Curriculum Vitaes
Profile Information
- Affiliation
- Institute of Space and Astronautical Science, Japan Aerospace Exploration AgencyGraduate School of Science Department of Astronomy, The University of Tokyo
- J-GLOBAL ID
- 200901049964309113
- researchmap Member ID
- 5000001980
- External link
Research Interests
5Research Areas
2Research History
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Oct, 2017 - Present
Major Papers
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Journal of Astronomical Telescopes, Instruments, and Systems, 9(02), Apr 19, 2023
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Journal of Astronomical Telescopes, Instruments, and Systems, 9(02), Apr 12, 2023
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Progress of Theoretical and Experimental Physics, 2023(4), Nov 21, 2022Abstract LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. The Japan Aerospace Exploration Agency (JAXA) selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with an expected launch in the late 2020s using JAXA’s H3 rocket. LiteBIRD is planned to orbit the Sun–Earth Lagrangian point L2, where it will map the cosmic microwave background polarization over the entire sky for three years, with three telescopes in 15 frequency bands between 34 and 448 GHz, to achieve an unprecedented total sensitivity of $2.2\, \mu$K-arcmin, with a typical angular resolution of 0.5○ at 100 GHz. The primary scientific objective of LiteBIRD is to search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. We provide an overview of the LiteBIRD project, including scientific objectives, mission and system requirements, operation concept, spacecraft and payload module design, expected scientific outcomes, potential design extensions, and synergies with other projects.
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Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave, Aug 27, 2022
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Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave, Aug 27, 2022
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SPACE TELESCOPES AND INSTRUMENTATION 2022: OPTICAL, INFRARED, AND MILLIMETER WAVE, 12180, 2022LiteBIRD is a JAXA-led international project that aims to test representative inflationary models by performing an all-sky cosmic microwave background radiation (CMB) polarization survey for 3 years at the Sun-Earth Lagrangian point L2. We aim to launch LiteBIRD in the late 2020s. The payload module (PLM) is mainly composed of the Low-Frequency Telescope (LFT), the Mid-Frequency Telescope and High-Frequency Telescope (MHFT), and a cryo-structure. To conduct the high-precision and high-sensitivity CMB observations, it is required to cool the telescopes down to less than 5 K and the detectors down to 100 mK. The high temperature stability is also an important design factor. It is essential to design and analyze the cryogenic thermal system for PLM. In this study, the heat balance, temperature distribution, and temperature stability of the PLM for the baseline design are evaluated by developing the transient thermal model. The effect of the Joule-Thomson (JT) coolers cold tip temperature variation, the periodical changes in subK Adiabatic Demagnetization Refrigerator (ADR) heat dissipation, and the satellite spin that generates the variable direction of solar flux incident are implemented in the model. The effect of contact thermal conductance in the LFT and the emissivity of the V-groove on the temperature distribution and heat balance are investigated. Based on the thermal analysis, it was confirmed that the PLM baseline design meets the requirement of the temperature and the cooling capability of the 4K-JT cooler. In addition, the temperatures of the V-groove and the LFT 5-K frame are sufficiently stable for the observation. The temperature stability of the Low Frequency Focal Plane (LF-FP) is also discussed in this paper.
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Proceedings of SPIE - The International Society for Optical Engineering, 11453, 2020© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. LiteBIRD has been selected as JAXA's strategic large mission in the 2020s, to observe the cosmic microwave background (CMB) B-mode polarization over the full sky at large angular scales. The challenges of LiteBIRD are the wide field-of-view (FoV) and broadband capabilities of millimeter-wave polarization measurements, which are derived from the system requirements. The possible paths of stray light increase with a wider FoV and the far sidelobe knowledge of-56 dB is a challenging optical requirement. A crossed-Dragone configuration was chosen for the low frequency telescope (LFT: 34-161 GHz), one of LiteBIRD's onboard telescopes. It has a wide field-of-view (18° x 9°) with an aperture of 400 mm in diameter, corresponding to an angular resolution of about 30 arcminutes around 100 GHz. The focal ratio f/3.0 and the crossing angle of the optical axes of 90a-▪ are chosen after an extensive study of the stray light. The primary and secondary reflectors have rectangular shapes with serrations to reduce the diffraction pattern from the edges of the mirrors. The reflectors and structure are made of aluminum to proportionally contract from warm down to the operating temperature at 5 K. A 1/4 scaled model of the LFT has been developed to validate the wide field-of-view design and to demonstrate the reduced far sidelobes. A polarization modulation unit (PMU), realized with a half-wave plate (HWP) is placed in front of the aperture stop, the entrance pupil of this system. A large focal plane with approximately 1000 AlMn TES detectors and frequency multiplexing SQUID amplifiers is cooled to 100 mK. The lens and sinuous antennas have broadband capability. Performance specifications of the LFT and an outline of the proposed verification plan are presented.
