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 プロジェクト研究員
- 研究者番号
- 00846842
- ORCID ID
https://orcid.org/0000-0002-6587-9314- J-GLOBAL ID
- 202001002548601133
- researchmap会員ID
- R000014086
論文
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IEEE Transactions on Applied Superconductivity 33(5) 1-4 2023年8月
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IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 33(5) 2100805-2100805 2023年4月 査読有り
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Journal of Low Temperature Physics 211(5-6) 255-264 2023年2月4日Abstract 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.
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Journal of Low Temperature Physics 211(3) 255-264 2023年2月 査読有り
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IEEE Transactions on Applied Superconductivity 1-5 2023年
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Journal of Low Temperature Physics 209(3-4) 518-524 2022年11月7日
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Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray 2022年8月31日
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NATURE ASTRONOMY 6(10) 1163-+ 2022年8月 査読有りVolatile and organic-rich C-type asteroids may have been one of the main sources of Earth's water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of -30 degrees C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition.
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JOURNAL OF LOW TEMPERATURE PHYSICS 2022年7月 査読有りWe developed transition-edge sensor (TES) microcalorimeters to measure gamma rays with up to a few megaelectron volts. Our TES devices have a thick silicon membrane that supports a large absorber. We fabricated devices with different sizes of the TES and membranes to study the thermal conductance of the membrane. We found that the thermal conductance G of the membrane is less dependent on the distance between the TES and heat bath because heat is mainly transported by ballistic phonons in the thick membrane. In addition, gamma-ray irradiation experiments were conducted using a TES device with a large bismuth absorber (1 mm x 1 mm x 1 mm) and a thick membrane (6 mu m); the energy response of the device was found to be largely linear.
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日本惑星科学会誌遊星人 31(2) 153-164 2022年6月25日2020年12月6日に小惑星探査機「はやぶさ2」はC型小惑星リュウグウ表層物質を収めた再突入カ プセルを地球に帰還させた．回収された再突入カプセルに収められた試料コンテナは，オーストラリア現地でのガス採取を実施した後，JAXA相模原キャンパスの惑星物質試料受入設備に搬入され，チェンバー導入前の部品取り外し・洗浄等のプロセスを経てクリーンチェンバー内で真空中での開封・高純度窒素環境下での帰還試料の取り出し･初期記載が行われた．これらのリュウグウ帰還試料の初期記載の結果，これまでに回収されたどの隕石よりも反射率が低く，全体密度が小さい事が判明した．また，赤外反射スペクトルの吸収特性から水酸基を含む含水鉱物と炭酸塩鉱物，及びCH結合に富む有機物が試料中に含まれることが明らかになった．これらの情報を既知の隕石と比較すると，CIコンドライト隕石に最も似ていると言える．また探査機搭載機器によって得られた可視･近赤外スペクトルと比較した結果，帰還試料はリュウグウ表層全体を代表している事が分かった．取り出された試料の一部は既に初期分析チーム，2次キュレーションチーム，NASAへ配分され，更に国際公募研究による配布が予定されている．本稿では一連の試料取り扱いプロセス・初期記載内容について述べる．
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PROCEEDINGS OF THE JAPAN ACADEMY SERIES B-PHYSICAL AND BIOLOGICAL SCIENCES 98(6) 227-282 2022年6月 査読有りPresented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements from the particles are in close agreement with those of CI chondrites. Bulk Ryugu particles show higher delta O-18, Delta O-17, and epsilon Cr-54 values than CI chondrites. As such, Ryugu sampled the most primitive and least-thermally processed protosolar nebula reservoirs. Such a finding is consistent with multi-scale H-C-N isotopic compositions that are compatible with an origin for Ryugu organic matter within both the protosolar nebula and the interstellar medium. The analytical data obtained here, suggests that complex soluble organic matter formed during aqueous alteration on the Ryugu progenitor planetesimal (several 10's of km), <2.6 Myr after CAI formation. Subsequently, the Ryugu progenitor planetesimal was fragmented and evolved into the current asteroid Ryugu through sublimation.
