1. Scintillator based muon upgrade / BELLE Super B Factory Workshop In Hawaii 19-22 Jan 2004, Honolulu, Hawaii 1.Scintillator strip option 2.Geiger photodiodes (SiPM & MRS APD) 3.Scintillator tile option 4.First tests at BELLE 5. Conclusions Outline M.Danilov, D.Liventsev, R.Mizuk, P.Pakhlov, V.Rusinov, E.Tarkovsky, I.Tikhomirov, T.Uglov (ITEP Moscow)

2. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov2 Scintillator Strip Geometry (1) System consists of ~17k scintillator strips with WLS fiber readout.

3. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov3 Scintillator Strip Geometry (2) Max. strip length ~2.8m.

4. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov4 Light Yield in MINOS Scintillator Strips 1cm x 4cm, 1.2mm Y11 fiber 5p.e. correspond to efficiency of about 99%. Mirroring of fiber far end increases light yield by a factor 2 (at the end). N p.e. Distance along strip, m

5. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov5 Problems with PM Readout Complicated transportation of light with clear fibers. Difference of gain between different pixels (up to factor 3). Cross-talk ~ 5-10% → ghost clusters (at acceptable level).

6. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov6 SiPM For further details see: «Advanced study of SiPM» http://www.slac.stanford.edu/pubs/icfa/fall01.html 2ns 2mV SiPM main features: Sensitive size 1x1mm 2 on chip 1.5x1.5 mm 2 Gain 2  10 6 U bias ~50V Recovery time ~ 100 ns/pixel Number of pixels: 576-1024 Insensitive to magnetic field Dynamic range ~10 3 /mm 2

7. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov7 Gain & Efficiency of SiPM vs. Overvoltage Efficiency = QE   geom  geom ~0.3 (B.Dolgoshein et al. )

8. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov8 SiPM Cross-talk Pixel Gain, 10 5 Interpixel Cross-talk (>1 to 1 ratio)

9. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov9 Efficiency vs. Wavelength 200300400500600700800 0 20 40 60 80 QE  geom SiPM PMT XP2020Q number 40979 (according to Philips Photonics) APD EG&G C30626E (NIM A428 (1999) 413-431) room temperature QE, % Wavelength, nm (B.Dolgoshein et al. )

10. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov10 Emission Spectrum of Y11 WLS Fiber Measured at distances 10cm, 30cm, 100cm and 300cm from source.

11. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov11 SiPM Noise random trigger 1p.e. 2p.e. 3p.e. Ped. noise rate vs. threshold Optimization of operating voltage is subject of R&D at the moment. 1p.e. noise rate ~2MHz. threshold 3.5p.e. ~10kHz threshold 6p.e. ~1kHz

12. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov12 Scan of Strip Using Cosmics Setup LEDcosmics ∑ Poiss  Xtalk·G(x 0 +i·Δx,  0 +  1 ·√i) Center of strip, N pixels (peak) = 9.7 groove depth 2.5mm

13. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov13 Scan of Strip Using Cosmics Setup (2) Poisson mean for MIP at normal incidence Strip 200x2.5x1cm 3 MC: light yield for 4x1cm 2 strip will be ~25% smaller. In the middle of 280x4x1cm 3 strip we expect ~ 9p.e. With threshold 4.5p.e. noise rate <10kHz efficiency  98% average efficiency >99% Similar detector - MRS APD - with smaller x-talk and similar efficiency is under investigation now. Expect efficiency >99.5% with noise <1kHz

14. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov14 Metal-Resistor-Semiconductor APD (CPTA, Moscow)

15. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov15 MRS APD Cross-talk

16. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov16 MRS APD Efficiency vs. Wavelength

17. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov17 Scintillator Tile Geometry (1)

18. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov18 Scintillator Tile Geometry (2)

19. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov19 Light Yield from 16x16x0.5cm 3 Tile with Circular WLS Y11 MC 1mm fiber, Vladimir Scintillator

20. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov20 Experience of CALICE (1)

21. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov21 Experience of CALICE (2) Amplitude distributions for LED and for triggered 90 Sr signals in 5x5x0.5cm 3 tile.

22. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov22 Experience of CALICE (3) Light Yield from 129 Minical tiles.

23. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov23 Measurement of Scintillator Sensitivity to Neutron Background at BELLE

24. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov24 Neutral KLM Clusters with Matching ECL Originating from Background cos θ MC (no continuum) BB + bg BB only data exp 13 (lab.system) Random K L background exists already at present background rates even if coincidence between two layers is required. With scintillator KLM even one layer clusters could be considered for K L reconstruction. cos θ

25. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov25 Conclusions 1. Most probably RPC KLM will not be able to work good enough at higher luminosity in end-cap region. 2. Scintillator technique can be used to build reliable, very efficient and simple in operation KLM. 3. Many parameters should still be optimized.

26. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov26 Tests of Different Shapes of Grooves

27. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov27 Amplitude Dependence on Temperature T=+9.5 o C T=+14.6 o C T=+20.1 o C T=+25.3 o C

28. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov28 Light Yield from 5x4x1cm 3 Scintillator with Straight Central Groove (1mm Y11 WLS fiber, β-source)

29. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov29 Tests of Different WLS Fibers and Scintillator Types WLS Y11 MC 1 mm BC-92 SC 1 mm 5*5 cm circle 5*5 cm diagonal 11 0.46 0.58 To understand different light loss with BC-92 for circular and straight grooves light loss in a fiber loop was tested:  -source scint PM R=22mm Y11 has 6% light loss; BC-92 -27% (with respect to a straight fiber) I. Comparison of Y11 and BC-92. BICRON-408 scintillator gives x1.5 more light than Russian scintillators. It is order of magnitude more expensive. Therefore we use Russian scintillator.

30. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov30 Light Yield of Individual MINOS Sc. Strips There is a substantial difference in individual strip responce. However all strips give more than 3p.e. at 3m. Nonuniformity across strip is about 5% only for 4cm x 1cm strips.

31. Super B Factory Workshop In Hawaii, 19-22 Jan 2004, M.Danilov31 Problems with RPC Hit rate at 1200mA/800mA –Barrel: ~ 0.02 Hz/cm 2 (~same as no beam case) –Endcap: ~ 0.1 Hz/cm 2 Extrapolation to x20 beam current (assuming linear) –Barrel: at most ~ 0.4 Hz/cm 2 at most a few % efficiency drop, acceptable –Endcap: ~ 2 Hz/cm 2 significant efficiency drop, something must be done