101

102

103

10−4

10−3

10−2

10−1

100

101

102

lensingr=0.05

r=0.01

BK14CMB component

DASICBICAPMAPBoomerangWMAP

QUADBICEP1QUIET−QQUIET−W

PolarbearSPTpolACTpol

Multipole

l(l+

1)C

lBB/2

π [

µK

2]

Development of horn coupled superconducting kinetic inductance detectors array

7

Inflation�

Recombination�Dark age�

Begin of the Universe�

Re-ionization�

CMB �First star�Foregrounds�Now�

Inflation�

Recombination�Dark age�

Begin of the Universe�

Reionization�

CMB � First star� Foregrounds� Now�

Era thomson scatterings, i.e. CMB-electron scatterings, were end

Era thomson scatterings, i.e. CMB-electron scatterings, were resumed

B-mode

Graviton

+ +BigBang

GroundBIRD

r: tensor / scaler

Large scale Small scale

Our targetScan by Earth Rotation

Covering a half of all-skyComparable with satellite observations

��� times

Galactic radiation map(FDS dust model @ 94GHz)

CoveredArea

Covered areaper rotation

BICEP2 ~ 2%

Leakage fromother polarization

Leakage fromTM mode

Observing band

Signal transmission Cross-talk

Each components are optimized using electromagnetic simulation. Performance of the GB-KIDs are simulated and the result satisfies requirements. Signal transmission is greater than 80% and cross-talk from other pol. and other EM mode are less than 0.01% with in the observing band of 145±25 GHz.

Common mark

Good alignment

Aligner: large exposure area Stepper: good alignment

Si waferNb

Photo resist

Exposure

Etching

Photomask

Si waferNb

Exposure

Etching

Photo resist

Etching process w/ particles

Resonator

Feedline

�

Equivalent circuit

Feedline

Resonator

Antenna

ffeed [GHz]fdetector

FeedlineTransmission (S21)

Antenna

Resonator

Feedline

�

Equivalent circuit

Feedline

Resonator

Antenna

ffeed [GHz]fdetector

FeedlineTransmission (S21)

Antenna

ffeed [GHz]fdetector

FeedlineTransmission (S21)

Resonator

Feedline

�

Equivalent circuit

Feedline

Resonator

Antenna

CMB radiation

γ

Cooper-pair breaking

+ ΔL + ΔL

Antenna

L1 L2 L3 L4 L5 L6

dB

Hz

transmittance Al_KIDs@130mK

HMDS crystal

Disposal pipet

Introduction

In the Big Bang theory, the early universe was an extremely hot and dense condition. Cosmic Microwave Background(CMB) is the remaining radiation of the Big Bang. The inflation, exponential expansion of the space before the Big Bang, is proposed to explain horizon problem and flatness problem. The Inflation produced primordial gravitational waves. Finally, they made the parity odd polarization patterns “B-modes“ on the CMB. The groundBIRD experiment aims to measure the B-mode spectrum at the large angular scale.

GroundBIRD experiment

Kinetic Inductance Detectors(KIDs)

Angular scale of the B-modes is expected to be more than a few degree. GroundBIRD has a unique rotating cooled optics to measure large area (x25 of the past exp.). GB has an excellent sensitivity for large-scale B-modes which is not sensible by other experiments.

Superconductor has an inductance due to the inertia of cooper-pairs. When the energy is deposited and cooper-pairs are broken in the superconductor, the inductance is also changed. The energy threshold of th is phenomena i s 1/2000 of ord inary S i s em i conduc to r de t ec to r. K IDs cons i s t o f superconducting LC resonator and they capacitively coupled to the feed line. Each resonators has their original inductance. KIDs are frequency domain multiplexed detector.

ffeed [GHz]fdetector

FeedlineTransmission (S21)

Resonator

Feedline

�

Equivalent circuit

Feedline

Resonator

Antenna

CMB radiation

γ

Cooper-pair breaking

+ ΔL + ΔL

Antenna

L1

Design of GroundBIRD(GB)-KIDs

GB-KIDs consists of corrugated horn, probe antenna and mili-meter wave circuits. First two orthogonal polarizations are focused by horn and absorbed by antenna. Each polarizations are transmitted to two KIDs separately.

Simulated results GB-KIDs

Photolithography

Devices are fabricated by photo-lithography technology. Exposure device is required to have larger expose area and accurate overlay. We combined g-line aligner and i-line stepper@NAOJ using common alignment mark. The alignment accuracy between aligner pattern and stepper pattern is reasonable.

The GB required larger area device to integrate many devices. We need to improve yield to fabricate a large device. Especially, particle contamination in the photo resist and HMDS cause defects like short or disconnection. Once the feed line has a defect, every KIDs on that wafer is dead. Disposal pipets drastically improved the yield.

The first prototype of GB-KIDs array

First GB-KIDs is processed and its production period of one month. Optical micrograph shows the design is correctly produced. Currently, this device is testing under cryogenic temperature.

* E-mail: kenji_kiuchi@riken.jp

1

55pix,110detectors

Dual-pol.antennasTwoKIDsforeach

FirstPrototype

1

Light

CorrugatedHorn

ProbeAntenna

145GHz

145GHz

145GHz

145GHz

145GHz

145GHz

220GHz

aRIKEN, bKEK, cNAOJ, dTohoku Univ., eKorea Univ., fThe Univ. of Tokyo, gSaitama Univ., hInstitute for Basic Science, iSOKENDAI, jUniv. of Tsukuba

Kenji Kiuchi*a, Jihoon Choih, Thushara Damayanthia, Makoto Hattorid, Masashi Hazumib, Hikaru Ishitsukai, Satoru Mimaa, Ryo Koyanog, Hiroki Kutsumad, Kyungmin Leee, Makoto Minowaf, Makoto Nagaij, Taketo Nagasakib, Shugo Ogurib, Chiko Otania, Yutaro Sekimotoc,

Munehisa Semotog, Jun'ya Suzukib, Tohru Tainog, Osamu Tajimab, Nozomu Tomitaf, Eunil Wone, Tomohisa Uchidab, and Mitsuhiro Yoshidab