Faculty Profiles - SHIMIZU Hirohiko

Papers - SHIMIZU Hirohiko

Division display 461 - 475 of about 475 ／ All the affair displays >>

Development of Analog-to-Digital Converters toward Multi-Channel Detector System

YAMAZAKI Takuro, MIYAZIMA Shigeyuki, SATO Hiromi, SHIMIZU Hirohiko, FUJIMAKI Akira

IEICE technical report Vol. 106 ( 503 ) page： 7 - 12 2007.1

Publisher：The Institute of Electronics, Information and Communication Engineers

We have proposed a Cryostat-integrated Superconducting Tunneling Junction (STJ), Single Flux Quantum Analog to Digital (SFQ-A/D) converter. The sampling frequency of the A/D converter was measured to be 12.7GHz with an SNR of 23.7dB. The integration of the STJ and the A/D converter makes possible the development of a multi-channel detector system that can be used in the detection of X-rays and THz electromagnetic waves with higher efficiency. The detection of the STJ is accompanied with the formation of magnetic field in the Cryostat. This magnetic field is a major drawback to the proper functioning of the SFQ. We have implemented magnetic shielding in the Cryostat which has resulted into the normal functioning of the SFQ-A/D converter.

Small-angle neutron scattering (SANS) and dynamic light scattering (DLS) analyses of the initial aggregation process of tau by oxidative stress Reviewed

Sachio Naito, Susumu Ikeda, Hirohiko Shimizu, Hideki Mochizuki, Toru Yasuda, Yoshikuni Mizuno, Michihiro Furusaka, Satoru Fujiwara, Junichi Suzuki, keiji Wada

NEUROSCIENCE RESEARCH Vol. 58 page： S176 - S176 2007

Terahertz Imaging with a Superconducting Detector Array

ARIYOSHI Seiichiro, OTANI Chiko, DOBROIU Adrian, MATSUO Hiroshi, SATO Hiromi, TAINO Tohru, KAWASE Kodo, SHIMIZU Hirohiko M.

IEICE technical report Vol. 106 ( 403 ) page： 59 - 63 2006.12

Publisher：The Institute of Electronics, Information and Communication Engineers

Terahertz radiation is the electromagnetic range between radio waves and light waves. The imaging technology in this range is expected to generate many novel applications such as nondestructive inspection in commercial industries and security systems, medical diagnosis and astronomy. However, detector arrays for terahertz imaging are still under development, and large-scale and high-sensitivity detector arrays are acutely needed in many fields. We have designed, fabricated, and characterized a superconducting detector array using superconducting tunnel junctions (STJs) for terahertz imaging applications. The detector is composed of linearly distributed junctions placed on a superconducting microstrip line and is integrated on two wings of a log-periodic antenna. It is based on the photon-assisted tunneling process. In this paper, we explain the detector outline, performances and future prospects, and demonstrate terahertz imaging using the STJ linear array.

Superconducting Tunnel Junction with Substrate Absorber for THz waves Detector

TAINO Tohru, ISHII Hirokazu, YOSHIMURA Shota, MYOREN Hiroaki, TAKADA Susumu, OTANI Chiko, ARIYOSHI Seiichiro, SATO Hiromi, SHIMIZU Hirohiko, KAWASE Kodo

IEICE technical report Vol. 106 ( 403 ) page： 53 - 57 2006.12

Publisher：The Institute of Electronics, Information and Communication Engineers

Terahertz electromagnetic waves (THz waves) are very attractive features for various fields such as engineering, medical and sciences. We have developed superconducting tunnel junctions (STJs) for THz waves detector. Our proposed detectors utilize a substrate of the STJ. This is called phonon-mediated method. In this paper, we introduce the results of STJ for THz waves detector with phonon-mediate method.

Thermal neutron refraction by material prism Reviewed

Takenao Shinohara, Katsuya Hirota, Tomohiro Adachi, Kazuaki Ikeda, Hirohiko M. Shimizu, Jun-ichi Suzuki, Takayuki Oku

PHYSICA B-CONDENSED MATTER Vol. 385-86 page： 1232 - 1235 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Neutron refractive optics is a powerful tool for beam focusing due to its large effective aperture compared to reflective optics. Because neutron refraction angle decreases with shorter wavelengths, the application of refractive optics has been restricted to the cold neutron range. To expand the applicable wavelength range, we have developed a new refractive optics using an amorphous perfluoropolymer. This refractive optics is composed of several hundred thin sheets, each of which has a large number of grooves on the top surface. The refraction experiment was performed at the H-8 beam port of KENS, and it was confirmed that the thermal neutron beam can be refracted using this material prism. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2006.05.418

Web of Science

Scopus

Moire fringes of cold neutron with large divergence angle Reviewed

Kaoru Taketani, Haruhiko Funahashi, Yoshichika Seki, Masahiro Hino, Masaaki Kitaguchi, Yoshie Otake, Hirohiko M. Shimizu

