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June 23, 2005 - Nicolas BILLOT - NDIP Beaune Meeting CEA DSM Dapnia SAp Recent Achievements in the Development of HERSCHEL/PACS Bolometer Arrays Nicolas BILLOT [email protected] CEA - Saclay/DAPNIA/SAp UMR - Astrophysique Interaction Multi-echelle
Transcript of Recent Achievements in the Development of ... - NDIP 2020ndip.in2p3.fr › beaune05 › cdrom ›...
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
Recent Achievements in the Development of HERSCHEL/PACS Bolometer Arrays
Nicolas [email protected]
CEA - Saclay/DAPNIA/SAp UMR - Astrophysique Interaction Multi-echelle
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
Acknowledgements
CEA-Saclay / SApBoulade Olivier, Doumayrou Eric, Horeau Benoit,
Lepennec Yannick, Martignac Jerome, Okumura Koryo,Révéret Vincent, Rodriguez Louis, Sauvage Marc
CEA-Grenoble / LETI / LIRAgnèse Patrick, Cigna Jean-Charles , Pornin Jean-Louis, Simœns Francois
IAPVigroux Laurent
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
Overview
• What is Far-IR and Sub-millimeter Astronomy?
•The HERSCHEL Mission
• Bolometers and submm imagers
• PACS bolometers
• Some results from the lab
• Future
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
The cold Universe: a history of star formation
• ‘Warm’ dust grains @ 10-50K• Star formation tracers• Galaxy evolution• Better transparency @ longer λ• Many transition lines in submm• Only 3 or 4 atmospheric windows!
What do we see in the sub-millimeter wavelength range?
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
HERSCHEL Mission
• 4th ‘cornerstone’ of ESA's science programme• Photometry and Spectroscopy in the 60 - 670 µm range• 4 years mission• 2nd Lagrangian point orbit• Launch date 2007 (Ariane 5 at Kourou, French Guyana)• Dimensions 7.5 x 4 x 4 m• ISO-type superfluid Helium Cryostat (3500 liters)• Giant 3.5 m telescope passively cooled @ 70K
(Silicon carbide, WFE < 6 µm, emissivity ~ 5%)• 3 scientific instruments : HIFI, SPIRE and PACS
Which technology for PACS photometer?
Requirements:• Photometry in 60-210 µm range ( 10-5 eV!! )• Large format detector• High mapping efficiency• High sensitivity, photon noise limited
Heterodyne ?
Photoconductors ?
BOLOMETERS
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
Bolometer principles
• An absorber convert incident power into heat High sensitivity = low heat capacity (=> low temperature)
• A thermometric sensor measures the temperature increaseHigh sensitivity = strong dependence on T
T0
• Heat is evacuated to a cold heat sink to “reset” the detectorHigh thermal conductivity
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
So far in Submm Astronomy…
Submm imagers = bolometers• UKT14 (1986) : 1 pixel• SHARC I (1996) : linear monolithic array of 24 pixels• SCUBA (1998) : 37 + 91 pixels• SHARC II (2002) : 12x32=384 pixels
MAMBO 2
2.44Fλ
2Fλ
• Absorption issues: Winston cones
2Fλ
Nyquist sampling for pixel size of 0.5Fλ
16 pointings required to fully sample the PSF!
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
PACS
Features to remember:• 0.5Fλ pixels (750x750 µm): instantaneous PSF sampling• λ/4 reflecting cavity for optimum absorption• All-Silicon design (very high impedance doped Si thermometers)• 10x16x16 = 2560 pixels (collective manufacturing of 16x16 matrices )• Cold multiplexed electronics ( CMOS techno @ 300mK, 16 to 1 )• Qualified for space
λ/4
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
PACS
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
In the lab
Specifications:Background flux: 2 pW/pixelExpected source fluxes: ~1% of backgroundSensitivity: 0.3 fW/pixel (5σ , 1h)Photon noise limited
Qualified for Space?•Vibration tests OK• Irradiation tests OK
γ Rays : cumulated dose 30 krad (equivalent 15 years in space)Protons (expected 4.10-3impacts/s/pixel)α particules (expected 3.10-4impacts/s/pixel)
2 4 6 8 10 12
0.115
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0.12
0.121
time (s)
inte
nsity
(vol
ts)
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
In the lab
20 22 24 26 28 30 32 34 36
0.21
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time (s)
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20 22 24 26 28 30 32 34 36
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Responsivity : 2.1010 V/W
Noise : white noise @ 3 Hz: 4 µV.Hz-1/2
1/f noise knee frequency: 3 Hz
NEP = Noise/Responsivity = 2.10-16 W.Hz-1/2
Time constant = 3-5 Hz
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
Ground Adaptation
Possible adaptation of CEA bolometers for Ground telescopes in the 350 and 450 µm atmospheric windows:
• KOSMA (Swiss Alpes)
• APEX (Atacama desert)
• Concordia (Antarctica)
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
Extras
Photos…
pixel size 750 µm
Blue channel: 60-130 µm Red channel: 130-210 µm
32
64 32
16
pixel FOV-3.2”
2048 active pixels
256 blind pixels
pixel FOV-6.5”
512 active pixels
64 blind pixels
3.5’
1.75’1.75’
3.5’
diff
ract
ion
limit
@ 7
0µm
- 10
”
diff
ract
ion
limit
@ 1
70µm
- 24
”
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
PACS
June 23, 2005 - Nicolas BILLOT - NDIP Beaune MeetingCEA DSM Dapnia SAp
PACS
• Photometer Focal Plane• PACS Instrument
• Blue Array 2048 pixels• Blue Channel
