M. Takasaki

High Energy Accelerator Research Organization, Tsukuba, Ibaraki, Japan

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Publications (116)133.45 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: An electrostatic separator is one of the key elements of a secondary beam line at the Hadron experimental hall of J-PARC. It generates a transverse electric field along the beam axis to separate particles of the same momentum by their mass differences. Two beam lines for charged secondary particles, K1.8 and K1.1BR, are constructed, to provide kaon beams with less contamination of pions. Three experimental areas, K1.8, K1.8BR and K1.1BR are available for nuclear and particle physics experiments. Two 6-m-separators and a 2-m-separator of a Wien filter type are installed for the K1.8 and the K1.1BR beam lines.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 12/2013; · 1.19 Impact Factor
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    ABSTRACT: J-PARC Hadron Experimental Facility is designed to carry out a variety of particle and nuclear physics experiments with intense secondary particles generated by 750 kW proton beams. The first construction stage including the experimental hall, the primary beam line, and one secondary beam line (K1.8BR) has been completed at the end of December 2008. In order to handle the high intensity primary beam safely, we have developed many special devices working under severe radiation environment. The present article reports the current status of the Hadron Experimental Facility in detail.
    International Journal of Modern Physics E 01/2012; 19(12). · 0.63 Impact Factor
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    ABSTRACT: The new facility J-PARC has been constructed in Tokai, Japan. It aims at providing intense proton beams of 750 kW for next-generation particle and nuclear physics experiments. The Hadron Experimental Hall (HD-hall) is one of the two facilities at the J-PARC Main Ring and utilizes various secondary particles produced by the slowly extracted primary proton beam. We have constructed two charged and one neutral secondary beam lines. The K1.8 beam line transports separated charged secondaries with the maximum momentum of 2 GeV/c. Secondary particles are purified by two electrostatic separators (ESSs). The K1.8BR beam line is branched from the K1.8 at the bending magnet downstream of the first ESS. The K1.8BR delivers separated charged beams with the momentum up to 1.2 GeV/c. On January 27th, 2009, the first beam was successfully extracted to the HD-hall and transported to the beam dump. The first secondary beam extraction to the K1.8BR beam line succeeded in February 2009. The beam commissioning of the K1.8 and KL beam lines started in October 2009.
    Journal of Physics Conference Series 09/2011; 312(5):052027.
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    ABSTRACT: The target station in the hadron experimental facility at J-PARC consists of a production target and a huge vacuum chamber in which several secondary-beam-line magnets can work. This vacuum chamber system aims to remove the vacuum beam pipe from the magnet gap, because the cooling of the beam pipe is the most serious problem in the high intensity beam facility. We have developed indirectly cooled radiation-resistant magnets for the hadron target station. Their coils are made of solid-conductor type mineral-insulation cables and stainless-steel water pipes. They have the great advantages that electric circuits can be completely independent of water pass. The mechanical strength and the insulation performance of the coil are significantly improved also because the insulation water pipes can be avoided from the water pass. A C-type sector dipole and a figure-8-type quadrupole magnet have been fabricated by using indirectly cooled radiation-resistant magnet technology, and installed in the vacuum chamber. We have succeeded to operate them in vacuum stably with the current of DC 1000 A by improving the end structure of the MIC coils and increasing their emissivity. These magnets have been used for the real beam operation without any serious problems.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: More than 50 radiation-resistant electromagnets were constructed for the primary proton and the secondary particle beam lines of the Hadron Experimental Hall of Japan Proton Accelerator Research Complex (J-PARC). The main radiation-resistant technologies we employed were the Polyimide-resin Insulation conductor for magnets at the relatively low radiation exposure and the Mineral Insulation Cable for magnets at the seriously high radiation environment. The remote handling and maintenance scheme of radiation-resistant magnets for seriously high radiation environment was developed also based on the Chimney magnet technology and applied to magnets near the production target in the Hadron Hall. On January 27th 2009, the first proton beam was successfully introduced to the Hadron Hall from the main accelerator of J-PARC, i.e. 50 GeV Proton Synchrotron. On February 10th, the secondary particles were extracted to the experimental area of the Hadron Hall through the secondary particle beam line. No serious problem happened on magnets of both primary proton and the secondary particle beam lines until the end of the beam operation scheduled on February 26th .
