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Detector Upgrade from Belle to Belle II

Workshop on Synergy between High Energy and High Luminosity Frontiers. 
 January 10-12, 2011
Tata Institute of Fundamental Research, Mumbai, India. Detector Upgrade from Belle to Belle II. Toru Tsuboyama (KEK) 12 Jan. 2011. The purpose of the B factories.

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Detector Upgrade from Belle to Belle II

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  1. Workshop on Synergy between High Energy and High Luminosity Frontiers. 
 January 10-12, 2011
Tata Institute of Fundamental Research, Mumbai, India Detector Upgrade from Belle to Belle II Toru Tsuboyama (KEK) 12 Jan. 2011

  2. The purpose of the B factories • Explore the CP violation of B meson decay through the particular decay chain • e+ e– ϒ(4S)  BoBo (CP mode decay) + (tag mode decay) • ϒ(4S) decays into a coherent Bo Bo pair. • Only the vertices of Bo and Bo can be measured. • No particles from the decay vertex of ϒ(4S). • The tasks of a B factory detector: • Record the B meson decay reactions as efficient as possible. • Identify the B and B in the final state. • Measure the decay position of B and B mesons. • Combining these information, investigate the difference of particles and antiparticles. SEL 2011 meeting at Mumbai T.Tsuboyama

  3. Method of CP violation measurement CP mode decay t2 t1 m+ m - Ks ϒ(4S) resonance B0 B1 electron (8GeV) Tag mode decay n electron (3.5GeV) • D0 p+ • p+ K– • m- B2 B0 bg = 0.425 DZ~200mm S: mixing induced CP parameter SEL 2011 meeting at Mumbai T.Tsuboyama

  4. Belle Detector CsI(Tl)16X0 Super conducting solenoid 1.5T s/E=1.8%@1 GeV Eid eff=30 % (0.1% fake) Aerogel Cherenkov Countern=1.015~1.030 3.5 GeVe+ Kid eff = 90 % (6% fake) Central Drift Chamber small cell +He/C2H6 TOF conter st= 95 ps (spt/pt)2 [%2] = (0.19 pt)2+(0.34)2 8 GeVe- Silicon Vertex detector 4 layer silicon strip sensors m / KL detector 14/15 lyr. RPC+Fe s(Dz) = 100 mm Muon ID eff>90 % (2% fake) SEL 2011 meeting at Mumbai T.Tsuboyama

  5. Belle Detector SEL 2011 meeting at Mumbai T.Tsuboyama

  6. The adopted technology • Full reconstruction of B meson • Tracking: Central Drift Chamber and Uniform Solenoid field. • Calorimetry: CsI(Tl) for good energy resolution. • Particle Identification: dE/dx in CDC, TOF, Aerogel Cerenkov counters (Barrel/Forward), KL/MU detector in the return yoke. • B flavor tagging • bc + lepton: Lepton identifications by E/p, dE/dx, KL/MU: • bcs: Kaon identifications by ACC/TOF and • BD* X, D* pD: Slow pions reconstruction by CDC. SEL 2011 meeting at Mumbai T.Tsuboyama

  7. The adopted technology • Measurement of the positions of two B decay vertices. • Asymmetric Energy e+e– collider. • The B mesons travel significant distance in the laboratory frame before decay. • The decay time of B can be measured by the respective decay position. • Silicon vertex detector • The sensors are placed at 18 mm from the beam collision point. • The intrinsic position resolution is 5-10 mm. • B meson decay vertices are reconstructed with enough position resolution. SEL 2011 meeting at Mumbai T.Tsuboyama

  8. More physics channels • As the B factory detector is general purpose, we can explore following modes with high precision and high statistics. • Other important channels • B  tn, B KsKsKs, BKsp0g … • B+/B–, charmed mesons, baryons • Leptons especially t. • Two photon processes. • New baryon/meson states SEL 2011 meeting at Mumbai T.Tsuboyama

  9. Why Belle should be upgraded? • To accommodate 8x1035 /cm2/sec luminosity. • Belle was designed for 1x1035 /cm2/sec. • Physics rate amounts to 10 kHz • Beam background increases accordingly. • Beam energy asymmetry 8+3.5 GeV 7+4GeV • To Improve the detector performances • Better Tracking: • Beam pipe radius: 1.5cm  1.0 cm • Inner radius of vertex detector: 1.8 cm  1.3 cm • Outer radius of CDC 863 cm  1111 cm • Better PID performance • Threshold Cherenkov  Ring image Cherenkov SEL 2011 meeting at Mumbai T.Tsuboyama

  10. The Belle detector upgrade SEL 2011 meeting at Mumbai T.Tsuboyama

  11. IR (Interaction Region) SC Quads SEL 2011 meeting at Mumbai T.Tsuboyama

  12. Beam Pipe • The nano-beam option • The beam is squeezed to 60 nm thick at the collision point. • Beam current: 1.2 A 2.6 A(HER), 1.6 A  3.6 A(LER) • The beam pipe radius is reduced from 1.5 cm to 1 cm. • The e+ and e– beams collide with crossing angle, 83 mrad. • The two beams are separated significantly at 50 cm from the collision point. The beam pipe will have a crotch. SEL 2011 meeting at Mumbai T.Tsuboyama

