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LENA Photosensor R&D

LENA Photosensor R&D. Marc Tippmann Lothar Oberauer, Michael Wurm, Gyorgy Korga, Quirin Meindl, Michael Nöbauer, Thurid Mannel, Martin Zeitlmair, German Beischler Technische Universität München DPG-Frühjahrstagung 2011, Karlsruhe 2011/03/31. Overview. LENA photosensor requirements.

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LENA Photosensor R&D

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  1. LENA Photosensor R&D Marc Tippmann Lothar Oberauer, Michael Wurm, Gyorgy Korga, Quirin Meindl, Michael Nöbauer, Thurid Mannel, Martin Zeitlmair, German Beischler Technische Universität München DPG-Frühjahrstagung 2011, Karlsruhe 2011/03/31

  2. Overview

  3. LENA photosensor requirements

  4. LENA photosensor requirements: Overview Requirements on photo sensors • Sensor performance • Environmental properties • Availability until start of construction • Cost-performance-ratio Desired energy resolution for low energies: → Light yield ≥ 200 photoelectrons/MeV → 30% optical coverage → 3000m² effective photosensitive area needed → Current standard configuration: Liquid scintillator detector: 63,000 PMTs (8“) with Winston Cones (area ×1.75) Water cherenkov muon veto: 6,000 PMTs (8“)

  5. LENA photosensor requirements: List

  6. LENA photosensor requirements: List

  7. LENA photosensor requirements: List Michael Wurm, TUM, LENA - PMm² meeting 07/04/2009

  8. LENA photosensor requirements: List Teresa Marrodán, PhD thesis Photon Fast afterpulse

  9. LENA photosensor requirements: List Teresa Marrodán, PhD thesis

  10. LENA photosensor requirements Fast afterpulses (fAP): Ongoing measurements of fAP time distribution for candidate PMT series → • Investigate causes • Currently studying their influence on the efficiency of the p decay coincidence: Bachelor thesis by Thurid Mannel • Possible methods of discrimation from photons? Bachelor thesis by Martin Zeitlmair

  11. PMT characterization

  12. Measurements at the LNGS, Gran Sasso Borexino PMT testing facility • Pulsed ps laser diode light source: 410nm, light pulse FWHM <30ps • Total time resolution <140ps • Can measureupto 32 PMTs simultaneously • Measure transit time distribution (TDC), fast + ionic afterpulse time distribution (MTDC), charge spectrum (ADC) • Measured 1 sample each of: • Hamamatsu: R6091(3“), R6594(5“), R5912(8“) and R7081(10“) • ETEL: 9351(8“)

  13. Measurements @LNGS:R6594 vs. R7081 5“ 10“

  14. Measurements @LNGS:R6594 vs. R7081

  15. Measurements @LNGS:R6594 vs. R7081

  16. Measurements @ LNGS: Results At the moment no conclusive decision possible: Need to measure ≈10 PMTs/series and determine limits + implications on physics from simulations

  17. Outlook

  18. Outlook: Munich photosensor test stand • FADC: Acqiris DC282, 10bit, 8 GHz • Light sources: • Pulsed ps diode laser: Edinburgh Instruments EPL-405-mod, 403nm, pulse width 48ps • Fast LED driven byavalanche diode: 430nm, time jitter (FWHM) <≈1ns Currently being set up • Done: Light sources implemented and working, electronics running • Next steps: include fiber and beam widening optics, finish online analysis software based on Labview • Plan to study: PMTs: time distribution, fast AP, ionic AP, pulse shape, dynamic range, surface scans; also SiPMs

  19. Outlook: Optical module development Light Concentrators (Winston Cones) • MC simulations of light concentrators with geant4 • Incorporate results into optical model of detector (geant4 MC) → determine optimum light concentrator • Build prototype + scan with laser over aperture and incident angles Diploma thesis by Michael Nöbauer Pressure encapsulations • Design pressure encapsulations with FEM pressure simulation, e.g. spherical shape or conical shape, integrate Winston Cones + Mu-metal shielding into design • Build + test prototypes Bachelor thesis by German Beischler Borexino Winston Cone

  20. Summary • Approximate limits on photosensor properties known → do simulations to refine values • Have tested promising PMT series from Hamamatsu @ LNGS → repeat for more samples of Hamamatsu + ETEL PMTs in Munich • Also test SiPMs and Hybrid Phototubes • Have started development of pressure-withstanding optical modules for PMTs incorporating Winston Cones and Mu-metal

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