研究者業績
基本情報
- 所属
- 千葉大学 大学院理学研究院 物理学研究部門 特任研究員
- 学位
- 博士（理学）(千葉大学)
- 研究者番号
- 10573280
- J-GLOBAL ID
- 201801018344874900
- researchmap会員ID
- B000299091
主要な経歴
7-
2024年6月 - 現在
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2014年7月 - 2024年5月
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2009年5月 - 2014年6月
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2009年4月 - 2009年4月
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2007年4月 - 2009年3月
学歴
3-
2006年4月 - 2009年3月
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2004年4月 - 2006年3月
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2000年4月 - 2004年3月
委員歴
1-
2013年11月 - 2013年11月
論文
107-
Physics Letters B 843 138020-138020 2023年8月
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Journal of Physics: Conference Series 2374(1) 012114-012114 2022年12月6日 査読有り筆頭著者責任著者Around 1980, Japan’s High Energy Accelerator Research Organization, also known as the KEK laboratory, began developing silica aerogels as a Cherenkov radiator. In 1996, the high energy physics group at Chiba University, Japan, began aerogel research and development in collaborating with KEK. The design of state-of-the-art Cherenkov detectors is enabled by improving aerogel transparency. Simultaneously, ultrahigh- and ultralow-refractive-index aerogels were developed to bridge the gap in the available indices for identifying low- and high-momentum particles, respectively. These are and will be employed in ongoing and future particle physics experiments all over the world. We report the latest results from the aerogel development and applications to threshold-type and ring-imaging Cherenkov detectors.
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Physics Letters B 826 136913-136913 2022年3月 査読有り
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Astrobiology 21(12) 1451-1460 2021年8月27日 査読有りThe Tanpopo experiment was the first Japanese astrobiology mission on board the Japanese Experiment Module Exposed Facility on the International Space Station (ISS). The experiments were designed to address two important astrobiological topics, panspermia and the chemical evolution process toward the generation of life. These experiments also tested low-density aerogel and monitored the microdebris environment around low Earth orbit. The following six subthemes were identified to address these goals: (1) Capture of microbes in space: Estimation of the upper limit of microbe density in low Earth orbit; (2) Exposure of microbes in space: Estimation of the survival time course of microbes in the space environment; (3) Capture of cosmic dust on the ISS and analysis of organics: Detection of the possible presence of organic compounds in cosmic dust; (4) Alteration of organic compounds in space environments: Evaluation of decomposition time courses of organic compounds in space; (5) Space verification of the Tanpopo hyper-low-density aerogel: Durability and particle-capturing capability of aerogel; (6) Monitoring of the number of space debris: Time-dependent change in space debris environment. Subthemes 1 and 2 address the panspermia hypothesis, whereas 3 and 4 address the chemical evolution. The last two subthemes contribute to space technology development. Some of the results have been published previously or are included in this issue. This article summarizes the current status of the Tanpopo experiments.
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Astrobiology 21(12) 1461-1472 2021年8月27日 査読有り
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Planetary and Space Science 195 105141-105141 2021年1月 査読有り
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Progress of Theoretical and Experimental Physics 2020(12) 2020年12月15日 査読有り<title>Abstract</title> The emission of muonium ($\mu^+e^-$) atoms into vacuum from silica aerogel with laser ablation on its surface was studied with various ablation structures at room temperature using the subsurface muon beams at TRIUMF and Japan Proton Accelerator Research Complex (J-PARC). Laser ablation was applied to produce holes or grooves with typical dimensions of a few hundred $\mu$m to a few mm, except for some extreme conditions. The measured emission rate tends to be higher for larger fractions of ablation opening and for shallower depths. More than a few ablation structures reach the emission rates similar to the highest achieved in past measurements. The emission rate is found to be stable at least for a couple of days. Measurements of spin precession amplitudes for the produced muonium atoms and remaining muons in a magnetic field determine a muonium formation fraction of $(65.5 \pm 1.8)$%. The precession of the polarized muonium atoms is also observed clearly in vacuum. A projection of the emission rates measured at TRIUMF to the corresponding rates at J-PARC is demonstrated taking the different beam condition into account reasonably.