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
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    ABSTRACT: J‐PARC Hadron Experimental Facility is designed as a multi‐purpose experimental facility for particle and nuclear physics experiments using high‐intensity secondary particles (Kaons, pions, and so on) produced by 50 GeV‐15 μA (750 kW) primary proton beams. Currently, three secondary beam lines (K 1.8 BR, K 1.8, and KL) have been constructed. The first beam extraction from 50 GeV proton synchrotron was on January 27th, 2009, and the beam commissioning of the primary and secondary beam lines are on going. The present article reports construction status and beam commissioning of Hadron Experimental Facility in detail.
    AIP Conference Proceedings. 05/2010; 1235(1):301-307.
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    ABSTRACT: The chromosomal translocation t(11;22)(q24;q12) generates the EWS-Fli1 fusion gene, which contributes to the development of Ewing Family Tumors (EFTs). Although p53 mutations are found only in 5-20% of EFTs, the p53 pathway is thought to be abrogated in EFTs. The role of EWS-Fli1 in the p53 pathway in the tumor is still poorly understood. In this study, using immunoprecipitation and co-localization, we show that EWS-Fli1 interacts with p53 within the nucleus in vivo. The introduction of EWS-Fli1 resulted in significant reduction of promoter activities and mRNA levels of p21 and mdm2, meanwhile it canceled p53-dependent growth suppression. In contrast, knockdown of EWS-Fli1 expression mediated by small interfering RNAs (siRNA) also augmented the induction of p21 and mdm2 in response to DNA damage. Furthermore, using serial deletion constructs of the EWS-Fli1 fusion protein, we determined that EWS-Fli1 binding to p53 as well as inhibition of p21 and mdm2 promoter activities was mediated by its N-terminal domain (amino acid residues 65-109). These observations suggest that the N-terminal region of EWS-Fli1 might associate with p53 and impair its transcriptional activity, subsequently inhibiting the expression of its downstream genes. These results might provide new insight into the oncogenesis of EFTs by EWS-Fli1 via the inhibition of p53 function.
    Cancer letters 02/2010; 294(1):57-65. · 5.02 Impact Factor
  • Strangeness in Nuclear and Hadronic Systems - SENDAI08 - The Sendai International Symposium; 01/2010
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    ABSTRACT: This study evaluated the accuracy of an image-free navigated total knee arthroplasty (TKA) system when used to align deformed tibia bone models. The accuracy was assessed in normal, 10 degrees varus, 20 degrees varus, 10 degrees valgus, and 20 degrees valgus tibia bone models (a total of five tibial models) by direct measurement of the navigated cutting guide. The mean angular errors in the tibial mechanical axes of the normal, 10 degrees, and 20 degrees varus models, respectively, were 0.0 degree, 0.7 degree varus, and 2.4 degrees varus. Thus, the errors seen with the two varus models were significantly larger than that associated with the normal model. The mean angular errors were 0.1 degree varus and 0.4 degree valgus in the 10 degrees and 20 degrees valgus models, respectively. These errors were not significantly different from those obtained with the normal model. These results suggest that in varus-deformed knees, image-free navigation has a tendency to cut the tibia in varus. This fact is considered to be one of the reasons for the lack of superiority of TKA alignment in severely deformed knees when using image-free navigation. Therefore, special attention must be paid when using image-free navigation TKA in such cases.