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Physical Review Letters 128(11) 2022年3月18日 査読有りWe have measured the 3d→2p transition x rays of kaonic He3 and He4 atoms using superconducting transition-edge-sensor microcalorimeters with an energy resolution better than 6 eV (FWHM). We determined the energies to be 6224.5±0.4(stat)±0.2(syst) eV and 6463.7±0.3(stat)±0.1(syst) eV, and widths to be 2.5±1.0(stat)±0.4(syst) eV and 1.0±0.6(stat)±0.3(stat) eV, for kaonic He3 and He4, respectively. These values are nearly 10 times more precise than in previous measurements. Our results exclude the large strong-interaction shifts and widths that are suggested by a coupled-channel approach and agree with calculations based on optical-potential models.
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Nature Astronomy 6(2) 214-+ 2021年12月20日 査読有り<title>Abstract</title>C-type asteroids1 are considered to be primitive small Solar System bodies enriched in water and organics, providing clues to the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing2–7 and on-asteroid measurements8,9 with Hayabusa2 (ref. 10). However, the ground truth provided by laboratory analysis of returned samples is invaluable to determine the fine properties of asteroids and other planetary bodies. We report preliminary results of analyses on returned samples from Ryugu of the particle size distribution, density and porosity, spectral properties and textural properties, and the results of a search for Ca–Al-rich inclusions (CAIs) and chondrules. The bulk sample mainly consists of rugged and smooth particles of millimetre to submillimetre size, confirming that the physical and chemical properties were not altered during the return from the asteroid. The power index of its size distribution is shallower than that of the surface boulder observed on Ryugu11, indicating differences in the returned Ryugu samples. The average of the estimated bulk densities of Ryugu sample particles is 1,282 ± 231 kg m−3, which is lower than that of meteorites12, suggesting a high microporosity down to the millimetre scale, extending centimetre-scale estimates from thermal measurements5,9. The extremely dark optical to near-infrared reflectance and spectral profile with weak absorptions at 2.7 and 3.4 μm imply a carbonaceous composition with indigenous aqueous alteration, matching the global average of Ryugu3,4 and confirming that the sample is representative of the asteroid. Together with the absence of submillimetre CAIs and chondrules, these features indicate that Ryugu is most similar to CI chondrites but has lower albedo, higher porosity and more fragile characteristics.
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Applied optics 60(33) 10462-10467 2021年11月20日 査読有りWe developed broadband antireflection structures for millimeter-wave and submillimeter-wave applications, particularly cryogenic applications. The structures were fabricated on silicon using deep reactive ion etching. Three-layer subwavelength structures were fabricated on both sides of a silicon plate with an area of 20mm2. The transmittances of the structures were measured at 28 K. The average transmittance was 97.6% in the frequency range of 200-450 GHz.
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IEEE Transactions on Applied Superconductivity 2021年8月 査読有り
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IEEE Transactions on Applied Superconductivity 31(5) 1-4 2021年8月 査読有りPosition-sensitive transition-edge sensor (TES) microcalorimeters (PoSTs) were developed to detectgammarays up to a few MeV. Each gamma-ray PoST comprised a 0.5 mm x 0.5 mm x19mmlead absorber with a TES on each end andworked as a 1D imaging spectrometer. Only one TES worked at low temperature and its results are reported herein. We irradiated the PoST device with gamma rays from a Cs-137 source, and the resultant pulses showed strong correlations between the pulse height and the rise time. To determine effective pixels, we separately divided the photo-peak and lead-K escape peak pulses into 19 groups after sorting them by their rise times. From the pulse shape distributions, we concluded that the TES was sensitive to the gamma-ray interaction position as long as it was not located too far away fromthe TES, and that it was probably possible to determine the interaction positions of the entire absorber, if both TESs were working. The PoST device was then modeled and the average pulses of the 19 effective pixels were compared to those of numerical simulations, where the rise time distributions of the actual pulses and simulated pulses were in good agreement.