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Progress of Theoretical and Experimental Physics 2020(9) 2020年9月1日 査読有りTheAerogel Ring Imaging Cherenkov (ARICH) counter serves as a particle identification device in the forward end-cap region of the Belle II spectrometer. It is capable of identifying pions and kaons with momenta up to 4 GeV c-1 by detecting Cherenkov photons emitted in the silica aerogel radiator. After the detector alignment and calibration of the probability density function, we evaluate the performance of the ARICH counter using early beam collision data. Event samples of D*+ → D0π + (D0 → K- π + ) were used to determine the π(K) efficiency and the K(π) misidentification probability. We found that the ARICH counter is capable of separating kaons from pions with an identification efficiency of 93.5 ± 0.6% at a pion misidentification probability of 10.9 ± 0.9 %. This paper describes the identification method of the counter and the evaluation of the performance during its early operation.
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Journal of Instrumentation 15(7) 2020年7月 査読有りIn the Belle II experiment, an aerogel-based proximity focusing ring-imaging Cherenkov (ARICH) counter is used for charged particle identification (PID) in the forward end-cap region. The goal is to separate kaons from pions at above 4σ significance level for momenta up to 4 GeV/c, which is critical for the measurements of rare B decays and CP violation in B decays. Chrerenkov photons are emitted in aerogel tiles and 144-channel Hybrid Avalanche Photo Detector (HAPDs) are used as the photo-detectors. We utilize a two-layer aerogel design with different refractive indexes in a focusing configuration. In Phase 3 of the Belle II operation (from Apr. 2019), the ARICH system has been operating smoothly. The performance of particle identification with ARICH has been well validated and is in agreement with simulation.
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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 952 2020年2月 査読有りThe Belle II Aerogel Ring Imaging Cherenkov (ARICH) counter uses the angular distribution of Cherenkov photons emitted in silica aerogel to discriminate between charged pions and kaons. The Hybrid Avalanche Photo Detector (HAPD) is used as the photo-sensor, and is clearly the most critical component of the detector. HAPDs were installed into ARICH in July 2017, and ARICH was installed in the Belle II spectrometer in the end of 2017. During the Belle II beam commissioning in spring 2018, the performance of HAPDs was evaluated through measurements of the offset value, noise level and pulse height. Long term stability of the signal-to-noise ratio and the fraction of dead channel was also monitored. The signal-to-noise ratio exceeded 6, and the fraction of dead channels was less than 1%. The results of the performance evaluation and of the commissioning showed that the ARICH counter fulfills the requirements.
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Nuclear Instruments and Methods in Physics Research A 952 161879 2020年2月 査読有り筆頭著者責任著者
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Springer Proceedings in Physics 238 705-708 2020年The current experimental information about interactions between the (formula presented) meson and nucleon (N) is not enough to understand the nature of the (formula presented) meson in a nucleus. We installed a new spectrometer and started an experiment to determine the (formula presented) scattering parameters at the Research Center for Electron Photon Science, Tohoku University. We present the current status of the experiment.
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Life 9(4) 2019年12月Space missions using probes to return dust samples are becoming more frequent. Dust collectors made of silica aerogel blocks are used to trap and bring back extraterrestrial particles for analysis. In this work, we show that it is possible to detect traces of adenine using surface-enhanced Raman spectroscopy (SERS). The method was first optimized using adenine deposition on glass slides and in glass wells. After this preliminary step, adenine solution was injected into the silica aerogel. Finally, gaseous adenine was successfully trapped in the aerogel. The presence of traces of adenine was monitored by SERS through its characteristic bands at 732, 1323, and 1458 cm−1 after the addition of the silver Creighton colloid. Such a method can be extended in the frame of Tanpopo missions for studying the interplanetary transfer of prebiotic organic compounds of biological interest.
