Development of Superconducting Detectors for Measurements of Cosmic

Development of Superconducting Detectors for Measurements of Cosmic Microwave Background. Mr. MIMA, Satoru (Okayama University) Co-Authors: ISHINO, Hirokazu (Okayama University) KIMURA, Nobuhiro (High Energy Accelerator Research Organization (KEK)) KAWAI, Masanori (High Energy Accelerator Research Organization (KEK)) NOGUCHI, Takashi (National Astronomical Observatory of Japan) WATANABE, Hiroki (The Graduate University for Advanced Studies) HATTORI, Kaori (Okayama University) KIBAYASHI, Atsuko (Okayama University) HAZUMI, Masashi (High Energy Accelerator Research Organization (KEK)) YOSHIDA, Mitsuhiro (High Energy Accelerator Research Organization (KEK)) SATO, Nobuaki (High Energy Accelerator Research Organization (KEK)) TAJIMA, Osamu (High Energy Accelerator Research Organization (KEK)) OKAMURA, Takahiro (High Energy Accelerator Research Organization (KEK)) TOMARU, Takayuki (High Energy Accelerator Research Organization (KEK)) 09/Jun/2011 TIPP 11 1

Contents �Motivation: Lite. BIRD �STJ (Superconducting Tunnel Junction) ◦ About STJ ◦ Antenna coupled STJ detectors �Parallel-connected Twin Junction �Microstrip Junction �MKID (Microwave Kinetic Inductance Detector) �Summary 09/Jun/2011 TIPP 11 2

Lite. BIRD Lite (light) Satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection �Purpose and concept ◦ B-mode polarization detection ◦ Whole sky scan ◦ Small & compact design ◦ Orbit：L 2 or LEO �Detector D IR Lite. B requirements ◦ 2, 000 Detectors ◦ Frequency 50 -250 GHz ◦ Noise Equivalent Power ~10 -18 W/√Hz Weight : 391 kg electricity : 480 W 09/Jun/2011 TIPP 11 3

Lite. BIRD Collaboration � ISAS/JAXA: TAKEI Yoh, FUKE Hideyuki, MATSUHARA Hideo, MITSUDA Kazuhisa, YAMASAKI Noriko, YOSHIDA Tetsuya � ARD/JAXA: SATO Yoichi, SHINOZAKI Keisuke, SUGITA Hiroyuki � Okayama Universiry: ISHINO Hirokazu, KIBAYASHI Atsuko, HATTORI Kaori, MISAWA Naonori, MIMA Satoru � UC Berkeley: Adnan Ghribi, William Holzapfel, Bradley Johnson, Adrian Lee, Paul Richards, Aritoki Suzuki, Huan Tran � LBNL: Julian Borrill � Kinki University: OHTA Izumi � ACCL/KEK: YOSHIDA Mitsuhiro � IPNS/KEK: ISHIDOSHIRO Koji, KATAYAMA Nobuhiko, SATO Nobuaki, SUMISAWA Kazutaka, TAJIMA Osamu, NAGAI Makoto, NAGATA Ryo, NISHINO Haruki , HAZUMI Masashi , HASEGAWA Masaya, HIGUCHI Takeo, MATSUMURA Tomotake � CSC/KEK: KIMURA Nobuhiro, SUZUKI Toshikazu, TOMARU Takayuki � SOKENDAI: YAGINUMA Eri � UT Austin: Eiichiro Komatsu � ATC/NAOJ: UZAWA Yoshinori, SEKIMOTO Yutaro, NOGUCHI Takashi � Tohoku University: CHINONE Yuji, HATTORI Makoto � Tsukuba University: TAKADA Suguru � RIKEN: OTANI Chiko � Yokohama National University: TAKAGI Yuta, NAKAMURA Shogo, MURAYAMA Satoshi

Superconducting detectors �Antenna coupled STJ ◦ fast response � can reduce the dead time caused by the cosmic ray attack ◦ wide frequency range �achievable for 50 -250 GHz using either photon assisted tunneling or Cooper pair breaking with a pure Al STJ �MKID ◦ frequency domain readout �thousand detectors can be readout with a single line ◦ easy to fabricate ◦ no bias �TES ◦ UC Barkley 09/Jun/2011 TIPP 11 5

STJ Superconducting Tunnel Junction • The STJ has a structure of SIS with the insulator thickness of about 1 nm. Insulator Superconductor Quasiparticle(electron) Cooper Pair S Superconductor I S Direct Cooper pair breaking Egap=2 DS I S Photon assisted Tunneling A photon having energy greater than 2 D can break a Cooper pair and generate two quasiparticles, which penetrate the insulator layer by the tunnel effect and are detected as an electric current. A photon having energy less than 2 D can also be detected using photon assisted tunneling effect. The valence electron can directly penetrate the insulator and go up to the conducting band with the assist of the photon energy. 09/Jun/2011

