CAPMAPCAPMAPCAPMAPCAPMAP

Measuring the Measuring the Polarization of thePolarization of the

CCosmic osmic

MMicrowave icrowave

BBackgroundackground

Measuring the Measuring the Polarization of thePolarization of the

CCosmic osmic

MMicrowave icrowave

BBackgroundackground

Dorothea Samtleben, Center for Cosmological Physics,University of Chicago

Center for Cosmological Physics Center for Cosmological Physics (CfCP)(CfCP)

Center for Cosmological Physics Center for Cosmological Physics (CfCP)(CfCP)

National Science Frontier CenterNational Science Frontier Center

Founded at the University of Chicago in August Founded at the University of Chicago in August 2001 for initially 5 years2001 for initially 5 years

Creation of an interdisciplinary environmentCreation of an interdisciplinary environment

14 faculty, 10 center fellows, 14 faculty, 10 center fellows, graduate students, associated graduate students, associated postdocs ...postdocs ...

National Science Frontier CenterNational Science Frontier Center

Founded at the University of Chicago in August Founded at the University of Chicago in August 2001 for initially 5 years2001 for initially 5 years

Creation of an interdisciplinary environmentCreation of an interdisciplinary environment

14 faculty, 10 center fellows, 14 faculty, 10 center fellows, graduate students, associated graduate students, associated postdocs ...postdocs ...

Research FocusResearch FocusResearch FocusResearch Focus

TheoryTheory

Structures in the UniverseStructures in the Universe

Cosmic Radiation BackgroundsCosmic Radiation Backgrounds

High Energy Particles from SpaceHigh Energy Particles from Space

TheoryTheory

Structures in the UniverseStructures in the Universe

Cosmic Radiation BackgroundsCosmic Radiation Backgrounds

High Energy Particles from SpaceHigh Energy Particles from Space

Four major research components:Four major research components:

Activities of the CenterActivities of the CenterActivities of the CenterActivities of the Center

Various formal and informal seminarsVarious formal and informal seminars

Workshops (Auger-workshop, COSMO-02)Workshops (Auger-workshop, COSMO-02)

VisitorsVisitors

Dedicated outreach and education effortsDedicated outreach and education efforts

Opportunities for sabbaticals for High Energy Opportunities for sabbaticals for High Energy Physicists Physicists

Various formal and informal seminarsVarious formal and informal seminars

Workshops (Auger-workshop, COSMO-02)Workshops (Auger-workshop, COSMO-02)

VisitorsVisitors

Dedicated outreach and education effortsDedicated outreach and education efforts

Opportunities for sabbaticals for High Energy Opportunities for sabbaticals for High Energy Physicists Physicists

Motivation What do we want to learn from our experiment?

Experimental approach Which strategy to choose?

Experimental design What does our experiment look like?

Motivation What do we want to learn from our experiment?

Experimental approach Which strategy to choose?

Experimental design What does our experiment look like?

Talk Outline Talk Outline

How can we improve our How can we improve our understanding of nature?understanding of nature?How can we improve our How can we improve our understanding of nature?understanding of nature?

Set up an experiment to study a well defined Set up an experiment to study a well defined configurationconfiguration e.g. High Energy Physicse.g. High Energy Physics

Study the outcome of an experiment which nature Study the outcome of an experiment which nature has set up has set up e.g. Astrophysicse.g. Astrophysics

Set up an experiment to study a well defined Set up an experiment to study a well defined configurationconfiguration e.g. High Energy Physicse.g. High Energy Physics

Study the outcome of an experiment which nature Study the outcome of an experiment which nature has set up has set up e.g. Astrophysicse.g. Astrophysics

Setup of nature‘s ‘experiment‘Setup of nature‘s ‘experiment‘

How can we find out what happened How can we find out what happened in the early universe?in the early universe?How can we find out what happened How can we find out what happened in the early universe?in the early universe?

We do have witnesses!We do have witnesses!

We will learn about the conditions in the infant We will learn about the conditions in the infant universe by a thorough questioning of the universe by a thorough questioning of the witnesses witnesses

We can compare our theories with the We can compare our theories with the information they provide and improve our information they provide and improve our understanding of the evolution of the universeunderstanding of the evolution of the universe

We do have witnesses!We do have witnesses!

