Exploring the primordial Universe with the Q U Bolometric Interferometer for Cosmology J.-Ch. Hamilton, APC, Paris, France (CNRS, IN2P3, Université Paris-Diderot)
Expected difficulties in the B-Modes Quest Sensitivity : B polarization is at best 10 times weaker than E Amplitude could be very small... 1 year of Planck is ~ S/N=1 for T/S=0.01 A dedicated space mission might not be for tomorrow. Foregrounds : Need to remove them accurately (can t just mask) Multiwavelength instruments Observe an ultra-clean region can t be too small as primordial B modes are mainly on large scales Systematic effects : Instrument induces leakage of T into E and B (and T>>E>>B) Cross-polarization, beams and ground pickup are major issues Need for accurate polarization modulation and detailed knowledge of instrument properties
Possible instruments Imagers with bolometers: No doubt they are nice detectors for CMB: - wide band - low noise Especially true for a satellite (small background) Interferometers: Long history in CMB - CMB anisotropies in the late 90s (CAT: 1 st detection of subdegrees anisotropies, VSA) - CMB polarization 1 st detection (DASI, CBI) Clean systematics: - No telescope (lower ground-pickup & cross-polarization) - Angular resolution set by receivers geometry (well known) Technology used so far - Antennas + HEMTs : higher noise - Correlators : hard to scale to large #channels Can these two nice devices be combined? Bolometric Interferometry C l FT correlator C l Visibilites V(u,v) FT P. Timbie Imager Interferometer l
Possible instruments Imagers with bolometers: No doubt they are nice detectors for CMB: - wide band - low noise Especially true for a satellite (small background) Interferometers: Long history in CMB - CMB anisotropies in the late 90s (CAT: 1 st detection of subdegrees anisotropies, VSA) - CMB polarization 1 st detection (DASI, CBI) Clean systematics: - No telescope (lower ground-pickup & cross-polarization) - Angular resolution set by receivers geometry (well known) Technology used so far - Antennas + HEMTs : higher noise - Correlators : hard to scale to large #channels Can these two nice devices be combined? Bolometric Interferometry Good sensitivity Good control of systematics Both
The collaboration APC Paris, France IAS Orsay, France CSNSM Orsay, France IRAP Toulouse, France Institut Néel, Grenoble, France Maynooth University, Ireland Università di Milano-Bicocca, Italy Università degli studi, Milano, Italy Università La Sapienza, Roma, Italy University of Manchester, UK Richmond University, USA Brown University, USA University of Wisconsin, USA + China (IHEP & PMO) about to join arxiv:1010.0645 ~ Astroparticle Physics 34 (2011) 705 71
design 45 cm Sky 0 GHz 20x20 horns14 deg. FWHM <1K Cold box Filters Half-wave plate Primary horns Switches Secondary horns Y polarization bolometer array (~30x30) Polarizing grid <1K X polarization bolometer array (~30x30) 300 mk Cryostat
design 45 cm Sky 0 GHz 20x20 horns14 deg. FWHM <1K Cold box Filters Half-wave plate Primary horns Switches Secondary horns Y polarization bolometer array (~30x30) Polarizing grid <1K X polarization bolometer array (~30x30) 300 mk Cryostat
