The SuperB Accelerator M. Biagini for the SuperB Accelerator Team Epiphany 2012 Conference Krakow, January 9-11, 2012

SuperB Accelerator SuperB is a 2 rings, asymmetric energies (e 4.18, e 6.7 GeV) collider with:  large Piwinski angle and “crab waist” (LPA & CW) collision scheme  ultra low emittance lattices  longitudinally polarized electron beam  target luminosity of cm -2 s -1 at the  (4S)  possibility to run at  /charm threshold with L = cm -2 s -1 Criterias used for the design:  Minimize building costs  Minimize running costs  Minimize wall-plug power and water consumption  Reuse of some PEP-II B-Factory hardware (magnets, RF) SuperB can be also a good “light source”: there will be some Sinchrotron Radiation beamlines (collaboration with Italian Institute of Technology) 2

3 World e + e - colliders luminosity B-Factories  -Factories Future Colliders Super Factories Linear colliders SuperB SuperB: highest world luminosity collider ever

Ultra-low emittance Very small    at IP Large crossing angle “Crab Waist” transformation Small collision area Lower    is  possible NO parasitic crossings NO x-y-betatron resonances Principle: beams more focused at IP + “large” crossing angle (LPA) + 2 sextupoles/ring to “twist” the beam waist at the IP (CW) Large Piwinski Angle & Crab Waist: a novel idea for Luminosity increase Proved to work at upgraded DA  NE  -Factory P.Raimondi, 2° SuperB Workshop, March 2006 P.Raimondi, D.Shatilov, M.Zobov, physics/

NEW COLLISION SCHEME DA  NE Peak Luminosity Design Goal 5

6 SuperB main features Goal: maximize luminosity while keeping wall power low 2 rings ( ~ 4 GeV and ~ 7 GeV) with flexible design Ultra low emittance optics: 7x4 pm vertical emittance Beam currents: comparable to present Factories LPA & CW scheme used to maximize luminosity and minimize beam size blow-up No “emittance” wigglers used (save power) Design based on recycling PEP-II hardware (save costs) Longitudinal polarization for electrons in the LER (unique feature) Possibility to push the cm energy down to the  -charm threshold with a luminosity of cm -2 s -1

Parameter Table Baseline + other 2 options: Lower y-emittance Higher currents (twice bunches) Tau/charm threshold running at Baseline: Higher emittance due to IBS Asymmetric beam currents RF power includes SR and HOM 7

SuperB layout Site Tor Vergata University (Rome II) campus Sinchrotron Light (SL) beamlines are becoming part of the layout (HER preferred at the moment) One tunnel will host both rings, which will probably have a tilt one respect to the other, to allow for easier crossing and SL beamlines from both HER and LER (if needed) The position of the Linac complex has still to be finalized, depending on the injection requirements The rings layout has been recently improved to accomodate Insertion Devices (ID) needed for SL users 8

Site LNF About 5 Km Tor Vergata University campus 9

Ground measurements Ground motion measurements performed on site in April show very «solid» grounds in spite of the vicinity of the highway, just 100 m away The highway is at higher level with respect to the site, and the traffic vibrations («cultural noise») are very well damped Ground x-section Volcanic soil 10

Tor Vergata SR Beamlines Injection complex 11 SR Beamlines Tomassini

12 Rings Lattice The two rings have similar geometry and layout, except for the length of dipoles The arcs cells have a design similar to that of Synchrotron Light Sources and Damping Rings in order to achieve the very low emittances In the latest version of the lattice some cells for Insertion Devices have been inserted Rings are separated about 2m in horizontal and 1m in vertical

Spin Rotator FF 3 ID cells Injection section RF section 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 Siniatkyn Collider Layout

14 α tilt =2.6 mrad Vertical separation 0.9 m Vertical rings separation Rings tilt at IP (by small solenoids not vertical bends) provides ~1 m vertical separation at the opposite point: (a) e+e- beams separation, (b) SR beamlines from both rings, (c) better equipment adjustment

Polarization in SuperB 90°spin rotation about x axis  90°about z followed by 90°about y “flat” geometry  no vertical emittance growth Solenoid scales with energy  LER more economical Solenoids are split & decoupling optics added The SR optics design has been matched to the Arcs and a similar (void) insertion added to HER This design poses severe constraints on the FF bending angles of LER and HER in order to achieve the “right” spin dynamics A polarimeter has been designed to measure polarization IPHER LER S.R. solenoids (90° spin) S.r. dipoles (270° spin) 15

Polarization resonances E LER Beam polarization resonances do constraint the beam Energy choice Plot shows the resonances in the energy range of LER Beam polarization computed assuming  90% beam polarization at injection  3.5 minutes of beam lifetime (bb limited) From this plot is clear that the best energy for LER should be 4.18 GeV  HER must be 6.7 GeV 16