We will learn about the conditions in the infant We will learn about the conditions in the infant universe by a thorough questioning of the universe by a thorough questioning of the witnesses witnesses

We can compare our theories with the We can compare our theories with the information they provide and improve our information they provide and improve our understanding of the evolution of the universeunderstanding of the evolution of the universe

The witnesses: Photons of the Cosmic Microwave Background Radiation

The witnesses: Photons of the Cosmic Microwave Background Radiation

-100 K +100 K

The sky observed at 90 GHz (COBE DMR)The sky observed at 90 GHz (COBE DMR)

What happened 300,000 years What happened 300,000 years after the Big Bang?after the Big Bang?What happened 300,000 years What happened 300,000 years after the Big Bang?after the Big Bang?

The plasma of photons, protons and The plasma of photons, protons and electrons became cold enough so that electrons became cold enough so that electrons and protons formed first atomselectrons and protons formed first atoms

The universe became transparentThe universe became transparent

These photons give us a direct snapshot of These photons give us a direct snapshot of the infant universethe infant universe

Still around today but cooled down (shifted Still around today but cooled down (shifted to microwaves) due to the expansion of the to microwaves) due to the expansion of the universeuniverse

The plasma of photons, protons and The plasma of photons, protons and electrons became cold enough so that electrons became cold enough so that electrons and protons formed first atomselectrons and protons formed first atoms

The universe became transparentThe universe became transparent

These photons give us a direct snapshot of These photons give us a direct snapshot of the infant universethe infant universe

Still around today but cooled down (shifted Still around today but cooled down (shifted to microwaves) due to the expansion of the to microwaves) due to the expansion of the universeuniverse

Expectations from inflationary models Expectations from inflationary models for CMB observationsfor CMB observationsExpectations from inflationary models Expectations from inflationary models for CMB observationsfor CMB observations

Blackbody spectrumBlackbody spectrum

Homogeneous, isotropicHomogeneous, isotropic

On large scales scale-invariant temperature On large scales scale-invariant temperature fluctuations (regions were not yet causally connected)fluctuations (regions were not yet causally connected)

On small scales temperature fluctuations from On small scales temperature fluctuations from ‘accoustic oscillations‘ (radiation pressure vs ‘accoustic oscillations‘ (radiation pressure vs gravitational attraction)gravitational attraction)

Polarization anisotropies, Polarization anisotropies, correlated with temperature anisotropiescorrelated with temperature anisotropies

Blackbody spectrumBlackbody spectrum

Homogeneous, isotropicHomogeneous, isotropic

On large scales scale-invariant temperature On large scales scale-invariant temperature fluctuations (regions were not yet causally connected)fluctuations (regions were not yet causally connected)

On small scales temperature fluctuations from On small scales temperature fluctuations from ‘accoustic oscillations‘ (radiation pressure vs ‘accoustic oscillations‘ (radiation pressure vs gravitational attraction)gravitational attraction)

Polarization anisotropies, Polarization anisotropies, correlated with temperature anisotropiescorrelated with temperature anisotropies

Characteristics of the CMBCharacteristics of the CMBCharacteristics of the CMBCharacteristics of the CMB

Frequency Frequency SpectrumSpectrum

Temperature Temperature AnisotropyAnisotropy

PolarizationPolarization

Frequency Frequency SpectrumSpectrum

Temperature Temperature AnisotropyAnisotropy

PolarizationPolarization

Frequency spectrum of the CMB (Compilation by Richard McCray)

Frequency spectrum of the CMB (Compilation by Richard McCray)

Temperature Anisotropy of the CMBTemperature Anisotropy of the CMB

Dipole due to peculiar velocity of solar system

Emission from the galactic plane

Remaining CMB anisotropy

Dipole due to peculiar velocity of solar system

Emission from the galactic plane

Remaining CMB anisotropy

COBE results

DASI: First Detection of CMB Polarization (September 2002)

DASI: First Detection of CMB Polarization (September 2002)

Map is 5 degrees square

200 K

100

0

-100

- 200 K

5 K

Spherical Spherical HarmonicHarmonicss

Spherical Spherical HarmonicHarmonicss

Description of Description of CMB by using CMB by using spherical spherical

harmonicsharmonics YYlmlm))

