GroundBIRD Experiment an experiment for CMB polariza on measurements at a large angular scale from the ground
Osamu Tajima (KEK) The GroundBIRD group GroundBIRD’s target Probing Inflationary Universe
B-modes in CMB polarization is
Primordial its smoking-gun signature !! Gravitational Foregrounds Now Waves CMB First star
Begin of the Universe
Inflation Big Bang Dark age Recombination Re-ionization Galaxy formation
Age 10-36 sec 380 Kyr 1 Myr 13.8 Gyr 2 Now Foregrounds Foregrounds Now First starCMB CMBFirst star
Begin of the Begin of the Universe Universe
Inflation Inflation Dark age Dark age Reionization RecombinationRecombination Reionization
10
Chaotic p=1 ) Chaotic p=0.2 2 SSB (N =47~62) 1 e -1 (uK 10 π -2 /2 10 r = 0.10 l 10-3 10-4 r = 0.01 l(l+1)C -5 Two bumps structure is expected 10 10 100 1000 3 Multipole l (=180o/θ) Primordial B-modes Natural to have an experimental target: spectrum measurements, i.e. simultaneous measurements of two bumps
Model predictions
10 ) Chaotic p=1 2 Chaotic p=0.2 SSB (N =47~62) 1 e
(uK 10-1 π
/2 -2 l 10 r = 0.10 10-3 -4 r = 0.01
l(l+1)C 10 10-5 10 100 1000 Multipole l (=180o/θ) 4 Advantage of spectrum measurements w.r.t. physics Spectrum shape allows us to distinguish whether the inflation model is ``standard’’ or ``beyond the standard’’
Just an example… At the case of Big Bounce model by exotic quantum-gravitational effects J. Grain, A. Barrau, T. Cailleteau, J. Mielczarek, Phys.Rev.D82:123520 (2010).
``Beyond the standard’’ is also big discovery !! 5 (whereas it may be dark horse targets … ) Advantage of spectrum measurements 10° 1° 0.1°
Model predic ons of Primordial B-modes 10 Chaotic p=1 E-modes ) Chaotic p=0.2
2 SSB (N =47~62) 1 e -1 Lensing B-modes (uK 10 π -2 /2 10 r = 0.10 l Primordial B-modes 10-3 -4 r = 0.01 l(l+1)C 10 10-5 10 100 1000 Mul pole l Lensing B-modes become dominant at a small angular scale
6 Advantage of spectrum measurements
Expansion of scan range is promising solu on 10° 1° 0.1°
Model predic ons of Primordial B-modes Model predic ons of
) Primordial B-modes
2 10 Chaotic p=1 aims to measure B-modes E-modes ) Chaotic p=0.2 2 1 SSB (N =47~62) spectrum shape (uK e
π -1 Lensing B-modes (uK 10 /2 π
l GroundBIRD
C -2 /2 10 r = 0.10 l Primordial B-modes 10-3 Primordial B-modes l(l+1) Lensing B-modes -4 r = 0.01 l(l+1)C 10 10-5 10 Mul pole l 100 1000 Mul pole l Lensing B-modes become dominant at a small angular scale Large angular scale is free from the lensing B-modes 7 GroundBIRD - overview Plan to have test observa on in CMB (FOV ±10°) Japan (early 2014). Then, instruments will be moved to Chile for science observa ons
Cold op cs at 4K Single scan pa ern at Chile Mizuguchi-Dragone Dual reflector Focal plane (0.5° at 150GHz) MKIDs at 0.25 K
High speed rotation
Rota on stage scan at 20 RPM
No decelera on !
To be 1/f noise free !8 GroundBIRD’s scan strategy
Very large observing area GroundBIRD: 30% of full sky
Other ground-based (e.g. QUIET ~3%)
Effec vely, it is similar to the low earth orbit (LEO) scan of the satellite experiments. GroundBIRD implements “Super-LEO” scan. 9 Elimina on of 1/f noise effects limits the scan range by the scan modula on Usual le -right azimuth scan GroundBIRD’s high-speed (average scan speed: 3o/sec) rota on scan (20 rpm)
60o
e.g., FOV 10o, EL 70o
o 60 Fast scan is the most promising way to eliminate 1/f noise effects GroundBIRD
Loss factor : A Detector’s 1/f noise A x Cl GroundBIRD maintains Δ fknee = 100 mHz No loss A = 1 at l = 6 1/f-noise-free condi on No 1/f noise (even w/o con nuous rota on of HWP) Loss factor : A
10 Average scan speed Another 1/f noise source Effects of atmospheric fluctua on
Typical atmospheric fknee is ≈ Hz at Atacama Desert in Chile (5,000 m), whereas it is not polarized in our observa on frequency bands
Simulation assuming atmospheric fknee = 10 Hz, detector’s intrinsic fknee = 100 mHz
10% gain diff.
