I. Strasik et al. ● Halo Collimation of Proton and Ion Beams in FAIR Synchrotron SIS 100 ● CERN 27.01.2014 Halo Collimation of Proton and Ion Beams in

I. Strasik et al. ● Halo Collimation of Proton and Ion Beams in FAIR Synchrotron SIS 100 ● CERN 27.01.2014

Halo Collimation of Proton and Ion Beams in FAIR Synchrotron SIS 100

I. Strasik1, I. Prokhorov1,2 and O. Boine-Frankenheim1,2

1GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany2Technical University Darmstadt, Germany


Introduction

FAIR – Facility for Antiproton and Ion Research at GSI

Synchrotron SIS 100 (fixed target)

1

• Beams

- protons (antiproton production)

- fully-stripped ions (e.g. )

- partially-stripped ions (e.g. )

• Lattice

- circumference ~ 1 km

- hexagonal shape (six superperiods)

- quadrupole doublet structure

- superconducting magnets

184018 Ar

2823892U

one superperiod


SIS 100 synchrotron

Accelerator Beam EnergyIntensity /

Cycle

SIS 18protons 4.5 GeV 6×1011

238U28+ 200 MeV/u 5×109

SIS 100protons 30 GeV 2×1013

238U28+ 2.7 GeV/u 4×1011

BeamNumber of bunches

IntensityMaximum beam

energy [GeV]Total beam energy [MJ]

SIS 100 proton 1, 2, 4 2.01013 29 0.093

SIS 100 238U28+ 1, 2, 4 4.01011 643 (2.7 GeV/u) 0.051

LHC proton 2808 1.151011 7000 362

Total beam energy

Beam parameters

2


Need for the halo collimation in SIS 100

Heavy ions

Protons and light ions

• Activation ("hands-on" maintenance limit)

1 W/m (1 GeV protons), 5 W/m (1 GeV/u uranium ions)

• Quenches

• Vacuum degradation due to desorption process

• Radiation damage

[Ref] I. Strasik et al., Physical Review ST AB 13, (2010)

[Ref] E. Mahner, Physical Review ST AB 11, (2008)

Uranium beam experiments, GSI

3


• Interaction with residual gas: U28+ → U29+.

• Cryocatchers - a combined collimation/pumping system developed to intercept heavy ions which lost electrons due to interaction with residual gas.

• Minimize the desorbed gas entering the beam pipe.

• Important also for the halo collimation

[Ref] L. Bozyk et al., Proceedings of the IPAC’12, p. 3237.

Cryocatchers in SIS 100

cryocatchers

prototype

Courtesy Lars Bozyk

4


[Ref] L. Bozyk et al., Proceedings of the IPAC’12, p. 3237.

Cryocatchers in SIS 100

Courtesy Lars Bozyk

Particle tracking:

Stripped ions distribution:

5


Two-stage betatron collimation system

• Primary collimator (thin foil) – scattering of the halo particles

• Secondary collimators (bulky blocks) – absorption of the scattered particles

Particles have small impact parameter on the primary collimator.

The impact parameter at the secondary collimator is enlarged due to scattering → reduced leakage of the particles.

[Ref] M. Seidel, DESY Report, 94-103, (1994).[Ref] T. Trenkler and J.B. Jeanneret, Particle Accelerators 50, 287 (1995).[Ref] J.B. Jeanneret, Phys. Rev. ST Accel. Beams 1, 081001 (1998).[Ref] K. Yamamoto, Phys. Rev. ST Accel. Beams 11, 123501 (2008).[Ref] N. Mokhov et al., Journal of Instrum. 6, T08005 (2011).

0 90 180 270 360-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

S2

S1P

Scatteredtrajectories

Nor

mal

ised

am

plitu

de

Betatron phase advance [deg]

Undisturbedtrajectory

6


Collimation of protons and fully-stripped ions

Location of the collimation system in SIS 100

SIS 100, Sector 1 - straight section, cell 3 and 4

rectangular apertureParameters of the collimators

Collimator Primary Secondary

Material tungsten tungsten

Thickness 1 mm 40 cm

Transverse position 4.5 σ 5 σ

7


Lattice and beam parameters

0 25 50 75 100 125 150 1750

5

10

15

20

25Beam directionP S2S1

x y

[m

]

s [m]

-6

-4

-2

0

2

4

D

D [m

]

