Super B CDR Detector Workshop Overview Detector Subsystems

Super. B (CDR) Detector & Workshop Overview • Detector Subsystems and Workshop Parallel Sessions (summaries Saturday plenary) • MDI Plenary tomorrow • Vertex Detector (SVT)- Plenary talk today • Drift Chamber (DCH) • Particle Identification (PID)-Plenary talk today • Electromagnetic Calorimeter (EMC)- Pl. talk today • Instrumented Flux Return (IFR) • Electronics- Plenary session tomorrow • Trigger, & DAQ-Plenary talk today • Computing- Plenary session tomorrow • Workshop Focus • Summary Blair Ratcliff SLAC Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Detector Overview ¡ Current B-Factory detectors have proven to be extremely effective instruments over the very broad physics program accessible at the U(4 S). l l l ¡ ¡ Two (+1) examples: Ba. Bar, Belle (Cleo-II). Serve as “world class prototypes” for Super. B! Optimized differently, but all were (are!) effective physics instruments. Comparisons between them help to define optimal strategies for subsystems in a Super. B detector. CDR detector design based on Ba. Bar (with reoptimization). Super. B machine acceptance limits similar to PEP-II: Ba. Bar’s geometry, field, and portions of several subsystems are rather close to optimal, Re-use of Ba. Bar gives excellent performance and saves money. Super. B Workshop, SLAC, Feb. 14 -16, 2008 2 Blair Ratcliff, SLAC

Directions for Detector Optimization ¡ From Machine and Environment: • Smaller Boost (7 x 4 Ge. V; bg=0. 28) Smaller radius beam-pipe to retain adequate vertex resolution. Larger barrel acceptance. More particles backward in detector with somewhat softer spectrum forward. • Some (though not all) components of machine background components will be substantially larger. Improve detector segmentation Improve detector speed Improve radiation hardness as needed. ¡ From physics goals, which emphasize rare decays, LFV in t physics, and recoil (n) physics l ¡ ¡ Would like best possible hermeticity, with good subsystem efficiency and performance. ~x 100 Luminosity Improved trigger, DAQ, & computing (~15 years later) Last, but not least, must replace aging components and technologies. Super. B Workshop, SLAC, Feb. 14 -16, 2008 3 Blair Ratcliff, SLAC

Baseline Detector Layout Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

CDR Detector Layout – Based on Babar BASELINE New detector elements OPTION 5 Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Detector Evolution-B Factory to Super. B Factory o With careful attention machine design and shielding in the IR, the backgrounds at a Super. B should be ~ to those we know (and love? ) at Ba. Bar An excellent Super. B detector is possible with ~ today’s technology l CDR Baseline based on Ba. Bar. It reuses ¡ ¡ ¡ Some elements have aged and need replacement. Others require moderate improvements to cope with the high luminosity environment, the smaller boost (4 x 7 Ge. V), and the high DAQ rates. l l l l l 6 Fused Silica bars of the DIRC & DCH Support Barrel EMC Cs. I(Tl) crystal and mechanical structure Superconducting coil & flux return (with some redesign). Small beam pipe technology Thin silicon pixel detector first layer, and a new 5 layer SVT. New DCH with CF mechanical structure, modified gas and cell size New Photon detection for DIRC fused silica bars Forward PID system (TOF in Baseline option) New Forward calorimeter crystals (LYSO) Minos-style extruded scintillator for instrumented flux return Electronics and trigger- x 100 real event rate Computing- to handle massive date volume Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

MDI- Convener Calderini Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Interaction Region Design • Strong mutual constraints on detector design come from accelerator design and vice versa. • High luminosity via small beam spot requires focusing elements very close to IP that constrain forward/backward detector acceptance and stay clear. • Detector field must be compensated from beam. asymmetric scales 8 Super. B Workshop, SLAC, Feb. 14 -16, 2008 • Particles hitting beam line elements in detector vicinity produce detector backgrounds. Large luminosity background from radiative Bhabhas. Blair Ratcliff, SLAC

