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  Explore the CP violation of B meson decay through the particular decay chain  e + e –  ϒ (4S)  B o B o  (CP mode decay) + (tag mode decay)  ϒ (4S) decays into a coherent B o B o pair.  Only the vertices of B o and B o 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. 2SEL 2011 meeting at Mumbai T.Tsuboyama

Method of CP violation measurement S : mixing induced CP parameter SEL 2011 meeting at Mumbai T.Tsuboyama3 electron (8GeV) electron (3.5GeV) ϒ (4S) resonance B1B1 B0B0 CP mode decay B2B2 B0B0 t 2 t 1  +   D 0     + K –     =  Z~200  m  Tag mode decay KsKs

 / K L detector 14/15 lyr. RPC+Fe C entral D rift C hamber small cell +He/C 2 H 6 CsI(Tl) 16X 0 Aerogel Cherenkov Counter n=1.015~1.030 Silicon Vertex detector 4 layer silicon strip sensors TOF conter Super conducting solenoid 1.5T 8 GeV e  3.5 GeV e  Belle Detector  t  = 95 ps  GeV Eid eff=30 % (0.1% fake) Kid eff = 90 % (6% fake) (  pt /p t ) 2 [% 2 ] = (0.19 p t ) 2 +(0.34) 2 Muon ID eff>90 % (2% fake)  (  z) = 100  m 4SEL 2011 meeting at Mumbai T.Tsuboyama

Belle Detector TasksSVDCDCTOFACCCsIKLM TRG DAQ CMP Record the B meson Events Efficiently ✔ Full reconstruction of B meson Tracking ✔✔ Calorimetry ✔ Particle ID ✔✔✔✔✔ Measure the decay vertex position of B mesons ✔✔ B flavor Tagging (Particle ID) ✔✔✔✔✔ High performance data processing: ✔ 5SEL 2011 meeting at Mumbai T.Tsuboyama

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*   D: Slow pions reconstruction by CDC. 6SEL 2011 meeting at Mumbai T.Tsuboyama

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  m.  B meson decay vertices are reconstructed with enough position resolution. 7SEL 2011 meeting at Mumbai T.Tsuboyama

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  , B  K s K s K s, B  K s  0  …  B + /B –, charmed mesons, baryons  Leptons especially .  Two photon processes.  New baryon/meson states 8SEL 2011 meeting at Mumbai T.Tsuboyama

Why Belle should be upgraded?  To accommodate 8x10 35 /cm 2 /sec luminosity.  Belle was designed for 1x10 35 /cm 2 /sec.  Physics rate amounts to 10 kHz  Beam background increases accordingly.  Beam energy asymmetry 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.Tsuboyama9

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

IR (Interaction Region) SEL 2011 meeting at Mumbai T.Tsuboyama11 SC Quads

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. 12SEL 2011 meeting at Mumbai T.Tsuboyama

Silicon Vertex detector SEL 2011 meeting at Mumbai T.Tsuboyama13 BelleBelle2 Beam pipe Radius (cm) Vertex detector Radius (cm) 1.8 < R < < R < 14,0 Layers4 layer DSSD2 Layer Pixel + 4 layer DSSD  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.

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

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. 15SEL 2011 meeting at Mumbai T.Tsuboyama

Silicon strip vertex detector  4 layer with double- sided silicon strip detectors.  3.8 cm < R < 14.0 cm 16SEL 2011 meeting at Mumbai T.Tsuboyama LayerR (mm)LaddersSensorsRO chips Sum

Silicon strip vertex detector SEL 2011 meeting at Mumbai T.Tsuboyama17  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. DSSDLargeWedgeSmall Dimension (mm 2 )124.88x x( )124.88x40.4 # strips (p)768/1535 # strips (n)511/ /1535 Strip pitch (p) Strip pitch (n) Synergy

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

 Fourth Batch :, 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) Better Photolithography Double Level Single Level Two class of processings Performance (I) 19SEL 2011 meeting at Mumbai T.Tsuboyama

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

Silicon strip vertex detector  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. 21SEL 2011 meeting at Mumbai T.Tsuboyama Synergy

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. 22SEL 2011 meeting at Mumbai T.Tsuboyama BelleBelle2 Radius of Inner Cylinder (mm)77160 Radius of Outer Cylinder (mm) Radius of innermost wire (mm)88168 Radius of outer most wire (mm) Number of Layers5056 Number of sense wires8,40014,336

Central Drift chamber  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. 23SEL 2011 meeting at Mumbai T.Tsuboyama  ~100  m HV (kV) X-T relation Residual distribution

Particle ID SEL 2011 meeting at Mumbai T.Tsuboyama24  Belle/Belle2 has the CsI calorimeter for full acceptance 15<  <150 o.  In order to keep its hermeticity, Belle adopted Threshold Aerogel Cherenkov counter for K/  separation.  Thanks to recent developments of new type photo tubes, ring image Cherenkov Counters can be installed to Belle2.  Significant improvement of K/  separation is expected.