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Life (Basel, Switzerland) 9(4) 2019年10月26日Space missions using probes to return dust samples are becoming more frequent. Dust collectors made of silica aerogel blocks are used to trap and bring back extraterrestrial particles for analysis. In this work, we show that it is possible to detect traces of adenine using surface-enhanced Raman spectroscopy (SERS). The method was first optimized using adenine deposition on glass slides and in glass wells. After this preliminary step, adenine solution was injected into the silica aerogel. Finally, gaseous adenine was successfully trapped in the aerogel. The presence of traces of adenine was monitored by SERS through its characteristic bands at 732, 1323, and 1458 cm-1 after the addition of the silver Creighton colloid. Such a method can be extended in the frame of Tanpopo missions for studying the interplanetary transfer of prebiotic organic compounds of biological interest.
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Nuclear Instruments and Methods in Physics Research A 923 38-44 2019年4月 査読有り
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Geochemical Journal 53(1) 53-67 2019年 査読有り© 2019 by The Geochemical Society of Japan. The Tanpopo mission is an astrobiology space experiment at the Japanese Experiment Module (JEM) 'Kibo' on the International Space Station (ISS). One of the sub-divided themes of the Tanpopo mission is for the intact capture of organic bearing micrometeoroids in low Earth orbit using ultralow density silica aerogel (0.01 g/cm 3 ). In order to evaluate damage to organic matter in micrometeoroids during hyper velocity impacts into the aerogel, Murchison meteorite powdered samples, analogs of organic bearing micrometeoroids, were fired into flight-grade silica aerogel (0.01 g/cm 3 ) using a two-stage light-gas gun with velocities of 4.4 and 5.9 km/s. The recovered Murchison grains were analyzed using scanning transmission X-ray microscopy/X-ray absorption near edge structure (STXM/XANES), transmission electron microscopy (TEM) and nanoscale secondary ion mass spectrometry (NanoSIMS). TEM observation did not show significant modifications of the recovered Murchison grains. Carbon-XANES spectra, however, showed a large depletion of the organic matter after the 5.9 km/s impact, but no such effects nor any significant hydrogen isotopic fractionation were observed after the 4.4 km/s impact.
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Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 901 1-5 2018年9月1日 査読有りThe J-PARC E36 experiment is searching for lepton universality violation with a stopped kaon beam by measuring the ratio of the K+ decay widths Γ(Ke2)∕Γ(Kμ2)=Γ(K+→e+νe)∕Γ(K+→μ+νμ). Since the radiative K+→e+νeγ decays are backgrounds to be removed in this measurement, the radiated γ rays were detected in a CsI(Tl) calorimeter. The energy calibration for the 768 CsI(Tl) modules was performed using mono-chromatic μ+s from the Kμ2 decays. The delayed e+ signals from the muon decays were required in order to improve the S/N ratio of the Kμ2 peak by suppressing background events. In addition, a new energy calibration method of the CsI(Tl) calorimeter using stopped cosmic muons has been established.
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Springer Proceedings in Physics 212 46-49 2018年A slow control system for the Aerogel Ring Imaging Cherenkov (ARICH) counter in the Belle II experiment was newly developed based on the development framework of the Belle II DAQ software. The ARICH detects Cherenkov photons by using Hybrid Avalanche Photo Detectors (HAPDs). Each HAPD has 144 pixels to be readout and requires 6 power supply (PS) channels, therefore a total of 2520 PS channels and 60480 pixels have to be configured and controlled. Graphical User Interfaces (GUIs) are also implemented to ease the detector operation. The slow control system was used in an integration test with cosmic rays and we confirmed it works in practical operation.
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Springer Proceedings in Physics 213 315-318 2018年We report behavior of Hybrid Avalanche Photon Detectors (HAPDs), which were newly developed for Aerogel Ring Imaging Cherenkov detector (ARICH) counter that will be installed in the endcap region of the Belle II detector, in the magnetic field. Since HAPDs are used in a 1.5 T magnetic field in the Belle II detector, we have tested 520 HAPDs from the mass production in the magnetic field. We observed anomalously large pulses in the magnetic field in many HAPDs. The main adverse effect of these large pulses is the induction of a short dead time of the readout electronics after each pulse. We performed several studies to understand the mechanism generating large pulses.
