Hiroshi Kawamata

High Energy Accelerator Research Organization

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Co-Authors

T. Ogitsu

High Energy Accelerator Research Organization

T. Nakamoto

High Energy Accelerator Research Organization

N. Higashi

High Energy Accelerator Research Organization

M. Sugano

High Energy Accelerator Research Organization

E. Todesco

European Organization for Nuclear Research

A. Terashima

High Energy Accelerator Research Organization

Koji Kaya

Ankara Yıldırım Beyazıt University

Atsushi Nakajima

Keio University

Naoki Okada

High Energy Accelerator Research Organization

Ryutaro Okada

High Energy Accelerator Research Organization

Cooperative Institutions

High Energy Accelerator Research Organization

102

Tianjin Hi-Tech Superconducting Electronic Technology (China)

Japan Proton Accelerator Research Complex

European Organization for Nuclear Research

The University of Tokyo

Japan Atomic Energy Agency

Kyoto University

Osaka University

Tohoku University

Tokyo Institute of Technology

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Eight-element-stressed Ge:Ga linear array: development and performance

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (1994)

Hiroshi Shibai Haruyuki Okuda Hiroshi Murakami Takao Nakagawa Norihisa Hiromoto

We have developed an eight-element stressed Ge:Ga linear array. It has a compact and stable structure. The pixel size is 0.9 X 0.9 X 0.9 mm³, the pitch of the array is 1.0 mm, and the total sensitive area is 8.0 mm X 1.0 mm. The longer wavelength cut-off is 200 microns, and the peak responsivity is 100 A/W in a high-background condition including cavity efficiencies. It has been demonstrated that this array has a useful performance in the high-background condition, such as for airborne and balloon-borne instruments. The structure of the stress assembly is provably extendable up to sixteen and more.

10.1117/12.185825

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Field Quality and Mechanical Analysis of the Beam Separation Dipole for HL-LHC Upgrade

IEEE Transactions on Applied Superconductivity (2014)

M. Sugano T. Nakamoto Qingjin Xu Hiroshi Kawamata E. Todesco

High luminosity upgrade of the Large Hadron Collider (HL-LHC) project has been launched to attain a ten times higher integrated luminosity than the current LHC that has been in operation for over ten years. For this goal, the quadruple and dipole magnets around two interaction points, the ATLAS and the CMS, will be upgraded. High Energy Accelerator Research Organization (KEK) is in charge of developing the new superconducting beam separation dipole magnet (D1). The main dipole field of 5.6 T in a large aperture of 150 mm is generated using a cos-theta coil wound with Nb-Ti cables at nominal operating current of 12.0 kA at 1.9 K corresponding to 75% of the load line ratio. The main challenges for the D1 are larger aperture, a high level of iron saturation, radiation resistance, and tight constraints on field quality. This article summarizes the results of a detailed analysis on field error. Electromagnetic simulation with ROXIE was carried out for the 2-D model of the new D1. As possible design changes, a diameter and position of heat exchanger holes in the iron yoke, and shape of the cryostat were considered. To reveal the influence on systematic error, packing factor of iron yoke, relative permeability of the stainless steel collar, and coil deformation during yoking were reflected to the baseline design. In addition, random geometric error was also estimated. Based on these results, contribution of each factor to field quality is studied.

Niobium-tin

Cryostat

Aperture (computer memory)

Dipole magnet

10.1109/tasc.2014.2364231

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Citations (18)

Study of efficient optical parametric generation in KTP crystal as pump source for DAST-DFG

Kouji Nawata Yoshiki Miyake Shin’ichiro Hayashi T. Notake Hiroshi Kawamata

We have developed injection-seeded KTP optical parametric generator for DAST-DFG terahertz-wave source. Using a microchip Nd:YAG laser, the energy conversion efficiency of 10% and peak-power output of 2.5 MW were obtained at 1300 nm.