design 45 cm Sky 0 GHz 20x20 horns14 deg. FWHM <1K Cold box Filters Half-wave plate Primary horns Switches Secondary horns Y polarization bolometer array (~30x30) Polarizing grid <1K X polarization bolometer array (~30x30) 300 mk Cryostat
design 45 cm Sky 1 horn open 0 GHz 20x20 horns14 deg. FWHM Filters Half-wave plate <1K Cold box Primary horns Switches Secondary horns Y polarization bolometer array (~30x30) Polarizing grid <1K 300 mk Cryostat X polarization bolometer array (~30x30)
design 45 cm Sky 10 10 5 5 0 0-5 -5 10 10 BS 10 1 horn open -10-10 -10 5-10 -5-5 0 0 5 5 10 10 0-5 -5 10 10-10 -10 5-10 -10 5-5 0 5 10-5 10 0 0-5 -5 10 10 BS 21 1 baseline BS 54 1 baseline Resulting BS 5 signal 1 baseline 2.5 2.5 2.0 2.0 1.5 1.5 1.0 1.0 0.5 0.5 2.5 0.0 2.5 0.0 2.0 2.0 1.5 1.5 1.0 1.0 0.5 0.5 2.5 0.0 2.5 0.0 2.0 2.0 1.5 1.5 1.0 1.0 8 0.5 0.5 0 GHz 10 10 10 20x20 horns14 deg. FWHM 2.5 2.5 5 5 0 0-5 -5 10 BS 21 Y polarization bolometer 0 array (~30x30) Resulting BS signal 5 <1K -10-10 -10 5-10 -5-5 0 0 5 5 10 10-5 10 10-10 5-10 5-5 0 5 10 0 0-5 -5 10 BS 2 Resulting signal 2.0 2.0 1.5 1.5 1.0 1.0 0.5 0.5 0.0 2.5 0.0 2.0 1.5 1.0 8 0.5 2.5 0.0 6 2.0 4 1.5 1.0 2 80.5 5 0-5 -10-10 -5 0 5 10 10 5 Polarizing grid 0 <1K -5 BS 2 Cold box Resulting signal 2.5 2.0 1.5 1.0 0.5 0.0 8 6 4 2 Filters Half-wave plate Primary horns Switches Secondary horns -10-10 -10 5-10 -5-5 0 0 5 5 10 10 0 0.0 2.5 0.0 6 2.0 4 1.5-10 -10-10 5-10 -5-5 0 0 5 5 10 10 0 0 0.0 6 4-10 -10-5 0 5 10 0-5 -5 total signal (all baselines) -10-10 -10-5 0 5 10-10 -5 10 1.0 2 0.5 0 0.0-5 -10-10 -5 0 5 10 X polarization bolometer array (~30x30) 2 0 300 mk Cryostat
design fringes successfuly observed in 2009 with MBI-4 [Timbie et al. 2006] 45 cm Sky 10 10 5 5 0 0-5 -5 10 10 BS 10 1 horn open -10-10 -10 5-10 -5-5 0 0 5 5 10 10 0-5 -5 10 10-10 -10 5-10 -10 5-5 0 5 10-5 10 0 0-5 -5 10 10 MBI-4 data 2009 campaign (PBO- BS 21 Wisc.) 1 baseline BS 1 & 54 2 1 baseline 1 & 3 Resulting BS 5 signal 1 baseline 2.5 2.5 2.0 2.0 1.5 1.5 1.0 1.0 0.5 0.5 2.5 0.0 2.5 0.0 2.0 2.0 1.5 1.5 1.0 1.0 0.5 0.5 2.5 0.0 2.5 0.0 2.0 2.0 1.5 1.5 1.0 1.0 8 0.5 0.5 0 GHz 10 10 10 20x20 horns14 deg. FWHM 2.5 2.5 5 5 0 0-5 -5 10 BS 21 Y polarization bolometer 0 array (~30x30) Resulting BS signal 5 <1K -10-10 -10 5-10 -5-5 0 0 5 5 10 10-5 10 10-10 5-10 5-5 0 5 10 0 0-5 -5 10 BS 2 Resulting signal 2.0 2.0 1.5 1.5 1.0 1.0 0.5 0.5 0.0 2.5 0.0 2.0 1.5 1.0 8 0.5 2.5 0.0 6 2.0 4 1.5 1.0 2 80.5 5 0-5 -10-10 -5 0 5 10 10 5 Polarizing grid 0 <1K -5 BS 2 Cold box Resulting signal 2.5 2.0 1.5 1.0 0.5 0.0 8 6 4 2 Filters Half-wave plate Primary horns Switches Secondary horns -10-10 -10 5-10 -5-5 0 0 5 5 10 10 0 2 & 3 0.0 2.5 0.0 6 2.0 4 1.5-10 -10-10 5-10 -5-5 0 0 5 5 10 10 0 0 0.0 6 4-10 -10-5 0 5 10 0-5 -5 total signal (all baselines) 2 & 4-10 -10-10 -5 0 5 10-10 -5 10 1.0 2 0.5 0 0.0-5 -10-10 -5 0 5 10 X polarization bolometer array (~30x30) 2 0 300 mk Cryostat
B.I. = Synthesized imager Primary horns array Synthesized beam Window: 403.0mm - Nhorns=400 0.2 Horn position in mm 0.1 0.0-0.1 2 u -0.2-0.2-0.1 0.0 0.1 0.2 Horn position in mm 0 GHz, 20x20 horns, 14 deg. FWHM, D=1.2 cm Synthesized beam used to scan the sky as with an imager
B.I. = Synthesized imager Primary horns array Synthesized beam Window: 403.0mm - Nhorns=400 0.2 Horn position in mm 0.1 0.0-0.1 2 u -0.2-0.2-0.1 0.0 0.1 0.2 Horn position in mm 0 GHz, 20x20 horns, 14 deg. FWHM, D=1.2 cm Synthesized beam used to scan the sky as with an imager