    Knee Surgery Sports Traumatology Arthroscopy 10/2009; 18(6):763-8. · 2.68 Impact Factor
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    ABSTRACT: The high intensity proton accelerator facility J-PARC is now in its final stage of construction. Soon intense primary proton beams will be slowly extracted to an experimental hall (HD-hall) and transported to a production target. Since the radiation level around the target will be very high, the beam line tunnel needs to be surrounded by 2.5 m-5 m thick concrete shields in the HD-hall. Radiation resistant magnets for handling high intensity beams are buried inside these thick concrete shields. This structure, however, brought us a problem of leading electric power lines to the magnets. For a solution to this problem, we have developed water cooled bus ducts penetrating radiation shield. These bus ducts enable us to connect the power supplies placed outside the shields to the magnets in the shortest power line length without any deterioration of protection ability of radiation shielding. The maximum power capacity of the bus duct is over 5000 A. The bus ducts plays an important part in our radiation resistant magnet system.
    IEEE Transactions on Applied Superconductivity 07/2008; · 1.20 Impact Factor
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    ABSTRACT: A series of construction works of the radiation resistant magnets for the Japan Proton Accelerator Research Complex (J-PARC) external beam facilities is now at the production and installation stage. The main accelerator of J-PARC is the 50 GeV proton synchrotron (50 GeV-PS). The designed intensity of the extracted proton beam from the 50 GeV-PS is 15 muA, i.e. a beam power of 750 kW. Then the radiation-resistant magnets are the key apparatus to construct the external beam lines and experimental facilities of the J-PARC 50 GeV-PS. The radiation-resistant magnets we have foreseen are approximately 50 magnets with Polyimide resin Insulation (PI) for radiation dose up to 10 Gy, and 20 magnets with completely Mineral Insulation Cable (MIC) for higher radiation dose up to 1011 Gy. Most of those magnets have already been fabricated and are waiting for being installed in primary and secondary beam lines. The installation will be completed by the middle of 2008. All the magnets are placed on the plug-in base assembled with water and electric-power quick disconnect devices. A new remote handling system of beam line magnets named "Chimney" has been developed and employed for magnets placed at the highest radiation area near the production target. The first beam will be introduced to the experimental area by the end of 2008.
    IEEE Transactions on Applied Superconductivity 07/2008; · 1.20 Impact Factor
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    ABSTRACT: In a high-intensity proton beam facility, beam line elements downstream of a production target are exposed to a huge amount of radiation and heat. Beam pipes are closer to the beam than the magnet poles and more difficult to cool sufficiently without tritium production. Therefore, the magnets are placed in a large vacuum chamber, instead of using vacuum pipes located within the pole gaps. We have adopted indirect-cooling mineral-insulation-cable (MIC) coils for these magnets. They have a great advantage that the mechanical strength and the insulation performance can be significantly improved by avoiding the use of ceramic insulation pipes, because electric circuits are completely separated from water passages. We have made coils using 1000-A-class solid-conductor MICs and stainless-steel pipes, and tested magnet operation in vacuum. By improving the structure of end parts of MICs and increasing their emissivity, we have successfully fed the current of DC 1000 A to the solid-conductor MIC coils in vacuum.
    IEEE Transactions on Applied Superconductivity 07/2008; · 1.20 Impact Factor
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    ABSTRACT: The new electrostatic (ES) separator to select and deliver 1–2GeV/c kaon beams is made for the secondary beam line at the high intensity proton accelerator facility. The ES separator will generate a 75kV/cm electrostatic field between parallel electrodes of 10cm gap and 6m in length along the beam direction. The K−/π− ratio of the line is expected to have a larger value than 1. It is designed so as to be radiation-proof and to lower spark rate comparing with the present separators.
    Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms - NUCL INSTRUM METH PHYS RES B. 01/2008; 266(19):4205-4208.
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    ABSTRACT: Since chondrosarcoma has a high resistance to conventional chemotherapy and radiotherapy, surgical resection is currently the only effective treatment. Histone deacetylase (HDAC) inhibitor exert anticancer effects, but have not been tested in chondrosarcoma. We investigated the phenotypic change in chondrosarcoma cells treated with SAHA by cell viability assay, Western blot, flow cytometric analysis and electron microscopy. SAHA inhibited the growth of chondrosarcoma cell lines and induced apoptosis in SW1353 with a cleaved-PARP expression and sub-G1 fragmentation according to flow cytometric analysis. On the other hand, in RCS and OUMS-27, SAHA induced autophagy-associated cell death as shown by the detection of autophagosome-specific protein and specific ultrastructural morphology in the cytoplasm. In addition, SAHA significantly inhibited tumor growth in an in vivo xenograft model. These results suggest that SAHA might be a promising agent for performing clinically useful chemotherapy against chondrosarcomas.
