The SuperB Detector

1. The SuperB Detector Fabrizio Bianchi University of Torino and INFN-Torino III Mexican Workshop on Flavour Physics Mexico City , 7-9 December 2011

2. Outline • The Physics Case. • The Machine. • The Detector. • Milestones.

3. The Physics Case • Current flavor physics landscape is defined by BaBar, Belle, CDF, D0, Cleo-c, BES results. • Triumph of the CKM paradigm. • Indirect constraints on New Physics. • Handed over to LHCb in the summer. • First collision in SuperB will be in 2016 and the first full run is expected in 2017. • LHCb will have re-defined some areas of Flavor Physics. • LHC may (or may not) have found New Physics. • In both scenarios SuperB results can be used to constraint Flavor Dynamics at high energy

4. The Energy Scale of NP: LNP (1) • SuperB does not operate at High Energy. • What’s the point of having it ? • Two paths in the quest for NP: • The relativistic path: • Increase the energy and look for direct production of new particles. • The quantum path: • Increase the luminosity and look for effects of physics beyond the standard model in loop diagrams. • Model dependent indirect searches for NP at SuperB reach higher scales then can be attained at LHC. • B mixing and top: everyone knew the top was light until ARGUS found B mixing to be large.

5. The Energy Scale of NP: LNP (2) • Example: MSSM. • Simple, constrained by LHC data, but general enough to • illustrate the issue: • In many NP scenarios the energy frontier experiments will • probe diagonal elements of mixing matrices. • Flavor experiments are required to probe off-diagonal ones.

6. The Timeline of Flavor Physics

7. Expected data sample for SuperBf • ϒ(4S) region: • 75ab−1 at the ϒ(4S) • Also run above / below the ϒ(4S) ~75 x109 B, D and t pairs (5 years run) • ψ(3770) region: • 1 ab−1 at threshold • Also run at nearby resonances ~4 x 109 D pairs (< 1 year run) R

8. Super B Physics Program in a Nutshell • Test of CKM Paradigm at 1% level. • B rare decays • Lepton Flavor Violation. • Charm Physics. • Bs Physics. • Many more topics: Electro-Weak measurements, new hadrons, … • See A. Perez presentation at this conference.

9. b = f1; a = f2; g = f3 The CKM Paradigm

10. Summer 2011: Triumph of CKM Good agreement: no evident discrepancy or “tension”, even with different statistical analysis.

11. Test of CKM Paradigm The "dream" scenario with 75ab-1 • Unitarity Triangle Angles • σ(α) = 1−2° • σ(β) = 0.1° • σ(γ) = 1−2° • Cabibbo-Kobayashi-Maskawa Matrix Elements • |Vub| : Incl. σ = 2%; Excl. σ = 3% • |Vcb|: σ = 1% • |Vus|: Can be measured precisely using τ decays • |Vcd| and |Vcs|: can be measured at/near charm threshold. • SuperB Measures the sides and angles of the Unitarity Triangle

12. CKM measurements: SuperB vs. LHCb

13. LHC: no Susy so far Susy mass scale is likely to be above 1 TeV.

14. B Rare Decays

15. Lepton Flavor Violation

16. Charm at SuperB • At the U(4S) with 75 ab-1: • Large improvement in D0 mixing and CPV: factor 12 improvement in statistical error wrtBaBar (0.5 ab-1). • Time-dependent measurements will benefit also of an improved (2x) D0 proper-time resolution. • At the Y(3770) with 500 fb-1: • coherent production with 100x BESIII data and CM boost up to βγ=0.56. • Almost zero background environment. • Possibility of time-dependent measurements exploiting quantum coherence. • Study CPV with Flavor and CP tagging.

17. Charm Mixing and CPV • Decays of Y (3770) D0D0produce coherent (C=-1) pairs of D0’s. Quantum correlations in their subsequent decays allow measurements of strong phases. • Required for improved measurement of CKM angle g. • Also required for D0mixing studies

18. Bs Physics • Can cleanly measure AsSL using U(5S) data • SuperB can also study rare decays with many neutral particles, such as , which can be enhanced by SUSY.

