Workshop on Synergy between High Energy and High

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 ß Explore the CP violation of B meson decay through the particular decay chain Þ Þ Þ e+ e– ϒ(4 S) Bo Bo (CP mode decay) + (tag mode decay) ϒ(4 S) decays into a coherent Bo Bo pair. Only the vertices of Bo and Bo can be measured. ß No particles from the decay vertex of ϒ(4 S). The tasks of a B factory detector: Þ Þ 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. 2 SEL 2011 meeting at Mumbai T. Tsuboyama

Method of CP violation measurement t 2 electron (8 Ge. V) ϒ(4 S) resonance B 1 electron B 2 (3. 5 Ge. V) CP mode decay t 1 m+ m- B 0 Ks n Tag mode decay bg = 0. 425 p+ K– m- D 0 DZ~200 mm p+ S: mixing induced CP parameter 3 SEL 2011 meeting at Mumbai T. Tsuboyama

Belle Detector Cs. I(Tl) 16 X 0 Super conducting solenoid 1. 5 T s/E=1. 8%@1 Ge. V Eid eff=30 % (0. 1% fake) Aerogel Cherenkov Counter n=1. 015~1. 030 3. 5 Ge. V e+ Kid eff = 90 % (6% fake) Central Drift Chamber TOF conter small cell +He/C 2 H 6 st = 95 ps (spt/pt)2 [%2] = (0. 19 pt)2+(0. 34)2 8 Ge. V e / KL detector Silicon Vertex detector 4 layer silicon strip sensors 14/15 lyr. RPC+Fe s(Dz) = 100 m Muon ID eff>90 % (2% fake) 4 SEL 2011 meeting at Mumbai T. Tsuboyama

Belle Detector Tasks SVD CDC TO F ACC Cs. I KLM Record the B meson Events Efficiently Full reconstruction of B meson Tracking ✔ ✔ ✔ Particle ID B flavor Tagging (Particle ID) CM P ✔ Calorimetry Measure the decay vertex position of B mesons TR GD AQ ✔ ✔ ✔ High performance data processing: ✔ 5 SEL 2011 meeting at Mumbai T. Tsuboyama

The adopted technology Þ Full reconstruction of B meson � � � Þ Tracking: Central Drift Chamber and Uniform Solenoid field. Calorimetry: Cs. I(Tl) for good energy resolution. Particle Identification: d. E/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, d. E/dx, KL/MU: b cs: Kaon identifications by ACC/TOF and B D* X, D* p. D: Slow pions reconstruction by CDC. 6 SEL 2011 meeting at Mumbai T. Tsuboyama

The adopted technology ß Measurement of the positions of two B decay vertices. Þ Asymmetric Energy e+e– collider. Þ 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. 7 SEL 2011 meeting at Mumbai T. Tsuboyama

More physics channels ß As the B factory detector is general purpose, we can explore following modes with high precision and high statistics. Þ Other important channels Þ Þ B tn, B Ks. Ks, B Ksp 0 g … B+/B–, charmed mesons, baryons Leptons especially t. Two photon processes. New baryon/meson states 8 SEL 2011 meeting at Mumbai T. Tsuboyama

Why Belle should be upgraded? ß To accommodate 8 x 1035 /cm 2/sec luminosity. Þ Þ ß Belle was designed for 1 x 1035 /cm 2/sec. Physics rate amounts to 10 k. Hz Beam background increases accordingly. Beam energy asymmetry 8+3. 5 Ge. V 7+4 Ge. V To Improve the detector performances Þ Better Tracking: Þ Beam pipe radius: 1. 5 cm 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 9 SEL 2011 meeting at Mumbai T. Tsuboyama

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

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

Beam Pipe ß The nano-beam option Þ Þ 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. 12 SEL 2011 meeting at Mumbai T. Tsuboyama

Silicon Vertex detector ß Background hit occupancy reduction Þ Þ ß APV 25 ASIC with faster shaping time. Pixel detector in the first 2 layers Smaller sensitive area per readout. Improve physics performance Þ Þ Vertex reconstruction and resolution Recover the smaller energy asymmetry. Sensor at smaller radius. Lager acceptance for Ks vertexing. larger radius. Belle 2 Beam pipe Radius (cm) 1. 5 1. 0 Vertex detector Radius (cm) 1. 8 < R < 9. 6 1. 4 < R < 14, 0 Layers 4 layer DSSD 2 Layer Pixel 13 + 4 layer DSSD SEL 2011 meeting at Mumbai T. Tsuboyama