Description of Description of CMB by using CMB by using spherical spherical

harmonicsharmonics YYlmlm))

),(),(,2

ϕθϕθ lmml

lmYaT ∑≥

=

Ylm

Pictures by Clem Pryke

Description of AnisotropiesDescription of AnisotropiesDescription of AnisotropiesDescription of Anisotropies

>=<+

=Δ *2

2

)1(lmlmll aaCC

llT

π Usually representation by power

spectrum Cl (variance at the multipole l)

Angular scale: ~ 180°/l

Usually representation by power spectrum Cl (variance at the multipole l)

Angular scale: ~ 180°/l

),(),(,2

ϕθϕθ lmml

lmYaT ∑≥

=

Statistical properties of CMB can be observed and compared with theory

Statistical properties of CMB can be observed and compared with theory

Temperature Power SpectraTemperature Power SpectraTemperature Power SpectraTemperature Power Spectra

Compilation by Wayne Hu

Compilation by Max Tegmark

Dependence on cosmological Dependence on cosmological parametersparametersDependence on cosmological Dependence on cosmological parametersparameters

Change in baryon densityChange in baryon density

Change in curvatureChange in curvature

Animations by Max Tegmark

Why is the CMB polarized?Why is the CMB polarized?Why is the CMB polarized?Why is the CMB polarized?

Thomson scatteringThomson scattering

Radiation incident along this axis

Charge moves along this axis

Radiation primarily scattered along this axis

Charge moves in two directions

Unpolarized radiation incident along this axis

Polarized radiation scattered in this plane

Pictures by Matthew Hedman

Quadrupole patternQuadrupole patternQuadrupole patternQuadrupole pattern

Quadrupole pattern in the radiation will create polarization

Quadrupole pattern in the radiation will create polarization

Quadrupole moment in motion of charge

Radiation scattered along this axis has a polarized component

A view on the dynamic universeA view on the dynamic universeA view on the dynamic universeA view on the dynamic universe

Quadrupole moments from Temperature anisotropies will be washed out

Dynamics in the early universe determine the polarization spectrum

Quadrupole moments from Temperature anisotropies will be washed out

Dynamics in the early universe determine the polarization spectrum

Density fluctuations E-modesGravity waves E- and B-modes, Amplitude determined by scale of inflation

Different Polarization patternsDifferent Polarization patternsDifferent Polarization patternsDifferent Polarization patterns

E-Mode (scalar, even parity)E-Mode (scalar, even parity)

B-Mode (vector or tensor, odd parity)B-Mode (vector or tensor, odd parity)

Why did the CMB polarization Why did the CMB polarization escape detection for so long?escape detection for so long?Why did the CMB polarization Why did the CMB polarization escape detection for so long?escape detection for so long?

Highly sensitive detectorsHighly sensitive detectors

Excellent control of systematics Excellent control of systematics (atmospheric, instrumental) (atmospheric, instrumental)

Excellent angular resolutionExcellent angular resolution

Highly sensitive detectorsHighly sensitive detectors

Excellent control of systematics Excellent control of systematics (atmospheric, instrumental) (atmospheric, instrumental)

Excellent angular resolutionExcellent angular resolution

Tiny fluctuations (1 part in 1 million) on small angular scale Challenge for the experiments:

Tiny fluctuations (1 part in 1 million) on small angular scale Challenge for the experiments:

Comparison of Power SpectraComparison of Power SpectraComparison of Power SpectraComparison of Power Spectra

How to catch and query the witnesses?How to catch and query the witnesses?How to catch and query the witnesses?How to catch and query the witnesses?

Based at ground , balloon, space?Based at ground , balloon, space?

Which frequency to observe?Which frequency to observe?

Which techniques to use Which techniques to use (HEMT,Bolometers)?(HEMT,Bolometers)?

What is an optimal scanning strategy?What is an optimal scanning strategy?

Based at ground , balloon, space?Based at ground , balloon, space?

Which frequency to observe?Which frequency to observe?

Which techniques to use Which techniques to use (HEMT,Bolometers)?(HEMT,Bolometers)?