19. Golden Measurements: SuperB vs. LHCb

20. The Machine

21. Machine: Parameter Requirements from Physics

22. e+e- Colliders

23. How to get 100 times more luminosity ? Present day B-factories PEP-II KEKB E(GeV) 9x3.1 8x3.5 Ib 1x1.6 0.75x1 n 1700 1600 I (A) 1.7x2.7 1.2x1.6 y* (cm) 1.1 0.6 y 0.08 0.11 L (x1034) 1 2 • xy Vertical beam-beam parameter • Ib Bunch current (A) • n Number of bunches • by* IP vertical beta (cm) • E Beam energy (GeV) Answer: Increase Ib Decrease y* Increase y Increase n

24. A New Idea • Pantaleo Raimondi came up with a new scheme to attain high luminosity in a storage ring: • Change the collision so that only a small fraction of one bunch collides with the other bunch • Large crossing angle • Long bunch length • Due to the large crossing angle the effective bunch length (the colliding part) is now very short so we can lower y* by a factor of 50 • The beams must have very low emittance – like present day light sources • The x size at the IP now sets the effective bunch length • In addition, by crabbing the magnetic waist of the colliding beams we greatly reduce the tune plane resonances enabling greater tune shifts and better tune plane flexibility • This increases the luminosity performance by another factor of 2-3

25. The Accelerator Strategy • 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 – ideas taken from ILC design • longitudinally polarized electron beam • target luminosity of 1036 cm-2 s-1 at the U(4S) • possibility to run at t/charm threshold still with polarized electron beam with L = 1035 cm-2 s-1 • Design criteria : • Minimize building costs • Minimize running costs (wall-plug power and water consumption) • Reuse of some PEP-II B-Factory hardware (magnets, RF) • SuperB can also be a good “light source”: work is in progress to design Synchrotron Radiation beamlines (collaboration with Italian Institute of Technology)

26. Baseline Collider parameters Baseline peak luminosity at Y(4S) is 10 36 cm-2 s -1 . It ca be increased by adding RF power up to a factor of 4 . The runs near charm threshold Y(3770) pay a factor O(10) in luminosity. At charm threshold the boost( bg ) can be increased up to 0.5 for time dependent measurements, still with a reasonable polarization. Injected 90% polarized electrons 3.5 min beam lifetime . CONTINUOUS INJECTION as in PEPII

27. Synchrotron light options@ SuperB • Comparison of brightness and flux for different energies dedicated SL sources & SuperB HER and LER from bending magnets .

28. Synchrotron light options@ SuperB • Comparison of brightness and flux for different energies dedicated SL sources & SuperB HER and LER with undulators. • Light properties from undulatorsbetterthanmostSL With Undulators

29. SuperBvsSuperKEKB

30. SuperB Luminosity Model 75 ab-1

31. The Detector

32. Detector Evolution: from to • Babar and Belle designs have proven to be very effective for B-Factory physics. • Follow the same ideas for SuperB detector. • Try to reuse same components as much as possible. • Main issues: • Machine backgrounds – somewhat larger than in Babar/Belle. • Beam energy asymmetry – a bit smaller. • Strong interaction with machine design. • A SuperB detector is possible with today’s technology. • Baseline is reusing large (expensive) parts of Babar. • Quartz bars of the DIRC. • Barrel EMC CsI(Tl) crystal and mechanical structure. • Superconducting coil and flux return yoke. • Some areas require moderate R&D and engineering developments to improve performance: • Small beam pipe technology. • Thin silicon pixel detector for first layer. • Drift chamber CF mechanical structure, gas and cell size. • Photon detection for DIRC quartz bars . • Forward PID system (TOF or focusing RICH). • Forward calorimeter crystals. • Minos-style scintillator for Instrumented flux return. • Electronics and trigger. • Computing: has to handle a massive amount of data.

