The Super B Project Marcello A Giorgi Universit
The Super. B Project Marcello A. Giorgi Università di Pisa and INFN Pisa V Super. B Workshop ENS May 9 -11, 2007 ENS –PARIS May 10, 2007 Marcello A Giorgi 1
Outline CDR is ready So we have a basic and conceptual project for the machine and for the detector TDR or RDR ENS –PARIS May 10, 2007 Marcello A Giorgi 2
CDR Ready !!!! The CDR of Super. B is ready! INFN/AE-07/02, SLAC-R-856, LAL 07 -15 Available online at: www. pi. infn. it/Super. B 476 pages Copies are being distributed They can also be requested from Lucia. Lilli@pi. infn. it ENS –PARIS May 10, 2007 Marcello A Giorgi 3
Signatures ENS –PARIS May 10, 2007 Marcello A Giorgi 4
Signatures: some numbers • • 320 Signatures About 85 institutions 174 Babar members 65 non Babar experimentalists. Signatures breakdown by country ENS –PARIS May 10, 2007 Marcello A Giorgi 5
Physics case depends on: Data sample Time of Super. B operation. The case becomes solid if: the sample is between 15 and 75 ab-1/year the Super. B running period is overlapped with LHC Super. B complementary with LHC ENS –PARIS May 10, 2007 Marcello A Giorgi 6
PHYSICS CASE for Super Flavour Factory The physics case for a Super Flavour Factory emerged solid if : The sample of data available in a few years of running would be bigger than 50 ab -1 and approaching 100 ab -1 (10 11 B Bbar, tau and charm pairs). L between 1036 and 1037 cm-2 s-1 WALL POWER<<50 MW as in KEKB and PEPII Background in the detector as in PEPII Possibility of running at lower CM Energy (4. 0 Ge. V) still with L >1035 for special runs on Charm (making use of the coherent production of D’s from y’. ) Possibility of one polarized beam for Tviolation studies in t. We in fact are planning both beams polarized. The running period is overlapped to LHC. (Results from Super Flavour Factory and LHC are largely complementary). REFERENCE DOCUMENTS see for example: Report from Roadmap committee (Slac. BABAR Analysis Doc#828 26 July 2004) The Discovery Potential of a Super B Factory (Slac-R-709) Letter of Intent for KEK Super B Factory ( KEK Report 2004 -4 ) Physics at Super B Factory ( hep-ex/0406071 ) Many documents available at the URL : www. pi. infn. it/Super. B BUT WHERE ARE WE NOW? ENS –PARIS May 10, 2007 Marcello A Giorgi 7
CPV requirements Angle b/F 1 and a/F 2 can be measured through time dependent asymmetries. Tools: Particle ID to tag meson decaying in CP eigenstate (B or anti. B) Precise measurement of decay time (Double Side Silicon Strip detectors). (Firstly used in Lep experiments) Boost the c. o. m of B-anti. B system (from Y 4 s) to allow mesons travel O(several 100 mm) before decay. (This method was fistly used for the measurement of charm lifetime in fixed target experiments at CERN) ASYMMETRIC MACHINE IS MANDATORY ENS –PARIS May 10, 2007 Marcello A Giorgi 8
Successo delle BFACTORIES 13 countries, 57 institutes, ~400 collaborators 8 x 3. 5 Ge. V 22 mrad crossing angle SCC RF(HER) Belle detector ARES(LER) Ares RF cavity e+ source 8 Ge. V (e-) 3. 5 Ge. V (e+) peak luminosity: since 1999 710. 254 /fb ENS –PARIS May 10, 2007 1. 7118 x 1034 cm-2 1662 m. A (LER) , 1340 m. A (HER) 1389 bunches Marcello A Giorgi 9
SUCCESS of BFACTORIES 11 Countries, 80 Institutions, 623 Physicists Lmax =12. 069× 1033 cm− 2 sec− 1 1722 bunches 2900 m. A LER 1875 m. A HER Ldt = 407. 69 fb– 1@{Υ(4 S)+off(~10%)} (>3. 7 x 108 B events) Charged tracking/vertexing • 5 -layer DSSD Si µstrip • 40 layers (He-isobutane) Hadron identification • tracker: d. E/dx • DIRC imaging Cerenkov Electron/photon • Cs. I calorimeter Muon/KL • Instrumented flux return ENS –PARIS May 10, 2007 Marcello A Giorgi 10
Successo straordinario della fisica degli acceleratori Total > 1. 1 ab− 1 Design Lumi PEP-II (Ba. Bar) 400 fb-1 ENS –PARIS May 10, 2007 KEKB (Belle) 710 fb-1 Marcello A Giorgi 11
