1. Characterization of the QUartz Photon Intensifying Detector (QUPID) Artin Teymourian UCLA Dark Matter Group Dept. of Physics and Astronomy

2. 06/10/2011Artin Teymourian, UCLA2

3. Overview Dual Phase TPC QUPID Concept QUPID Design Goals Test Systems/Results Support Structure Future DM Experiments Conclusion 06/10/20113Artin Teymourian, UCLA

4. Dual Phase TPC 06/10/20114Artin Teymourian, UCLA

5. Photo Cathode (-6 kV) APD (0 V) Quartz Al coating APD (0 V) Photo Cathode (-6 kV) Made by Synthetic Silica only. QUPID, The QUartz Photon Intensifying Detector 06/10/20115Artin Teymourian, UCLA

6. 06/10/20116Artin Teymourian, UCLA Actual QUPID

7. 7Artin Teymourian, UCLA06/10/2011 QUPID 3 inch R8520 1 inch R8778 2 inch XENON10 XENON100 XMASS LUX DarkSide XENON1T MAX, XAX Comparison of Low-radioactive Photon Detectors from Hamamatsu

8. QUPID Design Goals 06/10/2011Artin Teymourian, UCLA8 R8520 Radioactivity<4.7 mBq/cm 2 Quantum Efficiency>30% Total Gain>10 6 Pulse Width~10 ns Transit Time Spread~1 ns The QUPID should be better than standard PMTs in all aspects In addition: Photon Counting Capabilities Good Photocathode Uniformity Good Collection Efficiency

9. Radioactivity PhototubeEffective AreaUnits 238 U 226 Ra 232 Th 40 K 60 Co R85206.5 cm 2 mBq/cm 2 <2.3<0.056<0.0702.20.10 R11410- MOD 32 cm 2 mBq/cm 2 <2.9<0.076<0.0820.420.11 QUPID32 cm 2 mBq/cm 2 <0.540.0100.0120.17<0.0056 06/10/20119Artin Teymourian, UCLA arXiv:1103.3689, arXiv:1103.5831 Radioactivity measured at the Gator screening facility in LNGS, operated by University of Zurich R8520 is a 1” square PMT used in Xenon10 and Xenon100 R11410-MOD is a 3” Circular PMT being considered for future DM detectors The radioactivity of the QUPIDs are far better than the others per unit area 60 Co and 40 K emits  ’s that penetrate particularly far and is of greatest concern for large DM detectors

10. Quantum Efficiency Data taken at Hamamatsu Photocathode developed specifically for operation in Xenon >30% QE at 178 nm, the scintillation wavelength of Xenon 06/10/201110Artin Teymourian, UCLA

11. Argon and Xenon Versions of the QUPID 06/10/2011Artin Teymourian, UCLA11 The photocathode can be optimized for Argon operation, quartz is not transparent to Argon scintillation wavelength, so a WLS must be used to bring it to visible wavelengths The Quantum Efficiency of the Argon version peaks at ~40% near 400 nm TPB can be used to wavelength shift Ar scintillation light to the visible wavelengths Data taken at Hamamatsu

12. DC Cathode Linearity Data taken at Hamamatsu Photocathode also developed to withstand low temperatures with good linearity At Liquid Xenon temperature, the photocathode is linear up to >1  A 06/10/201112Artin Teymourian, UCLA

13. Liquid Nitrogen Cooling System 06/10/201113Artin Teymourian, UCLA

14. Readout Schematic 06/10/2011Artin Teymourian, UCLA14

15. Leakage Current Strong temperature dependence of Leakage Current Want to operate before breakdown to maximize gain 06/10/201115Artin Teymourian, UCLA

16. Leakage Current for Argon Operation 06/10/2011Artin Teymourian, UCLA16 Xenon Argon APD is inoperative below 120V bias At liquid xenon temperatures, the APD is still operative APD for liquid argon operation has been developed by Hamamatsu and is being integrated in the QUPID for Liquid argon temperature

17. Avalanche and Bombardment Gain Avalanche GainBombardment Gain Avalanche Gain shows strong temperature dependence, Bombardment Gain does not Maximum Avalanche Gain ~200, maximum Bombardment Gain ~750 Total Gain ~10 5 06/10/201117Artin Teymourian, UCLA

18. Photon Counting Capabilities and Pulse Shape ns Rise time1.8 ± 0.1 Fall time2.5 ± 0.2 Pulse width4.20 ± 0.05 Transit time spread0.16 ± 0.03 06/10/201118Artin Teymourian, UCLA

