Upload
kerrie-chambers
View
222
Download
0
Embed Size (px)
Citation preview
LENA Photosensor R&DLENA Photosensor R&D
Marc TippmannMarc TippmannLothar Oberauer, Michael Wurm, Gyorgy Korga, Quirin Lothar Oberauer, Michael Wurm, Gyorgy Korga, Quirin
Meindl, Michael Nöbauer, Thurid Mannel, Martin Meindl, Michael Nöbauer, Thurid Mannel, Martin Zeitlmair, German BeischlerZeitlmair, German Beischler
Technische Universität MünchenTechnische Universität München
DPG-Frühjahrstagung 2011, KarlsruheDPG-Frühjahrstagung 2011, Karlsruhe2011/03/312011/03/31
Overview
LENA photosensor requirementsLENA photosensor requirements
LENA photosensor requirements: Overview
Requirements on photo sensors• Sensor performance• Environmental properties• Availability until start of
construction• Cost-performance-ratio
Requirements on photo sensors• Sensor performance• Environmental properties• Availability until start of
construction• Cost-performance-ratio
Desired energy resolution for low energies:→ Light yield ≥ 200 photoelectrons/MeV→ 30% optical coverage → 3000m² effective photosensitive area needed→ Current standard configuration:Liquid scintillator detector: 63,000 PMTs (8“) with Winston Cones (area ×1.75)Water cherenkov muon veto: 6,000 PMTs (8“) 1/9
TimingTTS (spe, FWHM) <3.0ns
Early pulses <1%
Late pulses <4%
LENA photosensor requirements: List
2/9
TimingTTS (spe, FWHM) <3.0ns
Early pulses <1%
Late pulses <4%
LENA photosensor requirements: List
Photo detection efficiencyPDE for λpeak=420nm >20%
Dynamic range spe – 0.3pe/cm²
2/9
Michael Wurm, TUM, LENA - PMm² meeting 07/04/2009
LENA photosensor requirements: List
Noise (for PMTs)
Gain >3 10∙ 6
spe p/V >2
Dark count per area <15Hz/cm²
Ionic afterpulses (0.1-200 μs) <5%
Fast afterpulses (5-100 ns) <5%
TimingTTS (spe, FWHM) <3.0ns
Early pulses <1%
Late pulses <4%
Photo detection efficiencyPDE for λpeak=420nm >20%
Dynamic range spe – 0.3pe/cm²
2/9
LENA photosensor requirements: ListTeresa Marrodán, PhD thesis
TimingTTS (spe, FWHM) <3.0ns
Early pulses <1%
Late pulses <4%
Photo detection efficiencyPDE for λpeak=420nm >20%
Dynamic range spe – 0.3pe/cm²
Noise (for PMTs)
Gain >3 10∙ 6
spe p/V >2
Dark count per area <15Hz/cm²
Ionic afterpulses (0.1-200 μs) <5%
Fast afterpulses (5-100 ns) <5%Photon
Fast afterpulse
2/9
LENA photosensor requirements: ListTeresa Marrodán, PhD thesis
Environmental propertiesPressure resistance >10bar238U content <3 10∙ -8 g/g232Th content <1 10∙ -8 g/gnatK content <2 10∙ -5 g/g
Detector lifetime >30yrs
TimingTTS (spe, FWHM) <3.0ns
Early pulses <1%
Late pulses <4%
Photo detection efficiencyPDE for λpeak=420nm >20%
Dynamic range spe – 0.3pe/cm²
Noise (for PMTs)
Gain >3 10∙ 6
spe p/V >2
Dark count per area <15Hz/cm²
Ionic afterpulses (0.1-200 μs) <5%
Fast afterpulses (5-100 ns) <5%
2/9
Fast afterpulses (fAP):Ongoing measurements of fAP time distribution for candidate PMT series →• Investigate causes• Currently studying their influence on the efficiency of the
p decay coincidence: Bachelor thesis by Thurid Mannel• Possible methods of discrimation from photons?
