16 th June 2008 POSIPOL 2008L. Rinolfi / CERN CLIC e + sources status L. Rinolfi with contributions...

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16th June 2008POSIPOL 2008 L. Rinolfi / CERN

CLIC e+ sources statusL. Rinolfi

with contributions from

F. Antoniou, H. Braun, A. Latina, Y. Papaphilippou, F. Zimmermann / CERN

R. Chehab / IPNL/IN2P3 - Lyon, V.M.Strakhovenko / BINP - Novosibirsk

A. Variola, A. Vivoli / LAL - Orsay, A. Ferrari / Uppsala University

E. Buylak, P. Gladkikh / NCS / KIPT - Kharkov

W. Gai, W. Liu / ANL, J. Sheppard / SLAC

T. Kamitani, T. Omori / KEK, M. Kuriki / Hiroshima University

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The CLIC Injector complex in 2008

e- gun

3 TeV

Base line configuration

LaserDC gunPolarized e-

Pre-injector Linac for e-

200 MeV

e-/Target

Pre-injector Linac for e+

200 MeV

Primary beam Linac for e-

5 GeV

Inje

ctor

Lin

ac

2.2

GeV

e+ DR

e+ PDR

Boo

ster

Lin

ac

6.6

GeV 4 GHz

e+ BC1 e- BC1

e+ BC2 e- BC2e+ Main Linac e- Main Linac

12 GHz, 100 MV/m, 21 km 12 GHz, 100 MV/m, 21 km

2 GHz

e- DR

e- PDR

2 GHz 2 GHz 2 GHz

4 GHz 4 GHz

12 GHz 12 GHz

9 GeV48 km

30 m 30 m

2.424 GeV 2.424 GeV

e

Target

AMD

2.424 GeV365 m 2.424 GeV

365 m

473 m

228 m

365 m 365 m

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NLC

(1 TeV)

CLIC 2008

(3 TeV)

ILC

(Nominal)

Energy E GeV 8 9 15

Bunch population N 109 7.5 3.72 - 4 20

Nb bunches / train nb- 190 312 2625

Bunch spacing tbns 1.4 0.5

(6 RF periods)

369

Train length tpulsens 266 156 968625

Emittances x , ynm, nm.rad 3300, 30 600, 10 8400, 24

rms bunch length zm 90-140 43 - 45 300

rms energy spreadE 0.68

(3.2 % FW)1.5 - 2 1.5

Repetition frequency frepHz 120 50 5

Beam power P kW 219 90 630

Main beam parameters comparison

At the entrance of the Main Linac for e- and e+

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# of bunches per pulse

# of positrons per bunch

# of positrons per pulse

Total charge

(nC)

Current

(A)

Exit of BC2

= Entrance of Main Linac

( 9 GeV)

312 4 x 109 1. 24x1012 200 1.3

At exit Pre- Damping ring

(2.424 GeV) 312 4.4 x 109 1.37 x 1012 220 1.4

At exit Injector Linac

(2.424 GeV) 312 6.4 x 109 2 x 1012 319 2

At exit Pre- Injector Linac

(200 MeV) 312 6.7 x 109 2.1 x 1012 334 2.1

Assuming ~ 90 % efficiency between the PDR and the Main Linac

CLIC parameters relevant for e+ source

Repetition frequency 50 Hz

Total pulse length 156 nsAssuming ~ 70 % capture efficiency in the PDR

Assuming ~ 95 % efficiency between the Pre-Injector and the Injector Linac

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Conventional e+ source based on channelling

A e- beam impinges on the crystal: - energy of 5 GeV - beam size of 2.5 mm

crystalamorphous

e-

e-

e+

Yield: 0.9 e+ / e-

@ 200 MeV

R. Chehab, V. Strakovenko, A. Variola, A. Vivoli / LAL

•A crystal e+ source :• - a 1.4 mm thick W crystal oriented along <111> axis• - a 10 mm thick W amorphous disk

•Charged particles are swept off after the crystal:only (> 2MeV) impinge on the amorphous target.

