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QUIET
Q/U Imaging ExperimenT
QUIET Project
Miami Physics Conference 2009
December 16
Raul Monsalve for the QUIET Collaboration
University of Miami
What is QUIET ?
• Radiotelescope
that measures intensity and polarization of the
CMB
• Located in Chile
• Main science objective is to improve characterization of Emode polarization and detect the difficult B-mode polarization
• Two phases are planned. Phase-I is ongoing, started in August
2008. Phase II is planned to start in 2012, in a larger scale,
improving the techniques learned during phase-I
QUIET Collaboration
U. CHICAGO
FERMILAB
STANFORD
MANCHESTER
OXFORD
OSLO
COLUMBIA
JPL
PRINCETON
CALTECH
U. MIAMI
SITE
MPI-BONN
KEK
Science Goals
• We can measure the polarisation of the CMB
the same way as for light
• The Stokes parameters quantify the
polarization properties of a light ray
▫
▫
▫
▫
I = no filter at all
Q = linear polarizer at 0 and 90°
U = linear polarizer at -45 and 45 °
V = circular polarizer
• I is just the temperature
• Q and U combine to form E- and B-modes
• No known physical process can generate Vpolarized CMB radiation
Science Goals
Status and Forecast on the EE and BB characterization
Site and
Instrumentation
Site
• Chajnantor Scientific Reserve in Chile at 5080 m above sea level
• Among the best places for mm and submm astronomy
• Access to CBI infrastructure
• Accessible at all times
• 1 hour drive from San Pedro de Atacama
• Good sky coverage
• For outside work bottled oxygen systems are used
• Oxygen concentration in control room is increased ~27%
Phase-I Summary
Frequency
N° of HEMT Detectors
Resolution
Telescope Type
Module Sensitivity
Array Sensitivity
Observation Period
Q Band
W Band
40 GHz
90 GHz
17/2
84/6
28 arcmin (FWHM)
12 arcmin (FWHM)
Crossed Dragone
Crossed Dragone
300 μK s½
550 μK s½
70 μK s½
60 μK s½
Oct 2008 – June 2009
June 2009 – Mid 2010 ?
Mount
• Inherited from CBI
• Alt-Az axes
• Rotation about optical axis (boresight axis)
• Elevation range limited to 43 deg < el < 87 deg
Optics
• Crossed Dragone design
• 1.4 m primary and secondary mirrors
• FWHM: 28 (Q) and 12 (W) arcmin
Horn Arrays
• Conical corrugated feed horn arrays
• Excellent beam symmetry
• Low sidelobe response
• Low cross-polarization
• Broad frequency band
• Typical FWHM of ~7 deg
• Built by UM
OMTs
• Splits incoming radiation into L and R
• 20% bandwidth
• Low loss
• High isolation on the output ports to avoid
temperature-to-polarization leakage
Detector Modules
• Heart of the receiver
• Polarimeter on a chip
• Automated assembly and operation
• Measuring of Q and U simultaneously in each
pixel
• Operate at ~20K
Module/OMTs
Seven element demonstration array
Receiver
Calibration and
Preliminary Data
Calibration Strategy
Polarization
MOON
Once/7 days,
Relative Gains,
Angles
NOISE SOURCE
Once/1.5 hours,
Relative Gains,
Angles
TAU A
Once/2 days,
Absolute Gains,
Angles, Beams
Temperature
JUPITER
Once/7 days,
∆T Gains,
Beam
SKY-DIP
Once/1.5 hours,
Relative Gains,
Stability
Gain Stability
+ supplemental measurements
Calibration
Beam Shape using Jupiter
Calibration
Tau A Gains
Moon Polarization Fits
CMB Analysis
Observation Regions
Patch Centers
• Low foreground regions in coordination with ABS, Polarbear
(Multifrequency measurements for galactic foreground removal)
• Distribution to allow continuous scanning
4x(15x15)=900 [deg²]
Telescope Operation during Q-Band Season
Average 68.1%
Downtime mainly due to:
-Mechanical Problems
-Generator problems
-Bad weather
Phase-I, EE Power-spectra Forecasts
Q
W
Patch 2a Results (PRELIMINARY)
Other Interesting Observations
Galactic Center Polarization Maps with Q-Band Data (PRELIMINARY)
Other Interesting Observations
Galactic Center Temperature Map with Q-Band Data (PRELIMINARY)
QUIET
WMAP
Phase-II
Phase-II Summary
Beginning operations
2013 ?
N° of telescopes
3
Telescope type
Crossed Dragone
Ka Band
Q Band
W Band
32 GHz
40 GHz
90 GHz
N° of modules (P/T)
16/2
55/6
1389/108
Beamsize (FWHM)
28 arcmin
20 arcmin
8.5 arcmin
Module Sensitivity
165 μK s½
178 μK s½
364 μK s½
Frequency
Phase-II Power-spectra Forecasts
Current Performance
(noise, duty cycle, 1/f)
Likely Improvement
Appendix
• Alternate technique to identify gravitational lensing effects (Zaldarriaga(1999), Hu(2002))
• Lens reconstruction: Lensing Deflection Field calculation from cross-correlation of
E- and B-modes
•
Stronger constraints on cosmological parameters than using B-mode power
spectrum
• By measuring shape and amplitude of the
Deflection power spectrum QUIET Phase-II can
place constraints on parameters such as:
• Neutrino mass (Maltoni, 2004)
• Dark energy density (Stompor, 1999)
• Spatial curvature (Stompor, 1999)
Summary
• QUIET Science:
• Experiment addressing fundamental questions in physics
• Taking the CMB polarization knowledge to new levels
• QUIET Status:
• Largest HEMT-based focal plane array ever deployed, using state of the
art MMIC packaging techniques
• Phase-I observing and proposing Phase-II to start in 2012/2013
Systematic Errors
o Overall signal size
o Overall gain calibration
o Beamsize calibration
o Pointing error
o Fake signal source
o Instrumental I->Q/U : caused by OMT, 1% for Q-band. Negligible.
o Gain fluctuations
: up to 20% negligible for phase I.
o E->B mixing source
o Polarization angle
: calibration better than 5% for phase I.
o Optics cross polarization : only affects by order of ∆ө²
o Q/U gain mismatch
: relative gain between Q and U stable.
o Patch geometry
: finite patch, patch irregularity, pixelization
Systematic Errors
E->B, Patch geometry