DEPFET pixel detector ß ß ß 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). • The DEPFET group originally started the R&D for Syne the ILC vertex detector. rgy • Converting from ILC design to Belle 2 design is a challenge. 14 SEL 2011 meeting at Mumbai T. Tsuboyama

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

Silicon strip vertex detector ß ß 4 layer with doublesided silicon strip detectors. 3. 8 cm < R < 14. 0 cm Layer R (mm) Ladders Sensors RO chips 3 38 8 16 850 4 80 10 30 560 5 115 14 56 300 6 140 17 85 192 49 187 1902 Sum 16 SEL 2011 meeting at Mumbai T. Tsuboyama

Silicon strip vertex detector ß ß 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. Syne rgy DSSD Large Wedge Small Dimension (mm 2) 124. 88 x 59. 6 125. 58 x(41. 0 -60. 63) 124. 88 x 40. 4 # strips (p) 768/1535 # strips (n) 511/1023 768/1535 Strip pitch (p) 75 50 -75 50 Strip pitch (n) 240 160 17 SEL 2011 meeting at Mumbai T. Tsuboyama

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

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

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

Silicon strip vertex detector ß ß ß Readout chip: APV 25 developed for the CMS Silicon tracker. Syne r g Its 192 stage pipeline and dead-time y free readout fits the Belle 2 DAQ scheme. Belle 2 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. 21 SEL 2011 meeting at Mumbai T. Tsuboyama

Central Drift Chamber Þ Þ Þ 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. 22 Belle 2 Radius of Inner Cylinder (mm) 77 160 Radius of Outer Cylinder (mm) 880 1130 Radius of innermost wire (mm) 88 168 Radius of outer most wire (mm) 863 1111 Number of Layers 50 56 Number of sense wires 8, 400 14, 336 SEL 2011 meeting at Mumbai T. Tsuboyama

Central Drift chamber ß ß ß 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 30 MHz) measures the signal charge. X-T relation HV (k. V) s~100 mm 23 Residual distribution T. Tsuboyama SEL 2011 meeting at Mumbai

Particle ID ß ß Belle/Belle 2 has the Cs. I calorimeter for full acceptance 15<q<150 o. 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 Belle 2. Significant improvement of K/p separation is expected. 24 SEL 2011 meeting at Mumbai T. Tsuboyama

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

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

TOP: Barrel Cherenkov counter ß Square-shape multi-anode MCP-PMT Þ Þ Þ Multi-alkali photo-cathode Single photon detection Fast raise time: ~400 ps Gain=1. 5 x 106 (B=1. 5 T) T. T. S. (single photon): ~35 ps (B=1. 5 T) Position resolution: <5 mm 27 SEL 2011 meeting at Mumbai T. Tsuboyama

ARICH: Forward Ring Image Cherenkov counter ß Proximity focusing Cerenkov counter with: Þ Þ 2 layer Aerogel photon radiators Readout with Pixilated HADP Package size 72 x 30 mm 3 Pixels 12 x 12 Pixel size 4. 9 x 4. 9 mm 2 Effective are 67 % QE (typical) 25 % Gain ~ 105 Mass 220 g 28 SEL 2011 meeting at Mumbai T. Tsuboyama

Cs. I Calorimeter ß Extrapolation of background of Belle Þ Þ Þ ß Present status: Energy deposit in random event: 0. 5 Me. V/Crystal or 3 Ge. V/ECL. “Probably” proportional to Beam current 3– 10 x background in Super KEKB. Fine segment in time will be necessary 29 SEL 2011 meeting at Mumbai T. Tsuboyama

Cs. I Calorimeter ß Upgrade Plan: Þ Þ The Cs. I (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. 30 SEL 2011 meeting at Mumbai T. Tsuboyama

Cs. I Calorimeter ß Physics simulations show the performance is close to that of the ultimate upgrade with pure Cs. I crystals readout with PMT. Efficiency Cases B J/ΨKs, Ks p 0 p 0 has two p 0 reconstructed. Cs. I performance is essential. B tn requires no activities in Cs. I except for t decay particles. Sensitive to beam background. 31 Current Belle with 10 x BG 12. 4 ± 0. 2 % 7. 8 ± 0. 2 % DAQ upgrade 12. 0 ± 0. 2 % (Pure Cs. I + PMT readout ) 12. 3 ± 0. 2 % # BKG hits in B tn + + DAQ upgrade Pure Cs. I + PMT Eth (Me. V) SEL 2011 meeting at Mumbai T. Tsuboyama

