Curriculum Vitaes
Profile Information
- Affiliation
- Professor, Institute of Space and Astronautical Science, Japan Aerospace Exploration AgencyGraduate School of Science, Department of Physics, The University of Tokyo(PI), International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles (QUP)Graduate School of Science, Kitasato University
- Degree
- Ph. D.(Mar, 1996, The University of Tokyo)
- ORCID ID
https://orcid.org/0000-0003-4885-5537- J-GLOBAL ID
- 200901003330670433
- Researcher ID
- C-2252-2008
- researchmap Member ID
- 5000019022
- External link
Research Interests
8Research Areas
2Research History
2Education
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Apr, 1989 - Mar, 1993
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Apr, 1985 - Mar, 1989
Committee Memberships
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Oct, 2017 - Sep, 2023
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Oct, 2014 - Sep, 2017
Papers
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Cryogenics, 138 103795-103795, Mar, 2024 Peer-reviewed
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Journal of Geophysical Research: Space Physics, 128(12) e2023JA032069, Dec 19, 2023 Peer-reviewed
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Publications of the Astronomical Society of Japan, 75(6) 1324-1336, Nov 14, 2023 Peer-reviewedAbstract Observations of the hot X-ray emitting interstellar medium in the Milky Way are important for studying the stellar feedback and for understanding the formation and evolution of galaxies. We present measurements of the soft X-ray background emission for 130 Suzaku observations at 75° < l < 285° and |b| > 15°. With the standard soft X-ray background model consisting of the local hot bubble and of the Milky Way halo, residual structures remain at 0.7–1 keV in the spectra of some regions. Adding a collisional-ionization-equilibrium component with a temperature of ∼0.8 keV, much higher than the virial temperature of the Milky Way, significantly reduces the derived C-statistic for 56 out of 130 observations. The emission measure of the 0.8 keV component varies by more than an order of magnitude: assuming the solar abundance, the median value is $3 \times 10^{-4}\, \rm {cm^{-6}\ pc}$ and the 16th–84th percentile range is $(1\!-\!8) \times 10^{-4}\, \rm {cm^{-6}\ pc}$. Regions toward the Orion–Eridanus superbubble, having a large cavity extending from the Ori OB1 association, have the highest emission measures of the 0.8 keV component. While the scatter is large, the emission measures tend to be higher toward lower galactic latitudes. We discuss possible biases caused by the solar wind charge exchange, stars, and background groups. The 0.8 keV component is probably heated by supernovae in the Milky Way disk, possibly related to Galactic fountains.
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IEEE Transactions on Applied Superconductivity, 33(5) 1-4, Aug, 2023 Peer-reviewed
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Journal of Low Temperature Physics, 211(5-6) 255-264, Feb 4, 2023 Peer-reviewedAbstract A $$^{57}$$Fe nucleus in the solar core could emit a 14.4-keV monochromatic axion through the M1 transition if a hypothetical elementary particle, axion, exists to solve the strong CP problem. Transition edge sensor (TES) X-ray microcalorimeters can detect such axions very efficiently if they are again converted into photons by a $$^{57}$$Fe absorber. We have designed and produced a dedicated TES array with $$^{57}$$Fe absorbers for the solar axion search. The iron absorber is set next to the TES, keeping a certain distance to reduce the iron-magnetization effect on the spectroscopic performance. A gold thermal transfer strap connects them. A sample pixel irradiated from a $$^{55}$$Fe source detected 698 pulses. In contrast to thermal simulations, we consider that the pulses include either events produced in an iron absorber or gold strap at a fraction dependent on the absorption rate of each material. Furthermore, photons deposited on the iron absorber are detected through the strap as intended. The identification of all events still needs to be completed. However, we successfully operated the TES with the unique design under iron magnetization for the first time.
Misc.
