compton based polarized positron sources for e + /e - linear colliders

Compton Based Polarized Positron

Sources for e+/e- Linear Colliders

A. Vivoli*

Thanks to : A. Variola, R. Chehab, T. Omori, F. Zimmermann, E. Bulyak, M. Kuriki,

* E-mail : [email protected]

04/21/23 A. Vivoli, Compton Based Polarized Positron Sources

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CONTENTS

• Introduction to Pol. e+ Sources• Simulation Results• Different Schemes for Compton

Sources• Possible application to CLIC• Conclusions

MOTIVATION


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For next e-e+ colliders polarization of both e- and e+ would be very useful.(G. Moortgat-Pick et al., Physics Reports 460 (2008) 131-243 )

General Scheme of P.P.S.


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(Polarized) e+ are not available in nature!

Positron Source:

• Primary e- beam generation• Generation of Gamma rays (Ondulator, Compton, …)• Pair production in a target (W, Ti, Liquid Pb, …)• Capture of e+ • Acceleration and Transport• Stacking in a Damping Ring

Target

Compton Backscattering


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’

Linear Compton Backscattering

• ’ ≈ /(42) Optimum Energy for e+ production and capture: E ≈ 30 MeV≈m E ≈ 42hc/≈MeV ≈ 2500 Ee- ≈ 1.3 GeV

• , r02 = 6.66 ·10-25 cm2

e-

Ee-= mec2

A

NNfN

e

3

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Compton e+ Sources


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• Compton Ring + Stacking Cavity• ERL + Stacking Cavity(T. Omori, J. Urakava, M. Kuriki – KEK)(A. Variola, F. Zomer, R. Chehab – LAL) (E. Bulyak, P. Gladkikh – NSC KIPT)

• Linac + CO2 laser NO NEED STACKING(V. Yakimenko, I.V. Pogorelsky - BNL)

NEED STACKING IN DR

• Proof-of-principle demonstration: T. Omori et al., PRL 96 (2006) 114801

Very interesting, not treated here.

Stacking Cavity


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Laser power = W Cavity length = LLaser frequency = flaser Energy gain = G

flaser ≈ Elaser= W/ flaser ·Gc

L2

W


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By T. Omori


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By T. Omori


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Polarized Positron Source

e- injector +Bunch Compressor

Compton cavities

e-

ERL Scheme

e-

e+

Target

Capture Section with solenoid(+ Bunch Compressor)Up to ~150 (200) MeV

4.8 (2.2) GeVsuperconducting linac

with quadrupole focusing

(PRE)Damping Ring

e+

1.8 GeV superconducting linac

e-


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Gamma Production Scheme (by T. Omori)


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Simulation (CAIN)

Mean Energy : 27,7 MeV Number of photons simulated : 75177 105

Photons 1.8 GeV – 5 IP


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COMPARISON OF DIFFERENT ENRGY SCHEMES

1.3 GeV – 5 IP 1.3 GeV – 10 IP 1.8 GeV – 5 IP


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Positron Production (EGS)

• Number of e+ : 6470 105

• Mean energy : 17.627 MeV• Polarization : 21%

1.8 GeV – 5 IP


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5 - 10 Interaction points

e-

e+ (180 - 200 MeV)

1.3 – 1.8 GeV ERL

e-

Target

AMD

e-

79 Cavities

e-

e- source

Scheme of the Capture Section (up to 180 MeV)

Dump Solenoid


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Adiabatic Matching Device

• Length: L = 50 cm• Magnetic field at the

target : B0 = 6 T

• Magnetic field at the end : B(L) = 0.5 T

• Magnetic Field Behaviour :

zz

1

B)B(

0


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N. e+

105

x (rms) p

mm mrad

y (rms)

p mm mrad

<E> MeV

E

MeV

z (rms) mm

5499 1807 2444 19.35 11.69 0.31

2866 434 433 20.15 11.08 7.9

Beam parameters

Z = 0

Z = 50

Parameters of the positron beam at the exit of the target (z = 0 cm) and at the exit of the AMD (z = 50 cm)

Capture percentage : 52,12 %


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Captured Positron Beam


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New Cavity (1.3 GHz, SW, 100 KW CW)


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Pre-accelerator

Solenoid • Magnetic Field = 0.5 T• Length = ~ 57 mAccelerating Cavities:• Length = 56 cm• Aperture = 2. cm• Average accelerating

Field = ~ 3.3 MV/m • Number of cavities = 79Drift length between

cavities = 13 cm


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N. e+

105

x (rms)

mm mrad

y (rms)

mm mrad

<E> MeV

E

MeV

z (rms) mm

z (rms)

mm mrad

2866 434 433 20.15 11.08 7.9 7.29

1591 20 19 164.39 24.24 10.76 9.65

Beam parameters II

Z = 50

Z = 5775

Parameters of the positron beam at the exit of the AMD (z = 50 cm) and at the exit of the solenoid (z = 5775 cm)

