研究者業績
基本情報
- 所属
- 国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 宇宙物理学研究系 助教
- 学位
- 博士（理学）(2012年7月 東京大学)
- 研究者番号
- 20751176
- ORCID ID
https://orcid.org/0000-0002-5902-2672- J-GLOBAL ID
- 201901005927826680
- researchmap会員ID
- B000348585
宇宙素粒子物理学が専門です。現在はCMB偏光観測を行う衛星実験LiteBIRDの研究開発をしています。
宇宙初期の物理学、特にインフレーションやダークマターなどに興味があります。
研究キーワード
6経歴
5-
2020年6月 - 現在
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2020年4月 - 2020年5月
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2017年4月 - 2020年3月
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2014年4月 - 2017年3月
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2012年8月 - 2014年3月
論文
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Journal of Cosmology and Astroparticle Physics 2024年12月1日<jats:title>Abstract</jats:title> <jats:p>Large angular scale surveys in the absence of atmosphere are essential for measuring the primordial B-mode power spectrum of the Cosmic Microwave Background (CMB). Since this proposed measurement is about three to four orders of magnitude fainter than the temperature anisotropies of the CMB, in-flight calibration of the instruments and active suppression of systematic effects are crucial. We investigate the effect of changing the parameters of the scanning strategy on the in-flight calibration effectiveness, the suppression of the systematic effects themselves, and the ability to distinguish systematic effects by null-tests. Next-generation missions such as <jats:italic>LiteBIRD</jats:italic>, modulated by a Half-Wave Plate (HWP), will be able to observe polarisation using a single detector, eliminating the need to combine several detectors to measure polarisation, as done in many previous experiments and hence avoiding the consequent systematic effects. While the HWP is expected to suppress many systematic effects, some of them will remain. We use an analytical approach to comprehensively address the mitigation of these systematic effects and identify the characteristics of scanning strategies that are the most effective for implementing a variety of calibration strategies in the multi-dimensional space of common spacecraft scan parameters. We verify that <jats:italic>LiteBIRD</jats:italic>'s <jats:italic>standard configuration</jats:italic> yields good performance on the metrics we studied. We also present <jats:monospace>Falcons.jl</jats:monospace>, a fast spacecraft scanning simulator that we developed to investigate this scanning parameter space.</jats:p>
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Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 82-82 2024年8月23日
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Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 207-207 2024年8月23日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XII 2024年8月16日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XII 124-124 2024年8月16日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XII 120-120 2024年8月16日
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Applied Optics 2024年8月8日Mitigating the far sidelobes of a wide field-of-view telescope is one of the critical issues for polarization observation of the cosmic microwave background. Since even small reflections of stray light at the millimeter-wave absorbers inside the telescope may create nonnegligible far sidelobes, we have developed a method to measure the reflectance of millimeter-wave absorbers, including diffuse reflections. By applying the planar near-field measurement method to the absorbers, we have enabled two-dimensional diffuse-reflection measurements, in addition to characterizing specular reflection. We have measured the reflectance of five samples (TK RAM Large and Small Tiles and Eccosorb AN-72, HR-10, and LS-22) at two angles of incidence in the frequency range from 70 GHz to 110 GHz. Compared with conventional horn-to-horn measurements, we obtained a consistent specular reflectance with a higher precision, less affected by standing waves. We have demonstrated that the angular response and diffuse-to-specular reflectance ratio differ among various materials. The measurements also imply that some absorbers may affect the polarization direction when reflecting the incident waves.
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JOURNAL OF LOW TEMPERATURE PHYSICS 216(1-2) 119-128 2024年7月
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Progress of Theoretical and Experimental Physics 2024(2) 2024年1月22日Abstract Understanding telescope pointing (i.e. line of sight) is important for observing the cosmic microwave background (CMB) and astronomical objects. The Moon is a candidate astronomical source for pointing calibration. Although the visible size of the Moon (30′) is larger than that of the planets, we can frequently observe the Moon once a month with a high signal-to-noise ratio. We developed a method for performing pointing calibration using observational data from the Moon. We considered the tilts of the telescope axes as well as the encoder and collimation offsets for pointing calibration. In addition, we evaluated the effects of the nonuniformity of the brightness temperature of the Moon, which is a dominant systematic error. As a result, we successfully achieved a pointing accuracy of 3.3′. This is one order of magnitude smaller than an angular resolution of 36′. This level of accuracy competes with past achievements in other ground-based CMB experiments using observational data from the planets.