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Proceedings of SPIE - The International Society for Optical Engineering, 11453, 2020© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. We are developing a 100-GHz band 109-pixel MKID camera for the Nobeyama 45-m telescope. The camera optics contains plano-convex silicon (Si) lenses with 300-and 154-mm diameters located at the 4-K and 1-K stages, and a vacuum window of 320-mm diameter. Antireflective subwavelength structures (SWSs) for the Si lenses and the vacuum window were designed to reduce surface reflection. Cyclo olefin polymer (COP) was chosen as the base material for vacuum window as the dielectric loss is comparable with high-density polyethylene and it is easy to fabricate. Antireflective SWSs optimized for 100-GHz band were simulated using ANSYS HFSS. A one-layer rectangular pillar was designed for a Si lens of 300-mm diameter and a 320-mm diameter COP window to examine the fabrication process in large areas. For 154-mm diameter Si lens, a 1.2-mm depth tapered structure was used to obtain broadband characteristics. These designed structures were fabricated on both sides using a three-Axis numerically-controlled machine. An end mill and a metal-bonded dicing blade were used for cutting the COP and Si, respectively. W-band vector network analyzer was used for S-parameter measurements of the SWS formed flat surface at an ambient temperature. Average surface reflectance of Si lenses and transmittance of the COP window in the 90-110 GHz range were found at approximately 1% and 98%, respectively.
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IEEE Transactions on Terahertz Science and Technology, 9(6) 598-605, Nov, 2019 Peer-reviewed© 2019 IEEE. Polarization of the cosmic microwave background (CMB) has crucial information on the inflationary universe. To detect these signals, it is necessary to suppress far sidelobes of a telescope, which contaminate the CMB signals with strong foreground radiation, such as the Galactic plane. LiteBIRD is the only funded CMB observation satellite for the 2020s, and the low frequency telescope (LFT; 34-161 GHz) is one of its telescopes. We measured near-field antenna patterns of the LFT using its 1/4-scaled model and examined far sidelobes up to 60° from the peaks. To cover the 20° field of view of the LFT, we investigated the antenna patterns at the edges of the focal plane as well as at the center. The measurement frequencies were 140-220 GHz, which correspond to the lowest bands (35-55 GHz) of the full-scale LFT. The measurements were consistent with the simulated far-sidelobe patterns at least -50 dB level, and showed that far sidelobes for two orthogonal polarization directions are consistent with each other down to -40 dB level. We also measured the cross-polarization patterns, and their peak level was less than -20 dB.
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Journal of Astronomical Telescopes, Instruments, and Systems, 5(4), Oct 1, 2019 Peer-reviewed© 2019 Society of Photo-Optical Instrumentation Engineers (SPIE). Radiative cooling with thermal isolation shields can provide a reliable cooling system for instruments onboard satellites in orbit. We report the optimization study for the cryogenic architecture of the LiteBIRD satellite using radiative cooling. A trade study that changed the number of thermal shields and shield emissivity were conducted. The heat flow from 300 to 4.5 K, including active cooling by mechanical cryocoolers, was evaluated among the trade designs. We found that the design that consists of low-emissivity four-layer thermal shields is optimum in terms of thermal performance and system design. The optimum design achieved a heat load of 29.9 mW for the 4.5-K cooling stage, whereas the requirement was 30 mW with the assumed cryogenic system.
