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R&D for Future ZEPLIN

R&D for Future ZEPLIN. D.B. Cline, W.C. Ooi, F. Sergiampietri(a), H. Wang, P. Smith(b), X. Yang Physics and Astronomy, UCLA , (a) Pisa, (b) RAL&UCLA. J.T. White, J. Gao, J. Maxin, G. Salinas, R. Bissit, J. Miller,

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R&D for Future ZEPLIN

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  1. R&D for Future ZEPLIN D.B. Cline, W.C. Ooi, F. Sergiampietri(a), H. Wang, P. Smith(b), X. YangPhysics and Astronomy, UCLA , (a) Pisa, (b) RAL&UCLA J.T. White, J. Gao, J. Maxin, G. Salinas, R. Bissit, J. Miller, J. SeifertDepartment of Physics, Texas A&M UniversityT. Ferbel, U. Schroeder (Chemistry), F. Wolfs, W. Skulski, J. TokeDepartment of physics and Astronomy, Rochester UniversityY. GaoSouthern Methodist University, Texas M.J. Carson, H. Chagani, E. Daw, V.A. Kudryavtsev, P. Lightfoot, P. Majewski, M. Robinson, N.J.C. Spooner University of Sheffield Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  2. Presentation outline • Introduction • Detector geometry • Principles of operation - characteristics of an event • Light collection • Signal readout - charge gain in liquid xenon • Dark Matter limit • Program for R&D Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  3. Introduction • Our goals: • Large mass of sensitive LXe in a scale of Tonnes • Simple detector geometry • Very low background radiation • Sensitivity to very low energy events • - possibility of few photons detection • - large surface photocathode • - possibility of few electrons detection • -> Both requires high gain in liquid Large mass with maximum surface acting as a photocathode : SPHERICAL GEOMETRY Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  4. LXe physical properties • Energy/scintillation photon W_ph =21.6 eV • Scintillation Absorption length > 100 cm • Energy/el-ion pair: W=15.6 eV • Saturation velocity of electrons from E=3 kV/cm: v=2.6 mm/ms • Threshold electric field for proportional scintillation: E=400-700 kV/cm • Threshold electric field for electron multiplication: E~1 MV/cm • Maximum charge gain measured 200-400 (table from T.Doke NIM 196 (1982) 87) Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  5. Spherical TPC filled with LXe Outer sphere Photocathode coated with CsI Field shaping rings Central ball with charge readout Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  6. Detector structure Central ball 4p covered with charge collecting and amplifying micro-structure Requirements: • Sensitivity to single electron • High readout segmentation for • position information Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  7. Electric field distributionCan detector operate with a non uniform field ? Electron drift velocity = f (E) (L.S.Miller at al. Phys. Rev. Vol. 166, 1967) 3 kV/cm Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  8. Charge and light yield = f (E) Measured charge and light yield for E<5 kV/cm Extrapolation to E<75 kV/cm (Thomas-Imel model Phys.Rev A 38 (1998) 5793) (T.Doke et al. Jpn.J.Appl.Phys. 41 (2002) 1538) 5e/keVr @ 2KV/cm E= 3 kV/cm (E.Aprile et al. astr-ph/0601552) Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  9. Charge and light readout • Scintillation light photons converted into photoelectrons from the CsI photocathode - CsI QE ~ 30 % @ E>3 kV/cm (E.Aprile et al. NIM A 343, 1994) - 4p coverage except shadowing • Ionisation electrons and photoelectrons readout with segmented charge amplifying device delivering energy and position information - low primary charge sensitivity with charge gain Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  10. Charge amplification in LXE Conditions for electron multiplication and secondary scintillation in liquid xenon : Electric field threshold for avalanche development : ~ 1MV/cm Electric field threshold for proportional light: 100-150 kV/cm (B.A. Dolgoshein et al. JETP Lett. Vol. 6, 1967) 400-700 kV/cm (K.Masuda et al. NIM 160, 1979) H.Wang 1991, gain : 40 Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  11. Event generation (1) Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  12. Event generation (2) Interaction in the sensitive volume Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  13. Event generation (3) Simultaneous creation of scintillation UV light and … Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  14. Event generation (4) … creation of ionisation charge Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  15. Event generation (5) Scintillation UV photons converted into photoelectrons Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  16. Event generation (6) First pulse generated Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  17. Event generation (7) Proportional scintillation UV photons converted into photoelectrons Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  18. Event generation (8) Second pulse generated Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  19. Event generation (9) First after–pulse generated Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  20. Event generation (10) Second after–pulse generated and pulses generation continues … Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  21. Light collection MC calculations • Energy to produce UV • photon: W= 21.6 eV • Light attenuation • length: 100 cm • CsI QE : 20, 30 % • Electron lifetime: • 0.5, 1 and 5 ms 3D example: Shadowing Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  22. MC calculations: results At R=50 cm, light collection = 4-7.5 phe/keV Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  23. Charge amplification - wires M.Miyajima et al. NIM Vol 134 ,1976 maximum gain : 100 S.E Derenzo et al. Phys. Rev. A Vol 9,1974 maximum gain : 400 Readout wires Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  24. Problems with gain in liquid • Slow motion of avalanche ions building space charge • Local imperfections of the readout structure • Purity of LXe • Large amount of created UV photons causing after-pulses leading to discharge • Bubble formation on the sharp edges of the readout electrode hence conducting path creation (J.G. Kim et al. NIM A 535 2004) Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  25. Charge readout - microstructures High electric field ~ 1MV/cm with small differential voltage Cold field emission device: • Micropattern detectors : • micromegas • micro-dot • MSGC (already used in LXe • with gain =10) • (A.P.L. Policarpo et al. NIM A 365 1995) Already used in LAr (no gain due to discharges) (J.G. Kim et al. NIM A 535 2004) Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  26. Charge readout – simulation (1) Tools: Garfield (Analytic) by R.Veenhof (CERN) Maxwell (FEM) by Ansoft Electric field near wire surface Recalculated LXe gain in single wire chamber Townsend coefficient from S. Derenzo et al. Phys. Rev. A Vol 9,1979 (large errors) Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  27. Charge readout - simulation (2) Microstructure modelling • What is needed : • Local high electric field • for high gain • 100 % 4p charge collection • Electric field < 400 kV/cm • when V_cath=0 and • E_drift = 75 kV/cm 75 kV/cm Drift field 5 kV/cm Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  28. Charge readout – simulation (3) 75 kV/cm 0 V at the cathode Electric field strength on the axis of the cell Simulated multiplication Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  29. How to avoid feedback pulses ? Using HV switch : When V_cath = 0 E_max < 400 kV/cm Field at the cell entrance: Field on the cell axis: Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  30. Dark Matter Limit Backgrund sources in 1 Tonne LXe detector: (M.Carson et. al. NIM A 548 (2005) 418) • 222 Rn • events/year: 1.46*10^6 • B) PMTs (Hamamatsu R8778) • events/year: 3.65*10^5 • C) 85 Kr • events/year: 9.1*10^5 • Assumptions: • LXe mass: • 1 Tonne • Run period: • 1 year • Energy range: • 4-50 keVnr 1O events detected O events detected Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

  31. R&D program (goals to achieve) • Study of the scintillation properties of LXe at high electric field (scintillation light and charge yield) • Study of the electric field threshold for proportional light creation • Explore possibility of the high gain in LXe using micro-structure devices (study of the limitations: maximum gain, stability in time, energy resolution) • Work on the feedback pulses suppression Pawel Majewski, Univ. of Sheffield Cryogenic Liquid Detectors for Future Particle Physics; LNGS, 13-14 III 2006

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