Accelerator Summary John Seeman SLAC Super B Workshop
Accelerator Summary John Seeman SLAC Super. B Workshop March 16 -19, 2010 Annecy Super. B Workshop 1
Thanks to 25 speakers for 41 talks * * * * * * * Baylac: Low energy polarimetry Bertsche: Longitudinal phase compensation Biagini: Super. B status, CDR 2 status, Magnet summary Chance: Bunch compressor design Demma: Electron cloud, Fast ion, Intra-bunch scattering Drago: Longitudinal feedback, Low level feedback, Transverse feedback Fisher: Diagnostics Koop: Polarization, Levichev: Dynamic aperture, Liuzzo: Low emittance tuning Masuzawa: Super. KEKB status, Vibration measurements Moffeit: Polarization Monseu: Spin tracking Nosochkov: Lattice and ring issues Novokhatski: Single bunch instability, RF parameters, Be pipe heating Ohmi: Dynamic aperture, Beam-beam simulation Paoloni: MDI status Poirier: Positron source Raimondi: DAFNE status, Ring parameters, Future lattice work Rimbault: Beam-beam depolarization, Beam-beam diffusion Seeman: Needed PEP-II components, Injection polarization, Synchrotron radiation ports Shatilov: Beam-beam simulation Sullivan: Interaction region status, MDI interface issues Variola: Arc cell vacuum design Wienands: Polarization Annecy Super. B Workshop 2
Colliding bunches M. Masuzawa e- 2. 6 A Nano-Beam Super. KEKB e+ 3. 6 A New Superconducting / permanent final focusing quads near the IP Replace long dipoles with shorter ones (HER). Add / modify rf systems for higher currents. Redesign the HER arcs to reduce the emittance. Low emittance positrons to inject Low emittance gun New positron target / capture section Low emittance electrons to inject ~40 times gain in luminosity Ti. N coated beam pipe with antechambers Annecy Super. B Workshop 3
Super. KEKB Parameters as of Feb. 15, 2010 KEKB Design KEKB Achieved : with crab Super. KEKB Energy (Ge. V) (LER/HER) 3. 5/8. 0 4. 0/7. 0 Crossing angle (mrad) 22 0 (crab) 83 βy* (mm) 10/10 5. 9/5. 9 0. 27/0. 41 εx (nm) 18/18 18/24 3. 2/2. 4 σy(μm) 1. 9 0. 94 0. 059 ξy 0. 052 0. 129/0. 090 0. 09/0. 09 σz (mm) 4 ~6 6/5 Ibeam (A) 2. 6/1. 1 1. 64/1. 19 3. 6/2. 62 Number of bunches 5000 1584 2503 1 2. 11 80 Luminosity (1034 cm-2 s-1) Annecy Super. B Workshop 4 Parameters presented at KEKB MAC Review Feb. 15 -17, 2010
Super. KEKB IR design (Masuzawa) QC 1 magnets closer to IP Superconducting & permanent magnets 83 mrad Full crossing Annecy Super. B Workshop 5
DAFNE Peak Luminosity (Raimondi) SIDDHARTA KLOE DEAR FINUDA 1523 Annecy Super. B Workshop 1002 4. 53 E+32 6
View of the new KLOE IR PM le dipo rs nsato ompe skew rs recto cor QF QD c Annecy Super. B Workshop Raimondi) 7
Layout & geometry (Biagini) LER SR LER arc HER arc IP 66 mrad LER SR ¬HER and LER arcs are parallel to each other in the H-plane while separated by 2. 1 m. ¬Each ring has one inner and one outer arc. ¬Both inner and outer arcs provide the same bending angle but outer arc is made longer (increased drift space around the dipoles) in order to provide the same azimuth location as the inner arc Rings crossing e+ LER arc e- RF Annecy Super. B Workshop 8 HER arc
