QUIET-I and QUIET-II:QUIET-I and QUIET-II:

HEMT-based coherent CMB polarimetryHEMT-based coherent CMB polarimetry

Great Lakes Cosmology Workshop XGreat Lakes Cosmology Workshop XJune 14, 2010June 14, 2010

Immanuel BuderImmanuel Buder(for the QUIET Collaboration)(for the QUIET Collaboration)

Department of Physics, U. of ChicagoDepartment of Physics, U. of Chicago

OutlineOutline● Science Motivation● QUIET Experiment

– Timeline

– QUIET Collaboration

– Phase I Instrumentation and Observation

● Phase I Analysis Status● QUIET Phase II Plan

Science MotivationScience MotivationInflation, Primordial Gravity Waves

Baumann (2009)

CMB Polarization Anisotropy

WMAP Science Team

Primordial B-mode

Gravitational Lensing B-mode

QUIET TimelineQUIET TimelinePhase I Development

October 2008:Start Q-Band observing

Q-Band Observing Q-Band Analysis

W-Band Observing(Finish Dec. 2010)

August 2009:Start W-Band Observing

Phase II

Late 2010?Start Phase II

QUIET CollaborationQUIET Collaboration

CaltechJPL

Stanford(KIPAC)

Miami

Chicago (KICP)Fermilab

ColumbiaPrinceton

ManchesterOxford Oslo MPI-Bonn

KEK

Observing SiteChajnantor Plateau, Chile

5 countries, 14 institutions, ~35 scientists5 countries, 14 institutions, ~35 scientists

Michigan

QUIET Phase I SummaryQUIET Phase I SummaryFrequencies 44 (Q-Band) / 95 (W-Band) GHz

Angular resolutions 27 / 12 (FWHM) arcmin at each freq

Field centers and sizes 181/-39, 78/-39,12/-48, 341/-36

4x(15× 15) = 900

Ra/Dec (Deg)

Size (Deg2)

Telescope type crossed Mizuguchi-Dragone

Polarization Modulations Phaseswitch (4kHz&50Hz), Boresight, Sky rotation,

Fast scan

Detector type HEMT Bolometer, HEMT etc.

Location Chajnantor(Atacama),Chile

Instrument NEQ/U 64 / 57 µK s1/2, combined Q andU

Observation time range Oct. 2008 – Dec. 2010

Planned observing time 3600 / 7500 hours

Projected limit on r 0.5 (?) No foreground assumed

QUIET DetectorsQUIET Detectors

3cm module(W-Band)

cf. CAPMAP polarimeter, ~30cm

Miniaturized pseudo-correlation polarimeter on a chip, making large arrays feasible

QUIET Module OperationQUIET Module Operation● Simultaneously Measures Q

and U linear polarization parameters

● Gain difference between legs does not fake a signal

● Modulation– 1/f noise reduction– Double-modulation cancels

temperature to polarization leakage in the module

Detector Diode

L=EX+iEY R=EX−iEY

HEMT Amplifiers

Phaseswitch4kHz & 50Hz

180° Coupler

90° Coupler

+Q −Q |L± R|2

−U |L± iR|2+U

+1 ± 1

Phase I Detector ArrayPhase I Detector Array

W-Band array (90 elements): the world's largest HEMT-based array polarimeter

ModuleSeptum Polarizer

Phase I InstrumentPhase I Instrument

Groundscreen

3-axis Mount (azimuth, elevation, boresight): boresight rotation allows additional polarization modulation and suppresses residual temperature to polarization leakage

Electronics

Receiver–Feedhorn array–Septum Polarizers–Detector Modules

Secondary Mirror

Primary Mirror

QUIET ObservationsQUIET Observations

4 CMB

2 Galaxy Science

● CMB Patches chosen to minimize foregrounds

● Each patch is ~15° x 15°

Observing SiteObserving Site● Chajnantor Plateau, Atacama, Chile

– 5 km elevation

– Very low moisture

– Year-round observing, day and night

● Sky rotation causes the patches to rise and set– Follow with constant elevation azimuth scans

– Sky rotation modulates polarization each day

Q-Band Analysis: CMBQ-Band Analysis: CMB● Signal is small and there are

many possible contaminations

● Null tests verify cuts, calibration, treatment of systematic effects

● Divide data into two subsets (e.g. good/bad weather)

● Make maps m1 and m

2

● Compute “CMB power” of null map m

1 - m

2

PreliminaryQ-Band Null Test Suite (~40)

W-Band Analysis StatusW-Band Analysis Status● W-Band observation continuing until end of 2010

● Sensitivity (57 µK s1/2), responsivity, detector polarization angle, temperature to polarization leakage, optics sidelobes measured in field

ScanFrequency

QUIET Phase IIQUIET Phase II● Technology demonstrated in Phase I● Increase number of modules to ~1600● Same frequencies as Phase I plus 32 GHz for

foreground control

Phase I

Phase II

Phase II Science ForecastPhase II Science Forecast

● High S/N measurement of E-mode to ell ~2000● B-mode measurement to ell ~1200

– Detect r or limit to ~0.018 (at 2)

– Detect lensing at ~35 → limit m < 0.3 eV

ConclusionsConclusions● QUIET is a CMB polarimeter with a unique design

based on HEMT detector technology● HEMT technology gives us unique means of

controlling systematics and access to low frequency (synchrotron) foreground characterization

● Look for Phase I results soon● Phase II will have sensitivity to detect B-modes

with technology and control of systematic effects proven in Phase I

Backup Slides

Q-Band Analysis: GalaxyQ-Band Analysis: Galaxy● ~100 hours of data

from one Galactic patch in Q-Band

● Top: WMAP● Bottom: QUIET

PRELIMINARY

Phase I Science ForecastPhase I Science Forecast● Q-Band E-mode (MC sim.)● B-mode results compared

to existing measurements– Q-Band (data collected)

– W-Bandwill bethe worldbest

TT AssemblyTT Assembly● Replace Septum Polarizer with OMT+Magic Tee to

measure temperature anisotropy

Stokes ParametersStokes Parameters

● Q = Ex

2 – Ey

2

● U = Ea

2 – Eb

2

Ex

EyEaEb