Multiple stacking needed


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Energy (GeV) Yield e+/ (%) Pol (%)

1.0 0.9 48

1.3 1.7 48

1.5 2.3 33

1.8 4.0 27

COMPARISON OF YIELD & POLARIZATION FOR DIFFERNET Ee-


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Capture Section (+ CHICANE)

From Compton Cavities

To the accelerator

Target

Adiabatic MatchingDevice Pre-accelerator

Chicane

e-

e+

Solenoid Cavities

BendingMagnets

Drift = 8 - 10 cm

Magnetic field

Electric field


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Bending angle = 16 deg drift length = 200 cm BM length = 60 cm


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N. e+

105

x (rms) p

mm mrad

y (rms)

p mm mrad

<E> MeV

E

MeV

z (rms) mm

z (rms)

cm MeV

1591 20 19 164.39 24.24 10.76 9.65

701 17 15 180.02 6.79 16.24 2.44

Beam parameters II

Z = 5775

Z = 6540

Parameters of the positron beam at the exit of the solenoid (z = 5775 cm) and at the exit of the chicane (z = 6540 cm)


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CASE N. Yield

e+/ %

N. e+ z

cm MeV

x

mm mrad

y

mm mrad

E

MeV

z

cm

1.3/10 A

1.06 1010 0.31 3.26 107 1.86 19 21 4.14 1.93

1.3/10 A

1.06 1010 0.28 3.00 107 1.73 19 21 3.88 1.83

1.3/10 A

1.06 1010 0.25 2.62 107 1.58 19 20 3.42 1.64

1.3/5 0.67 1010 0.36 2.39 107 1.53 15 17 3.55 1.67

1.8/5 0.75 1010 0.88 6.65 107 2.15 19 19 5.60 1.85

RESULTS (180 MeV)


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Capture Section (+ B.C.)

From Compton Cavities

To the accelerator

Target

Adiabatic MatchingDevice Pre-accelerator Bunch Compressor

e-

e+

Solenoid Cavities

BendingMagnets

Drifts

Magnetic field

Electric field

Chicane


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e+

DriftsBending MagnetsTriplets

Bunch Compressor

Tesla Cavities


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N. e+

105

x (rms) p

mm mrad

y (rms)

p mm mrad

<E> MeV

E

MeV

z (rms) mm

z (rms)

cm MeV

701 17 15 180.02 6.79 16.24 2.44

701 19 16 177.08 9.03 3.05 2.62

Beam parameters III

Z = 6540

Z = 7961

Parameters of the positron beam at the exit of the chicane (z = 6540 cm) and at the exit of the BC (z = 7961 cm)


5 GeV superconducting LINAC

Quadrupoles length : L = 10 – 20 cmField at pole tip : B = 3 – 5 KGQuadrupoles aperture : R = 5 cm Cavities length : l = 1.25 mMean accelerating field : E = 9 MV/mCavities aperture : r = 3.5 cm

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N. e+

105

x (rms) p

mm mrad

y (rms)

p mm mrad

<E> MeV

E

MeV

z (rms) mm

z (rms)

cm MeV

701 19 16 177.08 9.03 3.05 2.62

681 1.48 0.80 5074 31.70 3.04 9.59

Beam parameters IVParameters of the positron beam at the exit of the BC (z = 7961 cm) and at the exit of LINAC (z ~ 105 cm)

Yield e+/ = 0.9 %

Z= 7961

Z~ 105


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PolarizationEstimations of polarization are made assuming that the initial polarization of the positrons doesn’t change. P = 60.3 %


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STACKING SIMULATIONS

By F. ZIMMERMANN

frep = 40.8 MHz : 1st turn of DR stacking

(1) 1st turn begin

(2) 1st turn end e+ bunches from ERL

6.15 ns

24.6 ns

e+ bunches from ERL

24.6 ns 6.15 ns

DR

DR

By T. Omori

04/21/23 35A. Vivoli, Compton Based Polarized Positron Sources

(b) frep = 40.8 MHz : 2nd turn of DR stacking

(1) 2nd turn begin

(2) 2nd turn end

e+ bunches from ERL

24.6 ns 6.15 ns

e+ bunches from ERL

6.15 ns

24.6 ns

DR

DR

By T. Omori


(b) frep = 40.8 MHz : 3rd turn of DR stacking

(1) 3rd turn begin

(2) 3rd turn end

e+ bunches from ERL

24.6 ns 6.15 ns

e+ bunches from ERL

6.15 ns

24.6 ns

DR

DR

By T. Omori


(b) frep = 40.8 MHz : 4th turn of DR stacking

(1) 4th turn begin

(2) 4th turn end

e+ bunches from ERL

24.6 ns 6.15 ns

e+ bunches from ERL

6.15 ns

24.6 ns

DR

DR

By T. Omori


(b) frep = 40.8 MHz : 5th turn of DR stacking

(1) 5th turn begin

(2) 5th turn end

e+ bunches from ERL

24.6 ns 6.15 ns

e+ bunches from ERL

6.15 ns

24.6 ns

DR

DR

By T. Omori


ILC-DR Snowmass ‘05 proposal

ILC 2008 – Compton “CR-B”

