Accelerator Overview M Accelerator Overview M. Biagini for the SuperB Accelerator Group XII SuperB Project Workshop, LAPP-Annecy 16-19 March 2010

Goals of this WS Get approved ! Keep momentum of collaboration Define lattice & parameters for TDR Discuss on site issues Discuss new topics not yet addressed (synchotron light beamlines, effects of detector solenoid and its fringe field, ...) Complete CDR2 Plan work in view of TDR

What’s new since December? Green: talks Updated ring lattices (V12) (Nosochkov) Updated beam parameters (not far from V10) (Raimondi) Updated RF studies (Novokhatski, Bertsche) Updated IR design (Sullivan) Simulations of bunch-by-bunch feedback (Drago) Spin tracking (Wienands, Monseu, Chao) Beam-beam depolarization and diffusion studies (Rimbault, Monseu) New Intra Beam Scattering code being developed (Demma, Chao) Low emittance tuning tools (Liuzzo) Dynamic aperture & beam-beam (Levichev, Shatilov) Injector design also progressing: Positron production (Poirier) Bunch compressor & Transfer lines design (Chancé) Measurement of polarization at injection by Mott technique (Baylac) CDR2 is 70% done

Layout & geometry LER SR IP 66 mrad LER SR LER arc LER arc HER arc HER 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 LER arc LER arc HER arc HER arc Rings crossing e- e+ RF

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

V12 Lattice Final Focus optimized: ARCs optimized: Shortened CCSx to decrease emittance growth and intrinsic chromaticity Y-CCS Bends rescaled to make +/- 33mrad Left-Right for both rings Distance between lines = 2.13 m ARCs optimized: Levichev: ARC sextupoles, although all –I paired, generate higher order aberrations due to X-Y interleaving. Last SD sextupole in the Dispersion Suppressor (DS) was not properly paired with its “ARC” twin. Fixed by changing DS dipole length and its position  less chromaticity (1 unit) but 1% ex increase LER Arc cell length readjusted to take into account different sagitta due to shorter bends Left-Right Arcs lengths readjusted Doglegs removed  secondary crossing (“parasitic) now in the first 3p cell in HER, lengthened by about 25 m

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. LER HER mx = 3p, my = p Cell in HER mx = 3p, my = p Cell in LER

“Parasitic” crossing Doglegs have been removed and the secondary crossing (“parasitic) is made by lengthening the first 3p cell in HER by about 25 meters This makes the two beam lines cross with and angle of about 165mrad (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,...)

LER Spin Rotators 2 SR just before and after the FF 4 solenoids and 5 quadrupoles each Lower chromaticity

Injection arc cells Injection into rings is performed in one modified arc cell (very compact design) High horizontal beta for higher efficiency Kick needed is very small Having dispersion at injection septum actually helps

Full rings optical functions

MAD tracking LER b vs Dp/p x-px plane (Dp/p=0) y-py plane (Dp/p=0) HER Each contour is a 10 s particle. Energy acceptance from tracking: 1%

IBS in SuperB LER (lattice V12) v=5.812 pm @N=6.5e10 h=2.412 nm @N=6.5e10 Effect is reasonably small. Nonetheless, there are some interesting questions to answer: What will be the impact of IBS during the damping process? Could IBS affect the beam distribution, perhaps generating tails? More sophisticated simulation in progress (Chao, Demma) z=4.97 mm @N=6.5e10 T. Demma

IR Design The white paper design uses the “Italian design” for QD0 and QF1 – self-compensating air core super-conducting quads next to each other We are taking a close look at the “Siberian design” of Panofsky style quads for QD0 and QF1 This design option is showing some promise More details in the IR talk M. Sullivan

The Present Baseline Design M. Sullivan

Energy change The baseline design has been studied to see how we change center of-mass energy while maintaining the same magnetic field strength ratio for QD0 and QF1 The result is we can get to all of the Upsilon resonances and are able to scan the center-of-mass energy above the 4S while maintaining a constant field ratio in both QD0 and QF1 without removing or changing any of the permanent magnets We have to remove most if not all of the permanent magnets to go down to the Tau-charm region M. Sullivan

Energy table M. Sullivan Resonance Upsilon 4S Upsilon 3S Upsilon 2S Ecm (GeV) 10.5794 10.3554 10.0236 9.4609 HER E (GeV) 6.694 6.553 6.343 5.988 QD0 (T/cm) -0.97584 -0.95329 -0.91969 -0.86285 QF1 (T/cm) 0.60408 0.59132 0.57232 0.54019 LER 4.18 4.091 3.96 3.737 -0.63941 -0.62522 -0.60435 -0.56882 0.37412 0.36616 0.35445 0.33450 QD0 ratio 1.52617 1.52472 1.52179 1.51693 QF1 ratio 1.61466 1.61491 1.61469 1.61490  1.02785 1.02787 1.02791 Boost () 0.23763 0.23773 0.23775 0.23793

Bunch-by-bunch feedback simulation Feedback kick Phase of a bunch vs # turns Longitudinal invariant of motion vs # turns

RF RF system complies with SR losses and beam currents requirements also for high current option Number of cavities ok for phase transient A. Novokhatski, K. Bertsche

Spin dynamics studies Carried out with different codes: SLICTRACK  Wienands (SLAC), Barber DESY) ZGOUBI  Meot, Monseu (Grenoble) GiuneaPig++  beam-beam depolarization effects  Rimbault (LAL)

Beam tilt in x-z and y-z planes due to lattice distortions A. Chao (SLAC) is speding a 3 months sabbatical at LNF Will study with 6D SLIM code the effect of solenoids, skew quads and sextupoles errors on the beam tilt at the IP, possibly affecting luminosity These effects may be small but need to be evaluated Will also work on new IBS code A. Chao

Beam dynamics “to do list” Spin rotator matching studies and spin dynamics Benchmark different tracking codes Evaluate the solenoid fringe field effect Evaluate beam-beam depolarization and diffusion Dynamic aperture & beam-beam ...

Polarimeter at injector M. Baylac

Bunch compressor after DR Due to the acceleration in the Linac, the longitudinal distribution of the beam will be changed and the energy spread may increase. Compression of the beam is performed after the DR and before the Linac in order to minimize the rms momentum spread A magnetic C-chicane (achromatic) will change the beam path according to its energy Used PEP-II LER dipoles A. Chancé

Status of CDR2 (White Paper) About 70% of text already received and assembled Need some more effort in order to finish soon Most of technical issues solved, some will be addressed here (ex. synchrotron radiation beamlines option)

Conclusions Lattice and parameters optimization continued for better and better performances and flexibility New beam dynamics issues studied (IBS, spin, beam-beam effects) Accelerator design is converging All aspects are starting to look feasible Need more manpower for TDR Hope to hear good news soon!