• The distance between the 2 targets is 2 meters.

e-

e+

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CLIC Channeling e+ source

Parameter Unit CLIC

Primary e- Beam

Energy GeV 5

N e- /bunch 109 7.5

N bunches / pulse - 312

N e- / pulse 1012 2.34

Pulse length ns 156

Repetition frequency Hz 50

Beam power kW 94

Linac frequency GHz 2

Beam radius (rms) mm 2.5

Bunch length (rms) mm 0.3

Parameter Unit

Target Crystal Amorph.

Material W W

Length mm 1.4 10

Beam power deposited

kW 0.2 7.5

Deposited P / Beam Power

% 0.2 8

Pulse energy density

1012 GeV/mm2 0.6 -

Energy lost per volume

109 GeV/mm3 0.8 1.9

Peak energy deposition

density (PEDD)J/g 6.8 15.5

Yield (at 200 MeV): 0.9 e+ / e-

Experimental limit found at SLAC: PEDD = 35 J/g

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Beam parameters with channeling

Positrons after capture section at 270 MeV

Parameter Unit CLIC

Energy (E) GeV 0.270

No. of e+ / bunch (N) 109 6.7

Bunch length (rms) mm 8

Energy Spread (rms) % 5

Longitudinal emittance (l) eV.m 105

Horizontal emittance (x) / (x) mm. mrad 12 / 6300

Vertical emittance (y) / (y) mm. mrad 12 / 6300

Q ~ 1 nC

See R. Chehab talk at this workshop

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Parameter UnitConventional target

CERN simulations

Channeling

LAL simulations

Energy (E) GeV 0.200 0.270

No. of e+ / bunch (N) 109 6.7 6.7

Bunch length (rms) mm 5 8

Energy Spread (rms) % 3.5 5

Horizontal emittance (x) mm. mrad 9200 6300

Vertical emittance (y) mm. mrad 9200 6300

Beam parameters comparison

Accelerating gradient MV/m 15 18

Positrons after capture section at the end of the pre-injector linac

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Longitudinal phase space at 2.4 GeV

Energy spread = 65 MeV

p/p (rms) = 2.7 %

If PDR acceptance is

p/p = ± 1 %

= > 82 % capture efficiency

e+

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Required CLIC Pre-Damping Ring

PARAMETER PDR

energy [GeV] 2.424

circumference [m] 365.2

bunch population [10+9] 4.4

bunch spacing [ns] 0.5

number of bunches/train 312

number of trains 1

store time/train [ms] 20

rms bunch length [mm] at injection 5

rms momentum spread [%] at injection 2.7

hor. normalised emittance [m] at ejection 63

ver. normalised emittance [m] at ejection 1.5

hor./ver./ lon./ damping times [ms] 1 / 1 / 0.5

number of RF cycles 1

repetition rate [Hz] 50

RF frequency [GHz] 2

> ± 1%

as small as possible

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CLIC base line configuration for e+ source

e-/TargetPrimary beam

Linac for e-

5 GeV

2 GHz

e

Target

AMD


200 MeV

Thermionic gun

For the base line configuration, based on channeling process, a solution exists with a single target station providing unpolarized e+ to fulfill the CLIC parameters.

The channeling process allows a good e+ yield and one of the main advantage is the reduction of the beam energy deposition in the targets.

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CLIC polarized e+ source

Undulator

Laser Compton Drive Beam Linac => no laser stacking cavity & no stacking

in the PDR

Storage Ring => laser stacking cavity + stacking in the PDR

ERL => laser stacking cavity + stacking in the PDR

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Undulator

K = 0.75

u = 1.5 cm

L = 100 m

Pre-Injector Linac

G = 20 MV/m

E = 200 MeV

fRF = 1.5 GHz

B = 0.5 T

Injector Linac

G = 17 MV/m

E = 2.424 GeV

f RF = 1.5 GHz

f rep= 50 Hz

CLIC 2007 based on undulator scheme

250 GeV

Cleaning chicane

NC Linac

2.2 GeV

To the IPe- beam

Ti alloy

450 m

e+ e+

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•Drive e- beam energy: 250GeV•Undulator K: 0.75 •Undulator period: 1.5cm•Length of undulator: 100m•Drift to target: 450m•Accelerator gradient and focusing: 50MV/m for beam energy

<250MeV, 0.5T background solenoid field focusing; for 250MeV to 2.4GeV, 25MV/m with discrete FODO set.