ILC 2008 – Compton “CERL-B”

CLIC pre-DR 2007 (NLC 2004 )

CLIC 2008 (& CLIC CERL Compton vers.)

beam energy 5 GeV 5 GeV 1.98 GeV 2.424 GeVcircumference 3223 m 6695 m 230.93 m 251.6 mparticles per extracted bunch 2.4x1010 2.0x1010 4.0x109 4.5x109

rf frequency 650 MHz 650 MHz 2 GHz 2 GHzharmonic number 6983 14516 1540 1677no. trains stored in the ring 10 (10/pulse) 52.5 (52.5/pulse) 4 (1/pulse) 1#bunches/train 280 50 312 312bunch spacing 4.202 ns 6.15 ns 0.5 ns 0.5 nsgap between trains 80 (336 ns) ~50 ns 73 (36.5 ns) 682.7 ns#e+ / injection 2.4x108 6.65x107 6.65x107 6.65x107 6.65x107

#turns btw inj. in 1 bucket 1 2 5 40 40injections/bucket per cycle 10 30 1020 (cont.) 3 80 (cont.)injection frequency ~240 MHz 80 MHz 32 MHz ~50 MHz 50 MHzfull cycle length 200 ms 200 ms 200 ms 80 ms 20 mstime between inj. periods 10 ms 10 ms - 1.9 ms -#turns between cycles 930 450 (5155) 2470 (20647)length of one inj.period 0.107 ms 1.34 ms 114 ms 0.046 ms 2.6837 msTI=total # injections/bucket 100 300 1020 60 80ST=store time after last inj. 109 ms 97 ms 86 ms 42 ms 17.3163 msIP=interval with inj. periods 91 ms 103 ms (114 ms) 38 ms (2.6837 ms)energy loss/turn 5.5 MeV 8.7x2 MeV 8.7x2 MeV 0.803 MeV 1.63MeV

(4.08 MeV)longitudinal damping time || 10 ms 6.4 ms 6.4 ms 2 ms 1.25 ms (0.5 ms)

Compton source megatable - 1


Compton source megatable - 2

ILC-DR Snowmass ‘05 proposal

ILC 2008- Compton “CR-B”

ILC 2008- Compton vers. “CERL-B”

CLIC pre-DR 2007 (NLC 2004)

CLIC 2008 (& CLIC CERL Compton vers.)

transv. normalized edge emittance at inj. (10x rms)

0.05 rad-m 0.063 rad-m 0.063 rad-m 0.063 rad-m

transv. normalized dynamic aperture (Ax+Ay)gamma

>>0.05 rad-m?

0.4 rad-m 0.2 rad-m 0.2 rad-m?

rms bunch length at injection 3 mm 9 mm 11.4 mm 3.8 mm 11.4 mmrms energy spread at injection 0.14% 0.06%(3MeV) 0.04% 0.28% 0.08% [2 MeV]final rms bunch length 6 mm 5.2 mm 5.12 mm 0.79 mm (0.47 mm)final rms energy spread 0.14% 0.091 % 0.089% 0.095% (0.12%)longit. “edge” emittance at inj. 0.7 meV-s 0.72 meV-s 0.72 meV-s 0.73 meV-srf voltage 20 MV 36 MV 1.72 MV 2 MV (16.3 MV)momentum compaction 3x10-4 4.2x10-4 1.69x10-3 9x10-5

2nd order mom. Compact. 1.3x10-3 - - 5.8x10-2 (3x10-4)synchrotron tune 0.0356 0.084 0.0188 0.0045 (0.0127)bucket area 292 meV-s 129 meV-s 10 meV-s 12meVs (234meVs)ICM=bckt area/edge emit. / 133 57 4 (102)RMIN=TI/ICM 0.75 18 15 (0.59)IP/RMIN/|| 12 1 1.3 (9.1)IP/RACT/|| 0.09 0.15 0.31 (0.09)synchronous phase 15.58o 28.97o 26.47o (14.49o)separatrix phases 1&2 164.42 o, -

159.19 o

151.03 o, -82.64 o 153.53 o, -95.66 o

(165.51 o, -163.83 o)

max. momentum acceptance +/-2.7% +/- 1.6% +/- 1.0% +/-1.6% (+/- 13%)injection offset ,z ramped in ramped in d +1.5%,0.01m ramped in (+13.20%, 0 m)simulated stacking efficiency 82% ~95% ~94% not comp. 95.5%final # positrons / bunch 2x1010 1.94x1010 6x1010 not comp. 5.1x109

Design of the Energy Compressor


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Tesla Cavities

…..

