PACS IHDR 12/13 Nov 2003 PACS Instrument Overview1 Instrument Design/Development Overview and System Performance PACS Instrument Overview A.Poglitsch MPE

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview2 Instrument Concept Imaging photometry –two bands simultaneously (60-85 or µm and µm) with dichroic beam splitter –two filled bolometer arrays (32x16 and 64x32 pixels, full beam sampling) –point source detection limit ~3 mJy (5 , 1h) Integral field line spectroscopy –range 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 x W/m 2 (5 , 1h) Focal Plane Footprint 32 x 16 pixels 6.4” x 6.4” 64 x 32 pixels 3.2” x 3.2”

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview3 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 IHDR 12/13 Nov 2003 PACS Instrument Overview4 CEA BOL/BAU BlueBol BAU RedBol BAU Warm Interconnecting Harness Instrument Overview and Subsystem Responsibilities DPU nominal DPU redundant IFSI-ROME DEC/MEC 2 MEC I/F-Module Redundant DSP Module Redundant RedDEC Module Base/PSU Redundant CSL-Liege BOL/COOL BOL 1 Module BOL 2 Module Cooler Control CEA FPU Cold FocalPlaneUnit KT/MPE BlueGe:GaArray &CRE MPE/ASTEQ/IMEC BlueBolArray &Read-out CEA RedBolArray &Read-out CEA RedGe:GaArray &CRE MPE/ASTEQ/IMEC 0.3K Cooler CEA Grating Assy CSL-Liege Chopper Assy MPIA 2FilterWheels KT 2CalSources KT SPU nominal SPU redundant IAC-Tenerife/TU-Wien CSL-Liege DEC/MEC 1 MEC I/F-Module DSP Module BlueDEC Module Base/PSU

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview5 FPU/Optics FPU Cold FocalPlaneUnit KT/MPE BlueGe:GaArray &CRE MPE/ASTEQ/IMEC BlueBolArray &Read-out CEA RedBolArray &Read-out CEA RedGe:GaArray &CRE MPE/ASTEQ/IMEC 0.3K Cooler CEA Grating Assy CSL-Liege Chopper Assy MPIA 2 FilterWheels KT 2 Calibrators KT Chopper sGeGaDetector Red Spectrometer Blue Bolometer Red Bolometer Calibrator I and II 0.3 K Cooler Filter Wheel I Filter Wheel II Grating GeGa Detector Blue Spectrometer Encoder Grating Drive Entrance Optics Photometer Optics Calibrator Optics Slicer Optics Spectrometer Optics

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview6 Design/Development Status of Technically Critical Components Optics FPU/Structure Photoconductors, CRE Bolometers Chopper Grating assembly Warm electronics

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview7 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 IHDR 12/13 Nov 2003 PACS Instrument Overview8 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 FPU Status

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview99

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview10 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 IHDR 12/13 Nov 2003 PACS Instrument Overview11 Responsivity of modules in Sixpack1_MPIA (left: before vibration, right: after vibration) A/W “Blue” Ge:Ga QM Detector Test Results Sixpack2_MPIA NEP ~ 5x Herschel/PACS BLIP (with QM CRE)

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview12 “Red” Ge:Ga QM Detector Test Results NEP (even with QM CRE) approaching advertised value Some “weak” pixels, varying from cooldown to cooldown Few “dead” pixels (open channels) BLIP Herschel/PACS FM14, FM12, FM11 QM12, QM11, QM8 FM11, QM7, QM9, QM3 QM12, QM11, QM8  Details from U. Grözinger

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview13 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 IHDR 12/13 Nov 2003 PACS Instrument Overview14 QM CRE (v05) Performance Linearity : 2V Cross talk between channels: <1% full range Linearity, cross talk meet requirements –with blind channel subtraction Noise too high by factor ~5 14 Raw ramp Blind channel subtracted

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview15 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 IHDR 12/13 Nov 2003 PACS Instrument Overview16 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 measured calculated PACS band

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview17 Bolometer Performance Tests Detector bandwidth measured ~4 - 5 Hz “1/f” noise “knee”/ stability measurement: no significant increase down to 0.05 Hz requirement goalrequirement = W/√Hz (requirement) ^

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview18 3 He Sorption Cooler Development First test with 10 µW applied load: mK extra load of 8-10 µW identified (potential heat switch problem) 10% undercharged  Details from L. Duband

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview19 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 19

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview20 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 IHDR 12/13 Nov 2003 PACS Instrument Overview21 Diffraction grating –QM grating fully characterised –Test of grating constant and grating periodicity: all parameters in or near spec (accepted by optics SE) Grating Assembly

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview22 Warm Electronics: AVM Instrument Level Tests

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview23 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 IHDR 12/13 Nov 2003 PACS Instrument Overview24 Status of AVM Tests (2) AVM SPU –Identified HW problem fixed –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 IHDR 12/13 Nov 2003 PACS Instrument Overview25 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 obtained data New version of on-board SPU has been “grounded” in less than five minutes work

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview26 Instrument Performance Instrument Requirements –Photometer –Spectrometer Instrument Model –Optical performance –Sensitivity budget optical transmission background detector performance

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview27 Photometer Performance Requirements Image quality –blur: telescope limited –distortion: ±1 pixel; alignment: <1/3 pixel Sensitivity (point source detection) –requirement: 5 mJy (5  ), 1h of integration –goal: 3 mJy (5  ), 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: Hz –goal: Hz

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview28 Spectrometer Performance Requirements Image quality –blur: telescope limited –distortion: ±1 pixel; alignment: <1/4 pixel Sensitivity (point source detection) –requirement: 3x W/Hz 1/2 (5  ), 1h of integration –goal: 2x W/Hz 1/2 (5  ), 1h of integration Dynamic range –detection from ~1x W to > W –contrast of up to 1:100 in one field Post-detection bandwidth –requirement: 5 Hz –goal: 10 Hz

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview29 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 IHDR 12/13 Nov 2003 PACS Instrument Overview30 (a) Values for the photometry modes from or µm / 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. Parameters of PACS Instrument Model (Present estimate, partly based on measurements)

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview31 Grating diffraction order efficiency Resolving power Telescope efficiency (main beam) Main beam / pixel coupling Spectrometer Performance

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview32 Detective quantum efficiency Background power [W] BLIP NEP [W/Hz 1/2 ] on-array chopping off-position chopping Sensitivity [W/m 2 ] (5 , 1 hour) Spectrometer Performance Requirement

PACS IHDR 12/13 Nov 2003 PACS Instrument Overview33 Photometer Sensitivity Assumed detector QE: 80% (based on FTS measurements) Assumed detector NEP: W/Hz 1/2 (based on electrical noise and responsivity measurements) Margin for requirement, goal likely to be met Wavelength [µm] Point source detection limit (5 , 1h) [mJy] goal