Background Sources Very high luminosity reached with beam currents similar to PEP-II (~ 2 A) Beam-gas (lost particle) backgrounds are modest. • Effects of synchrotron radiation fans can be limited by careful IR design • But……Touschek and physics backgrounds are concerns • Touschek scattering scales with bunch charge density (so could be much larger than current machines). • Luminosity backgrounds, especially radiative Bhabhas, become large. Maintaining background control constrains the design of machine lattice, collimation, & IR, with substantial IR shielding. Looks OK in present design, but detailed simulations must continue til the TDR as the machine design evolves. A robust detector design plays an important role. Basic elements include shielding, fine detector segmentation, fast detectors, and good radiation resistance in elements close to the beam. To deal with surprises, would like a factor of 5 -10 safety margin. 9 Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Origin of Radiative Bhabha Background m Need substantial shielding to prevent the produced shower from reaching the detector. m Super. B Workshop, SLAC, Feb. 14 -16, 2008 • Blair Ratcliff, SLAC

Detector Elements-SVT-Convener Rizzo Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Vertex Detector (SVT) 20 cm Layer 0 30 cm 40 cm • Design is based on a new SVT (very similar to that of the 5 layer Ba. Bar SVT) supplemented by a new layer 0 to measure the first hit as close as possible to the production vertex. Goal si coverage to 300 mrad both forward and backward. • Ba. Bar SVT cannot be re-used because of radiation damage and modest changes in geometry. • Beam pipe radius and thickness are crucial to obtain adequate resolution in vertex separation. Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

SVT Layer 0 Point resolution specs can be met either by double sided silicon strips or pixels. But…. performance in high background environment at small radius crucial! Possible Solutions 1) Striplets (CDR baseline) • • Available technology (with modest developments) Reduce strip length to cope with hits rates to ~ 1 MHz/cm 2) Monolithic Active Pixel Arrays (MAPs) • • • Requires substantial R&D (ongoing). Cooling and mechanical issues challenging. But much more robust against high backgrounds. 3) Hybrid Pixels Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Detector Elements-DCH-Convener Finnocchiaro Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

DCH Baseline Design • Provides precision momentum (and good particle ID via d. E/dx) for all low momentum tracks, even those that miss the PID system. • A new DCH (very similar to now aged Ba. Bar DCH, which must be replaced) • Same gas & cell shape (small improvements may be possible) • Carbon Fiber end plates (to reduce material before endcaps) • New electronics with location optimized. • Background simulation occpancy ~ OK (7% to 1. 5% depending critically on IR shielding). • R&D Issues include: • • • Ba. Bar DCH Electronics (location to avoid backward EMC, mass, cluster counting? ) Conical carbon fiber endplates. Background simulation/shielding optimization. Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Detector Elements-PID-Convener Leith Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

PID Detector (DIRC) • • Hadronic PID System essential for P > 0. 7 Ge. V/c. (d. E/dx < 0. 7 Ge. V/c) Baseline is to reuse Ba. Bar DIRC barrel-only design. • • Excellent performance to 4 Ge. V/c. Robust operation. Elegant mechanical support. Photon detectors outside field region. Radiation hard fused silica radiators. But. . . PMTs are slow and aging. Need replacement. Large SOB region senstive to backgrounds so volume reduction is desirable. Photon detector replacement • • Baseline. . . Use pixelated fast PMTs with a smaller SOB to improve background performance by ~x 50100 with ~ identical PID performance. Several other photon detector options are considered in the CDR. Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Forward PID Option in CDR • Modest solid angle but event acceptance for decays with multiple particles (e. g. , B Ks. KK) scale much faster than linearly. Physics case needs to be established. • Not just a PID problem. Overall detector optimization required. • • Adds material before EMC. Takes space from tracking. Bar used barrel-only PID. Very Fast Cherenkov-based TOF plausible. • • • Modest Space requirements. But many fast tubes with substantial material. R&D underway. Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Detector Elements-EMC-Convener Hitlin Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

