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

Halo Collimation of Proton and Ion Beams in FAIR Synchrotron SIS 100. I. Strasik 1 , I. Prokhorov 1,2 and O. Boine-Frankenheim 1,2 1 GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany 2 Technical University Darmstadt, Germany. Introduction.

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

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  1. 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, Germany 2Technical University Darmstadt, Germany

  2. Introduction • FAIR – Facility for Antiproton and Ion Research at GSI • Synchrotron SIS 100 (fixed target) • 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 one superperiod 1

  3. SIS 100 synchrotron • Beam parameters • Total beam energy 2

  4. Need for the halo collimation in SIS 100 • Protons and light ions • Activation ("hands-on" maintenance limit) 1 W/m (1 GeV protons), 5 W/m (1 GeV/u uranium ions) • Quenches [Ref] I. Strasik et al., Physical Review ST AB 13, (2010) • Heavy ions • Vacuum degradation due to desorption process • Radiation damage [Ref] E. Mahner, Physical Review ST AB 11, (2008) Uranium beam experiments, GSI 3

  5. Cryocatchers in SIS 100 • 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 prototype cryocatchers Courtesy Lars Bozyk [Ref] L. Bozyk et al., Proceedings of the IPAC’12, p. 3237. 4

  6. Cryocatchers in SIS 100 Particle tracking: Stripped ions distribution: Courtesy Lars Bozyk [Ref] L. Bozyk et al., Proceedings of the IPAC’12, p. 3237. 5

  7. 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). 6

  8. Collimation of protons and fully-stripped ions SIS 100, Sector 1 - straight section, cell 3 and 4 Location of the collimation system in SIS 100 Parameters of the collimators rectangular aperture 7

  9. Lattice and beam parameters Ion operation (fast extraction) 8

  10. Efficiency of the proton beam collimation Simulation tools Beam-material interaction: FLUKA Statistics: 700 000 particles Particle tracking: MAD-X Efficiency:~ 99 % 9

  11. Importance of the impact parameter 1 mm IP = 10 mm IP = 1 mm IP = 0.1 mm IP = 0.01 mm IP = 0.5 mm 10

  12. Impact parameter and beam energy Dependence of the collimation efficiency on the impact parameter and beam energy. 11

  13. Collimation of fully-strippedions • 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

  14. Magnetic rigidity Reference quantity →magnetic rigidity Magnetic rigidity →injection and extraction energy of the beam 13

  15. Scattering in the primary collimator Molière theory of multiple Coulomb scattering [Ref] J. Beringer et al. (Particle Data Group), Phys. Rev. D86, 010001 (2012). ATIMA code (1 mm, tungsten) ATIMA vs FLUKA 14

  16. Momentum losses in the primary collimator Bethe formula [Ref] J. Beringer et al. (Particle Data Group), Phys. Rev. D86, 010001 (2012). ATIMA code (1 mm, tungsten) ATIMA vs FLUKA 15

  17. Inelastic nuclear interactions Cross section for inelastic nuclear interaction - 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). - 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). Tripathi (1 mm, tungsten) Tripathi vs FLUKA (Br = 18Tm) Discrepancy for heavy ions - EMD 16

  18. Choice of the material for the primary collimator 40Ar ions High-Z materials are preferable. 17

  19. Efficiency of the ion beams collimation Simulation tools Beam-material interaction: ATIMA, FLUKA Statistics: 100 000 particles Particle tracking: MAD-X 18

  20. Impact parameter and imperfections of the lattice Dependence of the collimation efficiency on the impact parameter and COD. 1 mm ± 30 %magnet misalignment 19

  21. Collimation of partially-stripped ions Intermediate charge-state ions will be accelerated in SIS 100. [Ref] FAIR - Baseline Technical Report, GSI Darmstadt, (2006). Colimation concept - Stripping foil: - Deflection by a beam optical element 20

  22. Collimation of partially-stripped ions Slow extraction area in SIS 100 SIS 100 / Sector 5 / Cell 2 Cell 3 stripping foil warm quadrupoles beam direction The stripping foil for the halo collimation is placed in the slow extraction area in SIS 100 Slow extraction area - two warm quadrupoles [Ref] A. Smolyakov at al, EPAC2008, 3602 (2008). 21

  23. Charge state distribution after stripping Electron capture and electron loss equilibrium charge-state distribution code GLOBAL [Ref] C. Scheidenberger et al., NIMB 142 (1998) 441. injection energies high energies (2 GeV/u) fully-ionized state Stripping foil: 500 μm thick, titanium Medium-Z materials (Al – Cu) → optimal for efficient stripping for wide range of projectiles and beam energies 22

  24. Particle tracking of stripped ions Horizontal Vertical 23

  25. Charge state distribution after stripping Horizontal Vertical 24

  26. 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

  27. Thank you for your attention

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