n 1

test0 0 ax2

test0 1 axp2

test0 2 axpx

test0 3 ay2

test0 4 ayp2

test0 5 aypy



test0 6 emit_x

test0 7 emit_y

alfa_xaxpx

emit_x

alfa_yaypy

emit_y

beta_xax2

emit_x

beta_yay2

emit_y

gamma_x1 alfa_x2

beta_x

gamma_y1 alfa_y2

beta_y

test1 0 alfa_x

test1 1 alfa_y

test1 2 beta_x

test1 3 beta_y

test1 4 gamma_x

test1 5 gamma_y

m 0










i 0 nfor

test0

data

0.015 0 0.0150.0015

0

0.0015

datai 3

datai 2

With errors and correction

With errors and correction

x (m) y (m)

y (

rad)

x (

rad)

x (

rad)

y (

rad)

Comparisons of capture efficiency

Survived in physical apertures

Captured within DR Trans. acceptance

Captured within DR 6-D acceptance

W/o LTR With LTR 55.4% 53.3%

32.3%

49.8%

With LTR and collimation 49.6% 48.8% 48.5%

W/ errors W/o orbit correction 54.9% 42.8% 40.2%

With errors and orbit correction 55.4% 53.0% 49.8%

Summary and outlook• S2E optics for e+ source is developed.• S2E tracking w/o and w/ errors is performed: 49.8% of e+

from the target are captured within the DR 6-D acceptance after energy compression.

• e+ loss into DR is ~1% after LTR collimation; additional betatron collimators are needed to collimate 0.8% of e+.

• Field and alignment errors and orbit correction are analyzed.

• Toward EDR: optics and physical aperture optimizations; reducing e+ loss in the DR; modeling activation of the 5-GeV collimations; tolerances definition; and tuning requirements.

F. Zhou, Y. Batygin, Y. Nosochkov, J, C.Sheppard, and M. D. Woodley, “Start-to-end optics development and multi-particle tracking for the ILC undulator-based positron source”, SLAC-PUB-12239, Jan. 2007.

Documents

S2E optics design and particles tracking for the ILC undulator based e+ source