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Springer Proceedings in Physics 212 270-274 2018年The Aerogel Ring Imaging Cherenkov (ARICH) counter is an upgrade of the forward endcap particle identification device in the upcoming Belle II experiment to secure 4σ separation of charged kaons and pions up to momenta of 3.5 GeV. Developments and productions of Silica aerogel radiator, Hybrid Avalanche Photo Detector (HAPD) and its readout electronics, key components of the ARICH counter, are done while surrounding subsystems; a power supply, a readout slow control and a LED light injection system are in operation. And then construction of the ARICH counter is ongoing in parallel to cosmic ray test. Details of the detector components with construction status are described and the test operation are discussed in the letter.
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Springer Proc.Phys. 212 253-256 2018年 査読有り筆頭著者責任著者
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日本航空宇宙学会誌 66(6) 173‐179(J‐STAGE)-179 2018年「たんぽぽ計画」では国際宇宙ステーション（ISS）曝露部で微生物を採集することによって，この高度での微生物の存在可能性を検討する．また，微生物が宇宙空間で，どの程度の時間生存できるのかを，微生物を宇宙環境に曝露することによって調べる．生命の起原以前に，宇宙空間で合成された有機物が宇宙塵とともに地球に飛来した可能性がある．そこで，ISS上で宇宙塵の採集を行い，有機物を解析する．地球周辺には，スペースデブリが多量に蓄積している．本計画ではそのモニターも行う．これらの実験のために0.01g/cm3という超低密度のエアロゲルを開発した．これは今後の宇宙における様々な高速衝突微粒子採集に利用可能である．曝露試料は1年間，2年間，3年間曝露の後に地上に持ち帰り解析する．すでに，1年目と2年目の試料が地上に帰還して分析が行われている．1年間曝露した微生物の生存が確認された．
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Acta Physica Polonica B 48(10) 1801-1806 2017年10月Among the two-body dynamics of the meson-nucleon systems, the attractive interaction between the eta meson and nucleon is not well-known. A new photoproduction experiment is planned for the determination of the low-energy scattering parameters between the eta meson and nucleon at the Research Center for Electron Photon Science, Tohoku University. The emitted proton is measured at 0° for eta photoproduction on the deuteron at the incident energy of 0.94 GeV, which gives small relative momentum between the eta meson and neutron in the final state to increase rescattering probability. The kinematics is found to have a good resolving power of the scattering length and effective range. In this contribution, the current status of the new experiment is presented.
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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 847 136-141 2017年3月 査読有りA spiral fiber tracker (SFr) has been designed and produced for the J-PARC E36 experiment as an element of the tracking system for conducting a high-resolution momentum measurement of charged particles from kaon decays. A novel technique to wind the pre-made fiber ribbons spirally was employed for the configuration with four detector layers made of 1 mm diameter plastic scintillating fibers. Good position alignment and sufficiently high detection efficiency for charged particles with minimum ionizing energy were confirmed in cosmic ray test. The tracker was successfully used in the E36 experiment.
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ASTROBIOLOGY 16(5) 363-376 2016年5月 査読有りThe Tanpopo mission will address fundamental questions on the origin of terrestrial life. The main goal is to test the panspermia hypothesis. Panspermia is a long-standing hypothesis suggesting the interplanetary transport of microbes. Another goal is to test the possible origin of organic compounds carried from space by micrometeorites before the terrestrial origin of life. To investigate the panspermia hypothesis and the possible space origin of organic compounds, we performed space experiments at the Exposed Facility (EF) of the Japanese Experiment Module (JEM) of the International Space Station (ISS). The mission was named Tanpopo, which in Japanese means dandelion. We capture any orbiting microparticles, such as micrometeorites, space debris, and terrestrial particles carrying microbes as bioaerosols, by using blocks of silica aerogel. We also test the survival of microbial species and organic compounds in the space environment for up to 3 years. The goal of this review is to introduce an overview of the Tanpopo mission with particular emphasis on the investigation of the interplanetary transfer of microbes. The Exposed Experiment Handrail Attachment Mechanism with aluminum Capture Panels (CPs) and Exposure Panels (EPs) was exposed on the EF-JEM on May 26, 2015. The first CPs and EPs will be returned to the ground in mid-2016. Possible escape of terrestrial microbes from Earth to space will be evaluated by investigating the upper limit of terrestrial microbes by the capture experiment. Possible mechanisms for transfer of microbes over the stratosphere and an investigation of the effect of the microbial cell-aggregate size on survivability in space will also be discussed.
