JeanChristophe HAMILTON

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Low frequency and Scan-synchronous noise
reduction in the Archeops experiment
CMBNet Meeting Oxford, 6-7-8 Dec. 2000

• Jean-Christophe HAMILTON
• Alexandre AMBLARD
• PCC-Collège de France, Paris

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What is our signal like ?
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Low frequency drifts

• Correlated with temperature measurements in the
  cryostat

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Simultaneous decorrelation of temperature
fluctuations
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Fourier Power spectra
fknee reduced from 1-2 Hz to 0.2-0.3 Hz
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Parasitic signal decorrelation
Red line is just an average over 50 points

• The signal is seen simultaneously
• by all bolometers (radiation)

• It is brighter at higher frequency

• High frequency channel does not
• contain any CMB

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Parasitic signal decorrelation

• We work on maps

S underlying true sky signal map
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Reconstructed maps
No model of the dipole was included in the
decorrelation
The dipole appears !!!
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Orientation of the dipole
Angular shift compared to COBE/DMR (deg.)
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Conclusion

• Low frequency drifts reduced using bath
• temperature drifts

• Parasitic signal removed using high frequency
• channel

• Dipole maps and calibration

• maps are still striped