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

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

TOP: Barrel Cherenkov counter  Square-shape multi-anode MCP-PMT  Multi-alkali photo-cathode  Single photon detection  Fast raise time: ~400ps  Gain=1.5x10 6 (B=1.5T)  T.T.S. (single photon): ~35ps (B=1.5T)  Position resolution: <5mm 27SEL 2011 meeting at Mumbai T.Tsuboyama

ARICH: Forward Ring Image Cherenkov counter  Proximity focusing Cerenkov counter with:  2 layer Aerogel photon radiators  Readout with Pixilated HADP 28SEL 2011 meeting at Mumbai T.Tsuboyama Package size72x72x30 mm 3 Pixels12x12 Pixel size4.9x4.9 mm 2 Effective are67 % QE (typical)25 % Gain~ 10 5 Mass220 g

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 29SEL 2011 meeting at Mumbai T.Tsuboyama

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. 30SEL 2011 meeting at Mumbai T.Tsuboyama

CsI Calorimeter  Physics simulations show the performance is close to that of the ultimate upgrade with pure CsI crystals readout with PMT. Cases Efficiency Current Belle 12.4 ± 0.2 % Current Belle with 10x BG 7.8 ± 0.2 % DAQ upgrade 12.0 ± 0.2 % (Pure CsI + PMT readout ) 12.3 ± 0.2 % # BKG hits in B   + DAQ upgrade + Pure CsI + PMT Eth (MeV) B  J/ΨKs, Ks   0  0 has two  0 reconstructed. CsI performance is essential. B   requires no activities in CsI except for  decay particles. Sensitive to beam background. 31SEL 2011 meeting at Mumbai T.Tsuboyama

KLM: K L and  detector  Belle  RPC (resistive plate chamber): hit rate < 1Hz/cm 2  Endcap part will be replaced with Scintiilator + MPPC (SiPM) LayerBarrelForw ard Back ward , NA NA NA Hit rate (Hz/cm 2 ) expected of KLM at SuperKEKB R3150 R1305 Longest strip 2820 mm 32SEL 2011 meeting at Mumbai T.Tsuboyama

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 33SEL 2011 meeting at Mumbai T.Tsuboyama

Trigger  The collision luminosity will be 40 times larger than the present Belle experiment.  Physics event rate will be 10 kHz at 8x10 35 /cm 2 /s.  The trigger system should be tunable to accommodate the physics rate for given DAQ and computing performances. 34SEL 2011 meeting at Mumbai T.Tsuboyama

DAQ  At the full luminosity, the data rate amounts to 600 MB/sec.  A high performance DAQ system is designed. BelleBelle2 Level 1 Trigger Trigger rate (kHz) Event size (k Byte) Data rate (MB/s) High Level Trigger Reduction1/ 21/10 Storage Band Width (MB/s) SEL 2011 meeting at Mumbai T.Tsuboyama

Computing  Belle  computing resource is concentrated to KEK.  Belle2  x 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. 36SEL 2011 meeting at Mumbai T.Tsuboyama Synergy

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

Belle2 detector PID: New Cherenkov Detectors Barrel: Time of Projection counter Forward: Aerogel RICH counter Vertex detector: 2 layer DEPFET pixel detector 4 layer Si vertex detector Central Drift Chamber Small cell layout KL/  detector: Barrel: RPC End cap: Scintillator readout with MPPC CsI(Tl) with wave sampling readout COMP: High performance computer systems TRG/DAQ: New Dead time free readout (  /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) (  pt /p t ) 2 = (0.1 p t ) 2 +(0.3) 2 % 2 (with SVD) Muon ID eff>90 % (2% fake) Impact parameter resolution  z = 20  m 38SEL 2011 meeting at Mumbai T.Tsuboyama

Belle II Collaboration countries/regions, 53 institutes SEL 2011 meeting at Mumbai T.Tsuboyama

Summary  The Super KEKB is approved.  Improve the detector performances  Capability for data acquisition of 8x10 35 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  Commissioning of Belle2: 1 October SEL 2011 meeting at Mumbai T.Tsuboyama

Belle upgrade started  Dismantling of Belle detector components Central Drift chamber on 6 Jan 2011 SEL 2011 meeting at Mumbai T.Tsuboyama41

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.Tsuboyama42