Summary of Accelerator parallel sessions M.Biagini on behalf of 23 speakers SuperB09, LAL, Feb. 16 th 2009

Goals for this workshop In July 2008 the miniMAC reviewed the accelerator design and suggested topics we should concentrate on, in view of the next review (April 23-24, 2009) We started to study them in more details but we still need hard work to be able to answer to all questions raised We need to establish a collaboration team to procede with TDR  formalize a true international collaboration We need to have asap the name of a responsible into each box of the Accelerator structure in order to coodinate work

Parallel sessions: 25 Talks... Cannot describe all ! My apologies to those not mentioned in the following

...25 Talks

Main goals for the April mini-MAC Build a complete lattice for each ring  this needs to happen for aperture studies to start Produce an IR design that has optics for each ring  Produce a spin insertion for the HER  IR with detector solenoid Coupling compensation scheme Dynamic aperture studies of both rings  1 st -- perfect lattice, crab sextupoles off   2 nd – crab sextupoles on  3 nd – ring magnet errors  4 th – errors in spin rotators Further progress at DA  NE 

Topics Requiring further Study to Establish design- performance feasibility (from the last mini-MAC) Beam beam  perform strong-strong simulations for SuperB with large Piwinski angle  further experimental tests of crab waist at DA  NE  (to achieve design goals, or understand limitations) –exploit the DA  NE experiment to benchmark and validate the simulation –demonstrate that the crab waist improves the performance Low emittance generation, tuning, dynamic aperture  simulation needs to include effects of crab waist  need a table of tolerances  need to optimize dynamic aperture with interaction region (crab waist...)

Topics Requiring further Study to Establish design- performance feasibility ( from the last mini-MAC ) IR design (key issues are achieving low betas, stabilization)  begin first engineering design considerations to be sure there are no impediments to achieving very low beta and/or the stability needed for collision of tiny beam spots Continue making good progress on background simulations (single beam, luminosity)  Injection baseline configuration should be picked which is   capable of ensuring small enough charge fluctuations per bunch and  which can be matched to the ring acceptance(s)

Topics Requiring further Study to Establish design- performance feasibility ( from the last mini-MAC ) RF& Feedbacks  RF and feedbacks require performance much like PEP-II. However the ring impedances must be halved relative to PEP-II. This requires careful study, and constant attention to the details of the vacuum chamber design. The SuperB team must establish an impedance budget and a conscientious impedance-budget manager  determine the fundamental performance requirements of the coupled-bunch feedback systems. Build what is needed and make it robust, with special attention to protection against noise sources 

SuperB Parameters LER/HERUnitJune 2008Jan N b, I b /  2  y, 2N b E+/E-GeV4/7 Lcm -2 s -1 1x10 36 I + /I - Amp1.85 / / / /4.00 N part x /5.556/64.23/4.236/6 N bun I bunch mA  mrad2530 x*x* mm35/20 y*y* mm0.22 / /0.37 xx nm2.8/1.6 yy pm7/4 28/16 xx mm 9.9/5.7 yy nm39/3938/38 77/77 zz mm5/5 xx X tune shift0.007/ / yy Y tune shift0.14 / / / /0.063 RF stationsLER/HER5/6 5/87/11 RF wall plug power MW J. Seeman

Collisions with & without Crab Sextupoles CRAB OFF: Bigger blowup Sharp lifetime reduction for bunch currents > mA February 2009 Courtesy G. Mazzitelli Crab waist works ! C. Milardi, M. Zobov

Beam-beam simulations benchmarking M. Zobov Strong-Strong Beam-Beam Simulations (K. Ohmi) Single Bunch Luminosity Crab Waist On Crab Waist Off about 35% lower (Damping time = turns) 105 bunches

20 bunches Strong-Strong Beam-Beam Simulations (K. Ohmi) Single Bunch Luminosity Crab Waist On Crab Waist Off about 20% lower (Damping time = turns) 20 bunches M. Zobov

Beam-beam tails M. Zobov Much lower luminosity is achieved with crab sextupoles off. Besides stronger blowup, a sharp lifetime reduction is observed for bunch currents > 8-10 mA. This is in accordance with beam-beam simulations taking into account the realitic DAFNE nonlinear lattice. Linear latticeNonlinear lattice Linear lattice Crab ON Crab OFF

Ring Lattice P. Raimondi Arc cell flexible to match what we need There is space to further decrease the Power requirements by optimizing the ARC cell. The solution considered is based on decreasing the natural emittance by increasing mux/cell, and simultaneously adding weak dipoles in the drift spaces in the cell to decrease the Synchrotron radiation Longer damping time: about 30% more Same emittance, alfac etc… Main bends weaker: about 20% Cells are all the same:  x =0.75,  y =0.25 Fewer sextupoles: about 30% less Arcs Dynamic Aperture > 100  s x&y (y fully coupled)

Final Focus FF layout compatible with the two rings and spin rotator (Larger Y_CCS Bend, about 300mrad) Dilution of the dynamic properties seems tolerable (WW) Found a better solution for the FF in terms of dynamic properties and two- rings layout Convergence toward a solution with Spin Rotators seems very close Other options are still not excluded and need additional studies

HER FF with spin rotators W. Wittmer Spin rotator

Polarized positrons for the SuperB  L = 1 +  e +  e - 3 ways explored :  Compton: feasible but expensive  Selective Compton: only at higher energy  Polarised Bremmstrahlung: VERY PROMISING and quite for free!!! NEEDS study of effective capture and transport. e + Polarization Polarized e+ and e- beams:  Luminosity is constant but s (so rate…) increases  Effective polarisation (we+wp)/(1+ we wp) for physics - high also for a relative low positron polarization ( ) if electrons 0.8 (~ 0.9) A. Variola Rate increased by 1.5