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Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave, Dec 21, 2020
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X, Dec 16, 2020
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X, Dec 16, 2020
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Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave, Dec 15, 2020
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Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray, Dec 13, 2020
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Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray, Dec 13, 2020
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X-Ray, Optical, and Infrared Detectors for Astronomy IX, Dec 13, 2020
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Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 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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Proceedings of SPIE - The International Society for Optical Engineering, 10397, 2017 Peer-reviewedThe Soft X-ray Spectrometer (SXS) onboard the Hitomi (ASTRO-H) satellite observed several celestial objects. All the observations with the SXS were performed through a beryllium (Be) window installed on the gate-valve of the SXS dewar. However, the Be window had not been well calibrated before launching. Therefore, we measured the transmission of a spare Be window, which is from the same lot as the flight material. The measurements were preformed in 3.8-30 keV range with BL01B1 at SPring-8, and in 2.5-12 keV range combined with BL11B and BL7C at KEK-PF. In this paper, we report mainly the results of the KEK-PF experiment. With the KEK-PF, we measured five places of the Be window. Their estimated thicknesses are consistent with each other within 1.3 μm. In the five transmission data, we confirmed absorption edges by Fe-K, Ni-K and Mn-K and six edge like features at 3460, 6057, 6915, 7590, 8790 and 9193 eV, which can be interpreted as Bragg diffraction by Be polycrystal. By combining the transmissions measured at KEK-PF and at SPring-8, we estimated Be thickness of 259.73±0.01 μm. The amounts of contaminated materials are roughly comparable with the provided values from the provider. We also performed scanning measurements of whole surface in the Be window. In the results, thickness of Be window was found to be uniform in ±1μm from the measurement with 4 keV X-rays.
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Proceedings of SPIE - The International Society for Optical Engineering, 10397, 2017 Peer-reviewedDuring the Hitomi (Astro-H) commissioning observations the SXS dewar gate valve (GV) remained closed to protect the instrument from initial spacecraft outgassing. As a result, the optical path of the observations included the Be window installed on the GV. Both x-ray fluorescence (XRF) analysis and x-ray transmission measurements were performed in June 2016 on the flight-spare Be window which is the same lot as the flight material at SPring-8 in Japan. The beamline operating range is 3.8-30 keV. We used a beam spot size of 1 mm × 0.2 mm to measure two positions on the Be window, at the center of the window and at one position 6.5 mm off-center. We used simultaneous transmission measurements of standard materials for energy calibration. The transmission data clearly showed Fe and Ni K-edges, plus a marginal detection of the Mn K-edge. We found that our transmission data was best fit using the following component Be: 261.86±0.01μm, Cr: 3nm (fixed), Mn: 3.81±0.05nm, Fe: 10.83±0.05nm, Ni: 16.48±0.03nm, Cu: 5nm (fixed). The transmission is reduced 1% at the Fe K-edge. The amount of contaminated materials are comparable to the values of the value provided by the vender. The surface transmission is strained with σ = 0.11% of the unbiased standard deviation calculated variation in the residuals between the measured value and the model.
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116(269) 25-29, Oct 26, 2016
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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, 116(175) 37-39, Aug 8, 2016
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Proceedings of SPIE - The International Society for Optical Engineering, 9905, 2016 Peer-reviewedThe ESA Athena mission will implement 2 instruments to study the hot and energetic universe. The X-ray Integral Field Unit (X-IFU) will provide spatially resolved high resolution spectroscopy. This high energy resolution of 2.5 eV at 7 keV could be achieved thanks to TES (Transition Edge Sensor) detectors that need to be cooled to very low temperature. To obtain the required 50 mK temperature level, a careful design of the cryostat and of the cooling chain including different technologies in cascade is needed. The preliminary cryogenic architecture of the X-IFU instrument that fulfils the TES detector thermal requirements is described. In particular, the thermal design of the detector focal plane assembly (FPA), that uses three temperature stages (from 2 K to 50 mK) to limit the thermal loads on the lowest temperature stage, is described. The baseline cooling chain is based on European and Japanese mechanical coolers (Stirling, Pulse tube and Joule Thomson coolers) that precool a sub Kelvin cooler made of a 3He sorption cooler coupled with a small ADR (Adiabatic Demagnetization Refrigerator). Preliminary thermal budgets of the X-IFU cryostat are presented and discussed regarding cooling chain performances.