PHYSICA B-CONDENSED MATTER Vol. 385-86 page： 1222 - 1224 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Moire fringes were observed as a bright and high-contrast image using a. neutron spin interferometer with a relatively divergent cold neutron beam at the MINE2 beam line of JRR-3M. The two spin states were selectively deflected with the relative angle in the range of 92-184 nrad on transmission through the magnetic field gradient in the range of 3.2-6.4 G/cm produced by a 5 cm long quadrupole electromagnet. We analyzed the result with a first-order calculation taking into account the finite beam divergence and found that the beam divergence is required to be less than the angular separation of individual Moire loci, for the observation of Moire fringes, and is not required to be less than the angular separation of the two beam paths. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2006.05.412

Web of Science

Scopus

Development of neutron Anger-camera detector based on flatpanel PMT Reviewed

Katsuya Hirota, Setsuo Satoh, Kenji Sakai, Takenao Shinohara, Kazuaki Ikeda, Kenji Mishima, Satoru Yamada, Takayuki Oku, Jun-ichi Suzuki, Michihiro Furusaka, Hirohiko M. Shimizu

PHYSICA B-CONDENSED MATTER Vol. 385-86 page： 1297 - 1299 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

A neutron scintillating detector and its data taking system have been developed for neutron scattering measurement. A 64-channel flatpanel photomultiplier is used for the Anger-camera method. The detection efficiency of gamma-ray background is very low in the use of the ZnS/(LiF)-Li-6 scintillator. The spatial resolution is less than 1 mm. The effective area of this detector is around 25 cm(2), and it is easy to expand it to a larger area with small dead space using the multi-photomultiplier tubes system. The fast DAQ system has 10-bit 100 MHz flash ADCs, FPGA chips and USB2.0 device. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2006.06.058

Web of Science

Scopus

Development of a multichannel parabolic guide for thermal neutron beam focusing Reviewed

Satoru Yamada, Takenao Shinohara, Hajime Sasao, Takayuki Oku, Jun-ichi Suzuki, Hideaki Matsue, Hirohiko M. Shimizu

PHYSICA B-CONDENSED MATTER Vol. 385-86 page： 1243 - 1246 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We have developed a multichannel parabolic guide for thermal neutron beam focusing. The guide was designed with multichannel structure, seven channels in the present case, to focus a neutron beam with wide cross section effectively. The multichannel structure is made with parabolically bent NiC/Ti supermirrors with critical reflection angles in = 3.0 and 3.6 times as much as that of nickel and thickness of 0.55 mm. The guide consists of two focusing devices with each length of 900 mm, which are separated by a gap of 150 mm for neutron beta decay experiments. The focal length of the guide is 995 mm away from the exit of the guide. The cross section of the guide is 90 x 20 mm(2) at the entrance and 52.3 x 12.1 mm(2) at the exit. The guide was installed at a thermal neutron beam line for neutron-induced prompt gamma-ray analysis (PGA) of JRR-3M in JAEA with straight supermirror guides with in = 3.0. Focusing properties of the parabolic guide were measured at the focal point with a CCD imaging system and we obtained a gain of 9.6 and 4.1 in peak flux compared with those in cases of using the vacuum tube and the straight guide, respectively. The parabolic guide has been successfully used to enhance the efficacy of PGA and have also applied to neutron beta decay experiments. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2006.05.420

Web of Science

Scopus

Development of measurement system of neutron beta decay Reviewed

Kenji Mishima, Satoru Yamada, Hiromi Sato, Katsuya Hirota, Takenao Shinohara, Takahiro Morishima, Jun-ichi Suzuki, Takayuki Oku, Hirohiko M. Shimizu

PHYSICA B-CONDENSED MATTER Vol. 385-86 page： 1219 - 1221 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Precise measurement of neutron beta decay allows determining the coupling constant of weak interaction independent of any nuclear structure. We have developed measurement system of neutron beta decay at a thermal neutron beamline in JRR-3, JAEA. By using coincidence technique of two kinds of detectors, we have succeeded in detecting the signal of neutron beta decay with S/N of 0.63 aud count rate of 0.40cps. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2006.05.414

Web of Science

Scopus

A magnetic neutron lens based on an extended Halbach-type permanent sextupole magnet Reviewed

Takayuki Oku, Satoru Yamada, Hajime Sasao, Jun-ichi Suzuki, Takenao Shinohara, Katsuya Hirota, Kazuaki Ikeda, Tsuyosi Tsuzaki, Yoshiaki Kiyanagi, Michihiro Furusaka, Hirohiko M. Shimizu

PHYSICA B-CONDENSED MATTER Vol. 385-86 page： 1225 - 1228 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We have developed a magnetic neutron lens (MNL) based on an extended Halbach-type permanent sextupole magnet. The effective aperture size is 30 mm in diameter and the length is 2400 mm. The sextupole magnetic field distribution vertical bar B vertical bar = (G/2) r(2) with the gradient coefficient G = 10,660 +/- 530 T/m(2) are generated inside the magnet, where r is the distance from the magnet center axis. The neutron-focusing property is investigated by using pulsed polarized neutrons. The obtained results are discussed in comparison with numerical simulation results. The application to the focusing-geometry small-angle neutron scattering experiments is discussed. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2006.05.416