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JOURNAL OF SUPERCRITICAL FLUIDS 110 183-192 2016年4月 査読有り筆頭著者責任著者This study presents the development of large-area (18 cm x 18 cm x 2 cm), high refractive index (n similar to 1.05) hydrophobic silica aerogel tiles for use as Cherenkov radiators. These transparent aerogel tiles will be installed in a Cherenkov detector for the next-generation accelerator-based particle physics experiment Belle II, to be performed at the High Energy Accelerator Research Organization (KEK) in Japan. Cracking has been eliminated from the prototype aerogel tiles by improving the supercritical carbon dioxide (scCO(2)) extraction procedure when drying the wet gel tiles. Finally, a method of mass-producing aerogel tiles for the actual detector was established. It was confirmed that the experimentally manufactured aerogel tiles meet the required optical and hydrophobic characteristics and have a uniform tile density. (C) 2015 Elsevier B.V. All rights reserved.
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PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS 2016(3) 033H01 2016年3月 査読有りWe have developed a new type of particle identification device, called an aerogel ring imaging Cherenkov (ARICH) counter, for the Belle II experiment. It uses silica aerogel tiles as Cherenkov radiators. For detection of Cherenkov photons, hybrid avalanche photo-detectors (HAPDs) are used. The designed HAPD has a high sensitivity to single photons under a strong magnetic field. We have confirmed that the HAPD provides high efficiency for single-photon detection even after exposure to neutron and gamma-ray radiation that exceeds the levels expected in the 10-year Belle II operation. In order to confirm the basic performance of the ARICH counter system, we carried out a beam test at the using a prototype of the ARICH counter with six HAPD modules. The results are in agreement with our expectations and confirm the suitability of the ARICH counter for the Belle II experiment. Based on the in-beam performance of the device, we expect that the identification efficiency at 3.5GeV/c is 97.4% and 4.9% for pions and kaons, respectively. This paper summarizes the development of the HAPD for the ARICH and the evaluation of the performance of the prototype ARICH counter built with the final design components.
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY 77(2) 325-334 2016年2月 査読有り筆頭著者責任著者The fabrication of an ultralow-density hydrophobic silica aerogel for the intact capture cosmic dust during the Tanpopo mission is described. The Tanpopo experiment performed on the International Space Station orbiting the Earth includes the collection of terrestrial and interplanetary dust samples on a silica aerogel capture medium exposed to space for later ground-based biological and chemical analyses. The key to the mission's success is the development of high-performance capture media, and the major challenge is to satisfy the mechanical requirements as a spacecraft payload while maximizing the performance for intact capture. To this end, an ultralow-density (0.01 g cm(-3)) soft aerogel was employed in combination with a relatively robust 0.03 g cm(-3) aerogel. A procedure was also established for the mass production of double-layer aerogel tiles formed with a 0.01 g cm(-3) surface layer and a 0.03 g cm(-3) open-topped, box-shaped base layer, and 60 aerogel tiles were manufactured. The fabricated aerogel tiles have been demonstrated to be suitable as flight hardware with respect to both scientific and safety requirements. [GRAPHICS] .