  13. Silicon Vertex detector • Background hit occupancy reduction • APV25 ASIC with faster shaping time. • Pixel detector in the first 2 layers  Smaller sensitive area per readout. • Improve physics performance • Vertex reconstruction and resolution • Recover the smaller energy asymmetry. • Sensor at smaller radius. • Lager acceptance for Ks vertexing.  larger radius. SEL 2011 meeting at Mumbai T.Tsuboyama

  14. DEPFET pixel detector • The DEPFET group originally started the R&D for the ILC vertex detector. • Converting from ILC design to Belle2 design is a challenge. Synergy 2 layer DEPFET pixel detector Located at R=14 mm and 22 mm. The sensor are thinned to 50 mm thick, in contrast to the hybrid pixel sensors (>500 mm thick, including sensor, readout chip, cables and cooling). SEL 2011 meeting at Mumbai T.Tsuboyama

  15. DEPFET pixel detector The charge collected in each pixel is scanned by external clocks and sent to subsequent signal processing ASICs. Reduction of huge data size due to background hits is a big challenge. SEL 2011 meeting at Mumbai T.Tsuboyama

  16. Silicon strip vertex detector 4 layer with double-sided silicon strip detectors. 3.8 cm < R < 14.0 cm SEL 2011 meeting at Mumbai T.Tsuboyama

  17. Silicon strip vertex detector Synergy 3 types of DSSD sensors are used. Made from 6” (15 cm) diameter wafers, that became popular in the constructions of silicon trackers for Atlas, CMS, LHCb. SEL 2011 meeting at Mumbai T.Tsuboyama

  18. Activity at Tata Institute On 300 m thin n-type bulk silicon wafer of 4-inch diameter A clean room in Tata institute for the sensor characterization Working with a foundry in Bangalore. Double sided detector prototypes have been produced. For the first time truly Microstrip Detector developed in India. SEL 2011 meeting at Mumbai T.Tsuboyama

  19. Performance (I) Better Photolithography Two class of processings Single Level Double Level Fourth Batch : <111>, 2 to 4 kΩ-cm Single sided Microstrip Detectors, 1024 Strips Two different processing cycles Delivered : March 2009 < 1 nAm per strip (Meets the specification) SEL 2011 meeting at Mumbai T.Tsuboyama

  20. Performance (II) P – side response N – side response Rise-time 5ns Response to 1064nm pulsed laser Directly observed with an oscilloscope Expected responses are observed. SEL 2011 meeting at Mumbai T.Tsuboyama

  21. Silicon strip vertex detector Synergy Readout chip: APV25 developed for the CMS Silicon tracker. Its 192 stage pipeline and dead-time free readout fits the Belle2 DAQ scheme. Belle2 group utilizes the analog data in the pipe line for a wave form fit. A 100 times background rejection compared with Belle SVD is expected. SEL 2011 meeting at Mumbai T.Tsuboyama

  22. Central Drift Chamber • Small cell structure and improved readout electronics for immunity against high background rate. • Longer lever arm for better track momentum resolution, thanks to thinner Particle ID device. • 14,336 sense wires and 42,240 field wires. SEL 2011 meeting at Mumbai T.Tsuboyama

  23. Central Drift chamber X-T relation HV (kV) s~100mm Residual distribution The new electronics has been designed and tested. The drift time is measured with a TDC built-in in an FPGA. A slow FADC (around 30MHz) measures the signal charge. SEL 2011 meeting at Mumbai T.Tsuboyama

  24. Particle ID Belle/Belle2 has the CsI calorimeter for full acceptance 15<q<150o. In order to keep its hermeticity, Belle adopted Threshold Aerogel Cherenkov counter for K/p separation. Thanks to recent developments of new type photo tubes, ring image Cherenkov Counters can be installed to Belle2. Significant improvement of K/p separation is expected. SEL 2011 meeting at Mumbai T.Tsuboyama

  25. TOP: Barrel Cherenkov counter • Time of Propagation Counter: • The Cherenkov angle of radiated photons is measured with position (X, Y) and detection timing T. SEL 2011 meeting at Mumbai T.Tsuboyama

  26. TOP: Barrel Cherenkov counter Prototype quartz bar The Cherenkov angle of radiated photons is measured with position (X, Y) and detection timing T. SEL 2011 meeting at Mumbai T.Tsuboyama

  27. TOP: Barrel Cherenkov counter • Square-shape multi-anode MCP-PMT • Multi-alkali photo-cathode • Single photon detection • Fast raise time: ~400ps • Gain=1.5x106 (B=1.5T) • T.T.S. (single photon): ~35ps (B=1.5T) • Position resolution: <5mm SEL 2011 meeting at Mumbai T.Tsuboyama

  28. ARICH: Forward Ring Image Cherenkov counter • Proximity focusing Cerenkov counter with: • 2 layer Aerogel photon radiators • Readout with Pixilated HADP SEL 2011 meeting at Mumbai T.Tsuboyama