Responses in Stokes’ Q Fourier scape Pair gain diff. induces the residual effects in polariza on response. Calibra on is GB’s scan freq. (0.3 Hz) important ! 11 Calibra on during CMB observa on
Good demonstration by QUIET & ABS
Difference btw sky (10K) and sparse wires (300K) makes uniform polariza on signals
Rotation in constant speed Ideal modulation
O. Tajima et al. , J. Low Temp. Phys., 167, 936 (2012). 12 For the case of GroundBIRD Responses for each antenna (simula on) 1/2 Input: Atm. fknee = 10 Hz, detector’s fknee = 100 mHz & NET = 300 uKs , and 10% of pair gain diff. Response as a func on of me Response in Fourier scape
Calibra on cos2θ response signal (1/2 of fscan)
Calibra on 2 sin θ response signal (1/2 of fscan)
Before / After the calibration sin2θ response
5 min. of data precisely calibrates the pair gain difference. 13 Calibra on also makes good syst. error control
Precision of calibra on with 5 min. data
T = 0.5 K calibration Temperature anisotropy (TT) Tcalibration = 1.0 K Be er precision with lower fknee of atmospheric fluctua on
) 2 Systematic bias induced by (uK
π TT x pair gain diff. (0.1%)
Atmospheric f at Atacama Dessert/2 knee l Prospects that we can trace B-modes ( r = 0.01) pair gain difference with 0.1%
precision with the con nuous l(l+1)C itera on in every 5 min. Systema c errors can be controlled below the level of r = 0.01 Mul pole l 14 Systema c error control (cont.)
Temperature anisotropy (TT) Angle calibra on also does well
)
2 Alignment of wire Systematic bias induced by direc on should be
(uK precise
π TT x pair gain diff. (0.1%)
/2 EB mixing l with 0.1o of B-modes ( r = 0.01) angle precision l(l+1)C
Demonstration of this calibration strategy is one of the important Mul poletargets lof test observation 15 Status of the development Development of MKIDs with Developments of each all Japan technologies component in parallel RIKEN, NAOJ, Okayama, and KEK MKIDs See posters
Rota on stage Prototype Mirror
Rotary joints for electricity and helium gas
16 Rotatable Cryocooling System
Cryocooler Patent pending
Vacuum chamber Rev. Scien. Instru. 84, 055116 (2013). Wireless-LAN Scan speed x40 !! Real me monitoring Rota on stage
Rotary joints QUIET’s scan: ~3deg/sec
Simultaneous circula on of High pressure hoses electricity and helium gas !! (connected to the compressor) Weights on the stage for this test (~100 kg) Focal plane design High frequency detectors are useful to understand foregrounds; i.e., dust 145 145 GHz GHz
145 220 145 GHz GHz GHz 145 145 GHz GHz
Design by Karatsu & Ni a (NAOJ). Please visit poster P-16 Design array sensi vity ~ 10 uKs1/2 Posters about MKIDs • Devise R&D P-16: K. Karatsu, ``Development of MKID camera for future ground-based CMB observa ons’’ P-17: T. Noguchi, ``Influence of quasipar cles in the intra-gap states on the noise of a MKID’’ Student P-19: H. Watanabe, ``Hybrid MKIDs with ground-side deposi on - A novel method for microwave detec on with a resonator separated from an antenna’’ P-20: M. Yoshida, ``The development of MKIDs and its low nois amplifier for CMB experiment’’
• Readout system w/ common mode noise suppression P-21: Y. Kibe, ``Low noise readout system for MKIDs with frequency-domain mul plexing technique towards applica on of CMB observa on’’ Summary • GroundBIRD aims to measure inflationary B-modes ``spectrum’’ from the ground – Provides unique physics studies • Whether Standard or Beyond-standard inflation model • Free from lensing B-mode • Unique technologies realize the unique physics – High-speed rotation scan • Very large observing fields (fsky ~30%)New idea is challenge ! • 1/f-noise-free conditions Demonstration is important – Continuous calibration using sparse wires • Good systematic error control & eliminating the effects of atm. fluctuation – Cold optics conditions, i.e., instruments are compact • Plan to have test observation in Japan in 2014. • Then, we will move to Chile for scientific observations 20 Near term plan