What is an optimal scanning strategy?What is an optimal scanning strategy?

Height in the atmosphere at which radiation is attenuated by a factor 1/2Height in the atmosphere at which radiation is attenuated by a factor 1/2

Atmospheric TransmissionAtmospheric Transmission

Are there false witnesses?Are there false witnesses?Are there false witnesses?Are there false witnesses?

Dust Synchrotron Point Sources

Dust Synchrotron Point Sources

Gravitational Lensing S-Z from Clusters ???

Gravitational Lensing S-Z from Clusters ???

Compilation by Matthew Hedman

DASI 30(13) 20‘ South PoleCBI 30(13) 3‘ Atacama (Chile)VLA 8.4 6‘‘ Socorro (New Mexico)ATCA 8.7(5) 2‘ AustraliaAMIBA 90(19) 2‘ Mauna Loa (Hawaii)SPORT 22,32,60,90 7° ISS, full skyMAP 22,30,40(2),60(2),90(4) 13‘ L2, full skyPLANCK-LFI 30(4), 44(6),70(12), 100(34) 33,23,13,10 L2, full skyBAR-SPORT 32,90 30‘,12‘ Antarctic LDBPOLAR 30 7° WisconsinCOMPASS 30 7° WisconsinPIQUE 40,90 30‘,15‘ New JerseyCAPMAP 40(4),90(10) 7‘,3‘ New JerseyPLANCK-HFI 100(4),143(12),217(12),

353(6),545(8),857(6) 11‘,8‘,6‘,5‘ L2, full skyB2K+X 150(4), 240(4) 340(4) 10‘ Antarctic LDBMAXIPOL 150(12) 420(4) 10‘ US BalloonBICEP 150(96) 0.7 ° South Pole (?) POLARBEAR 150(~3000) 10‘ South Pole POLATRON 90 2‘ OvroQUEST 100,150(~30) 6‘ Atacama (Chile)

DASI 30(13) 20‘ South PoleCBI 30(13) 3‘ Atacama (Chile)VLA 8.4 6‘‘ Socorro (New Mexico)ATCA 8.7(5) 2‘ AustraliaAMIBA 90(19) 2‘ Mauna Loa (Hawaii)SPORT 22,32,60,90 7° ISS, full skyMAP 22,30,40(2),60(2),90(4) 13‘ L2, full skyPLANCK-LFI 30(4), 44(6),70(12), 100(34) 33,23,13,10 L2, full skyBAR-SPORT 32,90 30‘,12‘ Antarctic LDBPOLAR 30 7° WisconsinCOMPASS 30 7° WisconsinPIQUE 40,90 30‘,15‘ New JerseyCAPMAP 40(4),90(10) 7‘,3‘ New JerseyPLANCK-HFI 100(4),143(12),217(12),

353(6),545(8),857(6) 11‘,8‘,6‘,5‘ L2, full skyB2K+X 150(4), 240(4) 340(4) 10‘ Antarctic LDBMAXIPOL 150(12) 420(4) 10‘ US BalloonBICEP 150(96) 0.7 ° South Pole (?) POLARBEAR 150(~3000) 10‘ South Pole POLATRON 90 2‘ OvroQUEST 100,150(~30) 6‘ Atacama (Chile)

Overview of Polarization ExperimentsOverview of Polarization ExperimentsExperiment Freq in GHz (#chan) Beamsize Location Experiment Freq in GHz (#chan) Beamsize Location TechniqueTechnique

Overview of Polarization ExperimentsOverview of Polarization ExperimentsExperiment Freq in GHz (#chan) Beamsize Location Experiment Freq in GHz (#chan) Beamsize Location TechniqueTechnique

Based on compilation by Peter TimbieIn

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PrincetonD. Barkats, P. Farese, J. McMahon, S. T. Staggs + undergraduates

ChicagoC. Bischoff, M. Hedman, D. Samtleben, K. Vanderlind, B. Winstein+ undergraduates

MiamiJ. Gundersen, E. Stefaniescu

JPLT. Gaier

PrincetonD. Barkats, P. Farese, J. McMahon, S. T. Staggs + undergraduates

ChicagoC. Bischoff, M. Hedman, D. Samtleben, K. Vanderlind, B. Winstein+ undergraduates