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Proceedings of SPIE - The International Society for Optical Engineering, 10698, 2018 Peer-reviewed© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. LiteBIRD is a candidate for JAXA's strategic large mission to observe the cosmic microwave background (CMB) polarization over the full sky at large angular scales. It is planned to be launched in the 2020s with an H3 launch vehicle for three years of observations at a Sun-Earth Lagrangian point (L2). The concept design has been studied by researchers from Japan, U.S., Canada and Europe during the ISAS Phase-A1. Large scale measurements of the CMB B-mode polarization are known as the best probe to detect primordial gravitational waves. The goal of LiteBIRD is to measure the tensor-to-scalar ratio (r) with precision of r < 0:001. A 3-year full sky survey will be carried out with a low frequency (34 - 161 GHz) telescope (LFT) and a high frequency (89 - 448 GHz) telescope (HFT), which achieve a sensitivity of 2.5 μK-arcmin with an angular resolution 30 arcminutes around 100 GHz. The concept design of LiteBIRD system, payload module (PLM), cryo-structure, LFT and verification plan is described in this paper.
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IEEE Transactions on Applied Superconductivity, 25(3), Jun 1, 2015 Peer-reviewed© 2002-2011 IEEE. We developed SIS mixers for Atacama large millimeter/submillimeter array (ALMA) Band 8 (385-500 GHz) receiver cartridges and evaluated their performance. DC IV curves of the SIS mixers showed small leakage current at the high current density. The current density and quality factor (R-{sg}/R-{n}) of the Band 8 SIS junction were 13 \hbox{kA/cm}{2} and approximately 20, respectively. Double-sideband noise temperature of the 266 SIS mixers was 92.8 K at 4.0 K bath temperature on the average from 385 to 500 GHz with a standard deviation of 7.0%. A couple of sideband-separating (2SB) mixers for dual polarizations were used in the Band 8 receiver cartridge. The 73 receivers have met ALMA specifications of the noise temperature. Single-sideband noise temperature and image rejection ratio of the receivers were 139.5 K and 20.5 dB on the average from 385 to 500 GHz, respectively. These test results of the receivers indicate high quality and uniformity of the 2SB mixers.
Misc.
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宇宙科学技術連合講演会講演集(CD-ROM), 67th, 2023
Presentations
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電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, Jan 23, 2014
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Technical report of IEICE. SCE, Jan 16, 2014Microwave Kinetic Inductance Detector (MKID) camera has been developed at National Astronomical Observatory of Japan for millimeter-wave and terahertz astronomy. MKID composed of superconducting resonators can sense a number of quasi-particles which incident photons above the gap energy generate by breaking Cooper pairs. A bi-layer MKID such as Al/Nb is attractive because the gap energy or the threshold frequency is easily changed due to proximity effect. It is quite useful for space observatory or a remote site such as the Antarctica where power consumption of cryocoolers is severely limited. We report high quality resonators of bi-layer (Al/Nb) MKIDs fabricated by liftoff technique. And we found temperature dependence of bi -layer MKID quality factor showed different behavior as Al or Nb monolayer.
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Technical report of IEICE. SCE, Jan 16, 2014We propose a hypothesis that there are a few numbers of quasiparticle states inside the energy gap and analyze the surface resistance and the Q-values of a resonator of superconductor using the hypothesis. The conventional Mattis-Bardeen theory is extended by introducing the complex number of the superconducting gap energy, which well predicts the magnitude of the quasiparticle density of states inside the energy gap. Using the extended Mattis-Bardeen theory, the surface resistance of superconductors and the Q-value of superconducting resonators are calculated. It is shown that simulated temperature dependence of the surface resistance and Q-value of a superconductor agree very well with the experimental results. It is also demonstrated that the calculated residual quasiparticle number of a superconducting resonator using the density of states, which is obtained from the fitting of a dc I-V curve of SIS tunnel junction, quantitatively agrees with the measured one.
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Proceedings of SPIE - The International Society for Optical Engineering, Jan 1, 2014© 2014 SPIE. We have been developing a lens-integrated superconducting camera for millimeter and submillimeter astronomy. High-purity silicon (Si) is suitable for the lens array of the Microwave Kinetic Inductance Detector (MKID) camera due to the high refractive index and the low dielectric loss at low temperature. The camera is antenna-coupled Al coplanar waveguides on a Si substrate. Thus the lens and the device are made of the same material. We report a fabrication method of 721 pixel Si lens array with anti-reflection coating. The Si lens array was fabricated with an ultra-precision cutting machine. It uses TiAlN coated carbide end mills attached with a high-speed spindle. The shape accuracy was less than 50 μm peak-to-valley and the surface roughness was Ra 1.8 μm. The mixed epoxy was used as anti-reflection coating to adjust the refractive index. It was shaved to make the thickness of 185 μm for 220 GHz. Narrow grooves were made between the lenses to prevent cracking due to different thermal expansion coefficients of Si and the epoxy. The surface roughness of the anti-reflection coating was Ra 2.4 ∼ 4.2 μm.