33. Detector Layout

34. Silicon Vertex Tracker • The Babar SVT technology is adequate for R > 3cm: • use design similar to Babar SVT • Layer-0 is subject to large background and needs to be extremely thin: • More than 5MHz/cm2, 1MRad/yr, < 0.5%X0 • Striplets baseline option: mature technology, not so robust against background. • Marginal with background rate higher than ~ 5 MHz/cm2 • Moderate R&D needed on module interconnection/mechanics/FE chip (FSSR2) • Upgrade to pixel (Hybrid or CMOS MAPS), more robust against background, foreseen for a second generation of Layer-0

35. The Drift Chamber • Provides precision momentum measurements. • Provides particle ID via dE/dx for all low momentum tracks, even those that miss the PID system. • Build on BABAR drift chamber concept, but: • Lighter structure, all in Carbon Fiber (CF) • Preliminary studies show that dome-shaped CF end-plates with X0~2% seem achievable (compare 13-26% in BaBar DCH) • Faster & lighter electronics (taking into account detectors options to be possibly installed behind backward end-plates) • Some R&D issues: • Electronics location and/or mass to reduce effect on backward EMC, • Low Mass Endplates • Can we do better on dE/dx (counting clusters)? • Conical/stepped endplates or other ways to reduce sensitivity close to the beam. • Background simulation/shielding optimization

36. The Focusing DIRC • Hadronic PID system essential for p(p,K)>0.7GeV/c • use dE/dx for p<0.7GeV/c • Baseline is to reuse BaBar DIRC barrel-only design • Excellent performance to 4GeV/c • Robust operation • Elegant mechanical support • Photon detectors outside field region • Radiation hard fused silica radiators • To cope with high luminosity (1036 cm-2s-1) & high background: • Complete redesign of the photon camera (SLAC-PUB-14282) • A true 3D imaging using: • 25 smaller volume of the photon camera • 10 better timing resolution to detect single photons • Optical design is based entirely on Fused Silica glass • avoid water or oil as optical media

37. FDIRC: Photon Camera • Photon camera design (FBLOCK): • Initial design by ray-tracing (SLAC-PUB-13763) • Experience from the 1rst FDIRC prototype (SLAC-PUB-12236) • Geant4 model now (SLAC-PUB-14282) • Main optical components • New wedge (old bar box wedge was not long enough) • Cylindrical mirror to remove bar thickness • Double-folded mirror optics to provide access to detectors • Photon detectors: highly pixilated H-8500 MaPMTs • Total number of detectors per FBLOCK: 48 • Total number of detectors: 576 [12 FBLOCKs] • Total number of pixels: 576 32 = 18,432

38. Forward PID • Goal is to improve PID in the forward region. • Challenges : • Limited space available • Any additional detector should have a small X0 • Gain limited by the small solid angle • [qpolar~15 - 25 degrees] • The new detector must be efficient • Different technologies being studied • Time-Of-flight: ~10ps resolution needed • RICH: great performances but thick and expensive • Decision by the TDR time • Task force set inside SuperB to review proposals: • There is merit to leave some space (5cm) but more would damage the DCH performance. • Building an innovative forward PID detector would require additional manpower & abilities

39. The Electromagnetic Calorimeter Essential detector to measure energy and direction of g and e, discriminate between e and p, and detect neutral hadrons Barrel (5760 CsI(Tl) Crystals) : • BaBar barrel crystals not suffering signs of radiation damage. They’re sufficiently fast and radiation hard for SuperB needs • They can be reused. (Would have been) most expensive detector component • Background dominated by radiativeBhabhas. IR shielding design is crucial Endcaps: • Best possible hermeticity important for key physics measurements • New forward endcap • Backward endcap is an option

40. Forward and Backward EMC • Forward endcap • BaBarCsI(Tl) endcap inadequate for higher rates and radiation dose of SuperB • Need finer granularity • Faster crystals and readout electronics • comparable total X0 • Option 1: LYSO crystals • frees 10cm for a forw. PID system • radiation hard, fast, small Moliere radius, good light yield • expensive (~40$/cc) at the moment • Backward endcap (option) • Pb plates and scintillating tiles with fiber readout to SiPMs (or MPPC) • Veto device, 10% sensitivity increase in B-> tn

41. Forward EMC: LYSO + possible alternatives • LYSO -> finalizing results from Test Beam at BTF • roughening of crystals is ongoing, readout with 2 APD’s per crystals is ready • beam lines not available until beginning of 2012 (we are in contact with people for BTF, Mainz, SLAC) • more news soon • Other options: • Pure CsI, readout VPT and Photopentode • Measurements in LAB have started • PWO-II + LAAPD • Second generation of crystals L.O. increased by 85% • In contact with producers to order one crystal • BGO readout PMT • already some studies have been carried out • PMT readout + APD (to be done) • BGO and PWO measurements of LY with radiation damage at Caltech • FULL MATRIX TEST with ONE of the alternatives (1-2-3) in 2012 after measurements in LAB and simulation studies