•OMD: Non immersed, ramping distance 2cm• 1)7T-0.5T and 5T-0.5T, the thickness varies from 15cm to 80cm in

5cm steps;• 2) the thickness fixed at 20cm, B0-0.5T, B0 varies from 1 T to 10T

•Photon collimator: None•Target material: 0.4 rl Titanium, non-immersed•Yield is calculated as Ne+ captured/Ne- in drive beam.•Positron capture is calculated by numerical cut using damping ring

acceptance window: +/-7.5 degrees of RF(1.3GHz), x+y< 0.09m.rad,1% energy spread with beam energy ~2.4GeV

Optimizing for yield

W. Gai, W. Liu / ANL, J. Sheppard / SLAC

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Yield as function of drive beam energy & field

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Yield and polarization

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e+ injector, 2.4 GeV

e- injector2.4 GeV

CLIC 3 TeV

e+ main linace- main linac , 12 GHz, 100 MV/m, 21.02 km

BC2BC2

BC1

e+ DR

365m

e- DR

365m

booster linac, 9 GeV

decelerator, 24 sectors of 876 m

IP

BDS2.75 km

BDS2.75 km

48.3 km

drive beam accelerator2.38 GeV, 1.0 GHz

combiner rings Circumferences delay loop 72.4 m

CR1 144.8 mCR2 434.3 m

CR1CR2

delayloop

326 klystrons33 MW, 139 s

1 km

CR2delayloop

drive beam accelerator2.38 GeV, 1.0 GHz

326 klystrons33 MW, 139 s

1 km

CR1

TAR=120m

TAR=120m

245m 245m

e+ PDR365m

e- PDR365m

Linac with optical cavities

e- beam sent to

+ 240 ns

CLIC 20008 based on Linac scheme

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Linac scheme with Drive Beam

Parameters CLIC

Energy 2.38 GeV

Current 101 A

Nb bunches / train 2904

e- Bunch population 5 x 1010

Bunch charge 8.4 nC

Repetition fequency 50 Hz

2.4 GeV 100A e- beam beam e+

beam

to e+ conv. target

V. Yakimenko and I. Pogorelski (BNL) proposal for ILC to be investigated for CLIC

12 GHz

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The CLIC Injector complex (Compton)

3 TeV

Laser Compton ring configuration

Laser

Laser

DC gunPolarized e-

Pre-injector Linac for e-

200 MeVe+ Target


200 MeV

Inje

ctor

Lin

ac

2.2

GeV

e+ DR2.424 GeV365 m

Boo

ster

Lin

ac

6.6

GeV 4 GHz

e+ BC1 e- BC1

e+ BC2 e- BC2e+ Main Linac e- Main Linac

2 GHz

e- DR

e- PDR

2 GHz 2 GHz

2 GHz 4 GHz

12 GHz 12 GHz

9 GeV48 km

e- Drive Linac 1.3 GeV

Compton ring

e+ PDR and Accumulator

ring

2 GHz

RF

gun

Stacking cavity

2.424 GeV365 m 2.424 GeV

365 m

2.424 GeV365 m

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e+ t

arge

t

Pre-injector Linac for e+ 200 MeV

Inje

ctor

Lin

ac

2.2

GeV

e+ DR

2.424 GeV

2 GHz

2.424 GeV

Drive Linac 1.3 GeV

Compton ring

e+ PDR and Accumulator

ring

2 GHz50 Hz

CLIC Compton scheme

Compton configuration for polarized e+ and

low e+/yield

RF

gun

1 YAG Laser pulse

2 G

Hz

Stacking cavity

450 turns makes 312 bunches with 4.4x109 e+/bunch

C = 47 m, 156 ns/turn, 312 bunches with 6.2x1010 e-/bunch

9.8x106 pol. e+/turn/bunch

(23-29 MeV) 7x108 /turn/bunch

156 ns x450 turns => 70 s pulse length for both linacs

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PARAMETER PDR

energy [GeV] 2.424

number of trains 1

rms momentum spread [%] at injection 2.7

hor./ver./ lon./ damping times [ms] 1 / 1 / 0.5

repetition rate [ms] 20

RF frequency [GHz] 2

CLIC Pre-Damping Ring optimization

1) The rms momentum spread at injection could be reduced by implementing: a) a bunch compressor at the entrance of the injector Linac b) a harmonic cavity which smooth the longitudinal distribution.

