A 500-kV, 10-mA photocathode DC gun has been designed and is now under fabrication by the collabo... more A 500-kV, 10-mA photocathode DC gun has been designed and is now under fabrication by the collaboration efforts of JAEA, KEK, Hiroshima Univ. and Nagoya Univ. The Cockcroft-Walton generator and the ceramic insulator are installed upright in the SF6 tank. We have adopted a multiple-stacked cylindrical ceramic insulator, because this type of ceramic insulator has shown good stability and robustness at the 200-kV Nagoya polarized gun and the 250-kV JAEA FEL gun. The vacuum chamber, the guard-rings and the support-rod electrode are made of titanium alloy with very low out-gassing and robustness to high voltage performances. The Cockcroft-Walton generator, the ceramic insulator, the vacuum chamber and the guard-rings have been assembled and a high-voltage test has been successfully done with up to 550kV. The high-voltage test and up-to-date status of the gun development will be presented in detail.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1997
Abstract Lasing dynamics in a short-pulse FEL oscillator driven by a high-peak current RF linac i... more Abstract Lasing dynamics in a short-pulse FEL oscillator driven by a high-peak current RF linac is numerically studied. Chaotic lasing due to the nonlinear coupling between electron and laser pulses is observed. We suggest a chaos suppression method using a Michelson resonator having path difference shorter than electron bunch length.
For a free-electron laser application and energy- recovery linac based light source, high-stabili... more For a free-electron laser application and energy- recovery linac based light source, high-stability of accelerator RF amplitude and phase is required. A low- level RF controller of the JAEA-ERL has been improved to ensure high-stability accelerating RF field. The controller is a conventional analog Φ-A type controller. The controller performance is evaluated with a 499.8 MHz superconducting cavity and a 1300 MHz copper cavity. The phase and amplitude stabilities of the 499.8 MHz superconducting cavity within latter half of an RF pulse are 0.0055 deg-rms and 7.64×10-5, respectively. For the 1300 MHz copper cavity, the performance of pulse and CW modes are evaluated. In the case of pulse mode, the phase and amplitude stabilities are 0.011 deg-rms and 7.64×10 -5 , respectively. In the case of CW mode, the phase and amplitude stabilities are 0.011 deg-rms and 6.68×10 -5 , respectively. Therefore, the performance of the analog Φ-A type low-level RF controller is sufficient for a free-ele...
The 35-MeV Compact Energy Recovery Linac (cERL) is a superconducting test accelerator for the fut... more The 35-MeV Compact Energy Recovery Linac (cERL) is a superconducting test accelerator for the future 3-GeV ERL project (PEARL) at KEK. During the past year, we have finished key devices such as a 500-kV DC photocathode electron gun and 1.3-GHz superconducting-cavity (SCC) cryomodules for both an injector and a main linac. We installed these devices into a shielding room of the cERL, and carried out high-voltage or high-power tests successfully. A 5-MeV injector of the cERL has been completed and commissioned.
Third International Symposium on Laser Precision Microfabrication, 2003
The JAERI FEL group has successfully discovered, and realized the brand-new FEL lasing of 255fs u... more The JAERI FEL group has successfully discovered, and realized the brand-new FEL lasing of 255fs ultrafast pulse, 6-9% high-efficiency, one gigawatt high peak power, a few kilowatts average power, and wide tenability of medium and far infrared wavelength regions at the same time. The new lasing was named to be “high-degeneracy superradianct lasing of FEL”. Using the new lasing, we could realize a powerful and efficient free-electron laser(FEL) for industrial uses, for examples, pharmacy, medical, defense, shipbuilding, semiconductor industry, chemical industries, environmental sciences, space-debris, power beaming and so on. In order to realize such a tunable, highly-efficient, high average power, high peak power and ultra-short pulse FEL, we need the efficient and powerful FEL driven by JAERI compact, stand-alone and zero-boil-off super-conducting rf linac with an energy-recovery geometry. Our discussions on the FEL will cover market-requirements and roadmap for the industrial FELs, some answers from the JAERI compact, stand-alone and zero-boil-off cryostat concept and operational experience over these 10 years, our discovery of the new highly-efficient, high-power, and ultra-short pulse lasing mode, and the energy-recovery geometry.