EMC Ba. Barrel 5760 Cs. I(Tl) Crystals Essential detector to measure energy and direction of g and e, discriminate between e and p, and detect neutral hadrons. Baseline • • • Ba. Bar barrel crystals can be reused. Most expensive detector component. Backgrounds dominated by radiative Bhabhas. IR shielding design is crucial. Baseline is to retain barrel geometry and photo-diode readout. Due to decreased boast, will shift interaction point wrt normal crystal gap from -5 to +5 cm. Overall increase in Barrel coverage from 79. 5% to 84. 1%. Forward Endcap EMC • Ba. Bar Crystals are radiation damaged. Need replacement. • At forward angles in Super. B, Cs. I(Tl) is too slow (occupancy) and radiation soft. Propose LYSO. Option for Backward Endcap • • • Best possible hermiticity important for fully inclusive decays and decays with neutral energy. 4. 5% of solid angle is in backward endcap. But DCH material, DIRC bars, and DCH readout unavoidable. Physics gains need careful assessment. CDR considers veto device. Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Detector Elements-IFR-Convener Calabrese Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

IFR • • • Provides discrimination between m and charged hadrons (p & k). High m ID efficiciency and good hadron rejection efficiencies are both important. Good efficiency as a KL veto is helpful in analysis of final states with missing u energy (e. g. , B mu(g) ). Mainly depends on EMC and energy deposited in inner material. Baseline • • Add iron to Ba. Bar stack to improve m ID. 7 -8 detection layers. Re-use Ba. Bar steel (still to be fully assessed) Keep longitudinal segmentation in front of stack to retain KL ID capability. Backgrounds are problematic for gas detectors. Use Minos style scintillation bars. Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

IFR-Scintillation Detectors • • CDR discussed MINOS style extruded plastic scintillator with WLS readout into a cooled, pixelated APD. Production techniques well established. Robust against high backgrounds in all areas of the detector. More conservative dual-WLS fiber readout, and Geiger mode APDs are under study. Super. B Workshop, SLAC, Feb. 14 -16, 2008 MINOS Bar Blair Ratcliff, SLAC

Detector System Elements Electronics-Convener Breton Trigger & DAQ-Conveners Dubois-Felsmann/Luitz Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Electronics, Trigger & DAQ Baseline Design • • • Pipelined architecture both for front ends and DAQ. CDR design is similar to Ba. Bar in concept, but must accomodate much higher rates. Bar design comes from early 90’s ~ entire electronics plant needs to be redesigned and rebuilt with new technologies. Little re-use possible except for crates, power supplies, and maybe front ends. DAQ and trigger use established techniques and commodity computing components, but little re-use of existing components possible except perhaps for VME crates. Trigger & DAQ • Open trigger design, very similar to Ba. Bar, trying to preserve ~ 100% of physics events, with minimal deadtime. large number of events logged and reconstructed. ~100 -150 k. Hz trigger rate (35 KHz in Ba. Bar). Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Computing-Conveners Bianchi/Rama/Morandin Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Computing ¡ Computing “in” the TDR will be based on Babar+LHC experience: solvable problem l ¡ Fully detailed Computing TDR may even come a bit later than the detector TDR Computing “for” the TDR is essential from now to the TDR l Collaborative tools ¡ l Web, Code/document repository, Wiki, mailing lists, etc. Simulation tools Physics, Background, Detector optimization. ¡ Mostly using Babar-derived tools so far, but a more flexible and varied simulation infrastructure is needed ¡ Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Focus of Workshop Define/refine • Global System Issues • Subystem R&D needed to reach a final subsystem design • • • Design R&D Beam Tests Organization, Manpower, Institutions Costs Milestones • Interfaces and tools • Simulation for Physics studies and MDI • Computing • Electronics/DAQ/Trigger • CDR TDR in two years. Planning! 28 Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC

Summary § We have a sound conceptual design (presented in the Super. B CDR) for the Super. B detector, based on Ba. Bar. § Substantial R&D effort on individual Sub. Systems, Software tools, and Physics and Detector simulation studies will be essential during the next 2 years to move to a Technical Design (and a TDR). § We hope this workshop allows us to explore the challenges and opportunities for the next steps, and to join together to make progress towards a excellent new detector for Super. B. 29 Super. B Workshop, SLAC, Feb. 14 -16, 2008 Blair Ratcliff, SLAC