19. 06/10/2011Artin Teymourian, UCLA19 -6 kV -8 kV A new version of the QUPID is being made Operation will be possible up to -8 kV Much better photon counting is possible Data taken at Hamamatsu

20. Preliminary -8 kV Operation 06/10/2011Artin Teymourian, UCLA20 Data taken at Hamamatsu

21. Uniformity System Optical Fiber and Focusing Lens QUPID Phi AxisTheta Axis 06/10/201121Artin Teymourian, UCLA

22. Uniformity Photocathode UniformityCollection Efficiency Uniform photocathode response (within 20%) and collection efficiency 06/10/201122Artin Teymourian, UCLA

23. QUPID Characteristics Summary 06/10/201123Artin Teymourian, UCLA R8520QUPID Radioactivity<4.7 mBq/cm 2 <0.59 mBq/cm 2 Quantum Efficiency>30%>30% at 178nm Photocathode Linearity @ -100 o C 0.1 nA >1  A Total Gain>10 6 >10 5 (>10 6 with amplifier) APD Leakage Current---<1 nA at -100 o C Pulse Width~10 ns4.2 ns Transit Time Spread~1 ns160 ps 1, 2, 3 photoelectron peaks seen clearly Good photocathode uniformity Excellent collection efficiency over the entire photocathode

24. Operation in Liquid Xenon 06/10/2011Artin Teymourian, UCLA24

25. Single QUPID Holder -6 kV Contact Ti Clips for Support and Ground PTFE Holder for Contacts Copper Plate 06/10/201125Artin Teymourian, UCLA

26. 06/10/201126Artin Teymourian, UCLA

27. 06/10/201127Artin Teymourian, UCLA

28. 06/10/2011Artin Teymourian, UCLA28 QUPID Operation in Liquid Xenon

29. Scintillation Light of Xenon Observed 06/10/201129Artin Teymourian, UCLA 122 keV  2.0 pe/keV 5.3 MeV  1.6 pe/keV

30. 7 QUPID Holder PTFE Reflectors 7-QUPID Support 06/10/201130Artin Teymourian, UCLA

31. 06/10/201131Artin Teymourian, UCLA

32. Future Detectors 06/10/201132Artin Teymourian, UCLA DarkSide50 Xenon1Ton

33. Conclusion QUPIDs are a new, low radioactivity phototube for future DM experiments Excellent photon counting, uniformity, quantum efficiency, and photocathode linearity Has been operated in cryogenic temperatures and in Liquid Xenon, with scintillation light being observed Will be used in DarkSide50 and Xenon1Ton 06/10/201133Artin Teymourian, UCLA

34. Acknowledgements XENON100 Collaboration DarkSide50 Collaboration MAX Collaboration Hamamatsu Photonics “Characterization of the QUartz Photon Intensifying Detector (QUPID) for use in Noble Liquid Detectors” arXiv:1103.3689 “Material screening and selection for XENON100” arXiv:1103.5831 06/10/2011Artin Teymourian, UCLA34

35. Extra Slides 06/10/2011Artin Teymourian, UCLA35

36. Scintillation Light of Xenon Observed 06/10/201136Artin Teymourian, UCLA 122 keV  2.0 pe/keV 5.3 MeV  1.6 pe/keV

37. Published Decay Times 06/10/2011Artin Teymourian, UCLA37 Hitachi, et al. The values for the decay times and proportion of fast and slow components are comparable to published values

38. Scintillation Characteristics SourceTypeEneryLight YieldResolutionDecay TimePreviously Published Decay Times 57 Co  122 keV, 86% 136 keV, 11% 2.0 ± 0.2 pe/keV10.4 ± 1.2%39.1 ± 0.2 ns 34 ± 2 ns (Kubota, et al.) 45 ns (Hitachi, et al.) 210 Po  5.3 MeV1.6 ± 0.2 pe/keV2.5 ± 0.5% 4.5 ± 0.1 ns, fast (71%) 26.4 ± 0.4 ns, slow (29%) 4.3 ± 0.6 ns, fast (69%) 22.0 ± 2.0 ns, slow (31%) (Hitachi, et al.) 38Artin Teymourian, UCLA06/10/2011

39. DC Cathode Linearity Data taken at Hamamatsu QUPID photocathode 4 orders of magnitude better in linearity 06/10/201139Artin Teymourian, UCLA

40. Linearity System 06/10/2011Artin Teymourian, UCLA40 Continuous Filter Wheel Discrete Filter Wheel LED Fiber to QUPID Control Motors

41. Anode Linearity Anode linear up to ~2 mA at 10 5 gain Anode linearity independent of temperature Gradual non-linearity can be characterized and applied as a correction 06/10/201141Artin Teymourian, UCLA