Machine Parameters for 1036 cm− 2 s− 1 (Raimondi) The IP and ring parameters have been optimized based on several constraints to maintaining wall plug power, beam currents, bunch lengths, and RF requirements comparable to present B Factories. • Planning for the reuse as much as possible of the PEP-II hardware. • Simplifying the IR design as much as possible. In particular, reduce the synchrotron radiation in the IR, reduce the HOM power and increase the beam stay-clear. • Relaxing as much as possible the requirements on the beam demagnification at the IP. Improved chromatic correction in arc cells. Flexibility for the parameters choice: The horizontal emittance can be decreased by about a factor 2 in both rings by changing the partition number (by changing the RF frequency [LEP] or the orbit in the ARCS) and the natural ARC emittance by readjusting the lattice functions. • The Final Focus system as a built-in capability of about a factor 2 in decreasing the IP beta functions. • The RF system will be able to support higher beam currents (up to a factor x 1. 6) over the baseline, when all the available PEP RF units are installed. Annecy Super. B Workshop 9
Parameters Tau/charm threshold running at 1035 Baseline + other 2 options: • Lower y-emittance • Higher currents (twice bunches) Baseline: • Higher emittance due to IBS • Asymmetric beam currents RF power includes SR and HOM Annecy Super. B Workshop 10
Arcs * HER and LER arcs have conceptually the same lattice. LER arc dipoles are shorter (bend radius about 3 times smaller) than in the HER in order to match the ring emittances at the asymmetric beam energies. mx = 3 p, my = p Cell in HER LER HER mx = 3 p, my = p Cell in LER Annecy Super. B Workshop 11
“Parasitic” crossing (Raimondi) * * Doglegs have been removed and the secondary crossing (“parasitic) is made by lengthening the first 3 p cell in HER by about 25 meters This makes the two beam lines cross with and angle of about 165 mrad (was about 150 with the dogleg) and there should be no interference between the two beam lines (some readjustment still needed for LER in progress) This longer HER cell is suitable for the injection Lot of space remaining for utilities (RF, feedbacks, wigglers, . . . ) Annecy Super. B Workshop 12
HER FF optics (Nosochkov) • Shorter X-sextupole section -> reduced chromaticity, emittance. • “Spin rotator” optics is replaced with a simpler matching section. b* = 26 / 0. 27 mm • V 10 Y-sext Crab X-sext IP V 12 Y-sext X-sext Crab Annecy Super. B Workshop Match 13
LER FF optics (Nosochkov) • Same modifications as in HER, except that matching section is shorter to provide space for spin rotator optics. • ± 33 mrad bending asymmetry with respect to IP causes a slight spin mismatch between SR and IP resulting in ~5% polarization reduction. V 10 Y-sext X-sext Crab IP V 12 Y-sext X-sext Annecy Super. B Workshop Crab Match & SR 14
Tolerances on Orbit/dispersion Corrections (Liuzzo) * Annecy Super. B Workshop 15
Beam-Beam Simulations (Ohmi) * Annecy Super. B Workshop 16
Beam-Beam Tune Space (Ohmi) * Annecy Super. B Workshop 17
Magnet Shopping list (no IP doublets) (Biagini) PEP-II HER Super. B HER PEP-II LER Super. B LER Notes Dipoles (L =5. 4 m) 194 80 - - +114 Dipoles (L =4. m) - 22 -44 Dipoles (L =2. 8 m) - 10 - 6 -16 Dipoles (L =0. 45 m) - - 202 328 -126 (-63)* Quads (L =0. 56 m) 202 107 - 81 +14 Quads (L =0. 73 m) 81 54 - - +27 Quads (L =0. 215 m) - 22 -44 Quads (L =0. 43 m) - 106 353 200 +47 Sexts (L =0. 25 m) - 2 76 86 -12 Sexts (L =0. 30 m) 104 84 - - +20 Sexts (L =0. 35 m) - 8 8 8 -8 Sexts (L =0. 4 m) - 4 -8 Need to build 135 magnets out of 1256 needed. Annecy Super. B Workshop 18
Longitudinal Phase Matching (Bertsche) Annecy Super. B Workshop 19
RF Parameters (Novokhatski) * Annecy Super. B Workshop 20
Annecy Super. B Workshop 21