    Anticancer research 01/2008; 28(3A):1585-91. · 1.71 Impact Factor
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    ABSTRACT: Multimodal therapies play important roles in the treatment of osteosarcoma (OS) and Ewing's family of tumors (EFTs), two most frequent malignant bone tumors. Although the clinical outcome of primary OS and EFTs is greatly improved, the relapsed cases often are associated with multidrug resistance of the tumors and the prognosis of these patients is still poor. Flavopiridol, a pan cyclin-dependent kinase (CDK) inhibitor is a novel antitumor agent that can induce cell cycle arrest and apoptosis in many cancer cells. However, there have been no studies about the effects of flavopiridol on drug-resistant OS and EFTs. Here, we demonstrated that flavopiridol induced the cleavage of poly-ADP-ribose polymerase (PARP) in a time and dose dependent manner in adriamycin-resistant OS and EFTs cells expressing P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP(1)) as effectively as in their parental cells. Our data also showed that flavopiridol caused the release of mitochondrial cytochrome c and the activation of caspase-9, caspase-8 and caspase-3, with an increase ratio of the proapoptotic protein level (Bax) to the antiapoptotic protein level (Bcl-2 and Bcl-X(L)), while apoptosis was inhibited by pan caspase inhibitor (Z-VAD-FMK) and caspase-3 inhibitor (Z-DEVD-FMK), not by caspase-8 inhibitor (Z-IETD-FMK). The treatment with flavopiridol further inhibited the tumor growth in mouse models of the drug-resistant OS and EFTs. These results suggest that flavopiridol might be promising in clinical therapy for the relapsed OS and EFTs.
    International Journal of Cancer 10/2007; 121(6):1212-8. · 6.20 Impact Factor
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    ABSTRACT: In a high-intensity proton beam facility, beam line elements downstream of a production target are exposed to a huge amount of radiation and heat. A water-cooled beam collimator must be located between the target and the magnets, and the iron yokes of the magnets also have to be cooled by water. Moreover, beam pipes are closer to the beam than the magnet poles and more difficult to cool sufficiently without tritium production. Therefore, the magnets are placed in a large vacuum chamber, instead of using vacuum pipes located within the pole gaps. In order to reduce the residual radiation dose during maintenance, the chamber lid and feedthroughs are 4 meter above the beam line, and radiation-shielding blocks are also stacked in the chamber. We have tested magnet operation in vacuum using a dipole magnet with mineral-insulation-cable (MIC) coils and a nickel-coated yoke. A magnet with 2500-A-class hollow-conductor MIC coils has worked successfully with the current of DC 3000 A. The stability of operation in vacuum was confirmed by measuring the temperature with thermocouples and the magnetic field with a NMR probe. We have also succeeded in operating a 1000-A-class solid-conductor MIC coil in vacuum
    IEEE Transactions on Applied Superconductivity 07/2006; · 1.20 Impact Factor
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    ABSTRACT: Continuity R&D work is reported here on the radiation resistant magnets for the Japan Proton Accelerator Research Complex (J-PARC). The main accelerator of the J-PARC is the 50 GeV-15 mA proton synchrotron (50 GeV-PS) with beam power of 750 kW. The radiation resistant magnet is the key technology to realize the external beam lines and experimental facilities of the J-PARC 50 GeV-PS. The radiation resistant technologies we have selected for the J-PARC are; (1) Polyimide Resin Insulation (PI) for up to 10<sup>8</sup> Gy and, (2) Mineral Insulation magnet Cables (MICs) with larger cross sections for higher radiation dose up to 10<sup>11</sup> Gy. Approximately 20 polyimide insulation magnets and 10 MIC magnets are designed for the external beam lines of the 50 GeV-PS. The fabrication of those magnets has already started in 2005 and will continue until the end of 2007
    IEEE Transactions on Applied Superconductivity 07/2006; · 1.20 Impact Factor