Preface Oral Presentations: Nuclear Science and Applications with the Next Generation of High-Pow... more Preface Oral Presentations: Nuclear Science and Applications with the Next Generation of High-Power Lasers and Brilliant Low-Energy Gamma Beams at ELI-NP (S Gales) New Non-Intrusive Inspection Technologies for Nuclear Security and Nonproliferation (R J Ledoux) Development of Gamma-Ray Nondestructive Detection and Assay Systems for Nuclear Safeguards and Security at JAEA (R Hajima) Photonuclear Reaction Studies at HIgammaS: Developing the Science of Remote Detection of Nuclear Materials (C R Howell) Dipole Strength Around the Particle Threshold (D Savran) Resonant Photonuclear Reactions for Neutrino Nuclear Responses and Nuclear Isotope Detections (H Ejiri) Non-Destructive Testing for Control of Radioactive Waste Package (S Plumeri and F Carrel) Development of First Responders Equipment at RN Incident Sites (K Tsuchiya et al.) Compact Short-Pulsed Electron Linac Based Neutron Sources for Precise Nuclear Material Analysis (M Uesaka et al.) Laser-Driven Plasma Deceleration of Electron Beams for Compact Photon Sources (J-L Vay et al.) Advanced Laser-Compton Gamma-Ray Sources for Nuclear Materials Detection, Assay and Imaging (C P J Barty) Compact Gamma-Beam Source for Nuclear Security Technologies (P Gladkikh and J Urakawa) Developments of Optical Resonators and Optical Recirculators for Compton X/gamma Ray Machines (A Martens) Low-Lying "Pygmy" Dipole Resonances and Strength Functions (V Werner et al.) NRF-Based NDA of Nuclear Material Using Monochromatic gamma-Ray Beam (T Shizuma et al.) Improving the Assay of 239Pu in Spent and Melted Fuel Using the Nuclear Resonance Fluorescence Integral Resonance Transmission Method (C T Angell et al.) Laser Compton Scattering Gamma-Ray Beam Source at NewSUBARU Storage Ring (S Miyamoto et al.) Energy Calibration of Electron and Gamma-Ray Beams at NewSUBARU-GACKO (T Shima and H Utsunomiya) A Paradigm for the Nondestructive Assay of Spent Fuel Assemblies and Similar Large Objects, with Emphasis on the Role of Photon-Based Techniques (A M Bolind) Medium Modification of alpha Cluster Size in 6Li (T Yamagata et al.) Noninvasive Reactor Imaging Using Cosmic-Ray Muons (H Miyadera et al.) Compton Radiation for Nuclear Waste Management and Transmutation (E Bulyak and J Urakawa) Compact Intense Neutron Generators Based on Inertial Electrostatic Confinement of D-D Fusion Plasmas (K Masuda et al.) NRF Based Nondestructive Inspection System for SNM by Using Laser-Compton-Backscattering Gamma-Rays (H Ohgaki et al.) Development of Measurement Methods for Detection of Special Nuclear Materials Using D-D Pulsed Neutron Source (T Misawa et al.) SOFIA, a Next-Generation Facility for Fission Yields Measurements and Fission Study. First Results and Perspectives (L Audouin et al.) Present Status of Nuclear Data for Nuclear Nonproliferation (M Igashira) Development of the Experimental Photo-Nuclear Reaction Database in Hokkaido University (A Makinaga) Laser-Compton Scattering Photon Beams and Other Gamma-Ray Sources: Project for Coherent Gamma-Ray Source on Basis of Femtosecond Laser at ILC MSU (V G Nedorezov and A B Savelev) Laser Driven Ion Acceleration Study in JAEA (K Kondo) Status of New JENDL Photonuclear Data File (K Kosako et al.) Nuclear Research with Egamma<=15 MeV Photons (C Rangacharyulu) IRIDE: Interdisciplinary Research Infrastructure Based on Dual Electron Linac and Laser (M Ferrario) Poster Presentations: A Study of the Nuclear Resonance Fluorescence Reaction Yield Dependence on the Target Thickness of 208PB (H Negm et al.) Photodisintegration Reactions with Linear Polarized gamma-Ray Beam (T Hayakawa et