PLANCKHFI François PAJOT Institut dAstrophysique Spatiale Beyond CoRE June 26 th 2012 Introduction PlanckHFI first mission with NEP 10 17 WHz 12 bolometers 100 mK uninterrupted operation for nearly 30 months ID: 793891
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Slide1
Space environment and detection : lessons learned from
PLANCK/HFI
François PAJOT Institut d'Astrophysique Spatiale
Beyond CoRE, June 26
th
2012
Slide2Introduction
Planck/HFI first mission with
NEP ~10-17 WHz-1/2 bolometers
100 mK uninterrupted operation for nearly 30 months
0.01 Hz- 100 Hz flat noise requirement
polarization sensitive bolometers
high precision calibration
at SE Lagrangian L2
Outline
cosmic rays interactions
impact on design and tests
EMI/EMC
note on ground calibrations (
spectral, ADC,...)
Slide3Glitches
Slide4Planck/HFI data processing
glitches templates
1 s
glitches removal
Slide5High glitch rate on bolo and thermo
100/mn
Slide6Cosmic ray impact on HFI
CR on detectors
thermometergridwafer CR on 100 mK plate
CR secondary and showers
higher energy CR interacting with HFI or satellite then with bolometers or 100 mK plate
correlated events on many bolometers, big events on the 100 mK plate (elephants: still lacking an interpretation)
Slide7CR on bolometers
Cosmic Rays primary and secondary, hits thermometer, grid and wafer
NEP ~10-17
WHz
-1/2
means sensitivity down to a few 10 eV on grid or thermometer, but tens of keV on the wafer
Slide8CR on bolometers
total
longvery long
short
Slide9CR hits impact on 100 mK stage
Low frequency thermal fluctuations
CR hits on bolometer housing (many s)CR hits and showers on bolometer cold plate (10 s and more)CR hits on thermometers used by the PIDs (depends on PID)
Slide10Cosmic ray hits on 100 mK stage:
long term trend
bolometer plate PIDbolometer platedilution plate PID
SREM count (AU)
Solar activity minimum means higher CR rate below ~500 MeV
Slide11Cryochain stability: long term trend
About 4 nW power change on 100mK bolometer plate / 2 years
PID bolo
PID dilution
PID 1.6K
PID 4K
EOL
EOL
EOL
EOL
The power follows the Helium pressures at the pressure regulators
30 nW
correlated with SREM data (ie: sun waking up)
SCS switch over
Slide12Cosmic ray energy distribution
-> solar maximum
-> solar minimum est.
Slide13Planck/HFI noise PSD
Slide14Impact on design and tests
Minimize detector sensitivity to CR
minimize cross section to CR for absorber (grid,..) and thermometerminimize beams / frame thermal coupling to thermometer fast time response
differential measurements
model and test under representative environment (instrument + high energy particles : proton accelerators up to few 100 MeV – on going work in Orsay IAS and Grenoble LPSC & INéel)
Cryochain design
passive / active thermal regulation
need design sub-K stages more immune to cosmic rays showers.
Slide15EMI/EMC
Strict EMI/EMC design of Planck
no pertubation from transmittersno perturbation from other subsystemsexcept from known 4K cooler drive electronics
synchronization with modulation of bolometer readout gives very narrow lines
requires design at system level (ex SPICA/SAFARI)
Slide16Thoughts on ground calibrations
Temporal response
direct impact on C(l)more characterisationsADC calibration
large dynamics, but usefull range on a few bits
Spectral transmission calibration
the best achievable on ground may not be enough
check with multiband sky measurement
Polarization calibration...
Slide17Thank You !
Slide18The results presented here are a product of the Planck Collaboration, including individuals from more than 50 scientific institutes in Europe, the USA and Canada
Planck is a project of the European Space Agency -- ESA -- with instruments provided by two scientific Consortia funded by ESA member states (in particular the lead countries: France and Italy) with contributions from NASA (USA), and telescope reflectors provided in a collaboration between ESA and a scientific Consortium led and funded by Denmark.