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SPACE TELESCOPES AND INSTRUMENTATION 2016: ULTRAVIOLET TO GAMMA RAY, 9905, 2016 Peer-reviewedDIOS (Diffuse Intergalactic Oxygen Surveyor) is a small satellite aiming for a launch around 2022 with JAXA's Epsilon rocket. Its main aim is a search for warm-hot intergalactic medium with high-resolution X-ray spectroscopy of redshifted emission lines from OVII and OVIII ions. The superior energy resolution of FES microcalorimeters combined with a wide field of view (30' diameter) will enable us to look into gas dynamics of cosmic plasmas in a wide range of spatial scales from Earth's magnetosphere to unvirialized regions of clusters of galaxies. Mechanical and thermal design of the spacecraft and development of the TES calorimeter system are described. Employing an enlarged X-ray telescope with a focal length of 1.2 m and fast repointing capability, DIOS can observe absorption features from X-ray afterglows of distant gamma-ray bursts.
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SPACE TELESCOPES AND INSTRUMENTATION 2016: ULTRAVIOLET TO GAMMA RAY, 9905, 2016 Peer-reviewedThe Soft X-ray Spectrometer (SXS) is a cryogenic high-resolution X-ray spectrometer onboard the ASTRO-H satellite, that achieves energy resolution better than 7 eV at 6 keV, by operating the detector array at 50 mK using an adiabatic demagnetization refrigerator. The cooling chain from room temperature to the ADR heat sink is composed of 2-stage Stirling cryocoolers, a He-4 Joule-Thomson cryocooler, and superfluid liquid He, and is installed in a dewar. It is designed to achieve a helium lifetime of more than 3 years with a minimum of 30 liters. The satellite was launched on 2016 February 17, and the SXS worked perfectly in orbit, until March 26 when the satellite lost its function. It was demonstrated that the heat load on the He tank was about 0.7 mW, which would have satisfied the lifetime requirement. This paper describes the design, results of ground performance tests, prelaunch operations, and initial operation and performance in orbit of the flight dewar and cryocoolers.
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SPACE TELESCOPES AND INSTRUMENTATION 2016: ULTRAVIOLET TO GAMMA RAY, 9905, 2016 Peer-reviewedThe Astro-H (Hitomi) Soft X-ray Spectrometer (SXS) was a pioneering imaging x-ray spectrometer with 5 eV energy resolution at 6 keV. The instrument used a microcalorimeter array at the focus of a high-throughput soft x-ray telescope to enable high-resolution non-dispersive spectroscopy in the soft x-ray waveband (0 : 3 12 keV). We present the suite of ground calibration measurements acquired from 2012{2015, including characterization of the detector system, anti-coincidence detector, optical blocking filters, and filter-wheel filters. The calibration of the 36-pixel silicon thermistor microcalorimeter array includes parameterizations of the energy gain scale and line spread function for each event grade over a range of instrument operating conditions, as well as quantum efficiency measurements. The x-ray transmission of the set of five Al/polyimide thin-film optical blocking filters mounted inside the SXS dewar has been modeled based on measurements at synchrotron beamlines, including with high spectral resolution at the C, N, O, and Al K-edges. In addition, we present the x-ray transmission of the dewar gate valve and of the filters mounted on the SXS filter wheel (external to the dewar), including beryllium, polyimide, and neutral density filters.
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SPACE TELESCOPES AND INSTRUMENTATION 2016: ULTRAVIOLET TO GAMMA RAY, 9905, 2016 Peer-reviewedThe calorimeter array of the JAXA Astro-H (renamed Hitomi) Soft X-ray Spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV, enabling essential plasma diagnostics. The properties that make the SXS array a powerful x-ray spectrometer also make it sensitive to photons from the entire electromagnetic band, and particles as well. If characterized as a bolometer, it would have a noise equivalent power (NEP) of < 4x10(-18) W/(Hz)(0.5). Thus it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. Additionally, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. Both of these needs are addressed by a series of five thin-film radiation-blocking filters, anchored to the nested temperature stages, that block long-wavelength radiation while minimizing x-ray attenuation. The aperture assembly is a system of barriers, baffles, filter carriers, and filter mounts that supports the filters and inhibits their potential contamination. The three outer filters also have been equipped with thermometers and heaters for decontamination. We present the requirements, design, implementation, and performance of the SXS aperture assembly and blocking filters.