B.I. = Synthesized imager Primary horns array Synthesized beam Window: 403.0mm - Nhorns=400 0.2 Horn position in mm 0.1 0.0-0.1 2 u -0.2-0.2-0.1 0.0 0.1 0.2 Horn position in mm 0 GHz, 20x20 horns, 14 deg. FWHM, D=1.2 cm Synthesized beam used to scan the sky as with an imager
B.I. = Synthesized imager Primary horns array Synthesized beam Window: 403.0mm - Nhorns=400 0.2 (including detector finite size and 30% BW) Horn position in mm 0.1 0.0-0.1 FWHM 0.54 deg. 8.5 deg. 2 u -0.2-0.2-0.1 0.0 0.1 0.2 Horn position in mm 0 GHz, 20x20 horns, 14 deg. FWHM, D=1.2 cm Synthesized beam used to scan the sky as with an imager
Map Making ~ as an imager Scan the sky with synthesized beam Az. scans at constant elevation following a single field Phi rotation around optical axis Reproject data on the sky ˆT = A t N 1 A 1 A t N 1 d Synthesized beam has multiple peaks Usual map making assumes A has a single non zero element in each column - Does not lead to good results Improved method with better beam approximation - Sparse matrices helps fast convergence of CG - First results on simulations are promising [Pierre Chanial @ APC]
Map Making ~ as an imager Scan the sky with synthesized beam Az. scans at constant elevation following a single field Phi rotation around optical axis Reproject data on the sky ˆT = A t N 1 A 1 A t N 1 d Synthesized beam has multiple peaks Usual map making assumes A has a single non zero element in each column - Does not lead to good results Improved method with better beam approximation - Sparse matrices helps fast convergence of CG - First results on simulations are promising [Pierre Chanial @ APC]
Map Making ~ as an imager Scan the sky with synthesized beam Az. scans at constant elevation following a single field Phi rotation around optical axis Reproject data on the sky ˆT = A t N 1 A 1 A t N 1 d Synthesized beam has multiple peaks Usual map making assumes A has a single non zero element in each column - Does not lead to good results Improved method with better beam approximation - Sparse matrices helps fast convergence of CG - First results on simulations are promising [Pierre Chanial @ APC]
Site: Dome C, Antarctica
Site: Dome C, Antarctica Great landscape
Site: Dome C, Antarctica Great landscape Healthy weather
Site: Dome C, Antarctica 0PWV (mm) Great Courtesy L. Valenziano landscape 1 0.5 Great for CMB observations Healthy weather
Detection Chain TES + + SiGe ASIC Mux CSNSM: Stefanos Marnieros APC: Michel Piat IRAP: Ludovic Montier 2 arrays of 992 NbSi TES Each array : 4x248 elements 100 mk bath (dilution) 3 mm size NEP ~ 5.10 - W.Hz -1/2 time constant ~ 10 ms Multiplexed Readout pre-amplifier+mux - 32:1 multiplexing SiGe ASIC (amp+mux) - 4:1 multiplexing 128 channels / ASIC Low noise: ~200 pv.hz -1/2 low power: ~ few mw
Total : 257 9 7 5 5 7 9 11 12 13 14 Wafer: 3" Bolos: 3mm + 0.2mm Total : 257 5 7 9 11 12 13 14 9 7 5 Bolos: 3mm + 0.2mm 3" Wafer: Detection Chain TES + + SiGe ASIC Mux CSNSM: Stefanos Marnieros APC: Michel Piat IRAP: Ludovic Montier 2 arrays of 992 NbSi TES Each array : 4x248 elements 100 mk bath (dilution) 3 mm size NEP ~ 5.10 - W.Hz -1/2 time constant ~ 10 ms Multiplexed Readout pre-amplifier+mux - 32:1 multiplexing SiGe ASIC (amp+mux) - 4:1 multiplexing 128 channels / ASIC Low noise: ~200 pv.hz -1/2 low power: ~ few mw Total : 257 Wafer: 3" Bolos: 3mm + 0.2mm 11 12 14 13 14 13 12 11 Wafer: 3" Bolos: 3mm + 0.2mm Total : 257