Dynamic aperture E. Levichev - DA reduced by the strong IR sextupoles can be recovered significantly (LER: 80  x x 600  y on energy; 40  x x 200  y off energy) by the weak sextupole magnets (~2% of the main ones strength). No ring sextupoles are used for optimization so further optimization is available. - One should be careful with the fringe fields of the QD0 in case the beam traverse it with an angle: even small sextupole component may degrade the aperture due to the high beta. Possible cure: introducing in the quadrupole a high order term producing, at the beam orbit, the counter-sextupole term (?) First results: no arc sextupoles optimization, no octupoles – possibility of additional DA increase

New IR design PM start the vertical plane focusing for the LER. With the larger crossing angle the beams are far enough apart at 0.35 m from the IP to have enough space to install a PM that can work on the LER M. Sullivan New QD0 design Larger crossing angle Compensating solenoids Maybe larger  for BaBar?

Cold mass space = 4 mm+4 mm Used space (supports) = 2.6 mm+2.6 mm  wire (Bare) = 1.3 mm Field quality around (Scan not performed yet) O NLY INTERNAL QUADS ON C OMPLETE CONFIGURATION Gauss S. Bettoni QD0 design

Synchrotron Radiation backgrounds SR rates are high near the physics window More iterations needed to see if the rates can’t be reduced M. Sullivan

Single beam backgrounds M. Boscolo

Luminosity backgrounds E. Paoloni

Luminosity monitor & IP feedbacks DA  NE IP Feedback N. Arnaud A. Drago K. Bertsche

RF: supply power A. Novokhatski Bunch lengthening

Impedance budget (“conscientious impedance-budget manager”) A. Novokhatski

Bunch-by-bunch feedbacks A. Drago

SLAC Response to Super-B Components of INFN Request (September 2008) A) North and South Damping ring components and injection/extraction lines  FACET B) Linac accelerator RF distribution waveguide (~72)  PEP-X C) Linac accelerating 3 m sections (~72)  PEP-X D) Linac klystrons (~36)  PEP-X E) Linac klystron modulators (~36)  PEP-X F) Linac QA and QB quadrupoles (23+13)  PEP-X G) Linac dipole correctors (~40)  PEP-X H) Linac polarized gun system & associated three spin rotators with cryo-systems (~1+3)  SuperB I) Linac e+ target and capture area (~1+spares)  SuperB J) LER and HER dipoles and quadrupoles (~1022)  SuperB and Project-X K) Dipole steering correctors (~836)  SuperB L) Magnet mechanical supports (~1000)  SuperB and Project-X M) Vacuum chambers (~~650)  SuperB N) RF stations (complete) (~15)  SuperB and PEP-X O) Feedback systems (~4)  SuperB and BEPC-II P) Diagnostics (~120)  SuperB, LCLS, SPEAR-3 Q) Injection hardware (LER and HER)  SuperB R) Temperature monitors (~2000)  SuperB S) Power supplies (~800)  SuperB and some SLAC spares M. Sullivan, J. Seeman

Conclusions (1) We have concentrated work on the issues pointed out by the miniMAC in July We are in a pretty good shape for what concerns the lattice design with polarization scheme included (a big perturbation) Dynamic aperture studies are the most important step to validate the lattice  urgent !!!! DA  NE results have confirmed the crab waist principle validity Beam beam simulations for DA  NE showed good (20%) agreement with measurements  good benchmarking of codes, good news for SuperB

Beam parameters have been adjusted so to have flexibility in tune shift value, keeping the goal of Work has started on low emittance tuning, essential for keeping the extremely low vertical emittance Other beam dynamics studies have confirmed no showstoppers if proper measurements are taken (ex. Solenoidal windings, pipe design and material and electrodes for e - cloud) We are in a very good shape, but much more work is needed for the TDR phase Conclusions (2)

TDR to do list (preliminary) Injection System Polarized gun damping rings spin manipulators linac positron converter beam transfer systems etc... Collider design Two rings lattice Polarization insertion IR design beam stay clear ultra-low emittance tuning detector solenoid compensation coupling correction orbit correction stability beam-beam simulations beam dynamics and instabilities single beam effects operation issues injection scheme etc… RF system RF specifications RF feedbacks Low level RF Synchronization and timing etc… Vacuum system Arcs pipe Straights pipe IR pipe e-cloud remediation electrodes bellows impedance budget simulations pumping system etc… Diagnostics Beam position monitors Luminosity monitor Current monitors Synchrotron light monitor R&D on diagnostics for low emittance etc… Feedbacks Transverse Longitudinal Orbit Luminosity Electronics & software etc… Control system Architecture Design Peripherals etc… Site Civil construction Infrastructures & buildings Power plants Fluids plants Radiation safety etc… Magnets Design of missing magnets Refurbishing existing magnets Field measurements QD0 construction Power supplies Injection kickers Etc… Mechanical layout and alignment Injector Rings etc… Many topics already addressed in the CDR, just need refinement

Short term action items Need names of responsables in boxes Template for each Lab with names and work availabilities: end of February  Frascati: Biagini/Raimondi  SLAC: Sullivan/Seeman  BINP: Levichev  Cockcroft: Bassi  IN2P3: Variola  IHEP: Zhang ????  KEKB: Ohnishi ? List of key topics we think will need attention in future and/or R/D to present to miniMAC Distribution list and web informations (MB) List of requests for people to hire Synergy with SPARX project Definition of services (fluids, power,…) needed (need a layout first)

Many thanks to all speakers !...and to the organizing committee !