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Development of very low threshold detection system for low-background experiments

International Workshop on New Photon-detectors 2012. Development of very low threshold detection system for low-background experiments. Presented by Ivan Alexandrov.

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Development of very low threshold detection system for low-background experiments

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  1. International Workshop on New Photon-detectors 2012 Development of very low threshold detection system for low-background experiments Presented by Ivan Alexandrov AkimovD.Yu.1, AkindinovA.V.1,Alexandrov I.S.1, Belov V.A.1, Burenkov A.A.1, Danilov M.V.1 ,Kobyakin A.S.1,Kovalenko A.G..1, Roudik D.G. 1, Stekhanov V.N.1 Bondar А.Е.2, Buzulutskov А.F.2 BolozdynyaА.I.3, Kirsanov М.А.3 1Institute for theoretical and experimental physics 2Budker Institute of Nuclear Physics Novosibirsk, Russia 3National Research Nuclear University "Moscow Engineering Physics Institute»

  2. Xe detectors for “Dark Matter” experiments Xenon10,100 at Gran Sasso XMASS at Kamioka All detectors utilizes PMTs for detection of the LXe VUV light. At present, PMTs (even low-background) are the most radioactive elements of detector. ZEPLIN III at Boulby mine Search for a replacement of PMTs for the future detectors is actual. LUX at DUSEL

  3. PMT MRS APD + WLS+THGEM Matrix MRS APD P M T MRS APD: P M T P M T Some advantages of MRS APD: • Small size • Made from clean materials • no high voltage

  4. Readout -Voper Multipixel avalanche Geiger photodiode Scheme of MRS APD Structure of 1 cell View of matrix cells

  5. Multipixel avalanche Geiger photodiode Multiplication: M = C*(U - Ubr) Charge: Q = e*Ncell*C*(U - Ubr) Photon Detection Efficiency: PDE= Q.E.*RG*εgeom Typical PDE for CPTA 2x2 mm2 CPTA “green” – blue, green, IR CPTA “blue” – blue, green, IR

  6. Wave Length Shifter in liquid xenon 1- emission of LXe, 2 – absorptionp-terphenil, 3 – emission of p-terphenyl, 4 – range of sensitiveMRS APD

  7. First tests. Results P. Benetti, et al., Nucl. Instr. Meth.A505, 89 (2003). For a blue sensitive PMT (QE ≈20%) with WLS: ~ 10%

  8. Single THGEM Experimental setup MRS APD WLS vacuum Anode (THGEM) LXe chamber Cathode Liquid nitrogen DiameterTHGEM (50 mm) less than diameterLXe chamber(106 mm) Anode (mirror) LevelLXe Cathode (Grid) VUV PMT

  9. THGEM principle of operation Electric field in GEM Photos of GEM GEM Anode Light A unique property of GEMs, as compared to other micro-pattern detectors, is their capability to operate in cascade Scheme of photo detector based on GEM

  10. Experimental setup Matrix MRS APD Step- 0.7 mm, Diameter- 0.4 mm, thickness- 0.25 mm THGEM WLS (p-terphenyl covered by poly-para-xylylen on saphiire) + grid MRS APD (CPTA) 2 mm 2 mm Matrix MRS APD + WLS

  11. FIRST RESULT UTHGEM = 1.6 kV UTHGEM=1.8kV Sum signal matrix MRS APD 9 mm Sum signal matrix PMT 5 mm 22 mm Dependence electroluminescence in THGEM on Δ U UTHGEM = 2.0kV

  12. SECOND TEST RUN (DOUBLE GEM) Sum signal matrix MRS APD Sum signal matrix PMT For field in 2nd THGEM 1st THGEM For field in liquid 2.5 kV/cm and in gas 4.90 kV/cm Area corresponds to 5950 ph.e. and 850 e (7 ph.e./e.) Electroluminescence from 2nd THGEM dependence on Δ U For THGEM2 U=1.6 kV MRS APD array signal ~150 cells ~300 for THGEM2 U=2.1 kV For 1V overvoltage ->3% PDE (MRS APD +WLS) Fill factor for array ~6% -> 50% So, it can be increased by a factor of 60, i.e. ~9000 cells ~ 10 cells/e Can be achieved.

  13. SECOND TEST RUN (DOUBLE GEM) Reconstruction of muon track by PMT Matrix MRS APD Matrix 0.19 mm 0.036 mm

  14. MONTE CARLO SIMULATION (GEM) Y, mm Y, mm Matrix MRS APD. Matrix PMT . X, mm X, mm Radius PMT. Radius MRS APD Radius SiPM. Radius of the event is determined by a centroid Radius of the event is determined by a centroid Radius of model event, mm Radius of model event, mm

  15. Conclusion • Large-size WLS plate with protection layer was tested successfully in Xe (electron life time seems O’k ) • THGEMS were tested in pure Xe • The estimated single electron signal is ~10 cells for 50 % fill of array and full PDE

  16. Backup

  17. ESTIMATION OF FIRED CELL NUMBER PER SINGLE IONIZATION ELECTRON EXTRACTED FROM LIQUID For THGEM2 U=1.6 kV MRS APD array signal ~150 cells ~300 for THGEM2 U=2.1 kV For 1V overvoltage ->3% PDE (MRS APD +WLS) Fill factor for array ~6% -> 50% So, it can be increased by a factor of 60, i.e. ~9000 cells For field in liquid 2.5 kV/cm and in gas 4.90 kV/cm Area corresponds to 5950 ph.e. and 850 e (7 ph.e./e.) ~ 10 cells/e Can be achieved.

  18. Spectrums шум CPTA “blue” αпик пьедестал PMT 1 ячейка Pulse area, V·ns Положения а пика 1 вариант 27 ячеек 2 вариант 84 ячейки 2 ячейка

  19. Схема электроники Tektronix 625 MHz I VI Триг-гер II VII V LeCroy LT344 500 MHz III IV GPIB Предуси-лители Усили-тели ФЭУ Блок выработки триггера -U VME SiPM 1 -U1 SiPM 19 V2718 VME – PCI контроллер -U19 200 MHz FADC 8 каналов 200 MHz FADC 2 блока ADC VME-V1720 (16 каналов) Блок питания Блок усилителей

  20. Результаты & вычисление эффективности 84ячейки

  21. SECOND TEST RUN (DOUBLE GEM)

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