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日本物理学会講演概要集, Mar 5, 2012
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Technical report of IEICE. SANE, Jun 19, 2008The ALMA (Atacama Large Millimeter Submillimeter Array) is an international project by Europe, North America, and Japan, which is constructing large millimeter and submillimeter array at an altitude of 〜5000m on Atacama desert in northern Chile. The array consisted of 80 high surface accuracy antennae with 12m or 7m diameter extends 14km to achieve 0.01 arc second resolution. Atmospheric windows from 30GHz to 900GHz are covered by 10 frequency bands. We present submillimeter cartridge-type superconducting low noise receivers dictated for ultimate sensitivity. The sensitivity of ALMA is two orders of magnitude larger than those of existing millimeter arrays. The partial operation of ALMA will be started from 2010 and the full operation will be started from 2012.
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Technical report of IEICE. SANE, Jun 18, 2004The ALMA (Atacama Large Millimeter Submillimeter Array) is an international project by Europe, North America, and Japan, which is constructing large millimeter and submillimeter array at an altitude of 〜5000 m on Atacama desert in northern Chile. The array consisted of 80 high surface accuracy antennae with 12 m or 7 m diameter extends 14 km to achieve 0.01 arc second resolution. Atmospheric windows from 30 GHz to 900 GHz are covered by 10 frequency bands. We present ALMA instruments dictated for ultimate sensitivity, especially cartridge-type superconducting low noise receivers and photonic local oscillator system. The sensitivity of ALMA is two orders of magnitude larger than those of existing millimeter arrays. The partial operation of ALMA will be started from the end of 2007 and the full operation will be started from 2012.
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Proceedings of the IEICE General Conference, Mar 8, 2004
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Meeting abstracts of the Physical Society of Japan, Mar 3, 2004
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IEICE technical report. Antennas and propagation, Jan 16, 2004This paper aims to introduce a submillimeter-wave horn antenna designed by the authors which possesses high gain, very low loss and very low cross-polarisation within a very wide range of frequencies. It is a well-known fact that corrugated horn antennae radiate with symmetry pattern and very low cross-polarized field [1]. It is for this reason that corrugated horn antennae have chosen to design low loss horn antennae for radio-astronomical telescopes. However, the circular horn could not perform good just created corrugations inside of their flares [2]. Especially, it have been difficult to design the feed horns for radio-astronomical telescopes because they are required to possess very low loss. This paper presents a new submillimeter-wave corrugated horn antenna designed by the authors inserting an unique mode-transform section between a feed circular waveguide and a flare of a corrugated horn antenna.
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Abstracts of the meeting of the Physical Society of Japan. Sectional meeting, Sep 20, 1993
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Abstracts of the meeting of the Physical Society of Japan. Annual meeting, Mar 16, 1993
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春の分科会講演予稿集, Mar 11, 1991
Teaching Experience
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Oct, 2022 - Jan, 2023High energy astrophysics (The University of Tokyo)
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Jul, 2020 - Aug, 2020Space astronomy (sokendai)
Research Projects
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Jun, 2023 - Mar, 2027
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2023 - Mar, 2027
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Japan Society for the Promotion of Science, Apr, 2017 - Mar, 2021
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Japan Society for the Promotion of Science, Jun, 2015 - Mar, 2020
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S), Japan Society for the Promotion of Science, May, 2015 - Mar, 2020
Industrial Property Rights
3Social Activities
1● 指導学生等の数
1-
Fiscal Year2021年度(FY2021)Doctoral program1Master’s program1Internship students9
● 指導学生の表彰・受賞
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Student NameHayato TAKAKURAStudent affiliation東京大学AwardB-mode from spaceDate2019-12-5
● 専任大学名
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Affiliation (university)東京大学（University of Tokyo)
