for the SuperB Accelerator Team SuperB III Collaboration Meeting Accelerator status M. Biagini for the SuperB Accelerator Team SuperB III Collaboration Meeting LNF, March 20-23, 2012

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

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

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

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

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

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 …..

Dynamic Aperture Dynamic aperture for HER was studied for different nonlinear sources DA was optimized in the working point Qx = 0.575 & 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.

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.

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 = 0.575 & Qz = 0.595 Piminov

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

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

Cryostat Magnets and PMs

QD0: cold test

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 50 T/m @ 2600 A Stored energy (i.e. energy to be dissipated during quench) comparable to the actual QD0 The second cold test in January 2012 was a success Hard work of Pasquale and his team during Xmas vacation to make it happen After some training the prototype ran @ 2600 A System survived several transitions @ 2750A The warm test to measure field quality will be made at CERN in a very short time scale depending on $ availability : (

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)

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

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

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

RF layout Boni

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

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

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 ?

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

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

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

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

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)

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