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TOP counter overview and issues

2008/7/3-4 2 nd open meeting for proto-collaboration. TOP counter overview and issues. Overview Design Performance Prototype construction Summary. K. Inami (Nagoya university). 1.5T. 1.2m. 2.6m. e + 3.5GeV. e - 8.0GeV. Side view of Super Belle detector. Introduction.

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TOP counter overview and issues

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  1. 2008/7/3-4 2nd open meeting for proto-collaboration TOP counter overview and issues • Overview • Design • Performance • Prototype construction • Summary K. Inami (Nagoya university)

  2. 1.5T 1.2m 2.6m e+ 3.5GeV e- 8.0GeV Side view of Super Belle detector Introduction • TOP (Time Of Propagation) counter • Developing to upgrade the barrel PID detector • For Super B factory • Lpeak~1035~36/cm2/s, 20~100 times higher than present • Need to work with high beam BG • To improve K/p separation power • Physics analysis • Bpp/Kp, rg, Knn etc. • Flavor tag • Full reconstruction • Target; 4s for 4 GeV/c 2008/7/3-4 2nd open meeting for proto-collaboration

  3. TOP counter • Cherenkov ring in quartz bar • Reconstruct ring image using ~20 photons on the screen reflected inside the quartz radiator as a DIRC. • Photons are detected with photon detectors. Different ring image for the pion and kaon of the same momentum Need large screen... 2008/7/3-4 2nd open meeting for proto-collaboration

  4. TOP counter • 2D position information  Position+Time • Compact detector! Simulation 2GeV/c, q=90 deg. Linear array PMT (~5mm) Time resolution s~40ps ~2m ~200ps K p Different opening angle for the same momentum  Different propagation length(= propagation time) + TOF from IP works additively. 2008/7/3-4 2nd open meeting for proto-collaboration

  5. Baseline design • Quartz: 255cmL x 40cmW x 2cmT • Focus mirror at 47.8deg. to reduce chromatic dispersion • Multi-anode (GaAsP p.c.) MCP-PMT • Linear array (5mm pitch), Good time resolution (<~40ps) •  Measure Cherenkov ring image with timing information TTS~35ps MCP-PMT 2008/7/3-4 2nd open meeting for proto-collaboration

  6. GaAsP photo-cathode Higher quantum-efficiency at longer wavelength → less chromatic error Multi-alkali p.c. + l cut filter (option) Light propagation velocity inside quartz Chromatic dispersion Variation of propagation velocity depending on the wavelength of Cherenkov photons Photon sensitivity at longer wavelength shows the smaller velocity fluctuation. 2008/7/3-4 2nd open meeting for proto-collaboration

  7. Focusing TOP • Remaining chromatic effect makes ~100ps fluctuation for TOP. • Use l dependence of Cherenkov angle to correct chromaticity  Focusing system to measure qc • l qc  y position • Reconstruct ring image from 3D information (time, x and y). Mirror image Focus Mirror Side view 2008/7/3-4 2nd open meeting for proto-collaboration

  8. Focusing TOP (2) • Dqc~12mrad over sensitive l range •  Dy~20mm (~quartz thickness) • We can measure l dependence and obtain good separation even with narrow mirror and readout plane, because of long propagation length. • Not need focusing block • Not need fine readout channels Dqc~12mrad Virtual readout screen 22mm x 5mm matrix Focusing mirror 1850mm 2008/7/3-4 2nd open meeting for proto-collaboration

  9. Performance • Focusing type + GaAsP photo-cathode • >400nm filter, Correction Eff.=35% 4.2s K/p for 4 GeV/c, q=70ﾟ 2008/7/3-4 2nd open meeting for proto-collaboration

  10. A module supporting quartz and PMT Quartz radiator Support by aluminum honeycomb box Black box MCP-PMT Assemble with front-end elec. Connect elec. part to honeycomb Not glue PMT with quartz Prototype construction 1st step) quartz 1m (forward, backward part) By the end of June  Beam test 2nd step) quartz 2m + focus mirror By the end of December TOP module 2008/7/3-4 2nd open meeting for proto-collaboration

  11. Size; 915 x 400 x 20 mm Flatness; <2mm Roughness; <0.5nm By Okamoto optics work, inc. Support by Aluminum honeycomb panel 1cm thickness With plungers Keep quartz in air ~1kg/plunger on honeycomb ~2.5kg/plunger on side panel Quartz radiator 2008/7/3-4 2nd open meeting for proto-collaboration

  12. Spherical mirror (R=5m) Check peak position of spherical mirror wrt. quartz edge By 3D measurement system at Nagoya univ. 0.33±0.30±0.20mm outside from bar edge Acceptable in simulation Cross check by interferometer in Okamoto optics work, inc. Spherical mirror (R=5m) 40cm 2cm Focusing mirror Lens Pin gauge Mirror Focusing mirror 2008/7/3-4 2nd open meeting for proto-collaboration

  13. MCP-PMT 27.5x27.5 mm square By Hamamatsu photonics Multi-alkali p.c.  beam test GaAsP p.c.  lifetime test PMT module HV divider AMP + CFD No CFD part for beam test PMT box 13 modules <40ps TTS for single photon Support modules and filters Attach to quartz box PMT box 2008/7/3-4 2nd open meeting for proto-collaboration

  14. Photon detector; main issue • Photo-cathodes of MCP-PMT • Multi-alkali (bi-alkali); OK. • Almost established production • Confirmed enough lifetime • GaAsP; in progress • Better efficiency at longer wavelength • Need more production R&D and lifetime test • Multi-alkali without Al protection layer on MCP (option) •  4sp/K separation for 4GeV/c • Improved efficiency (x1.6) • Almost established production, but need some modification to improve lifetime (3-layer MCP, operation with lower gain, etc.) Al layer 2008/7/3-4 2nd open meeting for proto-collaboration

  15. Summary • Baseline design • Focusing system • To correct Chromatic effect with narrow mirror (20mmt) • GaAsP photo-cathode MCP-PMT • Prototype shows the enough performance • TTS = 35ps for single photon, High Q.E. (>40% at 500nm) • Performance; >4s for 4GeV/c • Prototype construction is in progress. • Quartz bar + support structure • Focusing mirror  Need to measure the TOP performance • MCP-PMT + front-end elec. • Issues • MCP-PMT; Need better photon efficiency • Need help, • DAQ electronics (high precision TDC; s~10ps) • Structure construction, Software, ... 2008/7/3-4 2nd open meeting for proto-collaboration

  16. Test counter Test counter Beam test @ KEK PS p2 line 3 GeV/c p- beam qin=fin=90 degree 1mm pitch readout • Clear ring image • Reasonable • time resolution • Enough bar quality 2008/7/3-4 2nd open meeting for proto-collaboration

  17. ~10% dead space in f Maybe need to be overlapped layout Need to locate support structure in narrow space ~20mm between quartz and outer structure 18 counters in r-f Al wall (1mmt) Quartz Geometry Overlapped layout 2008/7/3-4 2nd open meeting for proto-collaboration

  18. Performance • Focusing type + Multi-alkali • >350nm filter, Correction Eff.=60% Because of complicated ring image 3.5s K/p for 3 GeV/c, q=70ﾟ 2008/7/3-4 2nd open meeting for proto-collaboration

  19. TOP configuration summary • Focusing type can reduce the dead space and remove middle PMT. 2008/7/3-4 2nd open meeting for proto-collaboration

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