1. SuperB Accelerator Status
M. Biagini
for the SuperB Accelerator Team
XV SuperB Workshop
Caltech, CA, Dec , 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 LNF (Tomassini)
Vibration studies (Bertsche)
Vibration 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 DIAMOND (Liuzzo)

3. Accelerator sessions Accelerator I - Lattice Accelerator - MDI
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, 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 CDR, xy = 0.17 CDR2, xy = 0.097 Shatilov
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.
QS1
QS3
QS2
QS4
[bxby]1/2
CCX
CCY
ROT IP
QD0P rotation
SC skew coil
Skew quad locations
New
Coupling angle after correction
Nosochkov
QD0P angle
unchanged
QD0P angle
optimized

14. Intra Beam Scattering 3 methods used, all in good agreement:
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)
ex,z vs bunch current

15. IBS in SuperB HER (h= v=2 s=40ms)
V13 vs V12
Demma
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
New
Demma
Input parameters for CMAD
=10x1011
=9x1011
=8x1011
Beam energy E[GeV]
6.7
circumference L[m]
1200
bunch population Nb
5.06x1010
bunch length σz [mm] 5
horizontal emittance εx [nm rad]
1.6
vertical emittance εy [pm rad] 4
hor./vert. betatron tune Qx/Qy
40.57/17.59
synchrotron tune Qz
0.01
momentum compaction 
4.04e-4
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
New
Drago
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 - completely new systems in place of the old systems designed in 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

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: Cons: Total length about 350 m
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. Proposed scheme (new wrt CDR2) positron linac combiner DC dipole
R. Boni, S Guiducci, M. Preger, P. Raimondi (LNF)
O. Dadoun,P. Hermes, F. Poirier, A. Variola (IN2P3)
A. Chancé, CEA Saclay e+
THERMIONIC
GUN
SHB
0.6 GeV PC
CAPTURE
SECTION
positron linac
BUNCH
COMPRESSOR
5.7 GeV e GeV e- e-
combiner
DC dipole
0.25 GeV
POL.
SLAC
50 MeV
Wien
filter
Mott
polarim
collimators
1 GeV
Parameter
Units
SLC
Electron charge per bunch nC 16
Bunches per pulse 2
Pulse rep rate Hz
120
Cathode area
cm2 3
Cathode bias kV
-120
Bunch length ns
Gun to SHB1 drift cm
150
en,rms,gun (fm EGUN)
10-6 m 15
from A. Brachmann - SuperB Workshop SLAC, 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 24

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 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 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?