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Proceedings of SPIE - The International Society for Optical Engineering, 9905, 2016 Peer-reviewedThe X-ray Integral Field Unit (X-IFU) on board the Advanced Telescope for High-ENergy Astrophysics (Athena) will provide spatially resolved high-resolution X-ray spectroscopy from 0.2 to 12 keV, with ∼ 5" pixels over a field of view of 5 arc minute equivalent diameter and a spectral resolution of 2.5 eV up to 7 keV. In this paper, we first review the core scientific objectives of Athena, driving the main performance parameters of the X-IFU, namely the spectral resolution, the field of view, the effective area, the count rate capabilities, the instrumental background. We also illustrate the breakthrough potential of the X-IFU for some observatory science goals. Then we brie y describe the X-IFU design as defined at the time of the mission consolidation review concluded in May 2016, and report on its predicted performance. Finally, we discuss some options to improve the instrument performance while not increasing its complexity and resource demands (e.g. count rate capability, spectral resolution).
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Proceedings of SPIE - The International Society for Optical Engineering, 9905, 2016 Peer-reviewedThe Soft X-ray Spectrometer (SXS) onboard the Astro-H (Hitomi) orbiting x-ray observatory featured an array of 36 silicon thermistor x-ray calorimeters optimized to perform high spectral resolution x-ray imaging spectroscopy of astrophysical sources in the 0.3-12 keV band. Extensive pre-flight calibration measurements are the basis for our modeling of the pulse-height-energy relation and energy resolution for each pixel and event grade, telescope collecting area, detector efficiency, and pulse arrival time. Because of the early termination of mission operations, we needed to extract the maximum information from observations performed only days into the mission when the onboard calibration sources had not yet been commissioned and the dewar was still coming into thermal equilibrium, so our technique for reconstructing the per-pixel time-dependent pulse-height-energy relation had to be modified. The gain scale was reconstructed using a combination of an absolute energy scale calibration at a single time using a fiducial from an onboard radioactive source, and calibration of a dominant time-dependent gain drift component using a dedicated calibration pixel, as well as a residual time-dependent variation using spectra from the Perseus cluster of galaxies. The energy resolution was also measured using the onboard radioactive sources. It is consistent with instrument-level measurements accounting for the modest increase in noise due to spacecraft systems interference. We use observations of two pulsars to validate our models of the telescope area and detector efficiency, and to derive a more accurate value for the thickness of the gate valve Be window, which had not been opened by the time mission operations ceased. We use observations of the Crab pulsar to refine the pixel-to-pixel timing and validate the absolute timing.
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Proceedings of SPIE - The International Society for Optical Engineering, 9905, 2016The Soft X-ray Spectrometer (SXS) onboard ASTRO-H (Hitomi) achieved a high energy resolution of ∼ 4.9 eV at 6 keV with an X-ray microcalorimeter array kept at 50 mK in the orbit. The cooling system utilizes liquid helium, and a porous plug phase separator is utilized to confine it. Therefore, it is required to keep the helium temperature always lower than the λ point of 2.17 K in the orbit. To clarify the maximum allowable helium temperature at the launch also considering the uncertainties of the initial operation in the orbit, we constructed a thermal mathematical model of the SXS dewar which properly implements the helium mass flow rate through the porous plug, and carried out time-series thermal simulations. Based on the results, the maximum allowable helium temperature at the launch was set at 1.7 K. We also conducted a transient thermal calculation using the actual temperatures at the launch as initial conditions. As a result, the helium mass flow rate when the helium temperature was in equilibrium is estimated to be 34-42 μg/s, and the life time of the helium mode is predicted to be ∼ 3.9-4.7 years. The present paper reports model structures, simulation results, and the comparisons with temperatures measured in the orbit.
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Proceedings of SPIE - The International Society for Optical Engineering, 9905, 2016 Peer-reviewedWe present the overall design and performance of the Astro-H (Hitomi) Soft X-Ray Spectrometer (SXS). The instrument uses a 36-pixel array of x-ray microcalorimeters at the focus of a grazing-incidence x-ray mirror Soft X-Ray Telescope (SXT) for high-resolution spectroscopy of celestial x-ray sources. The instrument was designed to achieve an energy resolution better than 7 eV over the 0.3-12 keV energy range and operate for more than 3 years in orbit. The actual energy resolution of the instrument is 4-5 eV as demonstrated during extensive ground testing prior to launch and in orbit. The measured mass flow rate of the liquid helium cryogen and initial fill level at launch predict a lifetime of more than 4 years assuming steady mechanical cooler performance. Cryogen-free operation was successfully demonstrated prior to launch. The successful operation of the SXS in orbit, including the first observations of the velocity structure of the Perseus cluster of galaxies, demonstrates the viability and power of this technology as a tool for astrophysics.