MiamiJ. Gundersen, E. Stefaniescu

JPLT. Gaier

CAPMACAPMAPP

CAPMACAPMAPP

ChicagoChicago

MiamiMiami

JPLJPL

PrincetonPrinceton

Experimental setupExperimental setupExperimental setupExperimental setup Telescope at Crawford Hill (New Jersey), Telescope at Crawford Hill (New Jersey),

7 m dish, off-axis, Cassegrain, 0.05 FWHM 7 m dish, off-axis, Cassegrain, 0.05 FWHM beambeam

Correlation receiverCorrelation receiver

W-Band (84-100 GHz) and Q-Band (36-45 GHz)W-Band (84-100 GHz) and Q-Band (36-45 GHz)

This winter 4 horns, final design 14 hornsThis winter 4 horns, final design 14 horns

Scanning on a small cap (1 degree diameter) Scanning on a small cap (1 degree diameter) around NCParound NCP

Telescope at Crawford Hill (New Jersey), Telescope at Crawford Hill (New Jersey), 7 m dish, off-axis, Cassegrain, 0.05 FWHM 7 m dish, off-axis, Cassegrain, 0.05 FWHM beambeam

Correlation receiverCorrelation receiver

W-Band (84-100 GHz) and Q-Band (36-45 GHz)W-Band (84-100 GHz) and Q-Band (36-45 GHz)

This winter 4 horns, final design 14 hornsThis winter 4 horns, final design 14 horns

Scanning on a small cap (1 degree diameter) Scanning on a small cap (1 degree diameter) around NCParound NCP

Gx Gy (Ea - Eb )Gx Gy (Ea - Eb )

Ex = Ea - EbEx = Ea - Eb

Ey = Ea + EbEy = Ea + Eb

EbEb EaEa

ExEx

EyEy

MultiplierMultiplier

GyGy GxGx

22

Correlation PolarimeterCorrelation Polarimeter

Phase SwitchPhase Switch 1±1±

Signal size ~10 W Amplification crucial

Not affected by drift of relative gains but sensitive to relative phase shifts

Output from multiplier ~ Ex, Ey eliminated by use of phase switch: signal in one line multiplied by square wave, after multiplication demodulated

Signal size ~10 W Amplification crucial

Not affected by drift of relative gains but sensitive to relative phase shifts

Output from multiplier ~ Ex, Ey eliminated by use of phase switch: signal in one line multiplied by square wave, after multiplication demodulated

22 22

-18-18

Sensitivity of experimentsSensitivity of experimentsSensitivity of experimentsSensitivity of experiments

TTsyssys : : System System temperaturetemperature: : BandwidthBandwidthTTintint : : Integration timeIntegration timeG/GG/G : : Relative gain drift Relative gain drift of of amplifier ~ 1/famplifier ~ 1/fSS : : SensitivitySensitivity

TTsyssys : : System System temperaturetemperature: : BandwidthBandwidthTTintint : : Integration timeIntegration timeG/GG/G : : Relative gain drift Relative gain drift of of amplifier ~ 1/famplifier ~ 1/fSS : : SensitivitySensitivityLarge bandwidth and low system temperature desirable

Expected CAPMAP sensitivity: Large bandwidth and low system temperature desirable

Expected CAPMAP sensitivity:

int

2

int min

tt1TT )( S

GG

sys ≈Δ+Δ=Δ ν

smKS 4.0=

Elimination of Elimination of drifts by drifts by ‘chopping‘‘chopping‘

Elimination of Elimination of drifts by drifts by ‘chopping‘‘chopping‘

Taking the difference of two measurements at different spots on the sky (same azimuthal position) gets ríd off drifts

Taking the difference of two measurements at different spots on the sky (same azimuthal position) gets ríd off drifts

