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 Photosensors for DBD & DM experiments

 Photosensors for DBD & DM experiments. Woonku Kang, Jungil Lee, Seunghyun Moon, Kyungju Ma, Yeongduk Kim Sejong University for KIMS collaboration Korea-China Joint workshop 2007. 11. 26. LAAPD ( Large Area Avalanche Photodiode ). Advanced Photonics 사의 16mm 직경의 LAAPD (world largest).

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 Photosensors for DBD & DM experiments

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  1.  Photosensors for DBD & DM experiments Woonku Kang, Jungil Lee, Seunghyun Moon, Kyungju Ma, Yeongduk Kim Sejong University for KIMS collaboration Korea-China Joint workshop 2007. 11. 26

  2. LAAPD(Large Area Avalanche Photodiode) Advanced Photonics사의 16mm 직경의 LAAPD (world largest)

  3. 5mm LAAPD Solovov(1999) • High quantum efficiency : 약 90% @ 500nm LAAPD는 -200도에서도 작동. Significantly reduced dark current Higher gains can be achieved Noise level can be reduced CaMoO4 + LAAPD can be excellent detector for DBD

  4. Previous Results of LAAPD Room temperature measurements • CsI(Tl) + 16mm LAAPD • 4.8%FWHM for 662 keV • LAAPD has better resolution than PMT due to high Q.E. 5.9 keV X-ray 9.3% FWHM =4.0% RMS M. Moszynski

  5. ORTEC PREAMPLIFIER 142AH (High Voltage 용 ) Crystal POWER SUPPLY(HV) Source LAAPD Output (Low Temperature) Output (Room Temperature) ORTEC AMPLIFIER 571 Test Setup - CsI(Tl) & CamoO4(Russia) ~10x10x10mm

  6. # of events (6%FWHM) Back scatters Comptonedge Channel number CsI(Tl)+LAAPD @Room temperature We confirmed good resolution of CsII(Tl)+LAAPD detector at room temperature

  7. mV p2 p0 p4 p5 Micro sec p6 CaMoO4+LAAPD @LowTemp • Decay time ~ 100 ms @ -150 oC • But shaping time of AMP is limited by 10 ms • Analyzed PreAmplifier Signal directly. • Source ; Cs-137 • Temp ; -159.2 oC ± 0.1

  8. CaMoO4+LAAPD @-159oC In reality, the resolution will be worse due to poorer light collection and large size of crystal.

  9. Future plan • Try to understand the cause of LAAPD failure, specially for the dye sensor. • New cryostat and vacuum chamber for LAAPD and new PMT + CaMoO4 tests down to 70K temperature.

  10. New PMTs of Hamamatsu - first talk with company -

  11. Current KIMS PMT • Green extended ETL pmt(9269B) • 26% @ 400nm • 17% @ 500nm 3” PMT (9269QA) : Quartz window, RbCs photo cathode ~5 Photo-electron/keV with CsI(Tl) crystal.

  12. new Hamamatsu PMTS • Ultra Bialkali : • R7600 or 3” Glass Bulb

  13. Hamamatsu will develop a new PMT based on R8520AL(XENON Group) with Ultra bialkili cathode for KIMS. • Size : 1” • Working temperature -100oC • Metal Case with Quartz window. • Will try to deliver a sample to KIMS until end of this year We will test a CaMoO4 crystal coupled with PMT at low temperature.

  14. Development of new hexagonal PMT (HAMAMATSU R8778MOD) for XMASS 800 kg • High quantum efficiency ~ 40% @ 175 nm • Metal package with Quartz window • Low temperature, will be immersed in Lxe.

  15. Test chamber Hexagonal PTFE Top PMT Inside of the chamber Bottom PMT

  16. LED (2mm thick PTFE filter) Hexagonal PTFE and Co-57 source position Distance between two PMTs : 1.5cm

  17. result 122keV 57Co data 18.9 p.e/keV 136keV Some photons are blocked by the source itself Photoelectron statistics limit of the resolution = 2.1%

  18. # of photoelectrons in various LXe experiments

  19. XENON group (at TAUP 2007) New Measurement of Scintillation Efficiency for < 10 keVr XeCube • Hamamatsu R8520 1’’×3.5 cm (metal channel) • bialkali-PC, Quartz window,operates at -100ºC and 5 bar • Quantum efficiency > 20% @ 178 nm • Custom HV divider on Cirlex base σ/E = 7.8 % http://xenon.astro.columbia.edu/

  20. Calorimetric 136Xe DBD • Q=2467 keV • 208Tl 2614.5 keV Compton edge 2381.7 keV • 0.7% energy resolution(17keV) @ 2467keV expected.  DBD peak and Compton edge separation is ~5 sigma. • Maybe worth to study in detail, specially for events between full peak and Compton edge for a specific detector geometry and shielding. • Both single & double phase can be tried.

  21. Summary • LAAPD has (dis)advantage. • New PMTs will improve the sensitivities of DBD and DM experiments. • Constant optimization is important.

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