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    ABSTRACT: The facility of the long baseline neutrino oscillation experiment using the J-PARC's 50 GeV-0.75 MW proton beam is now under way. The primary proton beam line consists of three sections, i.e. the first preparation (PP) section with normal conducting magnets, the second arc (ARC) section with superconducting magnets and the third final focus (FF) section with normal conducting magnets. In the PP section, we have to clean the primary proton beam extracted from the 50 GeV-PS and transport halo-less pure beam only to the ARC section. In the FF section the magnets have to be placed very close to the pion production target and horns. Therefore the normal conducting magnets have to work in the very high radioactive environment. The R&D works on the radiation resistant magnets for handling a high-intensity proton beam have already been continued at KEK as reported in . Another important point regarding high-intensity beam handling is to realize easy maintenance of the beam line. Any magnet experiencing trouble can be easily removed from beam line and repaired remotely. For this purpose, we developed new tools for the magnet maintenance. These are automatic sling apparatus, quick alignment and installation guide, and the quick disconnect devices of cooling water and electric power. In this paper, we will report the beam line maintenance scheme developed for the neutrino beam line, as well as the design of normal conducting magnet sections
    IEEE Transactions on Applied Superconductivity 07/2006; · 1.20 Impact Factor
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    ABSTRACT: Nondestructive beam profile monitor utilizing ionizations of residual gas has been developed for continuous monitoring of 3×10<sup>14</sup> protons at Japan Proton Accelerator Research Complex (J-PARC). Knock-on electrons produced in the ionizations of residual gas vacuumed to 1 Pa are collected with a uniform electric field applied between electrodes. Applying a uniform electric field parallel to the electric field is essential to reduce diffusion of electrons crossing over magnetic flux. A prototype monitor has been constructed and installed in EP2-C beam line at KEK 12 GeV proton synchrotron (12 GeV-PS). The profiles measured with the present monitor agree with the ones measured with the existing destructive profile monitor. The present monitor shows sufficient performances as a candidate of the profile monitor at J-PARC. In the present article, the working principle of the present monitor, the results of test experiments, and further developments are described in detail.
    Nuclear Science Symposium Conference Record, 2005 IEEE; 11/2005
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    ABSTRACT: The J-PARC Neutrino Experiment, the construction of which starts in JFY 2004, will use a superconducting magnet system for its primary proton beam line. The system, which bends the 50 GeV 0.75 MW proton beam by about 80 degrees, consists of 28 superconducting combined function magnets. The magnets utilize single layer left/right asymmetric coils that generate a dipole field of 2.6 T and a quadrupole field of 18.6 T/m with the operation current of about 7.35 kA. The system also contains a few conduction cooled superconducting corrector magnets that serve as vertical and horizontal steering magnets. All the magnets are designed to provide a physical beam aperture of 130 mm in order to achieve a large beam acceptance. Extensive care is also required to achieve safe operation with the high power proton beam. The paper summarizes the system design as well as some safety analysis results.
    IEEE Transactions on Applied Superconductivity 07/2005; · 1.20 Impact Factor

Publication Stats

586 Citations
133.45 Total Impact Points

Institutions

  • 2–2012
    • High Energy Accelerator Research Organization
      • • Institute of Particle and Nuclear Studies
      • • Institute of Materials Structure Science
      Tsukuba, Ibaraki, Japan
  • 2005–2010
    • Kyushu University
      • Department of Orthopaedic Surgery
      Fukuoka-shi, Fukuoka-ken, Japan
  • 1998
    • Meijo University
      Nagoya, Aichi, Japan
    • Kyoto Pharmaceutical University
      Kioto, Kyōto, Japan
  • 1989
    • Kyoto Sangyo University
      • Faculty of Science
      Kyoto, Kyoto-fu, Japan
  • 1988
    • Hiroshima University
      Hirosima, Hiroshima, Japan