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Instrument Design/Development Overview and System Performance

Instrument Design/Development Overview and System Performance. PACS Instrument Overview Poglitsch MPE. Instrument Concept. Focal Plane Footprint. Imaging photometry two bands simultaneously (60-85 or 85-130 µm and 130-210 µm) with dichroic beam splitter

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Instrument Design/Development Overview and System Performance

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  1. Instrument Design/Development Overview andSystem Performance • PACS Instrument Overview • Poglitsch • MPE PACS Instrument Overview

  2. Instrument Concept Focal Plane Footprint • Imaging photometry • two bands simultaneously (60-85 or 85-130 µm and 130-210 µm) with dichroic beam splitter • two filled bolometer arrays (32x16 and 64x32 pixels, full beam sampling) • point source detection limit ~3 mJy (5s, 1h) • Integral field line spectroscopy • range 57 - 210 µm with 5x5 pixels, image slicer, and long-slit grating spectrograph (R ~ 1500) • two 16x25 Ge:Ga photoconductor arrays (stressed/unstressed) • point source detection limit 3…10 x10-18 W/m2 (5s, 1h) 32 x 16 pixels 6.4” x 6.4” 64 x 32 pixels 3.2” x 3.2” PACS Instrument Overview

  3. Observing Modes • Combinations of instrument modes and satellite pointing modes • Instrument modes: • dual-band photometry • single-band photometry • line spectroscopy • observation of individual lines • range spectroscopy • observation of extended wavelength ranges • Pointing modes: • stare/raster/line scan • with/without nodding PACS Instrument Overview

  4. FPU Cold FocalPlaneUnit DEC/MEC 1 BlueGe:GaArray &CRE MPE/ASTEQ/IMEC MEC I/F-Module BOL/COOL BOL/BAU BlueBolArray &Read-out CEA BlueBol BAU BOL 1 Module DSP Module RedBolArray &Read-out CEA RedBol BAU BOL 2 Module BlueDEC Module CEA RedGe:GaArray &CRE MPE/ASTEQ/IMEC Cooler Control Base/PSU SPU nominal DPU nominal CEA CSL-Liege IAC-Tenerife/TU-Wien 0.3K Cooler CEA DEC/MEC 2 DPU redundant SPU redundant MEC I/F-Module Redundant Grating Assy CSL-Liege IFSI-ROME IAC-Tenerife/TU-Wien DSP Module Redundant Chopper Assy MPIA 2FilterWheels KT RedDEC Module Base/PSU Redundant 2CalSources KT Warm Interconnecting Harness KT/MPE CSL-Liege Instrument Overview and Subsystem Responsibilities PACS Instrument Overview

  5. FPU Cold FocalPlaneUnit Photometer Optics BlueGe:GaArray &CRE MPE/ASTEQ/IMEC Filter Wheel I Slicer Optics Blue Bolometer BlueBolArray &Read-out CEA 0.3 K Cooler RedBolArray &Read-out CEA Grating Red Bolometer Grating Drive RedGe:GaArray &CRE MPE/ASTEQ/IMEC Encoder sGeGaDetector Red Spectrometer 0.3K Cooler CEA Spectrometer Optics Chopper Grating Assy CSL-Liege Calibrator I and II Filter Wheel II Chopper Assy MPIA Calibrator Optics GeGa Detector Blue Spectrometer 2 FilterWheels KT 2 Calibrators KT Entrance Optics KT/MPE FPU/Optics PACS Instrument Overview

  6. Design/Development Status of Technically Critical Components • Optics • FPU/Structure • Photoconductors, CRE • Bolometers • Chopper • Grating assembly • Warm electronics PACS Instrument Overview

  7. Optics • Design of FPU optics unchanged, manufacturing of mirrors complete, filters partly delivered • Alignment of QM optics in progress, specs fulfilled so far • Analyses (geometrical-optical, diffraction) done; to be complemented by measurements with IL tests/ calibration • Baffle design and manufacture for QM FPU finished; optimisation for FM in progress • Calibration sources manufactured and tested • Details from N. Geis / D. Kampf PACS Instrument Overview

  8. FPU Status • Detailed design of FPU structure finished, but thermal strap interface issues open. • Manufacture of QM structure complete, manufacture of FM started • Cryo-vibration performed on STM • Photometer STM including cooler and Focal Plane Assembly • Grating STM, including new launch lock (without motor) • One of two filter wheels • Both photoconductor arrays (partly dummies) • Dummy chopper • Details from J. Schubert and D. Kampf PACS Instrument Overview