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Proceedings of SPIE - The International Society for Optical Engineering, 9905, 2016 Peer-reviewedWe summarize all the in-orbit operations of the Soft X-ray Spectrometer (SXS) onboard the ASTRO-H (Hitomi) satellite. The satellite was launched on 2016/02/17 and the communication with the satellite ceased on 2016/03/26. The SXS was still in the commissioning phase, in which the setups were progressively changed. This article is intended to serve as a reference of the events in the orbit to properly interpret the SXS data taken during its short life time, and as a test case for planning the in-orbit operation for future micro-calorimeter missions.
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Proceedings of the IEICE General Conference, 2015(1) 38-38, Feb 24, 2015
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Proceedings of the IEICE General Conference, 2015(2) "SS-32"-"SS-35", Feb 24, 2015
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2015 15TH INTERNATIONAL SUPERCONDUCTIVE ELECTRONICS CONFERENCE (ISEC), 2015 Peer-reviewedWe are developing low-power dc-SQUIDs to read out TES X-ray microcalorimeter arrays with frequency-division multiplexing (FDM) towards future X-ray satellite missions. In future space missions, large-format TES X-ray microcalorimeter arrays with hundreds to thousands of pixels are promising detectors achieving high energy resolution and high spatial resolution at the same time. To read out such a large-format array with a limited cooling power at the cryogenic stage, TES pixels are multiplexed in the frequency domain and read out using SQUIDs with small heat dissipations. We are developing low-powered dc-SQUIDs with an adequate gain and a low noise characteristic for TES FDM readouts. With these features, the SQUID can suffice to be the only amplifier in the cold electronics even though it can be placed at the cryogenic stage below 100 mK, enabling a simple single-staged cryogenic configuration. Using the low-power SQUID, we are developing multi-input SQUID chips with built-in bandpass filters used for the channel separation in FDM. Within the size of 2.5x2.5 mm, it carries the low-power SQUID, a TES shunt resistor, and LC bandpass filters for four channels. We are also developing a same-size extension chip that consists of the bandpass filters for four other channels, and it can be attached to the multi-input SQUID chip with only two bonding wires. With these chips, the cryogenic stage setup is drastically simplified. The designs and experimental results of the SQUIDs will be discussed.
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Technical report of IEICE. SCE, 114(247) 59-63, Oct 15, 2014Energy dispersive X-ray spectroscopy (EDS) performed with a scanning transmission electron micro-scope (STEM) is now playing an important role for compositional analysis in various research fields such as nan-otechnology, material science and biotechnology. However, due to a low energy resolution of 〜130 eV with a Si(Li) solid-state detector (SSD), generally used in a STEM-EDS, many spectral peaks are hard to separate. We are then developing a new STEM-EDS system with a superconducting transition-edge sensor (TES) microcalorimeter array to achieve a good energy resolution (< 10 eV) in wide-energy band (0.5 - 10 keV). We describe the design of 64-channel TES array prototype optimized for STEM-EDS and the result of the first X-ray irradiation test.
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Technical report of IEICE. SCE, 114(247) 53-57, Oct 15, 2014We are developing frequency-division multiplexing (FDM) systems for TES X-Ray microcalorimeter arrays toward the BIOS mission. We developed low-power dc-SQUID arrays along with SQUID multiplexers with EC-filters for FDM usable under the limited cooling capacity at cryogenic temperature. We are also developing and evaluating an analog front-end to interface the cryogenic circuit and the FPGA-based digital FDM electronics. We also evaluated tolerance of an externally applied magnetic field on gradiometer SQUIDs.
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Technical report of IEICE. SCE, 114(247) 49-52, Oct 15, 2014Observational targets of X-ray astronomy are wide-ranging; from planets to super clusters of galaxies. For future X-ray astronomy, a detector is desired to have both eV-level energy resolution and mega-pixel imaging capability. An X-ray microcalorimeter is a detector with the potentiality to satisfy these demands simultaneously. By using a thermistor or a transition edge sensor as a pixel at low temperature (〜 100 mK), it has achieved sufficiently high energy resolution. However, since each pixel needs at least a pair of wiring, the heat inflow from a room temperature system through wirings prevents it from attaining high imaging capability. In order to solve this problem, we develop Dielectric X-ray Microcalorimeter (DXMC). We use dielectric, strontium titante (STO), as a material of pixel, and have already detected signals of LED irradiation with DXMC.