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Nuclear Instruments and Methods in Physics Research A 795 206-212 2015年9月 査読有り筆頭著者責任著者
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ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES 45(1-2) 225-229 2015年6月 査読有り筆頭著者責任著者In this paper, we report the progress in developing a silica-aerogel-based cosmic dust capture panel for use in the Tanpopo experiment on the International Space Station (ISS). Previous studies revealed that ultralow-density silica aerogel tiles, comprising two layers with densities of 0.01 and 0.03 g/cm(3) developed using our production technique, were suitable for achieving the scientific objectives of the astrobiological mission. A special density configuration (i.e., box framing) aerogel with a holder was designed to construct the capture panels. Qualification tests for an engineering model of the capture panel as an instrument aboard the ISS were successful. Sixty box-framing aerogel tiles were manufactured in a contamination-controlled environment.
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Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 779 13-17 2015年4月 査読有り© 2015 Elsevier B.V. All rights reserved. The J-PARC E36 experiment will search for a violation of lepton universality by a precise measurement of the ratio of the kaon decay widths RK=Γ(K+→e+ν)/Γ(K+→μ+ν). Charged particles will be identified by the combination of three independent systems: a lead-glass Cherenkov counter, an aerogel Cherenkov counter, and a time-of-flight measurement. The performance of the lead-glass Cherenkov counter was investigated with e+, μ+, and π+ beams in the relevant momentum region from the K+ decays. By using a polyethylene degrader to slow down the beam momentum in front of the lead-glass block, we succeeded in reducing the muon mis-identification probability down to 5% while maintaining a high e+ detection efficiency of 98%.
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Impact Frequency Estimate of Micron-sized Meteoroids and Debris on Tanpopo Capture Panels on the ISSPROCEEDINGS OF THE 2015 HYPERVELOCITY IMPACT SYMPOSIUM (HVIS 2015) 103 334-340 2015年 査読有りThis study is a part of 'Tanpopo' mission, which is to be mounted on the Exposure Facility of the Japanese "Kibo" Module of the International Space Station. The purpose of this study is to comparing the impact frequency that is predicted from the debris environment model and the impact craters on the exposed instrument. There are two approaches to achieve this plan. The first is to predict the impact frequency of the micron-sized debris onto the Tanpopo capture panels which is exposed to space. The second is to establish methods for calculating key parameters in relation to impacting debris particles from excavated craters on the capture panel material. The debris impact frequency on the capture panels was predicted using the impact-risk analysis tool. It was found that impact of particles of 10 mu m or less in diameter was expected on the panels. Additionally, the relationship between the debris impact energy and crater was also derived by hypervelocity impact experiments. It was found that regardless of the projectile materials and impact speed, the relationship between the impact energy and the crater volume is nearly proportional. (C) 2015 Published by Elsevier Ltd.
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JPS Conf. Proc. 8 2015年 査読有り
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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 766 212-216 2014年12月 査読有り筆頭著者責任著者This paper presents recent progress in the development and mass production of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter, which will be installed in the forward end cap of the Belle II detector. The proximity-focusing A-RICH system is especially designed to identify charged kaons and pions. The refractive index of the installed aerogel Cherenkov radiators is approximately 1.05, and we aim for a separation capability exceeding 4a at momenta up to 4 GeV/c. Large-area aerogel Liles (over 18 x 18 x 2 cm(3)) were first fabricated in Lest productions by pin drying in addition to conventional methods. We proposed to fill the large end-cap region (area 3.5 m2) with 124 water-jet-trimmed fan-shaped dual-layer-focusing aerogel combinations of different refractive indices (1.045 and 1.055). Guided by the test production results, we decided to manufacture aerogels by the conventional method and are currently proceeding with mass production. In an electron beam Lest undertaken at the DESY, we confirmed that the Klif separation capability of a prototype A-RICH counter exceeded 4c at 4 GeWc. (C) 2014 Elsevier By. All rights reserved.
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PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS 2014(9) 091C01 2014年9月 査読有りEmission of muonium (mu(+)e(-)) atoms from a laser-processed aerogel surface into vacuum was studied for the first time. Laser ablation was used to create hole-like regions with diameter of about 270 mu m in a triangular pattern with hole separation in the range of 300-500 mu m. The emission probability for the laser-processed aerogel sample is at least eight times higher than for a uniform one.