  9. PACS Instrument Overview 9

  10. Photoconductor Arrays • All QM detector “sixpacks” (2 high-stress, 2 low-stress) delivered to MPE / MPIA for testing • Tests of all low-stress modules finished at MPIA, all high-stress modules + a few low-stress modules tested at MPE after repair at ASTEQ • QM schedule tight (critical path) – see below • Integration of modules with housing + filters has to start • FM schedule driven by • CREs: FM wafers (CRE v06) processed, AIT in progress • New contact (?) problem • Details from H. Richter PACS Instrument Overview

  11. “Blue” Ge:Ga QM Detector Test Results A/W Sixpack2_MPIA Responsivity of modules in Sixpack1_MPIA(left: before vibration, right: after vibration) NEP ~ 5x Herschel/PACS BLIP (with QM CRE) PACS Instrument Overview

  12. FM14, FM12, FM11 QM12, QM11, QM8 FM11, QM7, QM9, QM3 QM12, QM11, QM8 “Red” Ge:Ga QM Detector Test Results BLIPHerschel/PACS • NEP (even with QM CRE) approaching advertised value • Some “weak” pixels, varying from cooldown to cooldown • Few “dead” pixels (open channels) • Details from U. Grözinger PACS Instrument Overview

  13. Cryogenic Read-Out Electronics • CQM run (v05) • Integrated in QM modules + test modules • Tested extensively – current noise too high (at least for low-stress array – by factor ~5) • CQM not suitable for FS, but useful for QM ILT • FM run (v06) • Significant design modifications (3 variations implemented) • Wafers processed • First tests very promising in terms of noise performance • Delivery starting Nov/Dec ’03 • FS run my become necessary to reach all specs • should come in time to allow allow detector swapping • Details from P. Merken PACS Instrument Overview

  14. Raw ramp Blind channel subtracted QM CRE (v05) Performance • Linearity : <3% non-linearity over >2V • Cross talk between channels: <1% full range • Linearity, cross talkmeet requirements • with blind channel subtraction • Noise too high by factor ~5 PACS Instrument Overview 14

  15. Bolometer/Readout Development • QM blue focal plane array mounted at LETI • The working arrays showed a very large responsivity (good!) • The working arrays show very large noise and very slow response of the clocks, due to high contact resistance (~MΩ) at the 2K Buffer Unit level (known error in QM buffer run causing poor indium bumps hybridization) • A new blue focal plane is being mounted with FM Buffer Unit to be used in the CQM • More from L. Rodriguez et al. Blue Focal Plane PACS Instrument Overview

  16. Bolometer/Readout Development Red Focal Plane • A red focal plane with two sub arrays has been assembled • No tests because of known Buffer Unit problems. Decision to replace the BU right away • This detector is now completed and under test • The measured noise levels are good everywhere except for a few pixels on each array • Spectral response measured with FTS; absorption ~80% in band PACS band calculated measured PACS Instrument Overview

  17. requirement goal requirement ^ = 10-16 W/√Hz (requirement) Bolometer Performance Tests • Detector bandwidth measured ~4 - 5 Hz • “1/f” noise “knee”/ stability measurement: no significantincrease downto 0.05 Hz PACS Instrument Overview

  18. 3He Sorption Cooler Development First test with 10 µWapplied load: • • extra load of 8-10 µW identified (potential heat switch problem) • • 10% undercharged • Details from L. Duband 35 hours @ 291 mK PACS Instrument Overview

  19. Chopper • QM delivered for integration in FPU • Performance demonstrated • Scratches on mirror • t.b. avoided with FM • Tests of chopper control with DECMEC and LM concluded • Adjustment of control parameters for QM only during IL tests • Details from R. Hofferbert PACS Instrument Overview 19

  20. Grating Assembly • Grating Mechanism/Drive • STM including new launch-lock (without actuator) passed cryo-vibration test • STM mechanism shows better dynamic characteristics than before vibration. The apparent "friction" torque is roughly reduced by a factor 2 to 3. • Bearings qualified: no movement noise or hard point over the useful stroke • Transformer for Inductosyn position readout shows excellent cold performance. Dissipation measured £ 1.5 mW • CQM delivered to CSL • Few minor NCRs, one major (connectors swapped) • Functional/performance tests performed • FUB QM transformers integrated in QM ILT • Launch-lock actuator will be integrated • Loose spring washer, shaft-to-bearing coupling part has moved in cryo-vibration test PACS Instrument Overview

  21. Grating Assembly • Diffraction grating • QM grating fully characterised • Test of grating constantand grating periodicity: all parameters inor near spec(acceptedby optics SE) PACS Instrument Overview

