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R&D on CsI(Tl) + APD Optimisation of the energy resolution

R&D on CsI(Tl) + APD Optimisation of the energy resolution. M. Gascón I.Durán. R3B calorimeter. Main characteristics (from R3B Tech Proposal) :. Large dynamic range for detecting p, g Inner radius 3 5 cm ( house Si trackers). R&D on crystals + readout systems

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R&D on CsI(Tl) + APD Optimisation of the energy resolution

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  1. R&D on CsI(Tl) + APD Optimisation of the energy resolution M. Gascón I.Durán

  2. R3B calorimeter Main characteristics (from R3B Tech Proposal) : Large dynamic range for detecting p,g Inner radius 35 cm ( house Si trackers) R&D on crystals + readout systems Design based on CAD + GEANT4 full simulations see http://www.usc.es/~genp -> calorimeter -> reports and talks

  3. Calorimeter sectors Due to the Lorentz boost we identify three sectors: 45 130 15 8 8 ECM = 10 MeV β = 0.82 Demonstrator meeting, Madrid May-09

  4. Crystals !? R3B/EXL meeting Milan Oct-06

  5. Crystals M. Mozynski et al., NIM A 485(2002)504 (API LAAPD)

  6. XP3102 Standard 10-stage, 25 mm tube, borosilicate glass, bi-alkali XP1918 Standard 10-stage, 19 mm tube, fused silica, UV bi-alkali XP1901 Standard 10-stage, 19 mm tube, lima glass, Green bi-alkali S8665-55 (CMS) 5x5 mm S86641010(PANDA) 10x10 mm S5345+ API 19 mm2 UV extended (200-1000 nm) Material we used for test CsI (Tl) 10x10x10, 10x10x50 ,10x10x100, 10x20x170 mm CsI (pure) 10x10x10, 10x10x50 ,10x10x100 mm LaCl3(Ce) 10x10x10, 10x10x50 ,10x10x100, 10x20x170 mm St Gobain Photonis Hamamatsu R3B/EXL meeting Milan Oct-06

  7. R&d on crystals and APDs Crystals from StGobain (France) tested coupled to LAAPD from Hamamatsu (Japan) and API (USA)

  8. Data-taking setups • Standard pulse-height analysis : - preamplifiers: Canberra 2001A, Ortec R142 - Shapping amplifier: Canberra 2022 - Multichannel analyzer: Ortec Maestro or Amptek MCA-8000 • Pulse-shape analysis : - Oscilloscope Tektronix TDS3054B - Off-line Digital filtering: Trapezoidal finite-impulse algorithm Not used for APDs but providing the best results for PMT! R3B/EXL meeting Milan Oct-06

  9. Experimental setup

  10. Test at Genp-Lab (USC)

  11. Test at Genp-Lab (USC)

  12. APD gain vs. Bias Voltage 5 cm length The energy resoltution shows a minimum when The APD Bias Voltage=380 The energy resoltution depends on the APD gain and the Bias Voltage ~380V Dgain/DV= 2.84 %

  13. Dependence on shapping time For small crystals 4ms is a good compromise between energy-resolution and pile-up

  14. Dependence on the acquisition time Best results achieved for acquisition times between 30-60 s These curves conatin two effects: statistics and bias voltage drift. Could be solved by controling Temperature and Bias Voltage

  15. Dependence on Amplifier Gain Energy resolution improves by increasing the amplifier gain

  16. Best results

  17. Study of the non-uniformity Energy resolution dependence on the first interaction point Non-uniformity ~ 8.4 %, to compare with < 3% measured by St. Gobain Light collection uniformity CMS CAL P. Sempere PhD Thesis

  18. CsI(Tl) Resolution Energy resolution improves for increasing energy CsI(Tl) with a 60Co source (1171 keV) and (1332 keV) R3B/EXL meeting Milan Oct-06

  19. Some conclusions • Several test (wrapping, optical coupling,amplifier gain, shapping time) have been performed to optimise the energy resolution of CsI(Tl) • APDs from API showed the best energy resolution for CsI(Tl) crystals • APDs S8664-1010 from Hamamatsu showed a very good energy resolution • almost independent on the crysal size • The main drawback of APDs vs PMT is the strong dependence of the gain with Temperature and Bias Voltage • How to improve the resolution: • Better stabilisation of both temperature and bias-voltage. • - Better optical coupling --> Scionix • Surface coating --> Ukranian Institute for Crystals • - New generation of scintillating crystals

  20. T and V dependence Both Crystals and APDs response depends on Tº T must be kept very stable ! ~0.1o otherwise, T should be accurately measured in order to keep gain constant by controllingthe bias voltage

  21. Characterization of S8664-1010 APD T. Ikagawa et al., NIM A 538(2995) 640 T stabilisation ~0.1ºC keep the gain variarion ~ 0.3%

  22. Temperature stabilisation Refrigerator 4-5 º C radiator Ceramics Cold focus ~ 10ºC Resistor warm focus T probe T stable within 0.1ºC Humidity control box < 30% (1%) T controller 22ºC Allow pulse shape analysis with Tektronix TDS3054B

  23. Further tests through prototype • Good results are only achieved when there is a perfect matching between the crystal exit surface and the APD entrance area Type 2 View of the Barrel average dimensions 3x1x13 cm Crystal type-2 Bi-frustrum shaped Waiting for an agreement with StGobain and IMP- Lanzhou(China) --> Price drop! Exit face fits to LAAPD S8664-2010 under negotiation First prototypes done at Lanzhou (China

  24. Study of St. Gobain vs IMP Lanzhou crystals Tests performed with API APD Crystal dimensions 1x1x1 cm Very similar behaviour

  25. Resolution achieved IMP Lanzhou St. Gobain

  26. R3B Type Crystal

  27. Uniformity of the crystal Wrapped with ESR (from 3M), tested with 60Co

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