Production and Tests of Hybrid Production and Tests of Hybrid Photon Detectors for the LHCb Photon Detectors for the LHCb RICH Detectors RICH Detectors Introduction Hybrid Photon Detectors Production Test results Conclusions RICH 2007, Trieste, 17.10.2007 RICH 2007, Trieste, 17.10.2007 Stephan Eisenhardt, University of Edinburgh Stephan Eisenhardt, University of Edinburgh On behalf of the LHCb experiment On behalf of the LHCb experiment RICH2 RICH1 LHCb HPD
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Production and Tests of Hybrid Photon Detectors for the LHCb RICH Detectors
Production and Tests of Hybrid Photon Detectors for the LHCb RICH Detectors. Stephan Eisenhardt, University of Edinburgh On behalf of the LHCb experiment. Introduction Hybrid Photon Detectors Production Test results Conclusions. LHCb. HPD. RICH 2007, Trieste, 17.10.2007. RICH2. RICH1. - PowerPoint PPT Presentation
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Production and Tests of Hybrid Photon Production and Tests of Hybrid Photon Detectors for the LHCb RICH DetectorsDetectors for the LHCb RICH Detectors
Introduction Hybrid Photon Detectors Production Test results Conclusions
shape of spectra & absolute values full trust in DEP measurements
Quantum Efficiency - typical HPD sample
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0 100 200 300 400 500 600 700 800 900 1000
Wavelength l / nm
QE
, hq , (no u
nits)
.
H648005: DEP
H648005: PDTF
H612011: DEP
H612011: PDTF
H650003: DEP
H650003: PDTF
H545002: DEP
H545002: PDTF
4 tests across QE range
Q
E
wavelength [nm]
all tests: PDTF vs. DEP
Q
E –
PD
TF
QE – DEP
RICH 2007, Trieste, 17.10.2007 Stephan Eisenhardt 22
ConclusionsConclusions
Production & testing of >550 HPDs has finished Rigorous test programme with: ~98% of HPDs accepted
pass: 547 HPD
fail: 12 HPD
HPDs meet requirements of LHCb RICH detectors Very good results for vacuum quality and Dark Count Excellent results on Quantum Efficiency and S/N DEP Quantum Efficiency results confirmed by PDTF Commissioning is underway
with 288 HPD installed in RICH2
RICH 2007, Trieste, 17.10.2007 Stephan Eisenhardt 23
Backup SlidesBackup Slides
RICH 2007, Trieste, 17.10.2007 Stephan Eisenhardt 25
guideline for usability in RICH:– 161x class A+ : exceed specifications significantly
– 282x class A : clear pass in all aspects
– 60x class B : may fail specs, but recommended for usage• HPDs with slightly increased dark count
– 42x class E : flagged with an issue, still usable in RICH• HPDs with increased LC or 1…5% dead pixels
– 12x class F : clear fail reject
12 failed HPDs:– 9x replaced with good HPD
– 3x accepted as failure within LHCb responsibility misc:
– 4x repaired, retested and accepted as good
– 2x anode problem, but usable,
under study, not classified
Classification SystemClassification System
pass: 545+2 of 559~ 98%
fail: 12 of 559~ 2%
HPD category
161
282
60
42
12
0
50
100
150
200
250
300
A+ A B E F
RICH 2007, Trieste, 17.10.2007 Stephan Eisenhardt 26
QE – PDTF Test SetupQE – PDTF Test Setup measurement of the photocurrent, referenced with calibrated photodiode
)(
)()()(
lllhlh
PD
HPDPDq
HPDq I
I
differing DEP parameters:– Bias: 900V
– Ø: 10-15mm
– large photo currents
default: 100V
cross-check: 22V (just below He ionisation threshold)
Quartz-TungstenHalogen Lamp
Fused SilicaLens
FilterSystem
ReferencePhotodiodeHPD
IPD [pA]
Shutter , 10nm BP filter , IR or VIS block , ND filterRL
Dark Box
Interlock
IHPD [pA]
Bias [V]
photocurrent: <160nAimage Ø:~ 50mm
RICH 2007, Trieste, 17.10.2007 Stephan Eisenhardt 27
QE – Effect of degrading VacuumQE – Effect of degrading Vacuum
degraded vacuum causes:– increase of Ion Feed Back
– increase of charge per photoelectron
– increase of measured photo current
– fake increase in determined QE
cure:– measure photo current below
He ionisation threshold
– PDTF : IV curves 0…500V
– PDTF : bias = 100V, 22V
– DEP : bias = 900V22V
case of extreme
vacuum degradation
for good illustration
RICH 2007, Trieste, 17.10.2007 Stephan Eisenhardt 28