Longitudinal Feedback Simulator (Drago) * Annecy Super. B Workshop 22
Fast Ion Instability (Demma) Lgap=20 ns Lgap=180 ns Annecy Super. B Workshop 23
Simulation of FII (4) (Demma) Lgap=40 ns Lgap=20 ns Ntrain=5 Nb=50 Lsep=4 ns Lgap=180 ns Annecy Super. B Workshop 24
Variola: Approximation of the pressure distribution in Cell LER #2 and HER #2 at Super. B with synchrotron radiation from only dipoles LER E = 4 Gev I = 2. 28 A = 28 m = 4. 3. 1019 ph/s/m Ec = 5. 1 Ke. V P = 11 KW/m HER E = 7 Gev I = 1. 3 A = 139 m = 8. 5. 1018 ph/s/m Ec = 5. 5 Ke. V P = 2. 3 KW/m (ph/s/m) 1019 LER HER Rt = 25 mm Distance m Rt = 47, 5 mm Annecy Super. B Workshop 25 Distance m
LER Ring Relative Longitudinal Polarizatation at IP (Wienands) * Annecy Super. B Workshop 26
Low Energy (Mott) polarimetry (Baylac) * Annecy Super. B Workshop 27
Polarization Measurement ( Moffeit) Annecy Super. B Workshop 28
Preliminary results on depolarization due to beam-beam interaction at Super. B Cecile Rimbault LAL - Orsay 2 orders of magnitude less than previous study ! Annecy Super. B Workshop 29
Transfer Lines and Compressor (A. Chance) * Annecy Super. B Workshop 30
Super. B Positron Production Study (Poirier) 10 n. C Primary beam Linac for e 100 s Me. V e+/e. Target Pre-injector Linac for e+ ~280 Me. V ~300 Me. V 2. 856 GHz AMD e- gun Geant 4 1 Ge. V Damping Ring Parmela/Astra/G 4 Accelerating Capture Section 2. 856 GHz e(0. 6 to 1 Ge. V) Present study: 600 Me. V Tungsten Target W: 1. 04 cm Super. B thick Workshop Annecy ACS 31
At end of 4 th tank – 3000 MHz (Poirier) * Average Energy = ~333 Me. V Energy (Me. V) ~21. 9 m long beam line Energy (Me. V) Z (m) Total Yield = ~31. 9% sz=3. 5 10 -03 m Z (m) se=5. 2 (3. 2) Me. V sx’=1. 4 10 -3 rad, sy’=1. 46 10 -3 rad Annecy Super. B Workshop sx=8. 1 10 -3 32 m, sy=8. 1 10 -3 m
Example SR: NSLS-II Inelastic X-ray Scattering Beamline 2 nd Un 1 D Be Defin Comp Undu la ing A p ound Refra ctive r (IVU tor (IV erture High-β dulato t 22 -3 m U 22 -3 m & Abs straigh ) ) orber Lens Shutt er 20 m 2 nd Ho 2 nd Ver rizonta tical Fo cusing l Focu sing M irror h Q Re solutio n for Hig 40 m Mirror Shutt er Shutt Vertic 59 m al Foc Horiz 69 m ontal Samp le Multila Focus using Mono chrom CDDW r ing M irror llimatin g Mirro r Analyz e r or Annecy Super. B Workshop Storag e Ring onoch r ator omato r Shield Cai CC Mo nochr For 0. 1 omator me. V Phase Plate For Q > 40 n -1 m Mirro yer Co 64 m Detect CDDW er 0. 1 me. V Development Instrument (10 m) Pre-m 33 Wall
Frascati Site: Potential HER Synch Radiation Beam Lines LER HER Annecy Super. B Workshop 34
CDR 2 status (Biagini) * * * Planned CDR 2 was 26 chapters. Total will have ~190 pages. 24 authors so far. About 70% ready, some known fixes needed. Need to add something on synchrotron radiation sources possibilities. * Aim to finish by early April. Annecy Super. B Workshop 35
Super. B Conclusions * Accelerator design is converging with all aspects starting to look feasible. * Lattice and parameters optimization is continuing for better performances and with added flexibility. * More subtle beam dynamics issues are being studied (e. g. IBS, FII, emittance diffusion, beam-beam effects, feedbacks). * Component and lattice tolerances with corrections are being studied. * Polarization is progressing: beam-beam depolarization, trying to simplify the polarized gun, spin measurements. * Try to finish CDR 2 in a few weeks. * Start organizing soon the effort for the TDR. Annecy Super. B Workshop 36
- Slides: 36