space environment and detection : lessons learned from planck/hfi

Space environment and detection : lessons learned

from PLANCK/HFI

François PAJOT Institut d'Astrophysique SpatialeBeyond CoRE, June 26th 2012

F. Pajot – CoRE 2012

Introduction

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,...)

F. Pajot – CoRE 2012

Glitches

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Planck/HFI data processing

glitches templates

1 sglitches removal

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High glitch rate on bolo and thermo

100/mn

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Cosmic ray impact on HFI

CR on detectors thermometer grid wafer

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)

F. Pajot – CoRE 2012

CR 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

F. Pajot – CoRE 2012

CR on bolometers

total

longvery long

short

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CR 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)

F. Pajot – CoRE 2012

Cosmic ray hits on 100 mK stage:long term trend

bolometer plate PID

bolometer plate

dilution plate PID

SREM count (AU)

Solar activity minimum means higher CR rate below ~500 MeV

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Cryochain 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 regulators30

nW

correlated with SREM data (ie: sun waking up)

SCS switch over

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Cosmic ray energy distribution

-> solar maximum

-> solar minimum est.

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Planck/HFI noise PSD

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Impact on design and tests

Minimize detector sensitivity to CR minimize cross section to CR for absorber (grid,..) and

thermometer minimize 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.

F. Pajot – CoRE 2012

EMI/EMC

Strict EMI/EMC design of Planck no pertubation from transmitters no perturbation from other subsystems except from known 4K cooler drive electronics synchronization with modulation of bolometer readout gives

very narrow lines requires design at system level (ex SPICA/SAFARI)

F. Pajot – CoRE 2012

Thoughts on ground calibrations

Temporal response direct impact on C(l) more characterisations

ADC 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...

F. Pajot – CoRE 2012

Thank You !

F. Pajot – CoRE 2012

The 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.