Web of Science

Scopus

Focusing and polarized neutron ultra-small-angle scattering spectrometer (SANS-J-II) at Research Reactor JRR3, Japan Reviewed

Satoshi Koizumi, Hiroki Iwase, Jun-ichi Suzuki, Takayuki Oku, Ryuhei Motokawa, Hajime Sasao, Hirokazu Tanaka, Daisuke Yamaguchi, Hirohiko M. Shimizu, Takeji Hashimoto

PHYSICA B-CONDENSED MATTER Vol. 385-86 page： 1000 - 1006 2006.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

By employing focusing lenses of sextupole permanent magnet and biconcave MgF2 crystal, and high-resolution photomultiplier, SANS-J (pinhole small-angle neutron scattering spectrometer at research reactor JRR3, Tokai) was reconstructed to focusing and polarized neutron ultra-small-angle scattering spectrometer (SANS-J-II). Consequently, an accessible minimum wave number q(min) was improved from 3 x 10(-3) angstrom(-1) to 3 x 10(-4) angstrom(-1). Furthermore, we added He-3 sub-detectors with an analyzer super mirror at a sample position. With this setup, we perform polarization analysis at high q (> U angstrom(-1)) in order to quantitatively discriminate spin incoherent scattering from hydrogen or to perform spin contrast variation, by a dynamic nuclear polarization method (> 0.2 angstrom(-1)) (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2006.05.320

Web of Science

Scopus

Superconducting Detector Array for Terahertz Imaging Applications

Ariyoshi Seiichiro, Otani Chiko, Dobroiu Adrian, MATSUO Hiroshi, SATO Hiromi, TAINO Tohru, KAWASE Kodo, SHIMIZU Hirohiko M.

Japanese journal of applied physics. Pt. 2, Letters Vol. 45 ( 37 ) page： L1004 - L1006 2006.10

Superconducting detector array for terahertz imaging applications Reviewed

Seiichiro Ariyoshi, Chiko Otani, Adrian Dobroiu, Hiroshi Matsuo, Hiromi Sato, Tohru Taino, Kodo Kawase, Hirohiko M. Shimizu

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS Vol. 45 ( 37-41 ) page： L1004 - L1006 2006.10

Language：English Publishing type：Research paper (scientific journal) Publisher：INST PURE APPLIED PHYSICS

We designed, fabricated; and characterized a superconducting detector array for terahertz imaging applications. To evaluate the optical performance as an imaging array, we measured the spectral response of a 5-pixel linear array detector, and confirmed its sensitivity peaks to be at the same frequency within accuracy of one percent in the range of 0.65 THz. The frequency peaks are also in good agreement with a numerical calculation. This linear array was tested in the nondestructive imaging of a metallic pattern and an integrated-circuit card, and allowed the shortening of the total acquisition time. High fabrication yield of about 99% was achieved for single superconducting tunnel junctions, which led to 90% yield for the detectors.

DOI： 10.1143/JJAP.45.L1004

Web of Science

Scopus

Development of Terahertz Imaging Array Detector using Superconducting Tunnel Junctions

OTANI Chiko, ARIYOSHI Seiichiro, TAINO Tohru, KAWASE Kodo, SATO Hiromi, SHIMIZU Hirohiko M.

IEICE technical report Vol. 105 ( 629 ) page： 1 - 6 2006.2

Publisher：The Institute of Electronics, Information and Communication Engineers

Diagnosis using terahertz (THz) waves holds a great potential for various applications in fields such as medicine, biology, industry and agriculture because of its transmittance to soft matters as well as the good spatial resolution. In addition, the specific spectral absorption features can be also applicable for identifying materials inside opaque packages. In many such applications, imaging measurements with high sensitivity are required to obtain precisely the distribution of the transmitted THz waves of the measured objects and to distinguish the location of the materials of interest. We are developing two types of THz detectors using Nb-based superconducting tunnel junctions. In this paper, we introduce their detection principles, performances, and recent results including THz imaging.

Direct and Indirect Detection of Terahertz Waves using a Nb-based Superconducting Tunnel Junction Reviewed

Chiko Otani, Ran Nakano, Tohru Taino, Takayuki Shibuya, Seiichiro Ariyoshi, Shota Yoshimura, Hiroaki Myoren, Hiromi Sato, Hirohiko M. Shimizu, Susumu Takada, Kodo Kawase

7TH EUROPEAN CONFERENCE ON APPLIED SUPERCONDUCTIVITY (EUCAS'05) Vol. 43 ( 1 ) page： 1303 - 1306 2006

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IOP PUBLISHING LTD

We are developing a broadband THz detectors using Nb-based superconducting tunnel junctions. We found two components in a current signal for 1-2 THz pulse input. From the comparison of results obtained for the signals, the frequency response for the different size of STJs and the STJs fabricated on different substrate materials, we demonstrate that they correspond to photons absorbed with the superconductor electrode ( referred as 'direct' component) and phonons generated by photons absorbed with the substrate ( referred as 'phononmediated' component).

DOI： 10.1088/1742-6596/43/1/318

Web of Science

Scopus

　 PREV - NEXT 　

<SHIMIZU Hirohiko>

Papers - SHIMIZU Hirohiko