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Summary from Oide’s talk at 2005 2 nd Hawaii Super. BF Workshop • Present design of Super. KEKB (SAME CONSIDERATIONS FOR PEPII) hits fundamental limits in the beam-beam effect and the bunch length (HOM & CSR) Higher current is the only way to increase the luminosity. • Many technical and cost issues are expected with a new RF system We need a completely different collider scheme. . . HIGH CURRENT and HIGH BACKGROUND IS AN ISSUE FOR DETECTOR DESIGN WALL POWER NEEDED (even >>100 MW) ENS –PARIS May 10, 2007 Marcello A Giorgi 13
Crossing angle concepts Overlapping region Both cases have the same luminosity, (2) has longer bunch and smaller sx Sx Sz With large crossing angle X and Z quantities are swapped: Very important!!! 1) Standard short bunches Overlapping region Sz ENS –PARIS May 10, 2007 2) Crossing angle Sx Marcello A Giorgi 14
x …. and (finally) to crab the waist: e+ b. Y e- 2 Sx/q q 2 Sz*q z 2 Sx Why? Crabbed waist removes betratron coupling resonances introduced by the crossing angle (betatron phase and amplitude modulation) Vertical waist has to be a function of x: Crabbed waist realized with a sextupole in phase with the IP in X and at p/2 in Y ……. and slight increase of the luminosity. ENS –PARIS May 10, 2007 Marcello A Giorgi 15
Project The project is based on the low emittance scheme, large Piwinski angle and crab waist. Th CDR doesn’t contain the full simulation of Super. B with the insertion of the elements for the crab waist. A most recent study with some adjustment in the insertion of sextupoles has been recently made by P. R. and simulated by Ohnishi. The effect of sextupoles on the dynamic aperture doesn’t seem disruptive. ENS –PARIS May 10, 2007 Marcello A Giorgi 16
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We have a Machine Baseline A baseline of machine design for 1. 0 1036 is now available! It could operate at 4. 0 Ge. V c. o. m Energy at luminosity 1035 A preliminary estimate of fully inclusive. Wall Power is now available (17 MW+18 MW)=35 MW! As in PEPII Current as is now in PEPII (can manage Background !) One polarized beam(e-) is considered for tau physics. The possibility of adding polarized positron is uder study. It can enhance the events from annihilation processes (b, c, tau pairs) w. r. t. pair production (polarisation of positrons and electrons as considered produce almost a factor 1. 5 more of signal events) ENS –PARIS May 10, 2007 Marcello A Giorgi 18
All and just the PEPII RF system and most of the magnetic componenets fit the Super. B needs ENS –PARIS May 10, 2007 Marcello A Giorgi 19
The Università di Roma Tor Vergata Site • Area is available it belongs to the University • A joint engineering group created for site and infrastructure. • Synergy with approved and funded FEL (SPARX) 750 m ENS –PARIS May 10, 2007 Marcello A Giorgi 20
Photo from Villa Mondragone ENS –PARIS May 10, 2007 Marcello A Giorgi 21
DETECTOR CDR has used Babar detector as the basis for the conceptual design of Super. B. Belle could have been used as well. Therefore it is an exercise that could eventually be completely modified in future. ENS –PARIS May 10, 2007 Marcello A Giorgi 22
Detector Layout – Reuse parts of Babar (or Belle) BASELINE OPTION ENS –PARIS May 10, 2007 Marcello A Giorgi 23
Backgrounds Dominated by QED cross section – Low currents / high luminosity • Beam-gas are not a problem • SR fan can be shielded ENS –PARIS May 10, 2007 Marcello A Giorgi 24
Pair production • Huge cross section (7. 3 mbarn) • Produced particles have low energy and loop in the magnetic field • Most particles are outside the detector acceptance ENS –PARIS May 10, 2007 Marcello A Giorgi 25
We have an IR design coping with main BKG source Radiative Bha Need serious amount of shielding to prevent the produced shower from reaching the detector. ENS –PARIS May 10, 2007 Marcello A Giorgi 26
More studies are needed on Background And more simulation effort. ENS –PARIS May 10, 2007 Marcello A Giorgi 27