Operation mode Qx Qy

Proton 21.8 17.7

Ion (slow extraction) 17.31 17.8

Ion (fast extraction) 18.88 18.8

Beamx

[mm·mrad]

y

[mm·mrad]

Proton 13 4238U 34 14

Ion operation (fast extraction)

8


0 200 400 600 800 100010-7

10-6

10-5

10-4

10-3

10-2

10-1

100

Bea

m lo

sses

(re

lativ

e)

s [m]

Halo collimators Cryocatchers SIS 100 lattice

Efficiency of the proton beam collimation

Simulation tools

Beam-material interaction: FLUKA Statistics: 700 000 particles

Particle tracking: MAD-X Efficiency: ~ 99 %

9


Importance of the impact parameter

10

1 mm

IP = 10 m IP = 1 m

IP = 0.5 m IP = 0.1 m IP = 0.01 m


Impact parameter and beam energy

0.01 0.1 1 1098.6

98.8

99.0

99.2

99.4

99.6

Col

limat

ion

effic

ienc

y [%

]

Impact parameter [m]

0 5 10 15 20 25 3098.8

99.0

99.2

99.4

99.6

99.8

100.0

Col

limat

ion

effic

ienc

y [%

]

Beam energy [GeV]

Dependence of the collimation efficiency on the impact parameter and beam energy.

11


Collimation of fully-stripped ions

• Two-stage collimation system utilize also for fully-stripped ions Study of the following processes for various ion species

• Reference quantity - magnetic rigidity Injection and extraction energy

• Scattering in the primary collimator Molière theory (multiple Coulomb scattering), ATIMA code, FLUKA code

• Energy (momentum) losses in the primary collimator Bethe formula, ATIMA code, FLUKA code

• Inelastic nuclear interactions in the primary collimator Sihver, Tripathi, Kox, Shen formulae, FLUKA code

• Collimation efficiency Dependence on the ion species

12


Magnetic rigidity

Reference quantity → magnetic rigidityqp

B

Magnetic rigidity → injection and extraction energy of the beam

0.1 1 101

10

100

Mag

netic

rig

idity

B [

Tm

]

Kinetic energy [GeV/u]

1H1+

12C6+

40Ar18+

132Xe54+

238U92+

SIS 100

SIS 18

30

13


Scattering in the primary collimator

Molière theory of multiple Coulomb scattering

[Ref] J. Beringer et al. (Particle Data Group), Phys. Rev. D86, 010001 (2012).

00

ln038.01 6.13

Xx

Xx

Zcprms

10 1000.1

1

10

30

SIS

100

1H1+

12C6+

40Ar18+

132Xe54+

238U92+

Def

lect

ion

angl

e rm

s [mra

d]

Magnetic rigidity B [Tm]

SIS

18

5

ATIMA code (1 mm, tungsten)ATIMA vs FLUKA

-10 -8 -6 -4 -2 0 2 4 6 8 1010-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

Par

ticle

cou

nt (

rela

tive)

Deflection angle [mrad]

1H1+ ATIMA

1H1+ FLUKA

40H18+ ATIMA

40H18+ FLUKA

238U92+ ATIMA

238U92+ FLUKA

14


Momentum losses in the primary collimator

Bethe formula

22

ln214 2

2max

222222

I

TcmA

ZzcmrNdxdE eeeA

10 10010-6

10-5

10-4

10-3

10-2

10-1

100

SIS

100

Mom

entu

m lo

sses

-dp

/p)


1H1+

12C6+

40Ar18+

132Xe54+

238U92+ SIS

18

5

[Ref] J. Beringer et al. (Particle Data Group), Phys. Rev. D86, 010001 (2012).

ATIMA code (1 mm, tungsten)

-5.0x10-2 -4.5x10-2 -8.0x10-3 -4.0x10-3 0.00.000

0.005

0.010

0.015 1H1+ ATIMA

1H1+ FLUKA

40Ar18+ ATIMA

40Ar18+ FLUKA

238U92+ ATIMA

238U92+ FLUKA

Par

ticle

cou

nt (

rela

tive)

Momentum losses (-dp/p)

ATIMA vs FLUKA

15


Inelastic nuclear interactions

- Sihver formula (E > 100 MeV/u) [Ref] L. Sihver et al., Phys. Rev. C47, 1225 (1993).

- Tripathi formula (E > 10 MeV/u) [Ref] R. Tripathi et al., NIMB117, 347 (1996).