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Journal of Astronomical Telescopes, Instruments, and Systems 9(02) 2023年4月19日
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Ground test results of the electromagnetic interference for the x-ray microcalorimeter onboard XRISMJournal of Astronomical Telescopes, Instruments, and Systems 9(1) 18004 2023年1月1日
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Progress of Theoretical and Experimental Physics 2023(4) 2022年11月21日Abstract 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 (CMB) 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 μK-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. Subject Index LiteBIRD cosmic inflation, cosmic microwave background, B-mode polarization, primordial gravitational waves, quantum gravity, space telescope
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI 12190 2022年8月31日
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Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave 12180 2022年8月27日
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Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave 12180 2022年8月27日
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SPACE TELESCOPES AND INSTRUMENTATION 2022: OPTICAL, INFRARED, AND MILLIMETER WAVE 12180 2022年8月
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Journal of Low Temperature Physics 209(3-4) 441-448 2022年5月31日
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Journal of Cosmology and Astroparticle Physics 2022(4) 2022年4月
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Progress of Theoretical and Experimental Physics 2022(3) 2022年3月9日Abstract A microwave kinetic inductance detector (MKID) is a cutting-edge superconducting detector. It comprises a resonator circuit constructed with a superconducting film on a dielectric substrate. To expand its field of application, it is important to establish a method to suppress the two-level system (TLS) noise that is caused by the electric fluctuations between the two energy states at the surface of the substrate. The electric field density can be decreased by expanding the strip width (S) and gap width from the ground plane (W) in the MKID circuit, allowing the suppression of TLS noise. However, this effect has not yet been confirmed for MKIDs made with niobium films on silicon substrates. In this study, we demonstrate its effectiveness for such MKIDs. We expanded the dimension of the circuit from (S, W) = (3.00 μm, 4.00 μm) to (S, W) = (5.00 μm, 23.7 μm), and achieved an increased suppression of 5.5 dB in TLS noise.
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The Astrophysical Journal 915(2) 88-88 2021年2月5日We compute the expected sensitivity on measurements of optical depth to reionization for a ground-based experiment at Teide Observatory. We simulate polarized partial sky maps for the GroundBIRD experiment at the frequencies 145 and 220 GHz. We perform fits for the simulated maps with our pixel-based likelihood to extract the optical depth to reionization. The noise levels of polarization maps are estimated as 110 $\mu\mathrm{K~arcmin}$ and 780 $ \mu\mathrm{K~arcmin}$ for 145 and 220 GHz, respectively, by assuming a three-year observing campaign and sky coverages of 0.537 for 145 GHz and 0.462 for 220 GHz. Our sensitivities for the optical depth to reionization are found to be $\sigma_\tau$=0.030 with the simulated GroundBIRD maps, and $\sigma_\tau$=0.012 by combining with the simulated QUIJOTE maps at 11, 13, 17, 19, 30, and 40 GHz.
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Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave 11443 2020年12月21日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X 11453 2020年12月16日
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Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave 11443 2020年12月15日
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On-site performance of GroundBIRD, a CMB polarization telescope for large angular scale observationsGround-based and Airborne Telescopes VIII 11445 2020年12月13日
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Journal of Low Temperature Physics 200(5-6) 384-391 2020年11月16日
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AIP Adv. 10(9) 095320-095320 2020年9月21日 査読有りA microwave kinetic inductance detector (MKID) is a cutting-edge superconducting detector, and its principle is based on a superconducting resonator circuit. The superconducting transition temperature (Tc) of the MKID is an important parameter because various MKID characterization parameters depend on it. In this paper, we propose a method to measure the Tc of the MKID by changing the applied power of the readout microwaves. A small fraction of the readout power is deposited in the MKID, and the number of quasiparticles in the MKID increases with this power. Furthermore, the quasiparticle lifetime decreases with the number of quasiparticles. Therefore, we can measure the relation between the quasiparticle lifetime and the detector response by rapidly varying the readout power. From this relation, we estimate the intrinsic quasiparticle lifetime. This lifetime is theoretically modeled by Tc, the physical temperature of the MKID device, and other known parameters. We obtain Tc by comparing the measured lifetime with that acquired using the theoretical model. Using an MKID fabricated with aluminum, we demonstrate this method at a 0.3 K operation. The results are consistent with those obtained by Tc measured by monitoring the transmittance of the readout microwaves with the variation in the device temperature. The method proposed in this paper is applicable to other types, such as a hybrid-type MKID.
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Development of Large Array of Kinetic Inductance Detectors Using Commercial-Class External FoundriesJournal of Low Temperature Physics 200(5-6) 353-362 2020年9月1日
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Journal of Cosmology and Astroparticle Physics 2020(9) 2020年6月4日 査読有り
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Applied Physics Letters 115(3) 032603-032603 2019年7月15日 査読有りSuperconducting detectors are a modern technology applied in various fields. The microwave kinetic inductance detector (MKID) is one of cutting-edge superconducting detector. It is based on the principle of a superconducting resonator circuit. A radiation entering the MKID breaks the Cooper pairs in the superconducting resonator, and the intensity of the radiation is detected as a variation of the resonant condition. Therefore, calibration of the detector responsivity, i.e., the variation of the resonant phase with respect to the number of Cooper-pair breaks (quasiparticles), is important. We propose a method for responsivity calibration. Microwaves used for the detector readout locally raise the temperature in each resonator, which increases the number of quasiparticles. Since the magnitude of the temperature rise depends on the power of readout microwaves, the number of quasiparticles also depends on the power of microwaves. By changing the power of the readout microwaves, we simultaneously measure the phase difference and lifetime of quasiparticles. We calculate the number of quasiparticles from the measured lifetime and by using a theoretical formula. This measurement yields a relation between the phase response as a function of the number of quasiparticles. We demonstrate this responsivity calibration using the MKID maintained at 285mK. We also confirm consistency between the results obtained using this method and conventional calibration methods in terms of the accuracy.
