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activity: ( ) B @ 2009 11 5

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TOP group, N-lab Contents 1.Introduction 2.R&D of TOP counter components 3.Performance test of prototype 4.R&D of HAPD for A-RICH counter 5.Summary 2 B @ Nov 5, 2009

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TOP group, N-lab 1. INTRODUCTION 3 B @ Nov 5, 2009

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TOP group, N-lab 1. Our Motivation Upgrade of Belle PID system Current PID system of Belle /K separation power : 3 Barrel: TOF + ACC End cap: ACC 4 B @ Target Performance 3 4 (0.6 < p < 4 GeV/c) Upgrad e (ACC: Threshold type Aerogel Cherenkov Counter) Barrel: TOP counter End cap: Aerogel RICH Belle-II Current system 2.6m 1.2m e - 8.0GeV e + 3.5GeV 1.5T ForwardBackward Install here Nov 5, 2009

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TOP group, N-lab 2. Principle of TOP counter (1) DIRC (Detection of Internally Reflected Cherenkov light) technique Cherenkov radiator + screen (photo-detector matrix) Cherenkov light propagate to terminal of quartz with total reflection Ring image is detect as parabola 5 B @ Imaging with quartz Require large screen For same momentum, velocity of /K is different different ring images Nov 5, 2009

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TOP group, N-lab 2. Principle of TOP counter (2) 6 B @ TOP(Time Of Propagation) counter Cherenkov radiator + time sensitive screen Position (x, y) Position + time (x, t) Very compact & simple TOP counter measures TOF + RICH High performance expected! time includes TOF information 1.18m TOF TOP Nov 5, 2009 z y x

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TOP group, N-lab 3. Expected Performance in Belle-II /K separation power 4 for 2

TOP group, N-lab 2. Photo-detector Requirements Gain : 1.010 6 TTS : 20%@=400nm Usable in B -field 12 B @ (Micro Channel Plate) Only photo-detector satisfies requirements MCP-PMT Square type MCP-PMT Co-development with Hamamatsu Photonics Channel ~400 m ~10 m Channel ~10m, Bias angle of MCP : 13Usable in B-field Nov 5, 2009

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TOP group, N-lab 3. MCP-PMT R&D Output charge distribution 13 B @ Pedestal Output of single photon Gain 1.010 6 Single photon detection OK Nov 5, 2009

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TOP group, N-lab 4. MCP-PMT R&D 14 B @ =34.20.4ps QE 24%@400nm QE>20%@=400nm OK transit time [25ps] counts wavelength [nm] QE[%] TTS 40ps OK Single photon irradiation Nov 5, 2009

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TOP group, N-lab 3. PERFORMANCE TEST OF PROTOTYPE 15 B @ Nov 5, 2009

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TOP group, N-lab 1. Beam Test 16 B @ Detection of ring image Obtain N( ), number of detected photons par track TTS measurement Items to confirm electron beam 2GeV/c MCP-PMT Timing Counter MWPC2 MWPC1 Veto counter Trigger Counter TOP Counter Subtract em-shower events Beam trajectory t0 determination Setup of beam test at Fuji test beam line Nov 5, 2009 Performed in Jun. & Dec. 2008

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TOP group, N-lab 2. Result : ring image Proper action of total system of TOP counter is confirmed 17 B @ ch Ring image (data) Ring image simulation transit time[25ps] Nov 5, 2009

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TOP group, N-lab 3. Result : number of detected photons N() consistency confirmed Slightly different remaining shower event 18 B @ Number of detected photons/events arbitrary Nov 5, 2009

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TOP group, N-lab 1 st 2 nd 3 rd 1 st 2 nd 3 rd 4. Result : transit time distribution We confirmed consistency of transit time distributions for beam test & simulation 19 B @ TTS 1 st peak Data76.02.0 [ps] Simulation77.72.3 [ps] Beam irradiation point ( 875mm ) Beam irradiation point ( 875mm ) 875mm 915mm quartz 3 rd 2 nd 1 st ch29 transit time[25ps] [photons] transit time[25ps] datasimulation Nov 5, 2009

