Aaron Chippendale, Ravi Subrahmanyan, Ron Ekers

1
The Cosmological Reionization ExperimentCoRE

• Aaron Chippendale, Ravi Subrahmanyan, Ron Ekers
• 20 January 2009

RRI
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Overview

• Science
• Expected signal 30 mK / 5 MHz
• Design implication
• 1 mK / 1 MHz target
• Instrument
• Frequency independent antenna
• Correlation spectrometer
• Results
• System stability 1(bandpass and constant)
• 10 K / 2.5 MHz residuals in bandpass
  calibration
• Constant not yet calibrated

3
Theoretical Limits on 21 cm Monopole
possible signal (qualitative)
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Reionization Bubble Model
H
Ts TCBR
H
H
Ts Tm
H
H
H
H
H
H
H
e-
H
H
H
H
H
H
e-
H
H
H
e-
H
H
H
H
Tm gtgt TCBR
H
Tm lt TCBR
H
H
H
Sethi, 2005
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Expected Signal (WMAP3 Parameters)
1 mK/MHz
multiply all numbers by 0.752 for He correction
6 mK/MHz
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Correlation Receiver
r
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Correlation Receiver Integrating Down
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Frequency Independent Antenna
1 error at half power
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Frequency Independent vs. Log Periodic
Frequency Independentdefined by angles
Log Periodicdefined by geometric ratio
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Bandpass Calibration Residuals
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Bandpass Calibrated Spectra 10 K Residuals
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Bandpass Calibration ResidualsReference
Symmetric About Galactic Centre
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Measurement Resembles Simulation of Squinted Beam
Rotating About Boresight
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Normalized Drift-scans at all Frequencies
Measurement vs. Model
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Band Average Drift-scanMeasurement vs. Model
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System Stability 1 or better
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Future

• Future work
• rotating antenna
• split in free space

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The End

• End of main presentation
• Design details follow for discussion

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RFI Comparison
Culgoora, Narrabri (pop. 6000)
Murchison (pop. 110)
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Wiener Model used for RF Amplifier
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Nonlinear Response to Galaxy and RFI
RFI power equivalent to strongest narrowband
interferer at Narrabri
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RFI power equivalent to strongest narrowband
interferer at MRO
RFI power equivalent to strongest narrowband
interferer at MRO
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Aliased Bandpass
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Quantization Distortion Simulation Design
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Quantization Distortion Simulation Results
a25 dB
50th percentile at Narrabri
90th percentile at MRO
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Ideal ADC Signal to Distortion and Quantization
Noise Ratio
Gaussian noise truncated atks
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Ideal ADC Saturation Distortion as Fraction of
Total Power with Single Narrowband Interferer
Gaussian noise truncated atks
(10 dB)
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RFI Comparison
Culgoora, Narrabri (pop. 6000)
Murchison (pop. 110)
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Receivers and Correlator
Correlator
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(No Transcript)
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Correlation Receiver