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2021年6月21日<title>Abstract</title> C-type asteroids are considered to be primitive small Solar-System bodies enriched in water and organics, providing clues for understanding the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing and on-asteroid measurements with Hayabusa2, but further studies are expected by direct analyses of returned samples. Here we describe the bulk sample mainly consisting of rugged and smooth particles of millimeter to submillimeter size, preserving physical and chemical properties as they were on the asteroid. The particle size distribution is found steeper than that of surface boulders11. Estimated grain densities of the samples have a peak around 1350 kg m-3, which is lower than that of meteorites suggests a high micro-porosity down to millimeter-scale, as estimated at centimeter-scale by thermal measurements. The extremely dark optical to near-infrared reflectance and the spectral profile with weak absorptions at 2.7 and 3.4 microns implying carbonaceous composition with indigenous aqueous alteration, respectively, match the global average of Ryugu, confirming the sample’s representativeness. Together with the absence of chondrule and Ca-Al-rich inclusion of larger than sub-mm, these features indicate Ryugu is most similar to CI chondrites but with darker, more porous and fragile characteristics.
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The Review of scientific instruments 92(1) 013103-013103 2021年1月1日 査読有りWe have succeeded in operating a transition-edge sensor (TES) spectrometer and evaluating its performance at the SPring-8 synchrotron x-ray light source. The TES spectrometer consists of a 240 pixel National Institute of Standards and Technology (NIST) TES system, and 220 pixels are operated simultaneously with an energy resolution of 4 eV at 6 keV at a rate of ∼1 c/s pixel-1. The tolerance for high count rates is evaluated in terms of energy resolution and live time fraction, leading to an empirical compromise of ∼2 × 103 c/s (all pixels) with an energy resolution of 5 eV at 6 keV. By utilizing the TES's wideband spectroscopic capability, simultaneous multi-element analysis is demonstrated for a standard sample. We conducted x-ray absorption near-edge structure (XANES) analysis in fluorescence mode using the TES spectrometer. The excellent energy resolution of the TES enabled us to detect weak fluorescence lines from dilute samples and trace elements that have previously been difficult to resolve due to the nearly overlapping emission lines of other dominant elements. The neighboring lines of As Kα and Pb Lα2 of the standard sample were clearly resolved, and the XANES of Pb Lα2 was obtained. Moreover, the x-ray spectrum from the small amount of Fe in aerosols was distinguished from the spectrum of a blank target, which helps us to understand the targets and the environment. These results are the first important step for the application of high resolution TES-based spectroscopy at hard x-ray synchrotron facilities.
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Journal of Low Temperature Physics 200(5-6) 452-460 2020年9月27日 査読有り
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Journal of Low Temperature Physics 200(5-6) 233-238 2020年9月 査読有り
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Journal of Low Temperature Physics 200(5-6) 269-276 2020年9月 査読有り
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High Energy Background Event Identification Using Local Group Trigger in a 240-pixel X-ray TES ArrayJournal of Low Temperature Physics 200(5-6) 392-399 2020年9月 査読有り
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Journal of Low Temperature Physics 200(5-6) 247-254 2020年9月 査読有り
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Journal of Low Temperature Physics 199(3-4) 908-915 2020年5月5日 査読有り筆頭著者We herein report a concept study of a transition edge sensor (TES) X-ray microcalorimeter array with two different thickness absorbers. We developed an energy-dispersive X-ray spectroscope (EDS) with a 64-pixel TES array and installed it on a scanning transmission electron microscope (STEM) for material analysis. One of the key applications of the proposed system is the microanalysis of astromaterials, for which the relative abundance of light elements such as boron, carbon, and oxygen against silicon are crucial. However, the line sensitivity below similar to 500 eV for the our STEM TES EDS system was not enough to detect the X-ray from light elements because of the relatively high continuum emission and low detection efficiency, which occurs due to the X-ray window and the optical blocking filters. A simple solution to increase line sensitivity at low energy is the adoption of thin X-ray absorbers that leads to an improvement in the energy resolution. However, doing so causes the sensitivity to decrease for high energy lines. Utilizing the spot-size dependence of the polycapillary X-ray optics on energy, which are used in the STEM TES EDS system, we studied a design in which thin absorbers are distributed on the outer area of detector. We optimized the design using the raytracing analysis of optics. A thin (300 nm) absorber is placed on the 52 outer pixels, while a thick (3.5 mu absorber is placed on the central 12 pixels. The thin pixels detect approximately 50-60% of the total counts in 0.1-2 keV, while the central thick pixels detect approximately 50-80% of the total counts in 2-10 keV. We also demonstrated the fabrication process of two-thickness absorber arrays.