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Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan 12(ists29) Pk_29-Pk_34 2014年8月 査読有り筆頭著者責任著者
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ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES 44(1) 43-60 2014年2月 査読有りWe have proposed an experiment (the Tanpopo mission) to capture microbes on the Japan Experimental Module of the International Space Station. An ultra low-density silica aerogel will be exposed to space for more than 1 year. After retrieving the aerogel, particle tracks and particles found in it will be visualized by fluorescence microscopy after staining it with a DNA-specific fluorescence dye. In preparation for this study, we simulated particle trapping in an aerogel so that methods could be developed to visualize the particles and their tracks. During the Tanpopo mission, particles that have an orbital velocity of similar to 8 km/s are expected to collide with the aerogel. To simulate these collisions, we shot Deinococcus radiodurans-containing Lucentite particles into the aerogel from a two-stage light-gas gun (acceleration 4.2 km/s). The shapes of the captured particles, and their tracks and entrance holes were recorded with a microscope/camera system for further analysis. The size distribution of the captured particles was smaller than the original distribution, suggesting that the particles had fragmented. We were able to distinguish between microbial DNA and inorganic compounds after staining the aerogel with the DNA-specific fluorescence dye SYBR green I as the fluorescence of the stained DNA and the autofluorescence of the inorganic particles decay at different rates. The developed methods are suitable to determine if microbes exist at the International Space Station altitude.
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AIAA AVIATION 2014 -AIAA Atmospheric Flight Mechanics Conference 2014年 査読有りLately, a Mars Aero-yby Sample Collection (MASC) mission has been proposed at Japan Aerospace Exploration Agency (JAXA). For the purpose of improving the feasibil- ity of MASC, the development of a sampling system during ying in the Martian dusty atmosphere and the optimization of its system for sampling conditions are crucial. In this work, we have developed aerogel sample collector laboratory models using silica and carbon aerogels as well as a sample extraction and analysis system for particles smaller than 10 _m. The performance of these sample collector models has been investigated by carrying out arcjet heating and light-gas-gun experiments. In consequence, the superiority of the carbon aerogel against heating compared to silica aerogel has been validated. Also, estimated Martian dust particles were successfully captured by the sample collectors, and the particle extraction system has been demonstrated for 5 μm-class samples.
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Trans. JSASS Aerospace Tech. Japan 12(ists29) Tk_49-Tk_55 2014年 査読有り
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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 732 371-374 2013年12月 査読有りFor the Belle II spectrometer we are preparing a proximity focusing RICH with aerogel as the radiator. It will be positioned in the forward direction of the spectrometer in the small space between the drift chamber and the electromagnetic calorimeter inside a strong magnetic field of 1.5 T. The Hybrid Avalanche Photo Diode used as a photo sensor, is able to detect single photons with a high efficiency, can operate in the magnetic field and is resistant to the expected neutron and gamma fluxes in the detector. By detecting more than 11 photons per incident 4 GeV/c pion, with 15 mrad single photon Cherenkov angle resolution, the designed aerogel RICH should enable an efficient separation of kaons from pions in the wide range of particle momenta from 0.5 GeV/c up to 4 GeV/c. (C) 2013 Elsevier B.V. All rights reserved.
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IEEE Nuclear Science Symposium Conference Record 2013年 査読有りIn March 2011, a large earthquake hit Japan and damaged seriously. Because of this disaster, accidents was happen at Fukushima No.1 nuclear power plant and many radioisotope has been released into the Japanese coast of the Pacific Ocean. We pay attention to 90Sr and propose the method to detect it in an hour. © 2013 IEEE.