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SPACE TELESCOPES AND INSTRUMENTATION 2014: ULTRAVIOLET TO GAMMA RAY, 9144, 2014 Peer-reviewedDIOS (Diffuse Intergalactic Oxygen Surveyor) is a small satellite aiming for a launch around 2020 with JAXA's Epsilon rocket. Its main aim is a search for warm-hot intergalactic medium with high-resolution X-ray spectroscopy of redshifted emission lines from OVII and OVIII ions. The superior energy resolution of TES microcalorimeters combined with a very wide field of view (30-50 arcmin diameter) will enable us to look into gas dynamics of cosmic plasmas in a wide range of spatial scales from Earth's magnetosphere to unvirialized regions of clusters of galaxies. Mechanical and thermal design of the spacecraft and development of the TES calorimeter system are described. We also consider revising the payload design to optimize the scientific capability allowed by the boundary conditions of the small mission.
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2014 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC), 2014 Peer-reviewedAn energy dispersive spectrometer with a superconducting transition edge sensor (TES) microcalorimeter mounted on a transmission electron microscope (TEM) has been developed to improve the accuracy of nanoscale material analysis. TES microcalorimeters generally have a sensitive surface area on the order of 100 x 100 mu m(2). Furthermore, because of the magnetic field generated by the TEM objective lens, a TES microcalorimeter cannot be placed in a TEM column. Therefore, a polycapillary lens is used for collecting X-rays emitted by a TEM specimen on the TES microcalorimeter. The X-ray transmission characteristics of the polycapillary lens typically depend on the geometrical arrangements of the optics and the Xray energy. Energy spectrum measurements were carried out for X-rays transmitted by a polycapillary lens installed in a TEM for evaluating X-ray transmission characteristics of the optics. Values of the focal spot size and the intensity gain were obtained by analyzing the experimental energy spectra in the energy range of 1.0-14.0 keV.
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2014 ASIA-PACIFIC MICROWAVE CONFERENCE (APMC), 160-162, 2014 Peer-reviewedA 8-12 GHz monolithic microwave integrated circuit (MIMIC.) low noise amplifier (LNA) was designed for X-ray astronomy with cryogenic temperature and under radiation. The LNA was fabricated using a 0.15 mu m gate length GaAs-based pseudomorphic high electron mobility transistor (pHEMT) process. At 10 GIlz, the LNA module has a gain of 32.7 dB and a noise figure of 2.1 dB at 300 K. The module was cooled down to a cryogenic temperature of 77 K, where the LNA a achieved high gain of 33.8 dB. At 10G1Iz, the noise figure at 103 K was 0.86 dB. In additional, total ionizing dose (TID) test was performed for the LNA that are expected to be used in astronomy. The gain and the noise figure of this LNA module did not deteriorate before and after this TID test.
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Proceedings of SPIE - The International Society for Optical Engineering, 9144, 2014 Peer-reviewedWe present the development status of the Soft X-ray Spectrometer (SXS) onboard the ASTRO-H mission. The SXS provides the capability of high energy-resolution X-ray spectroscopy of a FWHM energy resolution of < 7eV in the energy range of 0.3 - 10 keV. It utilizes an X-ray micorcalorimeter array operated at 50 mK. The SXS microcalorimeter subsystem is being developed in an EM-FM approach. The EM SXS cryostat was developed and fully tested and, although the design was generally confirmed, several anomalies and problems were found. Among them is the interference of the detector with the micro-vibrations from the mechanical coolers, which is the most difficult one to solve. We have pursued three different countermeasures and two of them seem to be effective. So far we have obtained energy resolutions satisfying the requirement with the FM cryostat.
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Technical report of IEICE. SCE, 113(232) 31-36, Oct 2, 2013We are developing frequency-division multiplexing (FDM) systems with baseband feedback (BBFB) for TES X-Ray microcalorimeter arrays toward the DIOS mission. To meet the requirement of limited cooling capacity at cryogenic temperature, we developed low-power and FDM-optmized dc-SQUIDs. To make maximum use of the SQUIDs, we also developed digital electronics using FPGA evaluation boards and ADC/DAC FMC daughter cards, and evaluated signal-to-noise ratios and gain-bandwidth products.