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Journal of Low Temperature Physics 199(3-4) 1018-1026 2020年5月 査読有り
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Journal of Low Temperature Physics 199(3-4) 654-662 2020年5月 査読有り
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Journal of Low Temperature Physics 199(1-2) 339-347 2020年4月 査読有りTo show the technical feasibility of high-frequency and broadband anti-reflection (AR) coating for silicon optics in millimeter wavelengths, we fabricated a prototype of the four-layer sub-wavelength structure (SWS) using a combination of deep reactive ion etching (DRIE) and dicing processes. We also fabricated a three-layer SWS using a multi-layer DRIE technique. The described processes allow to obtain physical prototypes that are close enough to those designed that their simulated reflectances are slightly worse than expected. The simulations of the obtained three- and four-layer prototype showed the averaged reflectances of 5.2 % at 150–450 GHz and 3.7 % at 100–450 GHz, while the designed SWSs showed 1.6 % and 2.0 %, respectively.
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Physical Review Letters 123(22) 2019年11月26日 査読有り
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Proceedings of the 8th International Conference on Quarks and Nuclear Physics (QNP2018) 2019年11月8日 査読有り
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IEEE Transactions on Applied Superconductivity 29(5) 1-4 2019年8月 査読有り筆頭著者A quantitative microanalysis of astromaterials (e.g., meteorite, returned samples from asteroids) is a key technology to understand the history of our solar system formation. To fulfill this, we developed an energy-dispersive X-ray spectroscopy (EDS) using a transition-edge sensor (TES) microcalorimeterarray on a scanning transmission electron microscope (STEM) for material analysis. To reduce the systematic errors of a spectral analysis, we investigated and constructed the response function of the STEM-EDS system, which consists of detection efficiency and a two-dimensional response matrix. The latter represents the pulse-height redistribution functions of the incident photons of different energies. Using the constructed response function, we demonstrated the quantitative determination of SiO2 film and confirmed that the number-density ratio of oxygen to silicon (=2.29(-0.29)(+0.32)) is consistent with the expected value of 2 within the statistical errors. We further study the systematic errors of the concentration determination with simulations. We analyze the simulated spectra of TES-EDS and SDD (silicon drift detector)-EDS without a priori knowledge about the continuum spectra and find that the systematic deviations of parameters from the model values are smaller than 1% for TES-EDS and larger than 10% for SDD-EDS.
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Journal of Low Temperature Physics 194(5-6) 412-417 2019年3月 査読有り
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Journal of Low Temperature Physics 193(5-6) 1016-1023 2018年12月 査読有り
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JOURNAL OF LOW TEMPERATURE PHYSICS 193(5-6) 1282-1286 2018年12月 査読有り筆頭著者A detector head for an energy-dispersive X-ray spectroscopy (EDS) for a scanning transmission electron microscope (STEM) was designed, fabricated, and tested. A 64-pixel TES X-ray microcalorimeter and 64 SQUID array amplifiers (SAAs) are mounted on a detector head which is cooled to about 100 mK. The body of the detector head is a copper rod of about 1 cm(2) cross section and 10 cm length with 3 cm cubic structure at the bottom. The TES microcalorimeter is mounted at the top of the rod while the SAAs are mounted on the four side surfaces of the cubic structure. In order to reduce the number of wire bondings, we adopted a flip-chip bonding for the SAAs. In order to reduce the stress imposed on the flip-chip bondings due to the difference in the linear thermal expansion of the SAA chip and the mounting surfaces, we mounted the SAAs and connectors to the room-temperature electronics on sapphire circuit board and mounted the SAAs and connectors using a superconducting flip-chip bonding technology. Then, both the TES and the sapphire circuit board were mounted on the rod and are connected to the print circuit like superconducting wires, which are created on the multiple surfaces of the rod, with A1 wire bondings. We reduced the number of wire bondings from 768 to 256. The yield of the flip-chip bonding was not perfect but relatively high. We installed the detector head in the STEM EDS system, confirmed that the energy resolution and counting requirements, Delta E < 10 eV with 5 kcps were fulfilled.