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2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) 2013年 査読有りThe depth of interaction (DOI) PET detector is one way to achieve high resolution image by determining the depth where most of gamma ray energy is deposited in a scintillator. Because a 2D or 3D profile is obtained for each element, the large amount of data makes the image reconstruction difficult. In this study, we propose a new type of DOI PET detector and estimate a photon yield of a channel and the cost of the materials for manufacturing. An element block of the detector consists of 16 slices of inorganic scintillators, one flat panel PMT, wave length shifting fibers and 256 ch position sensitive (PS) PMT per six element blocks. The main principals of this detector are the condition of total reflection and wave length shifter material. We can see the position where photoelectric effect occurred using the scintillation light not satisfying the condition of total reflection. The photons from the position are transmitted to a channel of PS PMT by wave length shifting fibers. With this detector it is expected to achieve +/- 1.3 mm resolution for x direction, +/- 1.5 mm resolution for y and z direction. Ideally we can get the information of the position out of a 50 X 50 X 24 mm(3) element from only 40 bits signal. Unfortunately we could not perform experimented evaluation owing to delay of delivery of the GSO slices from a company.
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2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) 2013年 査読有りIn March 2011, a large earthquake hit Japan and damaged siriously. Because of this disaster, accidents was happen at Fukushima No. 1 nuclear power plant and many radioisotope has been released into the Japanese coast of the Pacific Ocean. We pay attention to 90Sr and propose the method to detect it in an hour.
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2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) 2013年 査読有りWe are developing a multi-purpose aerogel Cherenkov counter (M-ACC). M-ACC is a particle identification (PID) device which works in a narrow space and can cover large area with arbitrary shapes. It can also function in a magnetic field. M-ACC has a light guide comprising wavelength shifting fibers (WLSF), and its application is pi/K identification in high-energy physics experiments,,beta-ray detection from radioisotope, and so on. We concretely propose a design of M-ACC for LEPS II project. We produced a prototype M-ACC, and measured the performance of it in the LEPS beam line.
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51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 2013年 査読有りNew sample collector system is proposed for the sample return mission on Mars under consideration in JAXA. The new sample collector consists of silica aerogels and carbon aerogels to compensate each other for their unique characteristics. In order to demonstrate the concept and verify the technical difficulties, several experiments are conducted in this study. Heating tests are carried out to see whether the sample collector can be applied to the aerodynamic heating environment. From the heating tests, no significant difference is observed in the sample collector between before and after heating. Unlike the silica aerogels, the surface alteration that makes the dust capturing difficult are not observed on the surface of carbon aerogels. The light gas gun experiments are also performed to simulate the dust particle capturing by using the sample collector. It is confirmed from the study that 10-30μm dust particles with the relative velocity of 4km/s could be successfully captured by using the present sample collector. After the light gas gun experiments, several particles are picked out from the sample collector by using a nano-manipulating system. The SEM and EDS analysis is successfully performed for particles picked out from the sample collectors. Consequently, it is concluded that the dust particles would be analyzed by the present analysis scheme, if the present sample collector would be applied to the MASC mission. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
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2013 IEEE Nuclear Science Symposium and Medical Imaging Conference and Workshop on Room-Temperature Semiconductor Detectors 2013年 筆頭著者責任著者
主要なMISC
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日本物理学会講演概要集 72 95-95 2017年<p>π/K識別を目的として、Belle II測定器のエンドキャップに実装されるRICH検出器のシリカエアロゲル輻射体を開発した。高い透明度をもち、大面積（18 cm × 18 cm × 2 cm）で高屈折率（1.045と1.055）のエアロゲルの量産に成功した。疎水性エアロゲルをウォータージェットカッターで扇形に成形し、円筒形構造体の124のセルに2つの屈折率を組み合わせて組み込んだ。本講演では、エアロゲルの光学測定と組み込みの結果を報告する。</p>
共同研究・競争的資金等の研究課題
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日本学術振興会 科学研究費助成事業 基盤研究(C) 2021年4月 - 2024年3月
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日本学術振興会 科学研究費補助金 基盤研究(A) 2019年4月 - 2022年3月
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日本学術振興会 科学研究費助成事業 基盤研究(C) 2018年4月 - 2021年3月
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日本学術振興会 科学研究費補助金 基盤研究(B) 2016年4月 - 2019年3月
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日本学術振興会 科学研究費補助金 基盤研究(B) 2014年4月 - 2018年3月