Teaching Experience
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Mar, 2003 - PresentAstrophysics I (Dept. of Physics, University. of Tokyo)
Professional Memberships
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2010 - Present
Research Projects
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科学研究費助成事業 学術変革領域研究(A), 日本学術振興会, Nov, 2020 - Mar, 2025
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科学研究費助成事業 基盤研究(A), 日本学術振興会, Apr, 2019 - Mar, 2022
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科学研究費助成事業 基盤研究(B), 日本学術振興会, Apr, 2018 - Mar, 2022
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, Apr, 2018 - Mar, 2021
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科学研究費助成事業 基盤研究(S), 日本学術振興会, May, 2014 - Mar, 2019
教育内容やその他の工夫
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SubjcetGraduate School in ISASSummaryWe accept graduate students from University of Tokyo and Kitasato University. Our main scope is observational research of the large scale structure in the Universe utilizing X-ray spectroscopy.
During the graduate school, professional education for development of new detectors and their applications, and observational astrophysics are accessed.
● 指導学生等の数
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Fiscal Year2018年度(FY2018)Doctoral program1Master’s program1
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Fiscal Year2019年度(FY2019)Doctoral program1Master’s program3
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Fiscal Year2020年度(FY2020)Doctoral program1Master’s program3
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Fiscal Year2018年度(FY2018)Doctoral program1Master’s program1
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Fiscal Year2019年度(FY2019)Doctoral program1Master’s program3
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Fiscal Year2020年度(FY2020)Doctoral program1Master’s program3
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Fiscal Year2022年度(FY2022)Doctoral program3Master’s program2
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Fiscal Year2023年度(FY2023)Doctoral program2Master’s program1
● 指導学生の顕著な論文
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Student nameRyota TakakuStudent affiliation東京大学Author(s), journal, volume number, pagination (year of publication)Takaku et al. , Journal of Applied Physics, 128(22), id.225302, (2020)TitleBroadband, millimeter-wave anti-reflective structures on sapphire ablatedwith femto-second laserDOIhttp://doi.org/10.1063/5.0022765
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Student nameYuki NakashimaStudent affiliationUniv. of TokyoAuthor(s), journal, volume number, pagination (year of publication)Nakashima et al. Applied Physics Letters, 117 122601 (2020)TitleLow-noise microwave SQUID multiplexed readout of 38 x-ray transition-edge sensor microcalorimetersDOIhttp://doi.org/10.1063/5.0016333
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Student nameRyohei KonnoStudent affiliationKitasato Univ.Author(s), journal, volume number, pagination (year of publication)Konno et al. Journal of Low Temperature Physics 199, 654 (2019)TitleDevelopment of TES micsrocalorimters with solar-axion converterDOIhttp://doi.org/10.1007/s10909-019-02257-9
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Student nameRyo YamamotoStudent affiliationUniv. of TokyoAuthor(s), journal, volume number, pagination (year of publication)Yamamoto et al. , Journal of Cosmokogy and Astrophysics, 02 (2020) 011TitleA Search for a Contribution from Axion-Like Particles to the X-Ray Diffuse Background Utilizing the Earth's Magnetic FieldDOIhttp://doi.org/10.1088/1475-7516/2020/02/011
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Student nameNorio SekiyaStudent affiliationUniversity. of TokyoAuthor(s), journal, volume number, pagination (year of publication)Sekiya, Yamasaki, and Mitsuda, Publications of Astronomical Society in Japan, 68(SP1), S31 (2016)TitleSearch for a keV Signature of Radiatively Decaying Dark Matter with Suzaku XIS Observations of the X-ray Diffuse BackgroundDOIhttp://doi.org/10.1093/pasj/psv081
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Student nameIkuyuki MitsuishiStudent affiliationUniv. of TokyoAuthor(s), journal, volume number, pagination (year of publication)Mitsuishi, Yamasaki, and Takei, Publications of Astronomical Society in Japan, 65, 44 (2013)TitleAn X-Ray Study of the Galactic-Scale Starburst-Driven Outflow in NGC 253DOIhttp://doi.org/10.1093/pasj/65.2.44
● 専任大学名
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Affiliation (university)東京大学（University of Tokyo)
● 所属する所内委員会
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ISAS CommitteeSteering committee for ISAS nono-electronics clean room
