Path Toward the Next Generation CMB Missions

Path toward the next generation CMB missions

March 10th, 2016 Yale University, NPA Seminar

Akito Kusaka Lawrence Berkeley National Laboratory  Introduction  Experimental Approach  Atacama B-mode Search (~500)  POLARBEAR / Simons Array (~20k) › Cryogenic Half Wave Plate  CMB S4 (~500k) Introduction

 High energy: E › LHC ~104 GeV, Cosmic rays ~ 1010 GeV

 Early Universe: E[eV] ~ 10-4T [K] , T~3(1+z) › Decoupling ~ 10-10 GeV › Matter radiation equality ~ 10-8 GeV › BBN ~ 10-3 GeV › Inflation ~ 1016 GeV? A probe into the Early Universe

Picture from WMAP group A probe into the Early Universe

Hot High Energy

~3000K (~0.25eV) Photons

1016 GeV ? ~1010K (~1MeV) Neutrinos Gravitational waves Sound waves Is there a source? : inflation

 Inflation › Rapid expansion of universe  Quantum fluctuation of metric during inflation › Off diagonal component (T)  primordial gravitational waves Unique probe into gravity  quantum mechanics connection

Ratio to S (on-diagonal): r=T/S Theoretically interesting parameter space: 0.001 r  0.1 Tensor to Scalar ratio r

Planck Collaboration (2015) Is it detectable? How?

CMB

Cosmic Gravitational Waves Inflation

Last Scattering Surface Screen for GW to put its fingerprint Polarization – Stokes parameters: I, Q, U, V

I: Intensity

Q, U: Linear polarization (Q,U)=(2,0) -Q -U +U (Q,U)=(0,1) +Q (Q,U)=(1,1) V: Circular polarization

+V -V Polarization – E modes and B modes

E modes: curl free component 2 2 퐸 푥, 푦 ∝ div(푄, 푈) ∝ 휕푥 − 휕푦 푄 푥, 푦 + 2휕푥휕푦푈(푥, 푦)

퐸 푘푥, 푘푦 = cos 2휙푘 푄 푘푥, 푘푦 + sin 2휙푘 푈 (푘푥, 푘푦) 휙푘 = arctan 푘푦/푘푥

푘 B modes: divergence free component 2 2 퐵 푥, 푦 ∝ rot 푄, 푈 ∝ −2휕푥휕푦푄 푥, 푦 + 휕푥 − 휕푦 푈(푥, 푦)

퐵 푘푥, 푘푦 = − sin 2휙푘 푄 푘푥, 푘푦 + cos 2휙푘 푈 (푘푥, 푘푦)

푘 A huge GW detector

~2 deg. ~1019 km Is it detectable? How?

w/ recent updates by LIGO+VIRGO HF Pulsar timing

LIGO&VIRGO (2009) CMB is a promising channel, r=0.001 is feasible. Lensing B-mode

It’s about the stuff here Deflection by “stuff” in between

Deflection by lensing

(Nearly) Gaussian Non-Gaussian (Nearly) pure E modes Non-zero B modes Density perturbation Neutrino, Dark Matter, … Gravitational lensing

Lensing B modes (3’)

Primordial B modes (2)

Gravitational waves Inflation Current Status 2 0.2

 Gravitational lensing BB observed › Further improvement necessary for achieving interesting science.  No significant BB from gravitational waves detected. Experimental Approach A CMB Instrument

POLARBEAR telescope

Cryogenic readout components @ 350mK

Focal plane @ 250mK Cryogenic lens @ 4K

POLARBEAR2 receiver History of evolution 16 cm 100 nK

10 nK

APEX-SZ 1 nK 330 detectors 0.1 nK SPT-SZ 2000 05 10 15 20 960 detectors

38 cm CMB S4 POLARBEAR-1 ~500k detectors 1274 detectors Dual-Polarization

POLARBEAR-2 8,000 detectors Dual-Polarization 2 Colors/pixel ~1m (?) News in 2014

Scientific American (Mar. 17, 2014)

Washington Post (May 16, 2014)

APS News (Jan, 2016)

We are moving forward. Foregrounds

Planck Collaboration (2015) Foregrounds

Planck Collaboration (2015) Toward CMB S4 Improving sensitivity x100

 Detector count increase ~1/Ndet  Systematic error due to foregrounds › Multi-frequency observation mandatory  Uncertainty due to physics › Lensing signal and delensing.  Suppression of correlated noise

› Noise averages down as 1/Ndet only for uncorrelated noise. › Environmental and instrumental sources.  Systematic error due to instrument › Beam systematics mitigation. ABS (Atacama B-mode Search)

Princeton, Johns Hopkins, NIST, UBC, U. Chile What is ABS?