Interaction Region The Interaction Region must satisfy both machine and detector requirements:  Final Focus elements as close as possible to the IP  Small detector beam pipe  Enough beam stay clear  small emittance helps  Control Synchrotron Radiation backgrounds  Have an adequate detector solid angle  Magnet vibrations need to be damped (at the level of 10nm)  A state-of-the-art luminosity feedback is needed With the large crossing angle the beam is off-axis in the first quadrupoles, hence it is not only focused but also bent, producing unwanted SR backgrounds and emittance growth For SuperB a new design of the first doublet with «twins» quadrupoles was developed 17

Final Focus sections “Spin rotator” optics is replaced with a simpler matching section IP Y-sext X-sext MatchCrab HER Matching section is shorter than HER to provide space for spin rotator optics. ±33 mrad bending asymmetry with respect to IP causes a slight spin mismatch between SR and IP resulting in ~5% polarization reduction. IP Y-sext X-sext Match & Spin RotatorCrab LER  * = 26 / 0.25 mm  * = 32 / 0.21 mm 18

QD0 Design: 2 possible choices Vanadium Permendur “Russian” Design Air core “Italian” QD0, QF1 Design 19

Air-core QD0 is a SC iron free septum double quad 20 Field generated by 2 double helix windings in a grooved Al support

Construction of a model coil for addressing quench issues The coil has been constructed at ASG Superconductors and now is at INFN Genova for testing at 4.2K. The results of this test are crucial for the design. Test this month

Collettive effects Stored beams are subject to effects that can produce instabilities or degrade the beam quality, such as:  Intra-Beam-Scattering (IBS) inside the bunch produces emittance and energy spread growth (not important in Damping Ring)  Electron-cloud instability limits the current threshold of the positron beam  needs mitigation methods (ex. solenoids, beam pipe coating, clearing electrodes...)  Fast Ions Instability is critical for the electron beam  CSR (Coherent Synchrotron Radiation) degrades beam quality (not important in Damping Ring) These effects have been studied and remediation techniques chosen 22

23 Snapshot of the electron (x,y) distribution Density at center of the beam pipe is larger then the average value. E-cloud build-up in Free Field Regions Snapshot of the electron (x,y) distribution 50G solenoids on Solenoids reduce to 0 the e-cloud density at center of beam pipe

24 e-cloud buildup in HER Dipoles By=0.3 T;  =95% SEY=1.1  th = [e-/m 3 ] e- density at center of the beam pipe e- density averaged over the beam chamber 10 X beam sizes Snapshot of the electron (x,y) distribution “just before” the passage of the last bunch Demma

e-cloud clearing electrodes in DA  NE Very positive results: vertical beam dimension, tune shift and growth rates clearly indicate the good behaviour of these devices, which are complementary to solenoidal windings in field free regions Drago Beam loss above this current if no feedbacks 25

Low emittance tuning The extremely low design beam emittance needs to be tuned and minimized  careful correction of the magnet alignment and field errors These errors produce emittance coupling with transfer of some horizontal emittance to the vertical plane  this needs to be minimized Beta-beating (ring  -functions are not as in the model machine, but are perturbed by the magnet errors) also needs minimization Vertical dispersion at IP needs to be corrected to the lowest possible value not to compromise luminosity 26

LET Tool This tool has been successfully tested at Diamond (RAL) and SLS (PSI) synchrotron light sources, which have similar emittances as SuperB. This work allows to set tolerances on magnet alignment and once the machine is running is able to detect such errors for correction 27

First tolerance tests for HER V16 misalignmentsARCSFF QUAD SEXT DX,DY50 μm30 μm QUAD SEXT DPHI100 μrad50 μrad Monitor resolution1 μm Monitors OFFSETs50 μm DIPOLE DPHI and DTHETA 50 μrad 50 random sets, correcting with LET for 2 iterations after 3 orbit pre-correction iterations before 4.4 pmrad

Injection System Injection in top-up requires a very stable, reliable injection complex Latest design: Only e+ beam is stored in Damping Ring (DR) while e- beam is directly accelerated and injected  e+ stored in DR for the time between two injection pulses, achieving same emittance damping factor at twice the repetition frequency  possible with a 100 Hz Linac to inject at 50 Hz in each ring using a single bunch per pulse to make the current per bunch very uniform along the bunch trains Proposal: use SLAC gun (high charge, 10 nC) for the e+ line and have a custom made polarized, low charge, low emittance gun for the e- line R&D in progress at LAL/Orsay for the positron source Contacts with SPARC group in Frascati for the low emittance gun R&D at SPARC on C-band Linac maybe useful also (shorter) Boni, Guiducci, Preger, Variola et al) 29

