1. for the SuperB Accelerator Team SuperB III Collaboration Meeting
Accelerator status
M. Biagini
for the SuperB Accelerator Team
SuperB III Collaboration Meeting
LNF, March , 2012

2. Accelerator status
A cost estimate of the accelerator, based on the «blue book» parameters (Dec. 2010) needs to be ready by July
This meeting is essentially devoted to the organization of the team and discussions on costing
Lattice issues will be also addressed in order to be able to freeze it by summer
Most of the accelerator subsystems leaders have been identified and are ready to start the cost estimate

3. SuperB footprint @ Tor Vergata for the V16
Circumference= 1195 m
LER tilted wrt HER (about 3 mrad)
5 Photon lines for HER
6 Photon lines for LER

4. Main Rings Lattice
Main goal of V16 lattice (fall 2011) was to develop a footprint better satisfying the Tor Vergata site and optimize emittances:
Initial rings symmetry was broken in order to introduce a required crossing angle at IP (66 mrad)
Radial separation in the tunnel is ~2 m
A vertical beam tilt of 2.6 mrad between the LER and HER median planes was introduced in IR. As a result, the first horizontal dipole now declines the beam vertically also providing 0.9-m-rings separation in vertical plane at the IP counter point. This separation allows SR beam lines output from both LER and HER
Chromatic functions are corrected to provide high energy acceptance
Radiation parameters of arc cells are tuned
Injection sections with required parameters were inserted
Undulator (ID) sections (3m) were inserted in LER and HER
Rings optics was matched

5. LER & HER rings IP Circumference 1195 m
Horizontal separation of arc ~2 m
Vertical separation of RF section 0.9 m
Dimension sizes of rings 416 m x 342 m FF
Spin Rotator
3 ID cells
3 ID cells
Injection section
RF section

6. Scheme of ring separation
αtilt=2.6 mrad
Vertical separation 0.9 m
Siniatkyn

7. Lattice
We have identified all the points that need to be reviewed, changed or checked (short list below…)
Crossing angle to 30 mrad (now 33)
Solenoidal (BaBar) field & compensating solenoids (there is a previous version by Yuri Nosochkov, good enough to start) + coupling correction in the IR
IP doublet adjustments according to new design (space, gradients)
Insert pm quadrupoles
IP optical functions different in 2 rings (now equal)
Optimization of tunes (DA + bb)
Chromaticity correction in FF (to be optimized, crab sextupoles!)
Solenoids for rings tilt at IP (do we really need the tilt? Otherwise we need to design a chicane on the other side)
Injection sections (increase betas)
RF layout (check the two rings don’t interfere)
IDs sections (betas, space available) to be optimized
Reduce the LER emittance with IBS (2.3 nm -> 1.7 nm). For HER excess is 7%
Dynamic aperture optimization (energy acceptance, transverse) with crabs and errors
LET for tolerances in both rings (orbit , dispersion, coupling correction) including FF
Possibility to move IP doublet gradients to scan energy up and down
Low energy option
…..

8. Dynamic Aperture
Dynamic aperture for HER was studied for different nonlinear sources
DA was optimized in the working point Qx = & Qz = 0.595
Influence of crab sextupoles on DA is strong and harmful  needs effort to cure this effect
DA for present ideal lattice (25 x & 200 z) is enough to get a required luminosity and injection
First version of the DA tune scan was performed that provides a possibility of better tune point definition.

9. Crab Sexts Influence on Dynamic Aperture
Unfortunately switching on the crab sextupoles (even thin!) drastically reduces the dynamic aperture down.
Piminov
All nonlinearities
All w/o Crab Sexts
All w/o Kinematics
and Fringes
200 z
25 x
Kinematics and fringes break the –I condition at high amplitude.

