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Explore Ge:Ga detector testing at MPIA Heidelberg & MPE Garching. Learn about vibration tests, detector modules, response curves, responsivity data, NEP measurements, dark current, and summary findings.
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Ge:Ga-Detectors for the QM Tests and Performance MPIA Heidelberg MPE Garching QM-Ge:Ga-Detectors
Overview • Ge:Ga-Detector tests at MPE and MPIA => 14 High stressed modules tested at MPE (incl. „LENS-module“) IR-bandpass at ~190 µm => 12 Low stressed modules tested at MPIA Two IR-bandpasses, ~ 60 µm, ~ 109 µm • Cold vibration of • 1 High stressed module • 5 Low stressed modules • => after vibration tests repeated QM-Ge:Ga-Detectors
Detector Modules Six modules integrated in the test housing Low stressed module, 16 pixels High stressed module, 16 pixels QM-Ge:Ga-Detectors
Ge:Ga-Detector Test set-up at MPESchematic • Internal cold Black Body • IR Bandpass/ND Filters • Light tight compartement • Cold shutter QM-Ge:Ga-Detectors
Ge:Ga-Detector Test set-up at MPEPhotograph QM-Ge:Ga-Detectors
Ge:Ga-Detector Test set-up at MPIASchematic QM-Ge:Ga-Detectors
Ge:Ga-Detector Test set-up at MPIADrawing • External Black Body • Cold Bandpass and Neutral Density Filters • External Wheel Chopper for differential measurements • Cold Flip Mirror (Chopper) • Cold internal IR-Source QM-Ge:Ga-Detectors
Detector response curves Detectors Bandpass Low stressed Detectors High stressed Detectors QM-Ge:Ga-Detectors
Responsivity data of high stressed detectors QM-Ge:Ga-Detectors
Responsivity data of low stressed detectors Responsivity of module QM23 Responsivity of individual detector pixels UBias=200 mV, TDet =2.5 K, Cint=520 fF, <λ>=60 µm QM-Ge:Ga-Detectors
Responsivity before/after vibration Quotient after/before Vibration Responsivity [A/W] before after Vibration QM-Ge:Ga-Detectors
NEP of high stressed detectors QM-Ge:Ga-Detectors
NEP of low stressed Detectors NEP of Module FM26 (60µm BP) 16 1 QM-Ge:Ga-Detectors
Dark Current Measurements High str. Detectors Low str. Detectors Requirement 2.1K 2.5K 2.9K QM-Ge:Ga-Detectors
Summary I • Responsivity • Low str. Detectors : ca. 8 A/W (200 mV bias) => in expected range • High str. Detectors : ca. 110 A/W (40 mV bias) => higher than expected • NEP • Low str. Detectors : ca 2.5*10e-16 (200mV bias); requirement 4.7*10e-17 [W/sqrt Hz] • High str. Detectors : ca. 3*10e-17 (40 mV bias); requirement 1.1*10e-17 [W/sqrt Hz] • => Improved Cold Readout Electronics (CRE) for FM • Dark current: • Low str. Detectors : ~ factor 7 above specification => Improvement of baffling/thermal coupling in MPIA cryostat High str. Detectors : Dark current close to specification • Reproducibility: At MPIA only one dedicated measurement • => close to specification QM-Ge:Ga-Detectors
Summary II • Non Conformances Countermeasures • Performance (NEP) => Improved Readout Electronics for FM • => Improvements of test set-up‘s • (homogeneity of illumination, dark current) • Homogeneity => Selection of pixels to be improved • => Checks/Improvements of test optics • CRE malfunction/dead pixels => Bonding materials/process changed • Suspicious pixels => Investigation of wires, gluings, resistors at FEE-input started, gluing tests ongoing • => Repeated measurements in different cooling cycles QM-Ge:Ga-Detectors
Next steps • Refinement of test set-up • Extensive characterisation of the two spare Ge:Ga-detector modules • Repeated tests in different cooling cycles (reliability, reproducibility ...) • Exchange of detector arrays between MPE and MPIA for cross-check QM-Ge:Ga-Detectors