THERMIONIC GUN SHB 0.6 GeVPC BUNCH COMPRESSOR 5.7 GeV e+ 3.9 GeV e- POLARIZED SLAC GUN SHB 50 MeV CAPTURE SECTION e+ e- combiner DC dipole 0.2 GeV CAPTURE SECTION positron linac 1 GeV e+ ≈ 350 m L-band Positron Source Polarized Electron Source Main Linac e + Damping Ring Transfer lines Positron Source to Damping Ring Damping Ring to Main Linac Electron Source to Main Linac Main Linac to HER Main Linac to LER Transfer lines Positron Source to Damping Ring Damping Ring to Main Linac Electron Source to Main Linac Main Linac to HER Main Linac to LER Injection system layout Details: “SuperB Progress Reports – Accelerator”, (Dec. 2010) – Chapter “Updated Design of the Italian SuperB Factory Injection System”, IPAC’11

Injection Complex 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 31

Injection tracking with bb No beam-beam Crab = 1 Crab = 0.5 Crab = 0 Average over (1 ÷ 100) turns No beam-beam Crab = 1 Crab = 0.5 Crab = 0 Average over (4001 ÷ 4100) turns 32 No beam-beam Crab = 1 Crab = 0.5 Crab = 0 Average over (30001 ÷ 30100) turns

SuperKEKB 33

Feedbacks Drago 34

R&D on Controls (!CHAOS) This activity attracted interest from several other INFN structures and Universities Bisegni 35

SuperB not «just a collider» 36

Brilliance SuperB vs ESRF (and ESRF upgrade) Used U23 of ESRF ID27 ESRF parameters (4nm) 200 mA 0.7% coupling 2 m undulator ESRF upgrade (4nm) 300 mA 0.3% coupling 4 m undulator SuperB (2nm) 500 mA 0.7% coupling 2m undulator SuperB ESRF upgrade ESRF Bartolini 37 Compatibility with collider operation (current, orbit stability, heat load management,… ) needs to be studied

MC simulations of different targets for different particles production Quintieri 38

Summary on Accelerator work Lattice «close» to be frozen, some more work needed on beam dynamics issues We do have some systems «close» to TDR phase Some strategical design choices still to be taken (ex. in injection system) Most important issues to solve in the next months have been identified R&D on control system started R&D on new bunch-by-bunch feedback very positive (test at DA  NE) Tests on e-cloud suppression electrodes at DA  NE successfull 39

Organization The Cabibbo Laboratory, in charge of building and operating the SuperB Accelerator and Detector, has been founded on October 7th 2011 as a Consortium between INFN and University of Tor Vergata Systems (almost) ready for technical design:  Magnets, vacuum chamber, support structure of the main rings  Beam diagnostic and control  Power supplies  Damping ring  Linear accelerator  Polarized electron source and positron source 40

List of present partners Country PartnerLocationShort nameContact person WP Italy Istituto Nazionale Fisica Nucleare FrascatiINFN-LNFM. Biagini1,2,3,4,5,6,7,8, 9,10,14,16,17,1 8,19,20 Tor VergataINFN-ROMA2L. Catani7,10,15 Pisa + Genova + Napoli INFN-PI, GE, NA E. Paoloni8 PadovaINFN-PDM. Bellato10 BariINFN-BAG. IaselliTBD Italy Italian Institute of Technology GenovaIITE. Di Fabrizio11 USA DOE – Stanford Linear Accelerator StanfordSLACJ. Seeman20 France Centre National de la Recherche Scientifique OrsayIN2P3-LALA. Variola1,2,3,4,5,6 GrenobleIN2P3-LPSCM. Baylac15 AnnecyIN2P3-LAPPA. Jeremie7,8 UK John Adams Institute OxfordJAIA. Seryi7,8 DIAMONDRutherfordDIAMONDR. Bartolini6,11,13 Russia Budker InstituteNovosibirskBINPE. Levichev5,6,15,18 Poland Institute of Nuclear Physics PAS Krakow PAST. LesiakTBD

Conclusions I Organization of the accelerator structure is progressing We have a draft organization of the accelerator work structure in Work Packages, with milestones and deliverables, needs refinement We plan to commission to other laboratories/Institutions parts of the accelerator, taking into account their expertise in the field Some examples at present: France for the positron source, FF vibration control, ground measurements,… England for the Final Focus, IP feedback, SL beamlines,… BINP for DR, special magnets, vacuum pipe,… SLAC for PEP-II components (RF, magnets,…) Poland contribution to be discussed 42

Conclusions II An MOU with SLAC for procurement of PEP-II equipment is being prepared Synchrotron Light Italian community started to consider SuperB properties for SL users  needs more thoughts on maximum current, operation mode, experiments MC simulations on the possibility to have a «SuperBeamTestFacility» started  interest from users With the Cabibbo Laboratory now in place we will be ready soon to hire personnel and reinforce the collaboration in order to finish TDR and start digging the tunnel before the end of this year Thank you for your attention ! 43