KLM: KL and m detector ß ß Belle RPC (resistive plate chamber): hit rate < 1 Hz/cm 2 Endcap part will be replaced with Scintiilator + MPPC (Si. PM) Hit rate (Hz/cm 2) expected of KLM at Super. KEKB R 31 R 1 30 50 5 Longest strip 2820 mm 32 Layer Barre l Forw ard Bac kwa rd 0 3. 6 2. 4 3. 4 1 2. 3 2. 4 2. 9 2 1. 6 2. 4 2, 8 3 1. 1 2. 0 2. 8 4 0. 67 2. 2 2. 8 5 0. 60 2. 7 2. 9 6 0. 63 2. 7 1. 5 7 0. 43 3. 3 2. 6 8 0. 73 3. 1 3. 0 9 0. 47 3. 9 2. 8 10 0. 29 4. 7 3. 5 11 0. 39 5. 3 3. 0 12 0. 44 3. 7 NA 13 0. 42 NA NA SEL 2011 meeting at 0. 48 Mumbai NA T. Tsuboyama 14 NA

KLM HPK 1. 3× 1. 3 mm 667 pixels Vladimir (Russia) (used in T 2 K ND) Kuraray Y 11 MC No other competative option High efficiency; long atten. length 33 SEL 2011 meeting at Mumbai T. Tsuboyama

Trigger ß ß ß The collision luminosity will be 40 times larger than the present Belle experiment. Physics event rate will be 10 k. Hz at 8 x 1035/cm 2/s. The trigger system should be tunable to accommodate the physics rate for given DAQ and computing performances. 34 SEL 2011 meeting at Mumbai T. Tsuboyama

DAQ ß ß At the full luminosity, the data rate amounts to 600 MB/sec. A high performance DAQ system is designed. Trigger rate (k. Hz) Level Event size 1 Trigge (k Byte) r Data rate (MB/s) Reduction High Level Storage Trigge Band Width r (MB/s) Belle 2 0. 3 -0. 5 20 -30 40 300 20 6000 1/ 2 1/10 20 600 35 SEL 2011 meeting at Mumbai T. Tsuboyama

Computing ß ß Belle computing resource is concentrated to KEK. Belle 2 50 -100 x larger computation power and storage is necessary Þ Þ Þ Highly distributed computing environment: S ynerg y GRID with help of CLOUD is necessary. GRID technology established by LHC computing will be utilized. 36 SEL 2011 meeting at Mumbai T. Tsuboyama

Computing ß ß Belle computing resource is concentrated to KEK. Belle 2 50 -100 x larger computation power and storage is necessary Þ Highly distributed computing environment: GRID with help of CLOUD is necessary. 37 SEL 2011 meeting at Mumbai T. Tsuboyama

Belle 2 detector Cs. I(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) TRG/DAQ: New Dead time free readout COMP: High performance computer systems (spt/pt)2 = (0. 1 pt)2+(0. 3)2 %2 (with SVD) Vertex detector: 2 layer DEPFET pixel detector 4 layer Si vertex detector 38 SEL 2011 meeting at Mumbai T. Tsuboyama Impact parameter resolution sz = 20 m

Belle II Collaboration http: //belle 2. kek. jp 13 countries/regions, 53 institutes 39 SEL 2011 meeting at Mumbai T. Tsuboyama

Summary ß ß The Super KEKB is approved. Improve the detector performances Þ Þ Þ ß ß Capability for data acquisition of 8 x 1035 luminosity. Immunity to expected 30 x beam background Beam pipe radius: 1. 5 cm 1. 0 cm Vertex detector: 4 Layer DSSD + 2 layer DEPFET Lever arm of Vertex Detector + CDC: 210 cm 250 cm PID: Threshold Cherenkov Ring image Cherenkov. KID efficiency (Barrel): 90 % 99 %. Disintegration of Belle 2 has started Oct. 2010 Commissioning of Belle 2: 1 October 2014. 40 SEL 2011 meeting at Mumbai T. Tsuboyama

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

And more …. ß ß 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! 42 SEL 2011 meeting at Mumbai T. Tsuboyama