2) The transverse damping time should be ≈ 1 ms (in order to allow ≈ 10 damping times). It remains roughly 10 ms for the stacking.

3) The stacking efficiency could also be improved by putting 2 trains in the PDR.

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Compton e+ source parameters

Parameters CLIC 2007 CLIC 2008 ILC

Energy 1.3 GeV 1.06 GeV 1.3 GeV

Circumference 68 m 47 m 277 m

RF frequency 1.5 GHz 2 GHz 650 MHz

Bunch spacing 0.20 m 0.15 m 0.923 m

Nb bunches stored 311 312 280

e- Bunch population 6.2 x 1010 6.2 x 1010 6.2 x 1010

Nb optical cavities 1 1 30

Photons/bunch/turn 0.7 x 109 2.1 x 109 5.8 x 1010

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CLIC Compton ring

E. Bulyak, P. Gladkikh / NCS KIPT

Parameters CLIC 2007 CLIC 2008

Energy 1.3 GeV 1.06 GeV

RF frequency 1.5 GHz 2 GHz

RF voltage 50 MV 150 MV

e- Bunch charge 10 nC 10 nC

e- bunch length at IP 5 mm 5 mm

Synchrotron losses 400 keV/turn 213 keV/turn

Laser photon energy 1.164 eV 1.164 eV

Laser rms pulse length 0.9 mm 0.9 mm

Laser rms pulse radius 0.005 mm 0.005 mm

Laser pulse energy 600 mJ 592 mJ

Full cycle (turns) 15000 15000

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e+ t

arge

t

Pre-injector Linac for e+ 200 MeV

2 GHz

Drive Linac 1.06 GeV

Compton ring

2 GHz50 Hz

CLIC Compton scheme

Compton configuration for polarized e+ and high e+/yield

RF

gun

1 YAG Laser pulse

Stacking cavity

C = 47 m, 156 ns/turn, 312 bunches with 6.2x1010 e-/bunch

5 x108 pol. e+/turn/bunch

(10 - 20 MeV) 2.1x109 /turn/bunch

592 mJ

W sliced rod target 3 rad length => yield 0.48 e+ /

=> Stacking simplified

E. Bulyak / NCS KIPT

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Energy spread in CLIC Compton ring

E = 1.06 GeV

Double chicane

2 RF cavities => 150 MV

Emittances after 15000 turns:

H = 21 nm . rad

V = 1 nm . rad

Max energy spread ~ 1 %


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Photons from CLIC Compton ring


K: 0.5 mradI: 0.4 mradG: 0.3 mradE: 0.2 mradC: 0.1 mrad

Collimation anglesMax polarization ~ 75 %

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Studies and R&D for Compton scheme

Compton ring beam dynamics and design studies (NCS-KIPT, LAL, KEK, …)

Laser source (see Posipol 2006, 2007 and 2008 for companies involved )

Laser stacking cavity (KEK, LAL, IHEP, Hiroshima,… )

Target and e+ capture (LAL, IPNL-Lyon, ANL, CERN, IHEP,… )

e+ stacking in Pre-Damping Ring and Damping Ring (CERN,… )

Collaboration on CLIC study for e+ sources is always welcome

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Conclusion

1) After the CLIC major changes in 2007, studies and optimization continue on the CLIC structures and possible changes could still occur.

2) For the unpolarized e+, a conventional source, based on channeling process, fulfills the CLIC requirements with a single target station.

3) For polarized e+ based on Undulator, studies continue.

4) For polarized e+ based on Compton back scattering, progress have been made (Ring & Linac) but several studies and R&D are still necessary.

5) The design of a CLIC e+ Pre-Damping Ring has just started.

The Compton ring seems the most promising option for CLIC polarized e+.

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16 th June 2008 POSIPOL 2008L. Rinolfi / CERN CLIC e + sources status L. Rinolfi with contributions...

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