Development of very low threshold detection system for low-background experiments
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DEVELOPMENT OF VERY LOW THRESHOLD DETECTION SYSTEM FOR LOW-BACKGROUND EXPERIMENTS
Akimov D.Yu.1, Akindinov A.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
Bolozdynya А.I.3, Kirsanov М.А.3
1Institute for theoretical and experimental physics2 Budker Institute of Nuclear Physics Novosibirsk, Russia3National Research Nuclear University "Moscow Engineering Physics Institute»
International Workshop on New Photon-detectors 2012
Presented by Ivan Alexandrov
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XE DETECTORS FOR “DARK MATTER” EXPERIMENTS
Xenon10,100 at Gran Sasso
ZEPLIN III at Boulby mine
XMASS at Kamioka
LUX at DUSEL
All detectors utilizes PMTs for detection of the LXe VUV light.
At present, PMTs (even low-background) are the most radioactive elements of detector.
Search for a replacement of PMTs for the future detectors is actual.
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Matrix MRS APD
P M T
P M T
• Small size• Made from clean materials• no high voltage
MRS APD:
PMT MRS APD + WLS+THGEM
P M T
Some advantages of MRS APD:
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MULTIPIXEL AVALANCHE GEIGER PHOTODIODE
-Voper
Readout
Structure of 1 cellScheme of MRS APD
View of matrix cells4
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MULTIPIXEL AVALANCHE GEIGER PHOTODIODE
CPTA “green” – blue, green, IR CPTA “blue” – blue, green, IR
Typical PDE for CPTA 2x2 mm2
Charge: Q = e*Ncell*C*(U - Ubr)Multiplication: M = C*(U - Ubr)
Photon Detection Efficiency:PDE= Q.E.*RG*ε geom
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Wave Length Shifter in liquid xenon
1- emission of LXe, 2 – absorption p-terphenil, 3 – emission of p-terphenyl, 4 – range of sensitive MRS APD
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FIRST TESTS. RESULTS
Construction of WLS Ncells PDE ,%Р-terphenyl encapsulated by
saphfire window 24±0.59.7±1.2
Р-terphenyl cowered by poly-para-xylynen film 72±1.5
8.4±1.1
P. Benetti, et al., Nucl. Instr. Meth. A505, 89 (2003).For a blue sensitive PMT (QE ≈20%) with WLS: ~ 10%
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8VUV PMT
Cathode (Grid)
Anode (mirror)
Liquid nitrogen
Level LXe
Anode (THGEM)
WLSMRS APD
Cathode
Diameter THGEM (50 mm) less than diameter LXe chamber (106 mm)
LXe chamber
vacuum
Single THGEM Experimental setup
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THGEM principle of operation Electric field in GEM
Photos of GEM
Scheme of photo detector based on GEM
GEM
Light
Anode
A unique property of GEMs, as compared toother micro-pattern detectors, is their capability tooperate in cascade
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THGEM
WLS (p-terphenyl covered by poly-para-xylylen on saphiire) + grid
Step - 0.7 mm, Diameter - 0.4 mm, thickness - 0.25 mm
MRS APD (CPTA)
2 mm
2 mm
Experimental setupMatrix MRS APD
Matrix MRS APD+ WLS
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UTHGEM = 1.6 kV UTHGEM =1.8 kV
UTHGEM = 2.0 kV
FIRST RESULT
Dependence electroluminescence in THGEM on Δ U
9 mm
5 mm
22 mm
Sum signal matrix PMT
Sum signal matrix MRS APD
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SECOND TEST RUN (DOUBLE GEM)
2nd THGEM1st THGEM
Sum signal matrix MRS APD
Sum signal matrix PMT
Electroluminescence from 2nd THGEM dependence on Δ U
For field in
For field in liquid 2.5 kV/cm and in gas 4.90 kV/cmArea corresponds to 5950 ph.e. and 850 e (7 ph.e./e.)
For THGEM2 U=1.6 kVMRS APD array signal ~150 cells
~300 for THGEM2 U=2.1 kVFor 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/eCan be achieved.
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SECOND TEST RUN (DOUBLE GEM)Reconstruction of muon track by
PMT Matrix MRS APD Matrix
0.19 mm 0.036 mm
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MONTE CARLO SIMULATION (GEM)Matrix PMT .
Radius PMT. Radius SiPM.
Y, mm
X, mm X, mm
Y, mm Matrix MRS APD .
Radius MRS APD
Radius of model event, mm Radius of model event, mm
Radius of the event is determined by a centroid
Radius of the event is determined by a centroid
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Large-size WLS plate with protection layer was tested successfully in Xe (electron life time seems O’k ) THGEMS were tested in pure XeThe estimated single electron signal is ~10
cells for 50 % fill of array and full PDE
Conclusion
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Backup
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ESTIMATION OF FIRED CELL NUMBER PER SINGLE IONIZATION ELECTRON EXTRACTED
FROM LIQUIDFor THGEM2 U=1.6 kVMRS APD array signal ~150 cells
~300 for THGEM2 U=2.1 kVFor 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/cmArea corresponds to 5950 ph.e. and 850 e (7 ph.e./e.)
~ 10 cells/eCan be achieved.
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Pulse area, V·ns
CPTA “blue”
PMT
SPECTRUMS
шум
α пик
1 ячейка
2 ячейка
пьедестал
Положения а пика 1 вариант 27 ячеек
2 вариант 84 ячейки
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ФЭУ GPIB
I VI
III
II
IV
VVII
Блок выработки триггера
Предуси-лители
Усили-тели
Tektronix 625 MHz
LeCroy LT344 500 MHz
Триг
-гер
VME
200 MHz FADC
SiPM 1-U1
-U19
SiPM 19
-U
Блок питания
Блок усилителей
200 MHz FADC 8 каналов
V2718 VME – PCI контроллер
2 блока ADC VME-V1720 (16 каналов)
Схема электроники
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РЕЗУЛЬТАТЫ & ВЫЧИСЛЕНИЕ ЭФФЕКТИВНОСТИ
84 ячейки
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SECOND TEST RUN (DOUBLE GEM)