 Ground based  CMB polarization (with T sensitivity)  Angular scale: l~100(~2), B-mode from GW  TES bolometer at 150 GHz › 240 pixel / 480 bolometers › ~80% of channels are regularly functional › NEQ ~ 30 mKs (current, pol. efficiency included)  Unique Systematic error mitigation › Cold optics › Continuously rotating half-wave plate Site

 Chile, Cerro Toco › ~5150 m. › Minimal water, ~1 mm PWV › Year-round access › Observing throughout the year › And day and night

ACT ABS

PolarBear ABS instrument Optics

4 K cooled side-fed Dragone dual reflector. ~60 cm diameter mirrors. 25 cm aperture diameter. ABS focal plane Feedhorn coupled Focal plane ~300 mK Polarization sensitive TES

Ex TES

Inline filter

OMT Ey TES

1.6 mm

~30 cm 5 mm Fabricated at NIST Continuously rotating warm half-wave plate

A-cut sapphire (D=330 mm) f~2.5 Hz rotation  f~10 Hz modulation Air-bearing  Stable rotation No need for pair differencing Continuously rotating

warm half-wave plate

)

Q ( Q Demodulation Continuously rotating

warm half-wave plate Demodulation

ABS Collaboration Kusaka, Essinger-Hileman et. al. (2014) Observing and Data Fields Observed by ABS

Low foreground region selected

Field B

Galactic center

Field A

Field A: primary CMB field, ~2300 deg.2 Field B: secondary CMB field, ~700 deg.2 Calibration: Beam

Jupiter

Beam Point Spread Function (PSF) Calibration: Beam

Instrument’s response Observed True (Input)

퐼 푀퐼퐼 푀퐼푄 푀퐼푈 퐼 푄 = 푀푄퐼 푀푄푄 푀푄푈 푄 푈 푀푈퐼 푀푈푄 푀푈푈 푈 V (circular polarization) omitted

-Q -U +U +Q Calibration: Systematics

Instrument’s response Observed True (Input)

퐼 푀퐼퐼 푀퐼푄 푀퐼푈 퐼 ~ 100mK 푄 = 푀푄퐼 푀푄푄 푀푄푈 푄 ~ 1mK (E) <0.1mK(B) 푈 푀푈퐼 푀푈푄 푀푈푈 푈 V (circular polarization) omitted Beam Systematics

Leakage <~ 0.1% already at the map level Monopole constrained to ~0.01%.

Essinger-Hileman, Kusaka et. al. (2016) Null tests

 Split data into two 

(m1 – m2)/2 = mnull  Null test suite based on expected error › Detector batch › East vs. West › Syst. Large vs. Small  Evaluates possible excess noise and/or systematics Early vs. late batch detectors Atacama B-mode Search

 ABS › 480 TES + unique systematic mitigation › Continuously rotating HWP opens a very interesting phase space in experimental configuration  Larger angular scale  More information!  Status › Two years of data in hand › Analysis in good progress Future CMB lensing

both signal and noise source Lensing Lensing noise

Noise level at degree scale

We will have to measure both arcminute and degree scales simultaneously. Near Future: Simons Array

Three 2.5m telescopes in Chile -3 ~20000 detectors. s(r=0.1) ~ 6x10 Multiple frequency coverage s(Smn) ~ 40 meV (w/ DESI BAO) 95GHz, 150GHz, 220GHz, 280GHz.

Why HWP is important?

Raw

Modulated

Two distinct angular scales: Two distinct frequency ranges: Gravitational Waves: 2-8 degrees Gravitational Waves: 50-250 mHz Gravitational Lensing: 5-30 arcmin Gravitational Lensing: 1-6 Hz Two orders of magnitude ~0.5deg/sec scan dynamic range HWP: Thermal loading

 When warm, the HWP (sapphire) radiates. › Sensitivity reduction › Esp. for large bandwidth  Cryogenic HWP: two benefits › T drop  power drop. › Reduction of emissivity.

Sensitivity improvement equivalent to 50% more detectors. Baseline design

300K Linear Guide

50K Gripper

50K 3-stack sapphire

50K SMB

50K synchronous magnetic drive

Permalloy shield

 Gripper used to align rotor and support the HWP when warm  EM drive consists of 3-phase triplets of solenoids with a high- permeability core and monolithic return ring  < 1nT B-field expected at the TES bolometers (~1m distance)  Induced flux inhomogeneity at SMB expected to be < 0.5% Cryogenic HWP

 Establish design concept through a small prototype  Fabricate full-scale system and test/evaluate with Simons Array as a test platform.

Prototype fabrication & evaluation

Team

Sapphire for full scale Further future CMB S4 (2020~?) LiteBIRD (2023~?)

Satellite for ultimate r Ultimate ground telescopes ~0.001 휎 Σm휈 ~20meV, 휎 푟 ~0.001 Summary

 Physics of CMB polarization › Early Universe  Higher energy › Quantum – Gravity connection  Atacama B-mode Search › Unique feature: continuously rotating HWP › More modes on the sky, minimal systematics  Future › We are scaling up the instrument. › Cryogenic HWP as an important ingredient.