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Lifetime and loss rates due to Touschek and beam-gas for latest SuperB lattices

This study analyzes the lifetime and loss rates in SuperB lattices due to Touschek and beam-gas effects. It considers the horizontal and vertical collimators systems and provides insights into the reduction of losses through the use of different collimation techniques.

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Lifetime and loss rates due to Touschek and beam-gas for latest SuperB lattices

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  1. Lifetime and loss rates due to Touschek and beam-gas for latest SuperB lattices M. Boscolo M. Boscolo, Isola d'Elba, June 2010

  2. Outline: V12 lattice Touschek • Lifetime • Loss rates • Horizontalcollimators system +HER LER Beam- gas:Bremsstrahlung and Coulomb • Lifetime • Loss rates • Vertical collimators system +HER LER M. Boscolo, Isola d'Elba, June 2010

  3. nominal parameters for the V12 lattice M. Boscolo, Isola d'Elba, June 2010

  4. HER Overlap of betas and Dx from MAD and Touschek code bx* = 2.6 cm by* = 0.025 cm M. Boscolo, Isola d'Elba, June 2010

  5. HER V12 energy acceptance Loss Probability for Touschek energy deviated particles at nt=1 nt=2 nt=5 M. Boscolo, Isola d'Elba, June 2010

  6. HER v12 Lifetime M. Boscolo, Isola d'Elba, June 2010

  7. HER IR losses ex=2 nm (very small enlargement due to IBS, from 1.97 to 2.00 nm) NO COLLIMATORS, tTOU = 40 min QF1 QD0 QF1 QD0 Total losses |s|< 2 m IR losses |s|< 2 m M. Boscolo, Isola d'Elba, June 2010

  8. HER Touschek Trajectories, no collimators Trajectories of particles eventually lost at IR Particle losses M. Boscolo, Isola d'Elba, June 2010

  9. HER IR losses vs machine turns HER IR losses nt=1-5 IR losses nt=1 M. Boscolo, Isola d'Elba, June 2010

  10. Final Focus collimation system secondary collim. Primary collim. COL3 COL1 COL2 COL4 21.351 49.231 67.766 85.837 M. Boscolo, Isola d'Elba, June 2010

  11. Horizontal Collimators upstream the IR Idea is to collimate in the final focus upstream the IR intercepting the particles that would be lost at the QF1 Collimator jaw insertion = 0.9* phys. aperture(QF1)·sCOL/ sQF1 sx (QF1 )= 0.88 mm • bx(QF1)=390 m • bx(primary collim.) = 70 m • Dx(primary collim.) = 0.5 m • bx(secondary collim.) = 20 m • Dx(secondary collim.)= 0.4 m BSC(QF1)45 sx Phys. Apert = 0.04 cm M. Boscolo, Isola d'Elba, June 2010

  12. Reshaping of Beam pipe as collimators • The proposed horizontal collimation system results very efficient from simulations. • It is almost straightforward to model the beam pipe at the longitudinal positions of the primary horizontal collimators (two hor. Sextupoles) with a horiz. physical aperture corresponding to the one needed for the jaws to efficiently intercept the scattered particlesthat would be lost at the QF1. X IP --85.8 m -67.7 m SFX SFX A symmetrically shaped pipe is a better solution from wakefields and HOM point of view instead of collimators X

  13. Partial insertion of collimators Col3 = 1.6, -1.8 cm Col4 = -1.6, 1.8 cm Col1 = -1.2, 1.2 cm all Touschek particles tau=2185 s (36.4min) (about 8% reduction) IR losses reduced a factor 100: from 0.22e7Hz to 0.207e5Hz col3 col1 col4 M. Boscolo, Isola d'Elba, June 2010

  14. Partial further insertion of 4 COLLIMATORS -1.0,+1.2 -1.4 -1.4,+1.8 -1.8,+1.4 tau=1989 s (33.16 min) Reduction of about 16% IR losses = 8.5 KHz M. Boscolo, Isola d'Elba, June 2010

  15. HER Collimators Final set tTOU=33.2 min 16% lifetime reduction IR losses = 0.4 KHz /bunch reduction factor ≈5000 col4 col3 col2 col1 primary Primary: Col3 = 1.4, -1.8 cm Col4 = -1.4, 1.8 cm Secondary: Col2 = -1.0 cm Col1 = -1.0, +1.2 cm secondary Collimators efficiency In sigmax units: Col1= -26 /+31 sx Col2= -26 sx Col3= -36/ +28 sx Col4= -28/ 36 sx M. Boscolo, Isola d'Elba, June 2010

  16. HER: IR losses with final collimators set DE/E of IR losses Only downstream IR losses M. Boscolo, Isola d'Elba, June 2010

  17. HER IR losses vs nturn with final collimators set Total losses IR losses: only first turn losses M. Boscolo, Isola d'Elba, June 2010

  18. LER V12 Overlap of betas and Dx from MAD and Touschek code correct bx* = 3.2 cm by* = 0.020 cm M. Boscolo, Isola d'Elba, June 2010

  19. LER v12 Lifetime M. Boscolo, Isola d'Elba, June 2010

  20. LER no collimators, nominal ex= 1.8 nm tTOU = 356 s (5.9 min) IR losses = 8.6 MHz |s|≤2 nt =1-5 (no IBS) DE/E of IR losses M. Boscolo, Isola d'Elba, June 2010

  21. LER energy acceptance No IBS, ex=1.8nm Consistent with DA calculations: LER Dynamic Aperture ≈ 20% lower than HER Dynamic Aperture LER HER nt=2 nt=5 nt=1 M. Boscolo, Isola d'Elba, June 2010

