Toru Iijima / Nagoya TOP: what has to be done (before decision) Bar quality seems to be satisfactory. Photodetection is (probably) the most critical issue. TTS Chromatic dispersion optimum QE range Magnetic field immunity Good efficiency ×effective area ratio Position resolution Realistic cost, time for development High time resolution (pipe-line) read-out Background Geometry cf.) Npe = 6 with R59 00-U-L16 at the beam tes t Effective area ~ 40% Collection eff ~ 50% Toru Iijima / Nagoya (2002.8.31)
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Toru Iijima / Nagoya TOP: what has to be done (before decision) Bar quality seems to be satisfactory. Photodetection is (probably) the most critical issue.
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Toru Iijima / Nagoya
TOP: what has to be done (before decision)
Bar quality seems to be satisfactory.
Photodetection is (probably) the most critical issue. TTS Chromatic dispersion optimum QE range Magnetic field immunity Good efficiency ×effective area ratio Position resolution Realistic cost, time for development
High time resolution (pipe-line) read-outBackgroundGeometry
cf.) Npe = 6 with R5900-U-L16 at the beam test
Effective area ~ 40% Collection eff ~ 50%
Toru Iijima / Nagoya (2002.8.31)
Toru Iijima / Nagoya
Time Resolution w/ PrototypeGreatly improved by better polishing accuracy.t =85ps (L=0.3m), 100ps (L=1m), 150ps (L=2.3m) achieved.
~ Chromatic dispersion limit (almost)
Single pe resolution, bar quality are almost understood.
Toru Iijima / Nagoya
Bar TOP Beam Test ResultTime resolution t(w/o mirror) = t(w/ mirror)
Toru Iijima / Nagoya
Application in BelleCorrelation between in and TOP, TOF and Npe.
The most tough part is around in=45°.
35°45° 90° 140°
(T
OP
+T
OF
)/t
Forward photons Backward photons
TOP
TOF
Separation obtained by peN Npe/d~25 (d:bar thickness in cm)
Toru Iijima / Nagoya
Expected Performance in Belle502K photocathode (green extended bialkari) w/ QEpeak=20%
Bar thickness = 2cm
Bar thickness = 4cm
Toru Iijima / Nagoya
Photodetector Comparison
1,2,3 have been tested
4: tests are under way
5: B.Dolgoshein (MEPhI, Moscow) et.al., (see SLAC-J-ICFA-23)
Numbers in () are guess, and need be tested or confirmed.
Ceff. x t(TTS) B Gain note
1 R5900-U-L16 50% 1mm 70-80ps × O(106)
2 FM-PMT-L24 85% 1mm 100ps 1.0T O(106)
150ps 1.5T O(106)
3 HAPD (>80%)
OK 100ps OK O(104)
4 MCP-PMT (60%) OK 35ps OK O(106) Life?, Cost?, Size?
5 Si-PM (Geiger mode APD)
30% OK 50ps OK O(106) QE~80% (>500nm), Noise?, size??
Toru Iijima / Nagoya
MCP-PMTVery good timing performance TTS/photon < 50ps.Tests are underway.