PACS IBDR 27/28 Feb 2002 PACS Photometer1 PACS PHOTOMETER J.L Auguères L.Rodriguez CEA/DSM/DAPNIA Service d’Astrophysique

PACS IBDR 27/28 Feb 2002 PACS Photometer2 Development Status (1) Bolometers at LETI: –CQM run available (DC+RC & 2K buffers). BFPs: –Design finalised, Kevlar suspension validated. –Mounting tools: Design, detailed design, fabrication completed. Mounting procedure validated (some tuning from experience) –Test BFPs (used for bolometer test & selection): Detailed design finalised. A few sets available, additional sets under fabrication. 1st (blue type) BFP integrated and under test at LETI. –CQM Mechanic: Design finalised, detailed design almost completed. Optical filters: specified, design started but requires validation.

PACS IBDR 27/28 Feb 2002 PACS Photometer3 Main differences between SPIRE & PACS Bolometer arrays SPIRE arraysProblems MUX function perturb the high impedance bolometer bridge. MOS 1/f noise dominant. Correlated noise show sensitivity to RF. MUX only 8->1

PACS IBDR 27/28 Feb 2002 PACS Photometer4 Main differences between SPIRE & PACS Bolometer arrays PACS arrays Solutions Cold readout circuit under the pixel reflector: low capacitance. MUX now 16->1 MUX function after the readout. Large readout MOS to reduce 1/f noise. Blind pixels to remove all perturbations. We added 2 impedance adaptation stages: 2K, 130K. To cope with thermal budgets heater

PACS IBDR 27/28 Feb 2002 PACS Photometer5 BOLOMETER FOCAL PLANE The detector unit: A 16 x 16 pixel array + two rows of blind pixels…

PACS IBDR 27/28 Feb 2002 PACS Photometer6 BOLOMETER FOCAL PLANE …attached by the 0.3K-2K ribbon cable to the buffer unit…

PACS IBDR 27/28 Feb 2002 PACS Photometer7 BOLOMETER FOCAL PLANE 8 arrays butted on the common 300mK cooled by the strap…

PACS IBDR 27/28 Feb 2002 PACS Photometer8 BOLOMETER FOCAL PLANE

PACS IBDR 27/28 Feb 2002 PACS Photometer9 BOLOMETER FOCAL PLANE …under the 300 mK filter. The Buffer Units are assembled by 4

PACS IBDR 27/28 Feb 2002 PACS Photometer10 BOLOMETER FOCAL PLANE The 0.3 K stage suspended by Kevlar wires on the 2K structure…

PACS IBDR 27/28 Feb 2002 PACS Photometer11 BOLOMETER FOCAL PLANE Two half shells close the bolometer assembly…

PACS IBDR 27/28 Feb 2002 PACS Photometer12 BOLOMETER FOCAL PLANE...and a cone with air gap filter achieve the stray light rejection.

PACS IBDR 27/28 Feb 2002 PACS Photometer13 Development Status (2) PhFPU: –I/Fs with PACS FPU (almost) validated. S/C I/F: Connectors: OK, 2K straps: Outstanding issues. –4K & 2K Structures. Design completed. Detailed design started (goal end of Feb. 02). Call for Tender process started (SMs & CQM Models). –Cooler: Design, detailed design of STM, CQM, FM & FS completed. Manufacturing of 2 STM + 2 CQM parts completed. Mounting ongoing.

PACS IBDR 27/28 Feb 2002 PACS Photometer14 PHOTOMETER ASSEMBLY The 2K structure holds the Blue and Red BFPs…

PACS IBDR 27/28 Feb 2002 PACS Photometer15 PHOTOMETER ASSEMBLY …is insulated from the 4 K stage by stainless steel tubes…

PACS IBDR 27/28 Feb 2002 PACS Photometer16 PHOTOMETER ASSEMBLY The 4 K structure is mechanically interfaced with the remaining part of the instrument

PACS IBDR 27/28 Feb 2002 PACS Photometer17 PHOTOMETER ASSEMBLY The cooler is mounted on the bottom, the RF filter boxes are bolted on the rear side.

PACS IBDR 27/28 Feb 2002 PACS Photometer18 PHOTOMETER ASSEMBLY The cooler straps are finally located.

PACS IBDR 27/28 Feb 2002 PACS Photometer19 PHOTOMETER ASSEMBLY A black painted metal blanket achieve the stray light rejection.

PACS IBDR 27/28 Feb 2002 PACS Photometer20 BUDGETS Mass Budget Blue BFP= 630 g Red BFP= 520 g 2 K Struc.= 550 g 4 K Struc.= 2720 g Cryocooler= 1700 g RF Filters= 1260 g Total= 7380 g Thermal Budget 2 K Stage= 5 mW Elect.= 3.3 mW Cond.= 1.7 mW 4 K stage= negative 0.3 K Stage= 12 µW Cryocooler= 800 J/cycle

PACS IBDR 27/28 Feb 2002 PACS Photometer21 Development Status (3) Cryogenic Test Facilities: –BFP Test facilities: Designed to test BFP individually, they consist in: 1 cryostat equipped with 0.3K cooler and optical bench + 1 acquisition system. 2 identical facilities installed respectively at Saclay and LETI. Currently they are equipped with simplified optical benches. –PhFPU Test facility: Designed to test a fully assembled PhFPU, it consists in one cryostat equipped with simplified optical bench. Specified. Detailed drawing of cryostat almost completed. –Irradiation test facility: Cryostat ordered at IRlab. –FTS spectrometer test facility: Manufactured. Currently in acceptance tests.