Backgrounds • Super. B beam currents (2 A) are similar to PEPII/KEKB • Background is not too much larger than what with have today – Except for SVT Layer 0 – Detailed simulations ongoing, especially for radiative Bhabhas and Touschek backgrounds – Need to design a robust detector with the enough segmentation and radiation hardness to withstand surprises (x 5 safety margin) • IR design is critical • Shielding • More studies needed ENS –PARIS May 10, 2007 Marcello A Giorgi 28
Beam Pipe Radius and Detector • Small beam pipe radius possible because of small 7+4 Ge. V beam size – Studied impact of boost on vertex separation (B pp) Boost bg=. 28 – Rest of tracking is Babar Instead of 0. 56 – Beam pipe needs to be cooled. Study is in progress to keep total thickness low in the order of % of rad Separation significance ENS –PARIS May 10, 2007 Proper time difference resolution Marcello A Giorgi 29
SVT 20 cm Layer 0 30 cm 40 cm • Baseline: use an SVT similar to the Babar one, complemented by one or two inner layers. – Question on whether it would possible/economical to add a layer between SVT and DCH, or move L 5 to larger radius • Cannot reuse because of radiation damage • Beam pipe radius is paramount – inner radius: 1. 0 cm, – layer 0 radius: 1. 2 cm, – thickness: 0. 5% X 0 ENS –PARIS May 10, 2007 Marcello A Giorgi 30
SVT Layer 0 7. 7 cm • Depends critically on background level 1. 35 cm U – Striplet solution (baseline) • Basically already available technology but more sensitive to background. OK for 1 MHz/cm 2 • Some margin to improve background sensitivity V – Monolithic Active Pixel Solution solution (option) • R&D is still ongoing but giving a big safety margin in terms of performance and occupancy • Cooling and mechanical issues need to be addressed • See talks in the afternoon ENS –PARIS May 10, 2007 Marcello A Giorgi 31
Striplets detector concept ENS –PARIS May 10, 2007 Marcello A Giorgi 32
DCH • Basic technology adequate. • Cannot reuse Ba. Bar DCH because of aging – Faster gas and smaller cell would be beneficial • Baseline: – Same gas, same cell shape • Some gas improvement possible (order 20%) • Reducing cell dimension deteriorates resolution – Carbon fiber endplates instead of Al to reduce thickness – Backgrounds simulated, dominated by radiative Bhabhas • Depend critically on shielding • About 7% occupancy with current solution, could be reduced to 1. 5% • Options/Issues to be studied: – Miniaturization and relocation of readout electronics • Critical for backward calorimetric coverage – Conical, Carbon fiber endplate optimization of cell size/gas needed! ENS –PARIS May 10, 2007 Marcello A Giorgi 33
Particle ID • Barrel PID essential for hadron PID above ~0. 7 Ge. V. • DIRC baseline – Quartz bars are OK and can be reused • Almost irreplaceable – PMTs are aging and need to be replaced – Keep mechanical support • Barrel Options – Readout options motivated by reduction of background generated in SOB – SOB: Faster PMTs using the standoff box and water coupling – Smaller SOB: Pixilated Ma. PMTs and fused silica coupling – No SOB: Focusing readout with pixilated Ma. PMTs ENS –PARIS May 10, 2007 Marcello A Giorgi 34
Forward/Backward PID option • Extending PID coverage to the forward and backward considered • Possibly useful, physics case needs to be established quantitatively • Serious interference with other systems – Material in front of the EMC – Needs space • cause displacement of front face of EMC • require miniaturization and displacement of DCH electronics – TOF seems the only viable option Technologies • Aerogel-based focusing RICH – Working device – Requires significant space (>25 cm) • Time of flight – Need about 10 ps resolution to be competitive with focusing RICH – 15 -20 ps OK. 10 ps seems to be achievable, although not easy ENS –PARIS May 10, 2007 Marcello A Giorgi 35