Antenna coupled STJ: Parallel-connected twin junction Log-Periodic antenna � PCTJ (Parallel-Connected Twin Junction） ◦ The twin parallel STJs and the inductance form a resonant circuit. ◦ The circuit accumulates the millimeter wave power that generates the quasiparticles. Transmission line STJ PCTJ wire Log-Periodic antenna ( Nb ) STJ 09/Jun/2011 TIPP 11 7

Fabrication and test for the PCTJ detector 7μmφSTJ 8 illuminating 80 GHz STJ output current 0. 3 K refrigerator optics horn STJ bias the screen pattern millimeter wave input an obtained image polyethylene lens screen with a pattern signature of the photon assisted tunneling 09/Jun/2011 TIPP 11 8

Problems on the PCTJ detector � We have successfully detected 80 GHz millimeter wave with the photon assisted tunneling effect using the PCTJ detector. � However, there are some difficulties on fabricating the PCTJ detector. ◦ The impedance matching between the antenna and the PCTJ is not easy. �We need a fine tuning control for the fabrication on the insulator thickness and character. �related with the Josephson current control �It is not easy to increase the bandwidth. �the current design up to ~10% �Lite. BIRD requires 30% bandwidth, however. 2011/03/28 2011年日本物理学会年次大会 9

Microstrip STJ �The microstrip STJ has been proposed by Prof. T. Noguchi (NAO). ◦ The condition to match the impedances between the antenna and the STJ is easier for the microstrip STJ than the PCTJ. ◦ In addition, we have found the microstrip STJ can have frequency: 150 GHz wider bandwidth than the PCTJ. antenna coupled PCTJ antenna coupled bandwidth: 30% Microstrip STJ strip width : 2 um reflectivity frequency simulation 2011/03/28 results 2011年日本物理学会年次大会 frequency 10

Antenna-coupled Microstrip STJ �Design ◦ The microstrip STJ has a width of 2 mm and a length of l/4 at the resonant frequency. Nb transmission line Al-ＳＴＪ readout line antenna（Nb) 09/Jun/2011 TIPP 11 11 11

Fabrication of antenna coupled Microstrip STJ design STJ have successfully fabricated a pure Al microstrip STJ. � Three different detectors are fabricated for central frequencies of 60, 100 and 150 GHz. 60 GHz � We Frequ ency[ GHz] Lengt h[um] 60 ~60 100 ~40 150 ~20 100 GHz 150 GHz SEM images 09/Jun/2011 TIPP 11 12

First look at the microstrip pure Al STJ performance 0. 35 K The IV curve seems to be good : the gap energy is measured to be 0. 34 m. V, consistent with the pure Al SIS behavior. But we found the normal resistance is higher than expected by an order. We need more tuning on the fabrication. 09/Jun/2011 TIPP 11 13

Typical Absorption CPW-MKIDs Microwave Resonator Microwave feed line Frequency shift P. K. Day et al. , Nature 425 (2003) 817. 09/Jun/2011 TIPP 11 14

Absorption(typical) and Transmission MKIDs Z 0 Z 0 2Δf = 0. 04 MHz => Q=150, 000 Z 0 Q = 90, 000 This leads to enable feedback readout

Microstrip Nb-MKIDs CPW Al-MKIDs • CPW resonator • Aluminum : Tc = 1. 1 K f > 88 GHz Nb CPW Si. O 2 Si 基板 96 GHz Irradiation Microstrip CPW Feed-line Microstrip Resonator => Improving quality of process : EV, Wet etching, Target purity etc… => Adjusting coupling etc. Multichroic Detector Array

Design for Multichroic MKIDs �Based on Transmission Microstrip Nb-MKIDs Transmission MKIDs Sinuous Antenna Microwave Readout ↑ 4 Polarization× 4 Frequency× 5 Antenna = 80 ch From antenna Si. O 2 Al Nb Microstrip Nb-MKIDs Al 2 O 3 Si substrate ・Diffusion length　100 mm >> Penetration depth ・No diffusion from Al to Nb Final target : - Multichroic - 2000 ch

Summary �Lite. BIRD requires 2, 000 superconducting detectors �We are developing STJ and MKID: ◦ PCTJ STJ has detected 80 GHz successfully. ◦ Microstrip STJ has been newly developed. ◦ An antenna coupled MKID has been proposed for the multichroic readout. 09/Jun/2011 TIPP 11 18

backup slides 09/Jun/2011 TIPP 11 19

ＳＴＪ＋ＭＫＩＤｓ �Diffusion From Antenna Si. O 2 type MKIDs readout Al-STJ Al Nb Microstrip Nb-MKIDs Al 2 O 3 Si substrate == Merit == ・design is easy (can use current design) ・keep up the Q factor ・we can inject electromagnet wave arbitarily place == Problem == ・increasing layer ・Diffusion length　100 mm >> Penetration depth ・No diffusion from Al to Nb 2010/12/27 2010年ＫＥＫ年末発表会 20