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Journal of Low Temperature Physics 193(3-4) 618-625 2018年11月 査読有り
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Publications of the Astronomical Society of Japan 70(2) 2018年3月1日 査読有り責任著者Extending the earlier measurements reported in Hitomi collaboration (2016, Nature, 535, 117), we examine the atmospheric gas motions within the central 100 kpc of the Perseus cluster using observations obtained with the Hitomi satellite. After correcting for the point spread function of the telescope and using optically thin emission lines, we find that the line-of-sight velocity dispersion of the hot gas is remarkably low and mostly uniform. The velocity dispersion reaches a maxima of approximately 200 km s(-1) toward the central active galactic nucleus (AGN) and toward the AGN inflated northwestern "ghost" bubble. Elsewhere within the observed region, the velocity dispersion appears constant around 100 km s(-1). We also detect a velocity gradient with a 100 km s(-1) amplitude across the cluster core, consistent with large-scale sloshing of the core gas. If the observed gas motions are isotropic, the kinetic pressure support is less than 10% of the thermal pressure support in the cluster core. The well-resolved, optically thin emission lines have Gaussian shapes, indicating that the turbulent driving scale is likely below 100 kpc, which is consistent with the size of the AGN jet inflated bubbles. We also report the first measurement of the ion temperature in the intracluster medium, which we find to be consistent with the electron temperature. In addition, we present a new measurement of the redshift of the brightest cluster galaxy NGC 1275.
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IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 27(4) 2017年6月 査読有りTES microcalorimeters show a nonlinear pulseheight- to-energy relation, reflecting their nonlinear resistanceto- temperature relation on the transition edge. In some of TES applications, such as energy dispersive X-ray spectroscopy, a wide energy range (e.g. 0.5-15 keV) and a good energy calibration (e.g. within a few eV) are required. We have studied the method to calibrate the nonlinear pulse-height-to-energy and to correct for it in the data analysis. We irradiated a TES microcalorimeter with three radio isotopes simultaneously to obtain continuum-free line spectra covering from 3.3 to 17.8 keV. X-ray lines from those isotopes are, respectively, a line complex containing fine structures and/or satellite lines, which cannot be fully separatedwith TES microcalorimeters. Thus, a special treatment is necessary. We first established a method to estimate the relation between PHA (pulse height analyzed value by optimum filtering) and X-ray energy of the line complex precisely: we assumed that the relation could be approximated with a linear function, PHA = aE + b, locally in the narrow energy range containing one of the line complex, and determined a and b from the model fit of the PHA spectrum of the line complex. Then, fromthe PHA-to-energy relations of six line complexes, we determined an approximation formula which represented the global PH-to-energy relation. We then applied the global relation to convert PHA values of all pulses to energy equivalent value, which we call PI (pulse invariant). We then fitted the PI spectra with the model function to check the consistency of energy. We have done these processes starting fromtwo different forms of data; TES current as a function of time, and TES resistance as a function of time. The nonlinearity of PHA-to-energy was smaller for TES resistance pulses, and a better energy calibration is obtained. We found that the PI spectra obtained fromTES resistance pulses reproduced the X-ray energies within +/- 3 eV uncertainty, while the uncertainties becomes as large as 10 eV for the PI spectra obtained from TES current pulses.
