SuperB Accelerator Status

1. SuperB Accelerator Status M. Biagini for the SuperB Accelerator Team XV SuperB Workshop Caltech, CA, Dec. 14-17, 2010

2. What’s new since LNF meeting • Updated beam-beam tune scan (Shatilov) • Updated dynamic aperture (Piminov) • Estimation of synchrotron light properties from bends and undulators (Wittmer) • Feedbacks (Drago) • IBS and e-cloud studies (Demma) • Geological survey @ LNF (Tomassini) • Vibration studies (Bertsche) • Vibration measurements @ LNF (Brunetti) • Backgrounds studies (Sullivan, Perez) • IR coupling correction without solenoid (Nosochkov) • Second order momentum compaction estimate (Novokhatski) • Wakefields in the IR (Weathersby) • QD0 design/prototype work (Paoloni) • Site committee document (Raimondi/Tomassini) • Spin tracking in LER (Monseu) • LET studies @ DIAMOND (Liuzzo)

3. Accelerator sessions • Accelerator I - Lattice • IR lattice, Discussion • Accelerator - MDI • Geant4 model, Discussion • Accelerator II – Beam Dynamics • IBS, e-cloud, Spin tracking • Accelerator III – Site & Layout • Geological survey, Site Committee, Synchrotron light beamlines • Accelerator IV – Vibrations • Vibration studies, measurements • Accelerator V – IR & Backgrounds • Backgrounds, QD0, Wakefield calculations in IR • Accelerator VI – Discussion • Accelerator VII – RF & Feedbacks • B-by-B feedback, Second order ac, LET @ Diamond • Accelerator VIII – Discussion • Accelerator IX – Discussion • Accelerator Board (All invited)

4. CDR2 Accelerator • Accelerator part of CDR2 updated last week with: • New beam-beam scan (Cha. 8) • Dynamic aperture (Cha. 6) • Possible synchrotron light beamlines (Cha. 18) • Ready to be updated on arXiv

5. Lattice studies • Modified V12 (CDR2) 3p ARC cell lattice with alternating long and short arc cells  V13 • Modified Final Focus design for better performances • Near-IP lattice with detector solenoids and compensation of coupling  new scheme for coupling compensation solenoids OFF (Nosochkov) • Dynamic aperture checks and improvement of tools • Some studies also performed for a shorter Ring (V14)

6. Layout of HER arcs (Sep.’10) Sinyatkin V12 V13 V14

7. Parameter list comparison V12 = CDR2 lattice V13 = modified V12 (new arcs) V14 = shorter ring (on hold)

8. Beam-beam Shatilov • Beam-beam tune scan performed with latest beam parameters (V12) and latest beam beam code, improved to take into account crabbed beams • Comparison with previous parameters: lower bb tune shift increases tune operation area and achievable luminosity (10^36 in the large red area) • Needs to be run including lattice nonlinearities for bb tails and lifetime, as soon as the lattice is “reasonably” stable

9. Beam-beam tune scan Shatilov CDR, xy = 0.17 CDR2, xy = 0.097 L (red) = 1. ∙1036

10. Dynamic Aperture studies Piminov, Chancé Acceleraticum • Comparison between MADX (Chancé) and Acceleraticum (Piminov) codes • Found few discrepa-cies (MADX more realistic model)  corrected, now in agreement • Found that, as expected, crab-waist sextupoles reduce dynamic aperture HER LER

11. To do list for “lattice” • Decided to concentrate on just on lattice for lack of manpower • V13 with “new FF” was chosen. MAD8 files have been released (Indico page) • This lattice needs still fixes but it is a good approximation (not too far from) to what we have written on CDR2 • V14, short ring, needs to be further shorten to fit perfectly into LNF area, so this work has been postponed

12. To do list for “Lattice” • Action Items: • Build LER lattice • Adjust IR angles to comply with Spin Rotation requests • Insert near-IP solenoids & skew quads (detector, coupling compensation) • Optimize sextupoles arrangements • Verify possibility to vertically move HER wrt LER (by 30 cm or so) without increasing ey (would ease beamlines installation) • Beamlines from dipoles layout (HER/LER) • Insert undulators in both rings: • straigth sections • spin rotator sections (to verify) • Dynamic aperture optimization w/out undulators

13. Coupling correction with detector solenoid OFF Assumptions: 1) detector solenoid, bucking solenoids and anti-solenoid are OFF; 2) SC skew quad coil is ON; 3) Permanent quad QD0P rotation angle is adjustable. Correction is done using QS1,QS2, QS3,QS4 skew quads. QD0P rotation SC skew coil QS1 QS2 QS3 QS4 Skew quad locations IP CCY CCX ROT [bxby]1/2 New Coupling angle after correction Nosochkov QD0P angle unchanged QD0P angle optimized

14. Intra Beam Scattering ex,z vs bunch current Boscolo, Chao, Demma • 3 methods used, all in good agreement: • Bane (theoretical), allows for emittance growth rates estimate • Chao (theoretical), allows for emittance time evolution estimate • 6D MonteCarlo more accurate, all of above, will include non-gaussian tails, soon to be translated from Mathematica to Fortran for speed and precision reasons (collaboration with M. Pivi, SLAC)

15. IBS in SuperB HER (h= v=2 s=40ms) Demma V13vsV12 R=6% R=4.8% V-emittance H-emittance R=6% R=4.3% Momentum spread Bunch length R=2.5% R=2.5% R=2.1% R=2.1%

16. Emittance growth due to head-tail instability =10x1011 =9x1011 =8x1011 New Demma Input parameters for CMAD Taking into account the effect of solenoids in drifts,the interaction between the beam and the cloud is evaluated only in the magnetic regions of the SuperB HER (V12) for different values of the electron cloud density. The threshold density is determined by the density at which the growth starts:

17. Low Emittance Tuning for LER Liuzzo LER ARC's tolerances evaluated using a Response Matrix technique that optimizes orbit, in order to recover the design values for Dispersion, Coupling and Beta-beating, and obtain the lowest possible vertical emittance Different sets of correctors tested, may be reduced to 109. Final Focus introduces stringent restrictions on alignment of both FF and ARCS (even for no errors in FF)

18. From IR Summary @LNF • We have reset the crossing angle back to 60 mrads • This removes some of the space for the PM slices as well as the dual quad super-conducting magnets • Presently the dimensions of these elements are “snug” but acceptable at this stage (actual engineering requirements will no doubt alter the design again) • We have two designs that work for SR backgrounds • Vanadium Permendur (with Holmium as an option) • Parallel air-core dual quads + vanadium permendur Panofsky quads on the HER • Good progress is being made on the design of the QD0 • The engineering details for the “Italian” design are being studied • A prototype Panofsky style QD0 is planned for the BINP C-tau design • An overall vibration control design is being developed for the FF magnets • We have a first look at correcting the effects of the detector solenoid in hand • The polarimeter design is being studied to enable measuring transverse polarization

19. Bunch-by-bunch feedback upgrade During last month all the 6 DAFNE feedback have been upgraded VFB – new 12 bit iGp systems with larger dynamic range and software compatibility with the previous version LFB - completelynew systems in place of the old systems designed in 1992-1996 in collaboration with SLAC/LBNL: fe/be analog unit connected to iGp-8 as processing unit HFB: upgrade hw/sw of the iGp-8bit system already used Epics server upgraded to the last version of LINUX New front-end/back-end analog unit used in the longitudinal feedbacks New Drago

20. RF & Power Novokhatski New: wakefield in IR (Weathersby) Need collimators

21. HOMs Absorbers Novokhatski PEP-II absorbers suitable and available

22. Synchrotron light properties @ SuperB Wittmer • Comparison of brightness and flux from bending magnets and undulators for different energies dedicated SL sources & SuperB HER and LER • Synchrotron light properties from dipoles are competitive • Assumed undulators characteristics as NSLS-II • Light properties from undulators still better than most LS, slightly worst than PEP-X (last generation project) New

23. Injection System • Pros: • Main Rings injection rate: 50 Hz instead of 25 • Damping Ring operates just for positrons • Only 2 TL’s between Linacs and D.R., instead of 4; no special dipoles; no by-pass of the PC • No long flat top kickers in the damping ring and transfer lines • The gun for the positron line can be thermionic, thus delivering larger current • Cons: • Main Linac Klystron rep. rate: 100 Hz • The e- beam emittance is higher (round beam), can be reduced with scrapers/collimators • Total length about 350 m Boni, Chancé, Dadoun, Guiducci, Hermes, Poirier, Preger, Seeman, Variola

24. positron linac e+ THERMIONIC GUN CAPTURE SECTION SHB PC 0.6 GeV combiner DC dipole e+ e+ BUNCH COMPRESSOR 5.7 GeV e+ 3.9 GeV e- 50 MeV CAPTURE SECTION e- POL. SLAC GUN Wien filter Mott polarim 0.25 GeV SHB collimators Proposed scheme (new wrt CDR2) R. Boni, S Guiducci, M. Preger, P. Raimondi (LNF) O. Dadoun,P. Hermes, F. Poirier, A. Variola (IN2P3) A. Chancé, CEA Saclay 1 GeV from A. Brachmann - SuperB WorkshopSLAC, October 2009 Round beam Emittance @ 4.16 GeV = 1.8 nm Required bunch charge for electrons ≈ 0.3 nC … scrapers .. collimators needed R. Boni, XiV SuperB meeting, Frascati 29-09-2010

25. Site & Layout Tomassini • The rings footprint is at the moment the same as presented at Elba. Injection and transfer lines are also unchanged • A preliminary design of the civil infrastructure should be done by outsourcing • Few studies are still to be done about the positioning of the tunnel, buildings and access pits if LNF site is chosen • A second campaign of geological prospections has been done @ LNF (four additional holes) • A new campaign of ground motion measurements was carried out on October 4th with the collaboration of the LAPP group

26. Site Committee (Di Fabrizio, Esposito, Popolizio, Raimondi, Seeman, Tomassini) • Document on requirements for site choice • Site layout and geology: • Dimensions • Flatness and slope • Geology • Ground stability • Site conventional facilities: • Buildings • Electric power • Civil construction • Cooling water • Existing conventional facilities • Logistic • Site general requirements New

27. Accelerator TDR Effort • TDR work was organized during last meeting and some of the responsabilities decided. Still some question marks • 11 subsystems have been identified, 60 FTE needed • We need an injection of manpower to be able to complete it in a reasonable time • Only 2 of the 6 available positions from CNRS have been filled at the moment (Binivacuum, FoggettaRF) • M. Esposito left LNF for a CERN fellowship

28. Low Emittance Tuning @ Diamond New Liuzzo • The LET procedure studied for SuperB has been applied to the DIAMOND SL source (Rutherford) • Two MD shifts (Nov. 23th, Dec. 7th) • The procedure had to be modified to include BPM tilt errors in DIAMOND • Procedure is fast if compared with present DIAMOND LET procedure (LOCO code) • Very good results up to now (emittance coupling measured after correction 0.23%) but need more work on code and shifts

29. Conclusions • Work slowed down a bit since October meeting (commissioning of DAFNE for KLOE2 pretty much used all resources @ LNF) • Some of the collaborators left, some were (or will be) unable to continue work... • Site Committee has pointed out requirements for site choice • In this meeting: needs to address critical topics in group discussions and plan future (?) work • How do we proceed for the future?