42. The Instrumented Flux Return • Provides discrimination between m and p±. Help detection and direction measurement of KL (together with EMC) • Composed by 1 hexagonal barrel + 2 endcaps as in BaBar • Add absorber w.r.t. BaBar to improve p/m separation. Amount and distribution to be optimized • 7-8 absorber layers • reuse of BaBar IFR iron under evaluation • Use extruded scintillator a la MINOS coupled to geiger mode APDs through WLS fibers • expected hit rates of O(100) Hz/cm2d • single layer or double coord. layout depending onthe x-y resolution needs

43. Electronics, Trigger, DAQ • Working conditions • Trigger rate is expected to be of the order of 100 kHz at 1036. • The sole Bhabha’s background: 50 kHz. • baseline target rate of about 150 kHz. • Issue of safety margin. How much, and where do we put the safety ? • A readout window (1ms) has to be foreseen • Synchronous mode preferred. Clock O(56MHz). • Clock and Fast Control System • Clock distribution not at all trivial to ensure phase synchronization • Try to use commercial component as much as possible (FPGA) • Relying on SLHC development (such as GBT) very risky • Try to define strategic placement of components so that radiation damage is kept under control. • Different options to be studied and simulated • L1 Trigger – Primitives @ 7MHz • Dataflow – Local buffers, overlapping readout windows • Frontend model – synchronous, fixed latency • Radiation mitigation • High Level Trigger and pre-processing boards – input bw O(15MB/s)

44. SuperB Computing Model • Baseline is an extrapolation of BaBar computing model to a luminosity 100 times larger. • “Raw data” from the detector will be permanently stored, and reconstructed in a two step process: • a “prompt calibration” pass on a subset of the events to determine calibration constants. • a full “event reconstruction” pass on all the events that uses the constants derived in the previous step. • Monte Carlo data will be processed in the same way. • Selected subset of Detector and MC data, the “skims”, will be made available for different areas of physics analysis. • Very convenient for analysis. • Increase the storage requirement because the same events can be present in more than one skim. • Improvements in constants, reconstruction code, or simulation may require reprocessing of the data or generation of new simulated data. • Require the capability of reprocessing in a given year all the data collected in previous years.

45. An Attempt to Estimate theSuperB Detector Computing Needs • Limited precision due to many assumptions: • Raw Event size ~100kByte (= 3 x BaBar) • Mini/Micro event size = 2 x BaBar • CPU / unit lumi: 3 x BaBar • 2 copies of raw data • Skim expansion factor: 5 • Some fraction of Mini on disk (100% -> 10%) • Equivalent amount of MC “lumi” • Raw data stored on tape • Storage grows from O(50) PB to O(600) PB in 6 years. • CPU grows from 500 to 12,000 KHepSpec in 6 years.

46. Computing Infrastructure

47. Cost and Challenges • Crude estimate: O(5 Million Euros/year) assuming: • Validity of Moore’s law. • Start of data taking in 2016. • Purchase the hardware one year in advance. • Infrastructure cost is not included. • But: • Is Moore’s law still valid ? • Code must be optimized for running on multi/many core architectures. • How to access efficiently and reliably hundreds of PB of data ? • Identify a strategy to avoid I/O bottleneck. • Understand how to share and replicate data among sites. • How use efficiently and reliably hardware resources widely dispersed ? • Adopt/develop a distributed resource management framework. • R&D program is in place to address these issues. • Goal is to complete R&D and write a Computing TDR by end 2012

48. Milestones

49. December 2010: Project Approved • SuperB has been approved as the first in a list of 14 “flagship” projects within the new national research plan. • The national research plan has been endorsed by “CIPE” ( the institution responsible for infrastructure long term plans). • A financial allocation of 256 Million Euros in six years has been approved for the “SuperB Flavour Factory”.

50. May 2011: SuperB @ Tor Vergata Possible photon beamlines Campus of Tor Vergata about 30000 m2 available