Chicanes

Quadrupoles

Beam ellipse in the longitudinal phase space (z,E)


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FINAL RESULTS

04/21/23 44

Compton Ring (CR) vs Compton Energy Recovery Linac (C-ERL)

Unit CR C-ERL

Energy e- GeV 1.0 - 1.3 1.3 – 1.8

Bunch length (rms)

ps 10 - 20 ~ 1

Operation mode Burst ‘Almost’ CW

Bunch Charge

nC 5 - 10 0.5 – 1.6

A. Vivoli, Compton Based Polarized Positron Sources

REQUIREMENTS


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• ILC

Ne+ = 2·1010 x 2625 = 5.25·1013 e+ /pulse tpulse ~ 22 s fr= 5 Hz 2.625·1014 e+/s

Polarization : Min 30% Possibly ≥ 60%

• CLIC

Ne+ = 4·109 x 312 = 1.248·1012 e+/pulse tpulse = 156 ns fr= 50 Hz 6.24·1013 e+/s

Polarization : Min 30% Possibly ≥ 60%


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ILC - CRBy T. Omori, A. Variola et al.

100 bunchesT b_b = 18.45 ns

C=553 m

1.3 GeV Linac

GammaNg = 4 10exp10 bunch

2 10exp 8 positrons

CW linac3.5 GeV

564 bunchesTb_b =6.15ns

C=1040mTcool = 2 msecwait = 2 msec

single cycle ~2.5 msec

CW linac1.5 GeV

Stack 40 times416 microsec

Transfer at 400 HzIt means that in 100 msec => 40 shotsTotal 320 stackings/bunch in main-DR

Collision 226 turns (416micro sec) then wait 2 msec.Single cycle ~ 2.5 m sec.

To DR

Waiting timeBetween stackIn the same bucket= 1/200 Tcool

Compton Ring Scheme for ILC• Compton scattering of e- beam stored in storage ring off

laser stored in Optical Cavity.• 5.3 nC 1.8 GeV electron bunches x 5 of 600mJ stored

laser -> 2.3E+10 γ rays -> 2.0E+8 e+.

• By stacking 100 bunches on a same bucket in DR,

2.0E+10 e+/bunch is obtained.

Electron Storage Ring 1.8 GeV 1.8 GeV booster



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ILC – C ERLBy T. Omori, A. Variola et al.

ERL scheme for ILC• High yield + high repetition in ERL solution.

– 0.48 nC 1.8 GeV bunches x 5 of 600 mJ laser, repeated by 54 MHz -> 2.5E+9 γ-rays -> 2E+7 e+.

– Continuous stacking the e+ bunches on a same bucket in DR during 100ms, the final intensity is 2E+10 e+.

SC Linac 1.8 GeV

Laser Optical Cavities

PhotonConversi

onTarget

CaptureSystem

To PositronLiniac

RF Gun

Dump

1000 times of stacking in a same bunch



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CLIC - CRBy L. Rinolfi, E. Bulyak, P. Gladkikh

E. Bulyak, P.Gladkikh/ NSC KIPT

Compton ring design

Number of e- = 312 x 6.2 x 1010 = 1.93 x1013 in the ring1 cycle = 15 000 turns = > T = 156 ns x 15 000 = 2.3 ms C ≈ 47 mLaser on during 2500 turnsPhoton yield = 85 photons / e-


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

1.06 GeV

Compton ring

e+ PDR and Accumulator

ring

2 GHz50 Hz

CLIC Compton scheme

Compton configuration for

polarized e+

RF

gun

1 YAG Laser pulse

2 G

Hz

Stacking cavity

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

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

e+ 2.6x108 pol. /turn/bunch

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

600 mJ

L. Rinolfi



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CLIC – C ERLBy F. ZIMMERMANN

2008CLIC e+Comptonscheme-example


Conclusions

A Compton based Polarized Positron Source with stacking cavity scheme could fulfill the requirement of ILC (more difficult) and CLIC (easier), but improvements are necessary in :

• Laser technology (power/repetition rate) • Optical cavity technology (energy gain/repetition rate)• Capture section efficiency (higher yield, smaller

emittance, polarization)• Stacking (relaxation of too strict assumptions)


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THANKS.

The EndThe End

compton based polarized positron sources for e + /e - linear colliders

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