10. Betatron Tune Scan Working point is Qx = 0.575 & Qz = 0.595
Horizontal DA vs tune point
Vertical DA vs tune point
Working point is Qx = & Qz = 0.595
Piminov

11. Plans for DA
Compensation of interaction of Crab Sexts with Kinematics & Fringes should be found Piminov
Energy acceptance optimization with the help of non linear correctors is needed  Piminov
Realistic distribution of magnetic field in the FF region is needed  Paoloni
We should try to find good solution for the dynamic aperture and the energy acceptance for the best working point luminosity (Qx = 0.53, Qz = 0.57)  Piminov, Shatilov
Optimization of LER will be similar
Estimate of errors & misalignments influence on the dynamic aperture is needed  Liuzzo

12. General IR Design Features
Crossing angle is +/- 30 mrad
Tried 33 mrad – total crossing angle of 66 mrad – but found that SR backgrounds from large transverse (high sigma) orbits caused too much background on the detector beam pipe
Cryostat has a complete warm bore
Both QD0 and QF1 are super-conducting
Also the extra focusing quadrupoles for the HER (QD0H and QF1H)
PM in front of QD0
The magnet strength is as high as reasonable in order to get the most focusing in as close as possible to the IP
Soft upstream bend magnets
Reduce the SR power in IP area as much as possible. This applies especially to the inside walls of the cryostats

13. Cryostat Magnets and PMs

14. QD0: cold test

15. Cold test of the QD0 prototype
SC team
The QD0 prototype was designed to study the capability of such a light system to survive the quench
Design gradient A
Stored energy (i.e. energy to be dissipated during quench) comparable to the actual QD0
The second cold test in January was a success
Hard work of Pasquale and his team during Xmas vacation to make it happen
After some training the prototype 2600 A
System survived several 2750A
The warm test to measure field quality will be made at CERN in a very short time scale depending on $ availability : (

16. Polarization
Longitudinal polarization of electron beam in LER is a strong physics request
Two 90 spin rotators scheme with restoration of the vertical direction of a spin in the arcs is the option for E = 4.18 GeV and for some specific energies below
Polarization parameters were estimated analytically and by the ASPIRRIN computer code (BINP)
With present lattice max polarization in the ring 70% (assuming gun has P=90%... probably is 80%...)
More frequent injection of fresh beam can increase P at the cost of putting more stress on the injector
In Acceleraticum a spin tracking option was added recently. The code was tested without the BB and everything works well, the next step is a combination with BB LIFETRAC. To be compared to other codes (Barber, Monseu, Rimbault)

17. Collective effects
Most of these effects have been studied and remediation techniques chosen:
Intra-Beam-Scattering (IBS) inside the bunch produces emittance and energy spread growth (not important in Damping Ring)  effect estimated
Electron-cloud instability limits the current threshold of the positron beam  mitigation methods (solenoids, beam pipe coating, clearing electrodes...)
Fast Ions Instability, critical for the electron beam
CSR (Coherent Synchrotron Radiation) degrades beam quality (not important in Damping Ring)
Microwave instability threshold to be checked

18. Conclusions on Main Rings
Lattice «close» to be frozen, some more work needed on beam dynamics issues  deadline is summer
We do have clear ideas on what is needed to finalize the lattice and we are identifying the team for this
We will proceed with the estimate of the rings aperture and impedance budget asap  needed also for cost estimate of magnets and vacuum system
Key decisions on rings layout will be taken asap  needed for site layout and injection system

19. Injection Complex Present status Remaining work: Systems ready for TDR
Guiducci
Present status
Parameters and site layout selected
Layout and parameters of the system components defined
Beam dynamics evaluation started
Remaining work:
Baseline decision on electron source: direct injection or damping ring
Baseline decision on positron source: conversion at low energy (.6 GeV), L-band linac for capture and acceleration up to 1 GeV (or a combination of S and L band)
Transfer lines layout and composition follows
Systems ready for TDR
Damping ring
Main linac

20. RF layout
Boni

21. Polarized electron source
A design choice is needed: electrons injection with/without passing through the DR
Is it possible to produce and accelerate to 4.18 GeV polarized electrons with ~ 1 nC charge, low emittance and small energy spread?
Very preliminary beam dynamics study
Further checks are needed:
Very important to define the charge and bunch length needed/feasible at gun exit