Total : 257 9 7 5 5 7 9 11 12 13 14 Wafer: 3" Bolos: 3mm + 0.2mm Total : 257 5 7 9 11 12 13 14 9 7 5 Bolos: 3mm + 0.2mm 3" Wafer: Detection Chain TES + + SiGe ASIC Mux CSNSM: Stefanos Marnieros APC: Michel Piat IRAP: Ludovic Montier 2 arrays of 992 NbSi TES Each array : 4x248 elements 100 mk bath (dilution) 3 mm size NEP ~ 5.10 - W.Hz -1/2 time constant ~ 10 ms Multiplexed Readout pre-amplifier+mux - 32:1 multiplexing SiGe ASIC (amp+mux) - 4:1 multiplexing 128 channels / ASIC Low noise: ~200 pv.hz -1/2 low power: ~ few mw Total : 257 Wafer: 3" Bolos: 3mm + 0.2mm 11 12 14 13 14 13 12 11 Wafer: 3" Bolos: 3mm + 0.2mm Total : 257
Total : 257 9 7 5 5 7 9 11 12 13 14 Wafer: 3" Bolos: 3mm + 0.2mm Total : 257 5 7 9 11 12 13 14 9 7 5 Bolos: 3mm + 0.2mm 3" Wafer: Detection Chain TES + + SiGe ASIC Mux CSNSM: Stefanos Marnieros APC: Michel Piat IRAP: Ludovic Montier 2 arrays of 992 NbSi TES Each array : 4x248 elements 100 mk bath (dilution) 3 mm size NEP ~ 5.10 - W.Hz -1/2 time constant ~ 10 ms Multiplexed Readout pre-amplifier+mux - 32:1 multiplexing SiGe ASIC (amp+mux) - 4:1 multiplexing 128 channels / ASIC Low noise: ~200 pv.hz -1/2 low power: ~ few mw NEW: 1st 248 TES batch: Currently under tests Total : 257 Wafer: 3" Bolos: 3mm + 0.2mm 11 12 14 13 14 13 12 11 Wafer: 3" Bolos: 3mm + 0.2mm Total : 257
Cryostat Designed in Roma P. de Bernardis / S. Masi 45 cm window Stack (~20 cm) of zotefoam layers 1st stage: : Pulse-Tube Filters, horns, switches, HWP, 1st mirror 2nd stage: 300 mk: 7 He evaporation cooler 2nd mirror, polarizing grid, detectors
Systematics: Self-Calibration Unique possibility to handle systematic errors Use horn array redundancy to calibrate systematics - In a perfect instrument redundant baselines should see the same signal - Differences due to systematics - Allow to fit systematics with an external source on the field Unique specificity of Bolometric Interferometry [Bigot-Sazy et al., A&A 2012, arxiv:1209.4905] Example: exact horns locations (figure exagerated ) Redundant baselines : same Fourier Mode
Systematics: Self-Calibration Unique possibility to handle systematic errors Use horn array redundancy to calibrate systematics - In a perfect instrument redundant baselines should see the same signal - Differences due to systematics - Allow to fit systematics with an external source on the field Unique specificity of Bolometric Interferometry [Bigot-Sazy et al., A&A 2012, arxiv:1209.4905] Example: exact horns locations (figure exagerated ) Redundant baselines : same Fourier Mode
Systematics: Self-Calibration Unique possibility to handle systematic errors Use horn array redundancy to calibrate systematics - In a perfect instrument redundant baselines should see the same signal - Differences due to systematics - Allow to fit systematics with an external source on the field Unique specificity of Bolometric Interferometry [Bigot-Sazy et al., A&A 2012, arxiv:1209.4905] Example: exact horns locations (figure exagerated ) Redundant baselines : same Fourier Mode