  22. LER ex =1.8 nm (no IBS) M. Boscolo, Isola d'Elba, June 2010

  23. LER Final Focus horiz. collimators Same longitudinal positions as for HER secondary collim. Primary collim. COL1 COL2 COL3 COL4 21.351 49.231 67.766 85.837 M. Boscolo, Isola d'Elba, June 2010

  24. LER final collimators set: IR trajectories ex =2.4 nm Col1= -28 /+35 sx Col2= -35 sx Col3= +29 sx Col4= -25 sx IR losses = 14.5 kHz/bunch nt =1-5 |s|< 2 m M. Boscolo, Isola d'Elba, June 2010

  25. LER final collimators set IR trajectories ex =2.4 nm IR losses |s|< 4 m IR losses |s|< 2 m M. Boscolo, Isola d'Elba, June 2010

  26. LER final collimators set: IR losses ex =2.4 nm M. Boscolo, Isola d'Elba, June 2010

  27. CDR and CDR2 CDR CDR2 M. Boscolo, Isola d'Elba, June 2010

  28. Coulomb beam-gas scattering LER v12 lattice tCoul ≈ 1789 s P = 1 nTorr, Z = 8 Ibunch= 2.5 mA ex (IBS) = 2.4 nm (for 1 bunch at 2.5 mA) Tot. Losses = 36.6 MHz IR Losses = 6.4 MHz multiturn effect, as expected Machine turns Further Checks with analytical formula foreseen betatron oscillation excitation M. Boscolo, Isola d'Elba, June 2010

  29. Coulomb scattering LER v12lattice Mostly vertical losses losses (Hz) losses (Hz) by (m/1000) IP s(m) s(m) M. Boscolo, Isola d'Elba, June 2010

  30. Coulomb scattering qscatt(rad) Scattering angle as a function of the longitudinal position IP s(m) Scattering angle sums up to vertical beam size M. Boscolo, Isola d'Elba, June 2010

  31. Coulomb scattering LER v12lattice In the simulation cylindrical aperture, vertical physical aperture= 4 cm losses (Hz) s(m) QD0 M. Boscolo, Isola d'Elba, June 2010

  32. VERTICAL COLLIMATORS SDY1L SDY2L M. Boscolo, Isola d'Elba, June 2010

  33. Vertical Collimators upstream the IR Idea is to collimate in the final focus upstream the IR intercepting the particles that would be lost at the QD0 Collimator jaw insertion = 0.9* phys. aperture(QD0)·sCOL/ sQD0 LER -> by(QD0)=1490 m -> by(VCOL1, VCOL2)=996 m collimator opening = 2.9 cm (370 sy) With this value IR losses are reduced by a factor 1000 and NO lifetime reduction M. Boscolo, Isola d'Elba, June 2010

  34. Reshaping of Beam pipe as collimators A vertical beam pipe at the longitudinal position where the vertical Collimator should be placed (V. Sextup.) caould be modeled by the same aperture needed to collimate particles that would be lost at the QD0 y IP y

  35. Coulomb scattering LER v12lattice X and y positions of IR losses y(m) All horizontal trajectories of Coulomb scattered particles M. Boscolo, Isola d'Elba, June 2010

  36. LER Beam-gas Bremsstrahlung LER v12 lattice like Touschek with DE/E<0 for primary electrons particles undergoing inelastic scattering are lost either for physical/dynamic aperture or for exceeding RF bucket tBrems = 2.7·105 s tot losses= 2.4 MHz losses for phys./DA apert.= 91 kHz IR Losses = 0.6 kHz P = 1 nTorr, Z = 8 Ibunch= 2.5 mA losses for exceeding physical aperture 62% of total losses these are losses not taken into account with integrated cross section (enters only the RF acceptance) M. Boscolo, Isola d'Elba, June 2010

  37. LERBeam-gasBremsstrahlung V12 lattice All horizontal trajectories M. Boscolo, Isola d'Elba, June 2010

  38. Beam-gas scattering lifetime and losses summary M. Boscolo, Isola d'Elba, June 2010

  39. Conclusions: Lifetime summary M. Boscolo, Isola d'Elba, June 2010

  40. Beam Tails from Touschek Study of beam tails from Touschek are important also for synchrotron radiation LER V12 lattice Machine turns=1 Emit=2.4nm (with IBS) xdistribution at s= -2m upstream IP for Touschek scatteredparticles Collimators OUT Collimators IN x(m) x(m) M. Boscolo, Isola d'Elba, June 2010

  41. Longitudinal position for beam tail Collimators OUT Collimators IN

  42. Conclusions on beam tail distribution study First study has been performed for Touschek, same approach can be used to provide beam tails due to beam gas scattering. M. Boscolo, Isola d'Elba, June 2010

  43. back-up M. Boscolo, Isola d'Elba, June 2010

  44. Present parameters Table M. Boscolo, Isola d'Elba, June 2010

  45. Ploss 1 turn trackedparticles with Dp/p= 0.6%-0.8% are lost, with some efficiency. These have very large weight, this induces difference in lifetime estimation (Touschek function very non linear) SuperB: Comparison between lifetime estimate from formula and calculation from tracking (CDR lattice) generated Touschek particles per second all over the ring Reference: t(CDR)=330 s (Wienands) assuming that particles with |Dp/p|>1% are lost (like CDR): t = 308 s good agreement with CDR efficiency calculated from tracking t = 200 s Dp/p M. Boscolo, 2nd MINI-MAC, April 24th 2009

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