22. Positron Source What we are doing: What is planned:
Variola
What we are doing:
1) Study of the extension of the drive beam to 1 and 1.5 GeV (to study a full 3 GHz solution). Optimization of the production target and of the capture system
2) Study of the TM 020 L band cavity
3) Costing of the L Band solution
What is planned:
1) Hybrid solution (L and S band)
2) Coupling correction
3) Matching to the TL
4) Injection simulations

23. SuperB as SR source
Italian Society for Synchrotron Light (SILS) has published a document about possible experiments at SuperB
SuperB brilliance larger than ESRF, however parasitic operation and maximum current are a limitation
Collider has priority, SR operation could be delayed when B physics program is terminated ?

24. MOU with SLAC for PEP-II components
Draft MOU prepared and sent to SLAC for discussion and finalization
First list of PEP-II components is ready, final list will be presented a year from now
Similar MOU is being prepared for BINP

25. BINP offer
BINP has make an offer to build some components of the accelerator complex:
MR magnets
MR vacuum
Linac
This offer will be evaluated by two committees (Magnets, Linac).
The first one (Magnets) started the analisys of the magnetic system needed and available form PEP-II and the evaluation of the BINP proposal has been appointed in February
There are already two preliminary, independent cost estimates on the basis of the latest V16 lattice, to be discussed with BINP experts

26. First 18 job profiles identified for Cabibbo Lab personnel
Accelerator Physicist
Radio Frequency Engineer
Electronics Engineer for Feedback Systems
Diagnostics Engineer
System Manager for Control Systems
Developer in C++, Linux environment, for Control Systems
Electronics Engineer for Pulsed-Power Systems
Vacuum System Engineer
2 Mechanical Engineers
Magnet Engineer
Mechanical HVAC Engineer
Electrical Engineer
Construction Engineer
Management Engineer
Safety Engineer
Cryogenics Engineer
Electronics Engineer power converters
Soon available on web
Selections hopefully in April

27. List of present partners
Country
Partner
Location
Short name
Contact person
Field
Italy
Istituto Nazionale Fisica Nucleare
Frascati
INFN-LNF
M. Biagini
Tor Vergata
INFN-ROMA2
L. Catani
Controls
Pisa + Genova + Napoli
INFN-PI, GE, NA
E. Paoloni, P. Fabbricatore
IR, IR magnets
Padova
INFN-PD
M. Bellato
Timing
Bari
INFN-BA
G. Iaselli
TBD
Italian Institute of Technology
Genova
IIT
E. Di Fabrizio SR
USA
DOE – Stanford Linear Accelerator
Stanford
SLAC
J. Seeman
PEP-II comp.
France
Centre National de la Recherche Scientifique
Orsay
IN2P3-LAL
A. Variola
Injection
Grenoble
IN2P3-LPSC
M. Baylac
Annecy
IN2P3-LAPP
A. Jeremie
Vibrations meas. UK
John Adams Institute
Oxford
JAI
A. Seryi
FF, IR
DIAMOND
Rutherford
R. Bartolini
SR, FEL
Russia
Budker Institute
Novosibirsk
BINP
E. Levichev
Lattice, magnets, vacuum, Linac
Poland
Institute of Nuclear Physics PAS
Krakow
 PAS
T. Lesiak
Installation and test

28. Conclusions I
Organization of the accelerator structure is progressing: most of the accelerator subsystems leaders have been identified in order to start cost estimate asap
An MOU with SLAC for procurement of PEP-II equipment is being prepared
Two committees are in charge of evaluating BINP offers for magnets, vacuum and Linac
We have some system «close» to TDR phase
Some strategical design choices still to be taken (ex. in injection system, layout of rings)

29. Conclusions II
Most important issues to solve in the next months have been identified
R&D on control system is progressing fast
Beam dynamics studies in the injection system started, collective effects in the DR are ok
R&D on new bunch-by-bunch feedback very positive (test at DAFNE)
Collaboration with other INFN structures (besides international partners) is starting
Lattice issues will be fixed before summer