Systematics: Self-Calibration Unique possibility to handle systematic errors Use horn array redundancy to calibrate systematics - In a perfect instrument redundant baselines should see the same signal - Differences due to systematics - Allow to fit systematics with an external source on the field Unique specificity of Bolometric Interferometry [Bigot-Sazy et al., A&A 2012, arxiv:1209.4905] Example: exact horns locations (figure exagerated ) Redundant baselines : same Fourier Mode
Systematics: Self-Calibration Unique possibility to handle systematic errors Use horn array redundancy to calibrate systematics - In a perfect instrument redundant baselines should see the same signal - Differences due to systematics - Allow to fit systematics with an external source on the field Unique specificity of Bolometric Interferometry [Bigot-Sazy et al., A&A 2012, arxiv:1209.4905] Example: exact horns locations (figure exagerated ) Redundant baselines : same Fourier Mode RMS before RMS after Horns location 0.072 0.011 Individual beams 0.090 0.005 TES Intercalibration 0.029 0.007 pointing error, instrument effective Jones matrix......
Systematics: Self-Calibration Unique possibility to handle systematic errors Use horn array redundancy to calibrate systematics - In a perfect instrument redundant baselines should see the same signal - Differences due to systematics - Allow to fit systematics with an external source on the field Unique specificity of Bolometric Interferometry [Bigot-Sazy et al., A&A 2012, arxiv:1209.4905] Example: exact horns locations (figure exagerated ) Redundant baselines : same Fourier Mode Jones Matrix residual error 10-2 10-3 10-4 Horns location 0.072 0.011 Individual beams 0.090 0.005 TES Intercalibration 0.029 0.007 10-5 Accuracy on systematics estimations is only limited by statistics pointing error, instrument effective 10-6 Jones matrix RMS before RMS after...... 1 10 2 10 4 10 Time spent on each baseline (s) 6
Self-Calibration results l(l+1)cl/2π) [µk 2 ] 10 0 10-1 10-2 10-3 10-4 C BB for r=0.05 ( Target) range C EE leakage without self-calibration C EE leakage with self-calibration (2.5% of observation time) Expected signal (r=0.05) initial E B leakage Self-Calibration residual E B leakage 10-5 10 100 ell [Bigot-Sazy et al., A&A 2012, arxiv:1209.4905]
timeline 2012: Partially funded by french ANR 2013: Construction started for the 1st module 400 horns - 0 GHz - 1984 TES bolometers 2014: Integration at APC, Paris 20: First light at Dôme C, Antarctica Data taking : one to two years (incl. winter) with one module 20...: Full construction 6 modules at 90, 0 and 220 GHz
tensor/scalar ratio sensitivity 1.000 : l= - 1.0 years - NET = 200µK.Hz -1/2 90% C.L. upper limit on Tensor to scalar ratio r 0.100 0.010 WMAP7y Planck TT + WMAP Pol + HighL + BAO 1 Module 6 Modules 0.001
Summary is a novel instrumental concept Bolometric Interferometer optimized to handle systematics (self-calibration) - is an synthesized imager observing a selected range of spatial frequencies that can be accurately calibrated Dedicated to CMB polarimetry and inflationary physics High sensitivity with ~2000 TES bolometers Located at Dome C, Antarctica Target : - First module (0 GHz): r < 0.05 at 90% C.L. (first light ~ late 20) - Six modules (90, 0, 220 GHz) : r < 0.01 at 90% C.L.
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