Optical Pumping

Optical parametric amplifier

Potassium titanyl phosphate

Crystal (programming language)

10.1364/cleo_qels.2013.jth2a.52

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Citations (1)

Photoelectron spectroscopy and mass distributions of aluminum-sulfur cluster anions (Al S−)

Chemical Physics Letters (1995)

Atsushi Nakajima Nan Zhang Hiroshi Kawamata Takasuke Hayase Kojiro Nakao

Laser vaporization

10.1016/0009-2614(95)00653-l

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Citations (15)

Performance of the Quench Protection Heater for the HL-LHC Beam Separation Dipole

IEEE Transactions on Applied Superconductivity (2020)

Kento Suzuki Hirokatsu Ohata Naoki Okada Ryutaro Okada K. Sasaki

In collaboration with CERN, High Energy Accelerator Research Organization (KEK) has designed and developed short-scale model magnets of the beam separation dipole, MBXF, which will be installed for the High Luminosity Large Hadron Collider, HL-LHC. A new quench protection heater for MBXF was designed and tested during the cold test of the short-scale models. Combining data taken since the test of the 1st model magnet, we confirmed the maximum hotspot temperatures are well below 300 K in the case of the low field (1 T) and high field (5 T) quenches, respectively. In addition, a simulation model was developed and tuned with the obtained data for the full-scale prototype magnet. The hotspot temperature after quench initiation was then computed with the new heater circuit and found to be below 300 K even for the case of failure in firing the heater.

Magnetic separation

10.1109/tasc.2020.2971458

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Citations (5)

Mechanical Analysis of Pion Capture Superconducting Solenoid System for COMET Experiment at J-PARC

IEEE Transactions on Applied Superconductivity (2016)

Iio M Makoto Yoshida Ye Yang Taekyung Ki Takahiro Okamura

KEK is currently constructing a long series of superconducting solenoid beamline for the COMET Phase-I experiment at the Hadron facility of J-PARC. The magnet system consists of a 5-T pion capture solenoid, a curved muon transport solenoid, and a large bore detector solenoid. The pion capture solenoid system consists of a large cold mass including four coils with an inner diameter of 1340 mm and a small cold mass including six small coils with an inner diameter of 500 mm. The peak magnetic field on the conductor reaches to 5.4 T at an operation current of 2700 A. This paper presents the design and structural details of a magnet, radiation-resistant coil, cold mass and vacuum vessel, apart from the results of the electromagnetic analysis in two-dimensional (2-D) and 3-D.

Solenoid

Muon collider

10.1109/tasc.2016.2640189

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Citations (3)

DEVELOPMENT OF AN RFQ MODEL CAVITY IN KEK

Takumi Kato Y. Higashi Z. Igarashi C. Kubota T. Takenaka

Source

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Beam test of a new radio frequency quadrupole linac for the Japan Proton Accelerator Research Complex

Physical Review Special Topics - Accelerators and Beams (2014)

Yasuhiro Kondo Takatoshi Morishita Saisyun Yamazaki T. Hori Yuki Sawabe

We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.

Radio-frequency quadrupole

Duty cycle

Beam emittance

10.1103/physrevstab.17.120101

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Citations (9)

The machining of the disks of X band accelerator structure

Seisan Kakou, Kousaku Kikai Bumon Kouenkai kouen rombunshuu/Seisan Kako, Kosaku Kikai Bumon Koenkai (2004)

Kenji Ueno Toshikazu Takatomi Hiroshi Kawamata Yasuo Higashi T. Higo

To achieve the manufacturing of disks of the accelerator structure for the high gradient field, KEK develops to manufacture high precision disks. In manufacturing high precision disks, it is important for us to make sure the process sheet of the disk and report actual evidence. By this study we report how to manufacture the disks and the criteria of disk.

Manufacturing process

10.1299/jsmemmt.2004.5.45

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IR−UV Double-Resonance of Methyl Radicals and a Determination of the Detection Sensitivity of REMPI Bands

The Journal of Physical Chemistry A (2009)

Weiqing Zhang Hiroshi Kawamata A. J. Merer Kopin Liu

A novel method is exploited in this report to directly determine the relative detection sensitivity of the (2+1) resonance-enhanced multiphoton ionization (REMPI) bands of CH(3) and CHD(2) radicals. The basic idea is based on the simple fact that in an infrared (IR) absorption process the number of molecules being pumped from the lower state must be the same as the number of molecules in the excited upper state. Hence, the measured intensities of the respective REMPI bands should directly reflect their relative detection sensitivities. In order to ensure the processes involved and better quantify the measurements, extensive IR-UV double resonance spectroscopy was also performed. Using the REMPI-IR scheme, the IR spectrum of the v(1) fundamental (CH stretch) of CHD(2) was obtained and assigned for the first time. Using the IR-REMPI approach, high-resolution (2+1) REMPI spectra via the Rydberg 3p states of both radicals were demonstrated in a rotationally specific manner for both the origin and vibronic-excited bands, from which the predissociation rates of the Rydberg 3p states were deduced.

Resonance-enhanced multiphoton ionization

Rydberg state

10.1021/jp902969v

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Citations (21)