PIQUE data

Experimental setupExperimental setupExperimental setupExperimental setup

7m Telescope

Horn Radiometer RF IF IF

box

Data Acquisition

Horn Horn Horn Horn

Predicted and measured Beam Pattern

Model of the hornModel of the horn

15 cm15 cm

Schematics of CAPMAP radiometer

Schematics of CAPMAP radiometer Two different

temperature stages: 20 K and room temperature

In RF part rectangular waveguides, in IF part coaxial cables

Two different temperature stages: 20 K and room temperature

In RF part rectangular waveguides, in IF part coaxial cables

82 GHz

84-100 GHz

2-18 GHz

Setup at ChicagoSetup at ChicagoSetup at ChicagoSetup at Chicago

3 inch (7.6 cm)

IF sectionIF sectionIF sectionIF section

Phase matchingPhase matchingPhase matchingPhase matching

In-phase response

~A cos

In-phase response

~A cos

Out of phase response

(90 degree switch) ~A sin

Out of phase response

(90 degree switch) ~A sin

QuickTime™ and aMotion JPEG A decompressor

are needed to see this picture.

Data AcquisitionData AcquisitionData AcquisitionData Acquisition

PCI card, 32 channels

24 bit resolution

Sampling rate ~100 kHz, demodulation in software

Data rate ~250 Hz

7 GByte/day (final design 24 GByte/day)

PCI card, 32 channels

24 bit resolution

Sampling rate ~100 kHz, demodulation in software

Data rate ~250 Hz

7 GByte/day (final design 24 GByte/day)

Work at the telescope ...Work at the telescope ...Work at the telescope ...Work at the telescope ...

PIQUE setup at the telescopePIQUE setup at the telescopePIQUE setup at the telescopePIQUE setup at the telescope

First Data – Total Power First Data – Total Power ChannelsChannelsFirst Data – Total Power First Data – Total Power ChannelsChannels

Moon JupiterMoon Jupiter

Peak: 200 K Peak: 1 K

First Data – Polarization First Data – Polarization ChannelsChannelsFirst Data – Polarization First Data – Polarization ChannelsChannels

Moon Tau A (Crab Nebula)Moon Tau A (Crab Nebula)

Peak: 1 KPeak: 25 mK

AnalysisAnalysisAnalysisAnalysis

)2

1exp(

)det(

1)|( 1dCd

CCdP T −−∝

Measure temperature/polarization in a region of the sky and compare with expectation (likelihood analysis):

Measure temperature/polarization in a region of the sky and compare with expectation (likelihood analysis):

l-coverage determined by beam sizel-coverage determined by beam size

d : Data vector C = CN + CT

CN : Noise covarianceCT : Theory covariance

d : Data vector C = CN + CT

CN : Noise covarianceCT : Theory covariance

Expected SensitivityExpected SensitivityExpected SensitivityExpected Sensitivity

CAPMAP expectation

DASI result

CAPMAP expectation

DASI result

Summary and OutlookSummary and OutlookSummary and OutlookSummary and Outlook

CMB is the oldest light in the universeCMB is the oldest light in the universe

Provides direct view of the infant universe Provides direct view of the infant universe

Measurement of CMB Polarization is a big Measurement of CMB Polarization is a big experimental challenge, anisotropies of the order experimental challenge, anisotropies of the order of 1 part in 1 millionof 1 part in 1 million

CAPMAP uses a 7m telescope in New Jersey to CAPMAP uses a 7m telescope in New Jersey to observe the polarization at 90 and 40 GHzobserve the polarization at 90 and 40 GHz

Installation of 4 out of 14 horns underwayInstallation of 4 out of 14 horns underway

First data taking winter 2002/2003 First data taking winter 2002/2003

CMB is the oldest light in the universeCMB is the oldest light in the universe

Provides direct view of the infant universe Provides direct view of the infant universe

Measurement of CMB Polarization is a big Measurement of CMB Polarization is a big experimental challenge, anisotropies of the order experimental challenge, anisotropies of the order of 1 part in 1 millionof 1 part in 1 million

CAPMAP uses a 7m telescope in New Jersey to CAPMAP uses a 7m telescope in New Jersey to observe the polarization at 90 and 40 GHzobserve the polarization at 90 and 40 GHz

Installation of 4 out of 14 horns underwayInstallation of 4 out of 14 horns underway

First data taking winter 2002/2003 First data taking winter 2002/2003

Exciting time in cosmology, share it with us at the CfCP!Exciting time in cosmology, share it with us at the CfCP!