Bachelor thesis by Martin Zeitlmair
LENA photosensor requirements
3/9
PMT characterizationPMT characterization
Borexino PMT testing facility• Pulsed ps laser diode light source:
410nm, light pulse FWHM <30ps• Total time resolution <140ps• Can measure up to 32 PMTs
simultaneously• Measure transit time distribution
(TDC), fast + ionic afterpulse time distribution (MTDC), charge spectrum (ADC)
Measurements at the LNGS, Gran Sasso
Measured 1 sample each of: • Hamamatsu: R6091(3“), R6594(5“),
R5912(8“) and R7081(10“)• ETEL: 9351(8“)
4/9
5“
10“
Measurements @LNGS:R6594 vs. R7081
R6594 (5“) R7081 (10“)
Voltage +1670V +1520V
Gain 1.0 10∙ 7 1.3 10∙ 7
Photoelectrons (pe) per trigger
5.53% 2.91%
Threshold 0.2pe 0.2pe
TTS (FWHM) (Hamamatsu)
1.91ns (1.5ns)
3.05ns (3.5ns)
Early pulses (all non-gaussian)
2.95% 0.57%
Late pulses (after photon pulse peak)
3.13% 3.09%
5/9
Measurements @LNGS:R6594 vs. R7081
R6594 (5“) R7081 (10“)
Voltage +1670V +1520V
Gain 1.0 10∙ 7 1.3 10∙ 7
Photoelectrons (pe) per trigger
5.53% 2.91%
Threshold 0.2pe 0.2pe
TTS (FWHM) (Hamamatsu)
1.91ns (1.5ns)
3.05ns (3.5ns)
Early pulses (all non-gaussian)
2.95% 0.57%
Late pulses (after photon pulse peak)
3.13% 3.09%
Dark count (5.23kHz) 2.64kHz
Dark count per area
(46.3 Hz/cm²)
5.26 Hz/cm²
Ionic afterpulses 0.94% 5.12%
5/9
Measurements @LNGS:R6594 vs. R7081
R6594 (5“) R7081 (10“)
Voltage +1670V +1520V
Gain 1.0 10∙ 7 1.3 10∙ 7
Photoelectrons (pe) per trigger
5.53% 2.91%
Threshold 0.2pe 0.2pe
TTS (FWHM) (Hamamatsu)
1.91ns (1.5ns)
3.05ns (3.5ns)
Early pulses (all non-gaussian)
2.95% 0.57%
Late pulses (after photon pulse peak)
3.13% 3.09%
Dark count (5.23kHz) 2.64kHz
Dark count per area
(46.3 Hz/cm²)
5.26 Hz/cm²
Ionic afterpulses 0.94% 5.12%
Peak-to-valley ratio
3.88 3.095/9
Measurements @ LNGS: ResultsParameters + Constraints
R6091 (3“) with 1.8“ aperture
R6594 (5“)
R5912 (8“)
R7081 (10“)
ETL9351 (8“) no. 1732
ETL9351 (8“) average
Voltage +1760V +1670V +1425V +1520V +1500V ≈+1450V
Gain 1.0 10∙ 7 1.0 10∙ 7 1.3 10∙ 7 1.3 10∙ 7 1.0 10∙ 7 1.0 10∙ 7
pe/trigger (npe) 2.21% 5.53% 1.83% 2.91% 4.78% 5.19%
TTS (FWHM) <3.0ns(manufacturer)
1.89ns(2.0ns)
1.91ns (1.5ns)
2.04ns(2.4ns)
3.05ns (3.5ns)
2.16ns 2.76ns
EP (all nongauss.) <1% 0.14% 2.95% 1.93% 0.57% 1.23% 0.75% (3σ)
LP (after PP peak) <4% 6.26% 3.13% 2.88% 3.09% 4.08% 7.90% (3σ)
DN 0.192kHz (5.23kHz) 1.62kHz 2.64kHz 1.72kHz 2.48kHz
DN/area <15Hz/cm² 12.1 Hz/cm²(eff.)
(46.3 Hz/cm²)
5.1 Hz/cm²
5.3 Hz/cm²
5.3 Hz/cm² 7.7 Hz/cm²
Ionic AP < 5% 0.14% 0.94% 6.62% 5.12% 2.57% 4.9%
p/V >2 2.04 3.88 2.99 3.09 2.25 2.10
At the moment no conclusive decision possible: Need to measure ≈10 PMTs/series and determine limits + implications on physics from simulations 6/9
OutlookOutlook
Outlook: Munich photosensor test stand
• FADC: Acqiris DC282, 10bit, 8 GHz• Light sources:
• Pulsed ps diode laser: Edinburgh Instruments EPL-405-mod, 403nm, pulse width 48ps
• Fast LED driven by avalanche diode: 430nm, time jitter (FWHM) <≈1ns
Currently being set up Done: Light sources implemented and
working, electronics running Next steps: include fiber and beam
widening optics, finish online analysis software based on Labview
Plan to study: PMTs: time distribution, fast AP, ionic AP, pulse shape, dynamic range, surface scans; also SiPMs 7/9
Outlook: Optical module development
Light Concentrators (Winston Cones)• MC simulations of light concentrators
with geant4• Incorporate results into optical model of
detector (geant4 MC) → determine optimum light concentrator
• Build prototype + scan with laser over aperture and incident angles
Diploma thesis by Michael Nöbauer
Pressure encapsulations• Design pressure encapsulations with
FEM pressure simulation, e.g. spherical shape or conical shape, integrate Winston Cones + Mu-metal shielding into design
• Build + test prototypesBachelor thesis by German Beischler
Borexino Winston Cone
8/9
SummarySummary
• Approximate limits on photosensor properties Approximate limits on photosensor properties known known →→ do simulations to refine values do simulations to refine values
• Have tested promising PMT series from Have tested promising PMT series from Hamamatsu @ LNGS Hamamatsu @ LNGS →→ repeat for more repeat for more samples of Hamamatsu + ETEL PMTs in Munichsamples of Hamamatsu + ETEL PMTs in Munich
• Also test SiPMs and Hybrid PhototubesAlso test SiPMs and Hybrid Phototubes
• Have started development of pressure-Have started development of pressure-withstanding optical modules for PMTs withstanding optical modules for PMTs incorporating Winston Cones and Mu-metalincorporating Winston Cones and Mu-metal 9/9