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TOP group, N-lab 4. R&D OF HAPD FOR A-RICH 20 B @ 2.6m 1.2m e - 8.0GeV e + 3.5GeV 1.5T ForwardBackward Aerogel RICH Nov 5, 2009

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TOP group, N-lab 1. Aerogel RICH counter 21 B @ Nov 5, 2009

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TOP group, N-lab 2. HAPD R&D Hybrid structure Vacuum tube APD (5x5mm 2 matrix) Bialkali photocathode ~10 4 total gain Confirmed Single photon detection Available in 1.5T B-field Current issue Radiation hardness (neutron) study Photocathode study Nov 5, 200922 B @ 73mm Single photon irradiation Photo-detection in Magnetic field

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TOP group, N-lab 5. Summary & Issues Our Motivation: upgrade of PID system Target performance: separation power 3 4 Idea: barrel TOP, end cap Aerogel RICH TOP counter New idea of RICH: Position(x, y) Position(x) + time(=TOF+RICH) Basic performances are confirmed with prototype Issue Structure, reconstruction code, lifetime of PMT, readout, etc HAPD R&D Performances are available for ARICH Issue Neutron hardness, high QE photocathode study 23 B @ Nov 5, 2009

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TOP group, N-lab BACKUP 24 B @ Nov 5, 2009

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TOP group, N-lab Belle-II experiment Our target of development : Belle-II experiment 25 B @ Belle detector Higher statistics Higher luminosity ~40 B-factory Super B-factory Higher accuracy Belle detector upgrade e + e - asymmetric collider e + : 3.5GeV e - : 8.0GeV e + e - (4S) BB /K-ID is important for flavor tagging Nov 5, 2009

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TOP group, N-lab History of R&D Butterfly TOP 26 B @ Nov 5, 2009

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TOP group, N-lab timing 1m assumption Performance Parameterization Important parameters : N det, photodetector 27 B @ : Difference of TOF +TOP for /K 60ps : TTS of TOP counter : Detected photons/track 20 : TTS of photo-detector 40ps : Chromatic dispersion 1m propagation in quartz: 50ps 25ps Can suppress with cut filter Separation power : Nov 5, 2009

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TOP group, N-lab Chromatic Dispersion Chromatic dispersion 28 B @ group velocity of light [m/ns] wavelength [nm] number of detected photons Typical wavelength distribution of detected photons Typical wavelength distribution of group velocity of light Restricts TOP TTS This is because refraction index has wavelength dependence Nov 5, 2009

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TOP group, N-lab Suppression of Chromatic Dispersion Wavelength cut 29 B @ Group velocity of light Number of Cherenkov photons Transmittance of wavelength cut filter 350nm Suppression of chromatic dispersion with 350nm wavelength cut filter wavelength cut TTS improve N det decrease fine tune chromatic 50 25ps Nov 5, 2009

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TOP group, N-lab 1. Radiator Quartz (fused silica) Size 91540020 (mm 3 ) Weight 16kg Flatness < 1.2m/m Surface roughness 5 Refractive index 1.45 Co-development with Okamotokougaku 30 B @ Nov 5, 2009

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TOP group, N-lab Construction of Prototype 31 B @ Al honeycomb Quartz Al honeycomb Spring loaded polyathetal head plunger40/surface Distortion of frame is absorbed by spring Cross section of radiator part 23mm 46 mm Al honeycomb support Core density 0.037g/cm 3 Thickness 10mm Surface plate 0.3mm Al Sag < 80m Quartz flatness in Frame

TOP group, N-lab Summary for TOP Counter TOP counter is very compact & simple detector based on TOF + RICH technique Radiator propagates Cherenkov light without distortion Position(x, y) Position(x) + time (= TOF + TOP) Target performance of TOP counter >4 for 0.6 < p < 4GeV/c Key parameters Number of detected photons Prototype of TOP counter has been constructed We confirmed basic performances of prototype with following parameters: 38 B @ QuartzMCP-PMT Flatness : 1.2 m/mGain : ~1.0 10 6 Roughness : 5 TTS : < 40ps Shape accuracy : 10QE : > 20%@= 400nm Nov 5, 2009

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TOP group, N-lab Nov 5, 200939 B @