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Journal of Low Temperature Physics 194(5-6) 443-452 2019年3月15日
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Journal of Low Temperature Physics 193(5-6) 1066-1074 2018年12月1日 査読有り
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Journal of Low Temperature Physics 193(5-6) 1048-1056 2018年12月1日
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Journal of Low Temperature Physics 193(5-6) 841-850 2018年12月1日
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Journal of Low Temperature Physics 193(3-4) 562-569 2018年11月
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JOURNAL OF LOW TEMPERATURE PHYSICS 193(3-4) 203-208 2018年11月 査読有り
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Journal of Low Temperature Physics 1-8 2018年6月7日 査読有り
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IEICE TRANSACTIONS ON ELECTRONICS E100C(3) 298-304 2017年3月 査読有り
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27th International Symposium on Space Terahertz Technology, ISSTT 2016 2017年
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IEICE Transactions on Electronics 100(3) 298-304 2017年 査読有り<p>Antenna-coupled kinetic inductance detectors (KIDs) have recently shown great promise as microwave detection systems with a large number of channels. However, this technique, still has difficulties in eliminating the radiation loss of the resonator signals. To solve this problem, we propose a design in which the absorption area connected to an antenna is located on the ground-side of a coplanar waveguide. Thereby, radiation loss due to leakage from the resonator to the antenna can be considerably reduced. This simple design also enables the use of a contact aligner for fabrication. We have developed KIDs with this design, named as the ground-side absorption (GSA)-KIDs and demonstrated that they have higher quality factors than those of the existing KIDs, while maintaining a good total sensitivity.</p>
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JOURNAL OF LOW TEMPERATURE PHYSICS 184(3-4) 786-792 2016年8月 査読有り
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Phys.Lett.B 758 286-291 2016年7月10日 査読有り
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Journal of Low Temperature Physics 184(1-2) 443-448 2016年7月1日
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GROUND-BASED AND AIRBORNE TELESCOPES VI 9906 2016年 査読有り
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IEICE TRANSACTIONS ON ELECTRONICS E98C(3) 207-218 2015年3月 査読有り
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IEICE Transactions on Electronics 98(3) 207-218 2015年 査読有りA precise measurement of Cosmic Microwave Background (CMB) provides us rich information about the universe. In particular, its asymmetric polarization patterns, B-modes, are smoking gun signature of inflationary universe. Magnitude of the B-modes is order of 10 nK. Its measurement requires a high sensitive millimeter-wave telescope with a large number of superconducting detectors on its focal plane. Microwave Kinetic Inductance Detector (MKID) is appropriate detector for this purpose. MKID camera has been developed in cooperation of National Astronomical Observatory of Japan (NAOJ), Institute of Physical and Chemical Research (RIKEN), High Energy Accelerator Research Organization (KEK), and Okayama University. Our developments of MKID include: fabrication of high-quality superconducting film; optical components for a camera use; and readout electronics. For performance evaluation of total integrated system of our MKID camera, a calibration system was also developed. The system was incorporated in a 0.1 K dilution refrigerator with modulated polarization source. These developed technologies are applicable to other types of detectors.
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JOURNAL OF LOW TEMPERATURE PHYSICS 176(5-6) 691-697 2014年9月 査読有り
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JOURNAL OF LOW TEMPERATURE PHYSICS 176(5-6) 822-828 2014年9月 査読有り
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Rev.Sci.Instrum. 85(8) 086101-086101 2014年 査読有り
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Nucl.Instrum.Meth.A 757 33-39 2014年 査読有り
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SPACE TELESCOPES AND INSTRUMENTATION 2014: OPTICAL, INFRARED, AND MILLIMETER WAVE 9143 91431F 2014年 査読有り
MISC
50-
Ground test results of the electromagnetic interference for the x-ray microcalorimeter onboard XRISMSPACE TELESCOPES AND INSTRUMENTATION 2022: ULTRAVIOLET TO GAMMA RAY 12181 2023年3月2日
主要な講演・口頭発表等
92-
SPIE Astronomical Telescopes + Instrumentation, 2022 2022年7月
共同研究・競争的資金等の研究課題
12-
日本学術振興会 科学研究費助成事業 2023年4月 - 2028年3月
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日本学術振興会 科学研究費助成事業 2023年4月 - 2028年3月
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日本学術振興会 科学研究費助成事業 2024年4月 - 2027年3月
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日本学術振興会 科学研究費助成事業 挑戦的研究(萌芽) 2020年7月 - 2023年3月
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日本学術振興会 科学研究費助成事業 挑戦的研究(開拓) 2019年6月 - 2023年3月