EMC • Barrel Cs. I(Tl) crystals – Still OK and can be reused (the most expensive detector in Ba. Bar) – Background simulation indicates the need for a careful shielding design • dominated by radiative Bhabha’s • Forward Endcap EMC – Ba. Bar crystal are damaged by radiation and need to be replaced – Occupancy at low angle makes Cs. I(Tl) too slow – No doubt we need a forward calorimeter • Backward EMC option – Because of material in front will have a degraded performance • Maybe just a VETO device for rare channels such as B tn. – Physics impact needs to be quantitatively assessed – DIRC bars are necessarily in the middle – DCH electronics relocation is critical for the perfomance ENS –PARIS May 10, 2007 Marcello A Giorgi 36
Forward EMC crystals • Both pure Cs. I and LSO could be used in the forward EMC • LSO more expensive, but more light, more compact, and more radiation hard – Now LSO is available industrially – Cost difference still significant, but not overwhelming. • Use LSO as baseline – Gives better performance – Mechanically easier to assemble – Leaves PID option open • Cs. I option still open – in case of cost/availability issues ENS –PARIS May 10, 2007 Marcello A Giorgi 37
Crystal properties ENS –PARIS May 10, 2007 Marcello A Giorgi 38
IFR and steel • Ba. Bar configuration has too little iron for m ID – > 6. 5 l. I required; 4 -5 available in barrel • Fine segmentation overdid KL efficiency optimization • – Focus on m ID : fewer layers Baseline: and more iron – – Fill in Babar to use the gaps Is it possible IFR iron IFRwith in Kmore mode ? L veto – Leave 7 -8 detection layers – Need to verify structural issues – Scintillator bars à la MINOS • Cost effectiveness of steel reuse needs to be fully assessed ENS –PARIS May 10, 2007 Marcello A Giorgi 39
Electronics and Trigger/DAQ • L 1 Trigger rate of 100 -150 KHz – Unless a hardware Bhabha rejector is developed – Up from 5 KHz current Babar rate • Some electronics could be reusable – Especially front-end cards, maybe power supplies • The bulk of the electronics is obsolete and unmaintainable – Should be remade with state-of-the-art technology • Clearly a major cost driver – Costed using recent experiments experience (LHC) ENS –PARIS May 10, 2007 Marcello A Giorgi 40
CDR contains the conceptual solutions for various problems. BUT… More Simulations R&D Are needed to go from CDR to RDR (or TDR) ENS –PARIS May 10, 2007 Marcello A Giorgi 41
Cost estimate • A full cost estimate of the Super. B project has been done – Based on Babar/PEP-II actual costs – Escalated from 1995 to 2007 – Bottom-up for almost all elements • Separate new components from reused elements – Replacement value of reused components = how much would it cost today to rebuild those components (extrapolated from Babar/PEP-II costs) – New costs: everything that’s needed today, including refurbishing – Transport is not included, but disassembly and reassembly is. • Keep separate categories: – EDIA: engineering, design, inspection and administration (manmonths) – Labour: technicians (man-months) – Materials and Services: 2007 Euros. • All details available in the CDR – We have not tried to fully optimize the cost yet. Some reduction might be possible ENS –PARIS May 10, 2007 Marcello A Giorgi 42
Accelerator and site costs Note: site cost estimate not as detailed as other estimates. ENS –PARIS May 10, 2007 Marcello A Giorgi 43
Detector cost Note: options in italics are not summed. We chose to sum the options we considered most likely/necessary. ENS –PARIS May 10, 2007 Marcello A Giorgi 44
Schedule • Overall schedule dominated by: – Site construction – PEP-II/Babar disassembly, transport, and reassembly • We consider possible to be inside the commissioning phase after 5 years from T 0. ENS –PARIS May 10, 2007 Marcello A Giorgi 45
What money ? • The Super. B budget model still needs to be fully developed. It is based on the following elements (all being negotiated) – – – Italian government ad hoc contribution Regione Lazio contribution INFN regular budget EU contribution In-kind contribution (PEP-II + Babar elements) Partner countries contributions • Clearly the Super. B project is inherently international and will need to be managed internationally ENS –PARIS May 10, 2007 Marcello A Giorgi 46
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