PACS IBDR 27/28 Feb 2002 PACS Photometer22 BFP & PhFPU Test facilities

PACS IBDR 27/28 Feb 2002 PACS Photometer23 TESTS PROGRAM AND COLD FACILITIES BFP test facilityPhFPU test facility Irradiation test cryostat Spectrometer Filters measurements checknone yes Spectral responsivity none yes Responsivity yescheckyescheck Noise performances yes Gamma ray total dose no yesno Protons and heavy Ions no yesno

PACS IBDR 27/28 Feb 2002 PACS Photometer24 TESTS RESULTS Tests on bolometer arrays started only two weeks ago after unexpected Delays on ribbon cables delivery. We started by functional tests: Pixel multiplexing, electronic chopping, blind pixel differential mode including tests on background compensation Heater. 16 pixels Chopper on Multiplexing imposes to drive signals of 40 frames/s x 16 pixels x 2 (chop) =1280Hz

PACS IBDR 27/28 Feb 2002 PACS Photometer25 TESTS RESULTS: differential mode Without heating the blind pixels Heater on 300 mV on heaters 350 mV on heaters

PACS IBDR 27/28 Feb 2002 PACS Photometer26 BOLA is currently a « relay »: it adapts the output impedance of the BU to cope with the expected cable capacitance in a given 2 K power consumption. BOLA ISSUE Warm electronics 14 meters ?! BOLA is still today the baseline! heater

PACS IBDR 27/28 Feb 2002 PACS Photometer27 Bandwidth measurements in function of dissipated Power and output capacitance Hz Without capacitor +1 nf +2.2nf 6 mW 2.5 mW 1.25 mW BOLA ISSUE

PACS IBDR 27/28 Feb 2002 PACS Photometer28 TESTS RESULTS FUNCTIONNALITY: –Detector array measured is completely functional. –Responsivity (V/W) is not available because test filters are still to be measured and mounted. –Evaluation of multiplexing on noise increase currently explored. –Buffer Unit performances are compliant with noise specifications. CONCLUSIONS The detector system is a complex set up. It is completely functional. We already notice some minor problems: - diode protection on BU for the 300 mK stage to be removed, - modify geometry of even/odd MOS transistors (threshold slightly different).

PACS IBDR 27/28 Feb 2002 PACS Photometer29 PhFPU Models (1) SMs: –CEA SM: Consists in flight representative 2K & 4K mechanical structures equipped with dummy mass models of the BFPs and a Cryocooler SM. Goals: Validation of the mechanical concept. –KT SM: Consists in a flight representative 2K & 4K mechanical structure equipped with dummy mass models of the BFPs and of the Cryocooler. Validation of: the mechanical I/F with the instrument, the mounting procedure, the mechanical concept. SOAM (Structure and Optical Alignment Model) –Consists in the KT SM refurbished with optical marks. –To be used to perform Warm & Cold Alignment with the instrument.

PACS IBDR 27/28 Feb 2002 PACS Photometer30 PhFPU Models (2) CQM: –Fully representative Flight Model. –Performance restrictions: Blue Channel: 8 functional arrays, performances. Red Channel: 2 functional arrays, performances. FM: –Fully compliant. FS: –Spare BFPs & Cryo-cooler.

PACS IBDR 27/28 Feb 2002 PACS Photometer31 AIV & QA AIV: –Full PhFPU Models AIV diagram available. –AIV means identified (already available or development/procurement planned). QA: –QA organisation operational at SAp, LETI and SBT PA plans, Doc. Management, –PhFPU QA Documentation: DML (currently in draft) DPL (currently in draft) –Bolometer evaluation: Evaluation plan available

PACS IBDR 27/28 Feb 2002 PACS Photometer32 PROBLEM AREAS (1) Current lack of Bolometer Complete Test results: –Problem: The 1st blue BFP has been successfully integrated at LETI. We started measurements in an incomplete test bench, with some minor problems in stray light rejection, and 300 mK operation (new double stage 3He/4He cooler). –Solution: The tools needed to measure the performances will be validated and implemented in the fore coming weeks. cryogenic issues are under investigation. additional SAp staff support test at LETI. 2K Buffer characteristics: –Problem: Encouraging results have been obtained from preliminary tests at LETI and at Sap. Today, uncertainties on the stray capacitance of the wires and allocated 2K power budget prevent to remove BOLA. –Solution: BOLA is still the baseline and to remove it, is a system issue (we will have to take in account the EMI susceptibility).

PACS IBDR 27/28 Feb 2002 PACS Photometer33 PROBLEM AREAS (2) Optical filters: –Problem: filter housing design uneasy due to filter material behaviour. –Solution: Asking for samples of filter material to UC for housing prototyping at SAp. UC is investigating housing solutions as well (together with SPIRE opt. filter design). Cooler electrical insulation: –Problem: Detector insulation from the instrument mechanical ground (today only through the cryo-cooler). –Solution: Several solutions under investigation.

PACS IBDR 27/28 Feb 2002 PACS Photometer34 PROBLEM AREAS (3) Cold (4K) Vibration Tests: –Problem: Cold vibration cannot be carried out at PhFPU level. –Solution: Cold Qualification at instrument level. Procurement of Ribbon cables: –Problem: Provision relies on only one company. –Solution: Looking for other sources.

PACS IBDR 27/28 Feb 2002 PACS Photometer35 SCHEDULE