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Proceedings of International Symposium on Radiation Detectors and Their Uses (ISRD2016) 2016年11月14日 査読有り
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Journal of Low Temperature Physics 184(3-4) 688-693 2016年8月 査読有りWe present the latest update and progress on the future Japanese X-ray satellite mission Diffuse Intergalactic Oxygen Surveyor (DIOS). DIOS is proposed to JAXA as a small satellite mission, and would be launched with an Epsilon rocket. DIOS would carry on the legacy of ASTRO-H, which carries semiconductor-based microcalorimeters and is scheduled to be launched in 2016, in high-resolution X-ray spectroscopy. A 400-pixel array of transition-edge sensors (TESs) would be employed, so DIOS would also provide valuable lessons for the next ESA X-ray mission ATHENA on TES operation and cryogen-free cooling in space. We have been sophisticating the entire design of the satellite to meet the requirement for the Epsilon payload for the next call. The primary goal of the mission is to search for warm-hot intergalactic medium with high-resolution X-ray spectroscopy by detecting redshifted emission lines from OVII and OVIII ions. The results would have significant impacts on our understanding of the nature of "dark baryons," their total amount and spatial distribution, as well as their evolution over cosmological timescales.
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SPIE Proceedings 9905 2016年7月18日 査読有りDIOS (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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JOURNAL OF LOW TEMPERATURE PHYSICS 184(1-2) 91-96 2016年7月We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate (20 kcps), wide energy band (0.5-15 keV) and good energy resolution (10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 s which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed.
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Journal of Low Temperature Physics 184(1-2) 257-262 2016年7月 査読有り筆頭著者
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Journal of Low Temperature Physics 184(1-2) 454-459 2016年7月 査読有りA transition edge sensor (TES) microcalorimeter array as an X-ray sensor for a scanning transmission electron microscope system is being developed. The technical challenge of this system is a high count rate of 5000 counts/second/array. We adopted a 64 pixel array with a parallel readout. Common SQUID bias, and common TES bias are planned to reduce the number of wires and the resources of a room temperature circuit. The reduction rate of wires is 44 % when a 64 pixel array is read out by a common bias of 8 channels. The possible degradation of the energy resolution has been investigated by simulations and experiments. The bias fluctuation effects of a series connection are less than those of a parallel connection. Simple calculations expect that the fluctuations of the common SQUID bias and common TES bias in a series connection are and , respectively. We constructed 8 SQUIDs which are connected to 8 TES outputs and a room temperature circuit for common bias readout and evaluated experimentally. Our simulation of crosstalk indicates that at an X-ray event rate of 500 cps/pixel, crosstalk will broaden a monochromatic line by about 0.01 %, or about 1.5 eV at 15 keV. Thus, our design goal of 10 eV energy resolution across the 0.5-15 keV band should be achievable.
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Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 606(3) 233-237 2009年7月21日A super-fluid 4He target system has been successfully developed to experimentally search for deeply bound over(K, -) nuclei. From the experimental requirements, the amount of material around the liquid-helium target was drastically suppressed by using two approaches. One was to utilize the properties of super-fluid helium of extremely high thermal conductivity and low vapor pressure. The other was to develop a thin-walled CFRP vacuum chamber and a PET-based target cell. The wall thickness of the CFRP vacuum chamber was only 0.9 mm with the inner diameter of 310 mm. The dimensions of the target cell were 200 mm inner diameter and 150 mm length with the volume of 4.7 l, and it equipped 75 μ m thick beam windows made of a PET film. The present target system achieved a temperature of 1.3 K, and was stably operated throughout the experiment with the operational pressure below 40 mbar and a liquid-helium consumption rate of 45 l / day. © 2009 Elsevier B.V. All rights reserved.
MISC
7講演・口頭発表等
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19th International Workshop on Low Temperature Detectors 2021年7月28日
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Applied Superconductivity conference 2020 2020年11月3日
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13th Superconducting SFQ VLSI Workshop (SSV 2020) 2020年1月17日
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The 32nd International Symposium on Superconductivity 2019年12月3日
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18th International Workshop on Low Temperature Detectors 2019年7月25日
共同研究・競争的資金等の研究課題
7-
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 学術変革領域研究(A) 2020年11月 - 2025年3月
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日本学術振興会 科学研究費助成事業 若手研究 2020年4月 - 2024年3月
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日本学術振興会 科学研究費助成事業 学術変革領域研究(A) 2021年9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(萌芽) 2019年6月 - 2022年3月