  22. Warm Electronics: AVM Instrument Level Tests PACS Instrument Overview

  23. Status of AVM Tests (1) • CDMS simulator upgrade to V2.4 • Has solved some counter overrun problem and the time bug (now we have correct TAI) • Burst mode for PACS implemented • DPU OBSW: several updates • Mainly for 1355 link loss investigation • But solving only the other known problems (EEPROM, jump to application software) • Bug found in DPU ISR routine (by comparison with DECMEC) • New problem with 1553 interface discovered. HW? SW?DPU problems not solved in >1 year – start of ILT at risk! • DECMEC OBSW is pretty stable PACS Instrument Overview

  24. Status of AVM Tests (2) • AVM SPU • Identified HW problemfixed • A small problem related to the SPU-DMC 1355 link initial self-test has been found, but apparently this is inherent to the SMCS chip. Either the SPU_SUSW and/or the user manual need to be updated. • SPU HLSW upgraded to version 6.0 • It contains some performance improvements both with respect to CPU work load and compression ratio • Parallel mode will require small update • Goal for CQM is to develop, in parallel, an improved strategy (noise estimate from averaged ramp per pixel) and test it • Down-link of “near-raw” data to allow ramp modeling / glitch removal on ground • CPU load down presently still too high, optimisation in progress PACS Instrument Overview

  25. SPU Ground Simulator Ground simulation of SPU code useful for several reasons: • Use PACS “raw data” transmission mode to redo, on ground, the same operations as performed by the on-board S/W • Dispose of a test bed to try out new compression algorithms before they are up-linked and used by on-board S/W • Subject PACS simulator data to same artifacts, i.e. compression and reduction, as on-board obtaineddata • New version of on-board SPU has been “grounded” in less than five minutes work PACS Instrument Overview

  26. Instrument Performance • Instrument Requirements • Photometer • Spectrometer • Instrument Model • Optical performance • Sensitivity budget • optical transmission • background • detector performance PACS Instrument Overview

  27. Photometer Performance Requirements • Image quality • blur: telescope limited • distortion: ±1 pixel; alignment: <1/3 pixel • Sensitivity (point source detection) • requirement: 5 mJy (5s), 1h of integration • goal: 3 mJy (5s), 1h of integration • Dynamic range • detection from 3 mJy to >1000 Jy (goal: 3000 Jy) • contrast of up to 1:500 in one field • Post-detection bandwidth • requirement: 0.5 - 5 Hz • goal: 0.05 - 5 Hz PACS Instrument Overview

  28. Spectrometer Performance Requirements • Image quality • blur: telescope limited • distortion: ±1 pixel; alignment: <1/4 pixel • Sensitivity (point source detection) • requirement: 3x10-18 W/Hz1/2 (5s), 1h of integration • goal: 2x10-18 W/Hz1/2 (5s), 1h of integration • Dynamic range • detection from ~1x10-18 W to >10-13 W • contrast of up to 1:100 in one field • Post-detection bandwidth • requirement: 5 Hz • goal: 10 Hz PACS Instrument Overview

  29. Optical Performance • Optical design / implementation fulfills requirements regarding • field of view • spatial sampling • distortion • geometrical spot sizes (Strehl ratio) • alignment • internal calibration capability • chopping • spectral coverage and resolution • transmission / diffraction losses • Details from N. Geis / D. Kampf PACS Instrument Overview

  30. Parameters of PACS Instrument Model(Present estimate, partly based on measurements) (a) Values for the photometry modes from 60-85 or 85-130 µm / 130-210 µm, respectively. (b) The formal transmission of >1 takes into account the acceptance solid angle of the photoconductor light cones / bolometer baffles which differs from the beam solid angle. PACS Instrument Overview

  31. Telescope efficiency(main beam) Grating diffraction order efficiency Main beam / pixel coupling Resolving power Spectrometer Performance PACS Instrument Overview

  32. BLIP NEP [W/Hz1/2] Background power [W] Sensitivity [W/m2](5s, 1 hour) off-positionchopping on-array chopping Detective quantum efficiency Spectrometer Performance Requirement PACS Instrument Overview

  33. goal Point source detection limit (5s, 1h) [mJy] Wavelength [µm] Photometer Sensitivity • Assumed detector QE: 80% (based on FTS measurements) • Assumed detector NEP: 10-16 W/Hz1/2 (based on electrical noise and responsivity measurements) • Margin for requirement, goal likely to be met PACS Instrument Overview

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