  29. CsI Calorimeter • Extrapolation of background of Belle • Present status: Energy deposit in random event: 0.5 MeV/Crystal or 3 GeV/ECL. • “Probably” proportional to Beam current • 3–10x background in Super KEKB. • Fine segment in time will be necessary SEL 2011 meeting at Mumbai T.Tsuboyama

  30. CsI Calorimeter • Upgrade Plan: • The CsI (Tl) of present Belle is used again. • Shorten shaping time from 1μs to 0.5μs • Waveform sampling (18 bit, 2 MHz) • On board waveform fitting with FPGA. SEL 2011 meeting at Mumbai T.Tsuboyama

  31. CsI Calorimeter BJ/ΨKs, Ks p0p0 has two p0 reconstructed. CsI performance is essential. Btn requires no activities in CsI except for t decay particles. Sensitive to beam background. # BKG hits in B tn + DAQ upgrade + Pure CsI + PMT Eth (MeV) Physics simulations show the performance is close to that of the ultimate upgrade with pure CsI crystals readout with PMT. SEL 2011 meeting at Mumbai T.Tsuboyama

  32. KLM: KL and m detector Hit rate (Hz/cm2) expected of KLM at SuperKEKB R3150 R1305 Longest strip 2820 mm Belle  RPC (resistive plate chamber): hit rate < 1Hz/cm2 Endcap part will be replaced with Scintiilator + MPPC (SiPM) SEL 2011 meeting at Mumbai T.Tsuboyama

  33. KLM HPK 1.3×1.3 mm 667 pixels Vladimir (Russia) (used in T2K ND) Kuraray Y11 MC No other competative option High efficiency; long atten. length SEL 2011 meeting at Mumbai T.Tsuboyama

  34. Trigger The collision luminosity will be 40 times larger than the present Belle experiment. Physics event rate will be 10 kHz at 8x1035/cm2/s. The trigger system should be tunable to accommodate the physics rate for given DAQ and computing performances. SEL 2011 meeting at Mumbai T.Tsuboyama

  35. DAQ At the full luminosity, the data rate amounts to 600 MB/sec. A high performance DAQ system is designed. SEL 2011 meeting at Mumbai T.Tsuboyama

  36. Computing Synergy • Belle  computing resource is concentrated to KEK. • Belle2  50-100x larger computation power and storage is necessary • Highly distributed computing environment: • GRID with help of CLOUD is necessary. • GRID technology established by LHC computing will be utilized. SEL 2011 meeting at Mumbai T.Tsuboyama

  37. Computing • Belle  computing resource is concentrated to KEK. • Belle2  50-100x larger computation power and storage is necessary • Highly distributed computing environment: GRID with help of CLOUD is necessary. SEL 2011 meeting at Mumbai T.Tsuboyama

  38. Belle2 detector CsI(Tl) with wave sampling readout PID: New Cherenkov Detectors Barrel: Time of Projection counter Forward: Aerogel RICH counter (s/E)2 = (0.2/E)2+(1.6/√E)2 +(1.2)2 %2 Eid eff=30 % (0.1% fake) TOP: Kid eff = 99 % (1 % fake) ARICH: Kid eff = 96 % (1 % fake) KL/m detector: Barrel: RPC End cap: Scintillator readout with MPPC Central Drift Chamber Small cell layout Muon ID eff>90 % (2% fake) (spt/pt)2 = (0.1 pt)2+(0.3)2 %2 (with SVD) TRG/DAQ: New Dead time free readout Vertex detector: 2 layer DEPFET pixel detector 4 layer Si vertex detector COMP: High performance computer systems SEL 2011 meeting at Mumbai T.Tsuboyama Impact parameter resolution sz = 20 mm

  39. Belle II Collaboration http://belle2.kek.jp 13 countries/regions, 53 institutes SEL 2011 meeting at Mumbai T.Tsuboyama

  40. Summary • The Super KEKB is approved. • Improve the detector performances • Capability for data acquisition of 8x1035 luminosity. • Immunity to expected 30x beam background • Beam pipe radius: 1.5 cm  1.0 cm • Vertex detector: 4Layer DSSD  4Layer DSSD + 2layer DEPFET • Lever arm of Vertex Detector + CDC: 210 cm  250 cm • PID: Threshold Cherenkov  Ring image Cherenkov. KID efficiency (Barrel): 90 %  99 %. • Disintegration of Belle2 has started Oct. 2010 • Commissioning of Belle2: 1 October 2014. SEL 2011 meeting at Mumbai T.Tsuboyama

  41. Belle upgrade started Dismantling of Belle detector components Central Drift chamber on 6 Jan 2011 SEL 2011 meeting at Mumbai T.Tsuboyama

  42. And more …. We still need more human resources or collaborating institutes to construct our detector and stable operations. We welcome new group to join Belle 2. Please contact our spokes persons if you are interested. Thank you for attention! SEL 2011 meeting at Mumbai T.Tsuboyama

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