Cross section for inelastic nuclear interaction

10 1000.00

0.02

0.04

0.06

0.08

0.10

SIS

100

Pro

babi

lity

P


1H1+

12C6+

40Ar18+

132Xe54+

238U92+

SIS

18

5

- Kox formula (E > 10 MeV/u) [Ref] Kox et al. Phys. Rev. C35, 1678 (1987).

- Shen formula (E > 10 MeV/u) [Ref] Shen et al. Nucl. Phys. A491, 130 (1989).

Tripathi (1 mm, tungsten)

Probability P

Beam 1H1+ 40Ar18+ 238U92+

Tripathi 0.011 0.031 0.057

FLUKA 0.011 0.032 0.114

Tripathi vs FLUKA (B = 18Tm)

Discrepancy for heavy ions - EMD

16


Choice of the material for the primary collimator

Material Graphite Copper Tungsten

Deflection angle θrms [mrad] 1.51 1.51 1.51

Thickness L [mm] 51.8 4.1 1.0

Probability of nuclear interaction P 0.601 0.104 0.031

Momentum losses -dp/p 0.075 0.019 0.008

High-Z materials are preferable.

17

40Ar ions


Efficiency of the ion beams collimation

60

70

80

90

100

238U197Au132Xe84Kr40Ar20Ne12C4He

Halo collimatorsHalo collimators & Cryocatchers

Col

limat

ion

effic

ienc

y [%

]

Primary beam

1H

Simulation tools

Beam-material interaction: ATIMA, FLUKA Statistics: 100 000 particles

Particle tracking: MAD-X

18


Impact parameter and imperfections of the lattice

10-4 10-3 10-2 10-1 100 10160

70

80

90

100

Col

limat

ion

effic

ienc

y [%

]

Impact parameter [m]

12C 132Xe

40Ar 238U

Dependence of the collimation efficiency on the impact parameter and COD.

2 3 4 5 6 7 8 9 10 11 1260

70

80

90

100

12C 84Kr

40Ar 238U

Col

limat

ion

effici

ency

[%]

Closed orbit distortion [mm]

19

1 mm ± 30 %magnet misalignment


Collimation of partially-stripped ions

Intermediate charge-state ions will be accelerated in SIS 100.

178436

2213254

2418173

2519779

2823892 Kr,Xe,Ta,Au,U

[Ref] FAIR - Baseline Technical Report, GSI Darmstadt, (2006).

Colimation concept

9223892

2823892 UU- Stripping foil:

- Deflection by a beam optical element

20


Collimation of partially-stripped ions

Slow extraction area in SIS 100

[Ref] A. Smolyakov at al, EPAC2008, 3602 (2008).

Slow extraction area - two warm quadrupoles

The stripping foil for the halo collimation is placed in the slow extraction area in SIS 100

SIS 100 / Sector 5 / Cell 2

stripping foil

Cell 3

warm quadrupoles

beam direction

21


Charge state distribution after stripping

injection energies

high energies (2 GeV/u)

fully-ionized state

equilibrium charge-state distribution

[Ref] C. Scheidenberger et al., NIMB 142 (1998) 441.code GLOBAL

Stripping foil: 500 μm thick, titanium

Medium-Z materials (Al – Cu) → optimal for efficient stripping for wide range of projectiles and beam energies

Electron capture and electron loss

20 30 40 50 60 70 80 90 1000.0

0.2

0.4

0.6

0.8

1.0181Ta 238U197Au132Xe

Fra

ctio

n

Charge state

84Kr

22


Particle tracking of stripped ions

9223892

2823892 UU

Horizontal

Vertical

23


Charge state distribution after stripping

Horizontal

Vertical

102010

52010 NeNe

24


Conclusion

• Efficiency of the proton beam collimation: ~ 99%.

• Efficiency of the ion beam collimation: ~ 99% for fully-stripped ions < 20Ne.

• Efficiency of the ion beam collimation + cryocatchers: ~ 99% for fully-stripped ions < 132Xe.

• Efficiency of the ion beam collimation + cryocatchers: almost 90% for 238U.

• The collimation concept for the partially-stripped ions is based on the stripping of their electrons

• The stripped ions are then deflected using two warm quadrupoles.

25


Thank you for your attention

Documents

I. Strasik et al. ● Halo Collimation of Proton and Ion Beams in FAIR Synchrotron SIS 100 ● CERN 27.01.2014 Halo Collimation of Proton and Ion Beams in