al.) Test Experiment of gamma-Ray Diffraction for Crystal Monochromators (S Matsuba et al.) Overview of Laser Compton-scattered Photon Source at the cERL (R Nagai et al.) Development of a High-Brightness and High-Current Electron Gun for High-Flux gamma-Ray Generation (N Nishimori et al.) Design of ERL Spoke Cavity for Non-Destructive Assay Research (M Sawamura et al.) Measurements of Cosmic-Ray Muon-Capture X-Rays and Its Application to Nuclear Material Detection (Y Shimbara et al.) Active Neutron-Based Interrogation System with D-D Neutron Source for Detection of Special Nuclear Materials (Y Takahashi et al.) Closing Summary: Summary Comments: Nuclear Physics and Gamma-Ray Sources for Nuclear Security and Nonproliferation (C P J Barty)
Nowadays, generation of energy-tunable, monochromatic γ-rays is needed to establish a nondestruct... more Nowadays, generation of energy-tunable, monochromatic γ-rays is needed to establish a nondestructive assay method of nuclear fuel materials. The γ-rays are generated by collision of laser photons stored in a cavity and relativistic electrons. We propose a configuration of an enhancement cavity capable of performing polarization control fabricated by a combination of a four-mirror ring cavity with a small spot inside a cavity and a three-mirror of reflective optics as an image inverter for polarization-selectable γ-rays. The image inverter introduces a phase shift of specific polarization which can be used to generate an error signal to lock an optical cavity at a resonance condition.
Nuclear resonance florescence (NRF) is a powerful tool for non-destructive assaying of nuclear ma... more Nuclear resonance florescence (NRF) is a powerful tool for non-destructive assaying of nuclear materials. Detection system is a key issue for investigating nuclear materials using this technique. For a long time, Ge detectors were used because they have an excellent energy resolution but also have drawbacks of high cost and slow response time. On the other hand, LaBr3(Ce) detectors have
After extensive discussions on the future light source of the Photon Factory at the High Energy A... more After extensive discussions on the future light source of the Photon Factory at the High Energy Accelerator Research Organization (KEK), it has been concluded that a 5 GeV energy recovery linac (ERL) should be the most suitable candidate to foster cutting-edge experiments, as well as to support a large variety of user needs from VUV to X-rays. On the other hand, the Japan Atomic Energy Agency (JAEA), which has built a low energy (17 MeV) ERL, also proposed another 5-6 GeV ERL as a light source. These two institutes, with a participation of some members of the Institute for Solid State Physics (ISSP) of the University of Tokyo, agreed to promote an ERL-based next-generation synchrotron light source in Japan. Before constructing a 5 GeV ERL, it is necessary to develop several critical components, such as an electron gun and superconducting accelerating structures, and to prove their performance. To this end, we plan to construct a test ERL of 200-MeV class at the KEK site. An R&D team...
A 500-kV, 10-mA photocathode DC gun has been designed and is now under fabrication by the collabo... more A 500-kV, 10-mA photocathode DC gun has been designed and is now under fabrication by the collaboration efforts of JAEA, KEK, Hiroshima Univ. and Nagoya Univ. The Cockcroft-Walton generator and the ceramic insulator are installed upright in the SF6 tank. We have adopted a multiple-stacked cylindrical ceramic insulator, because this type of ceramic insulator has shown good stability and robustness at the 200-kV Nagoya polarized gun and the 250-kV JAEA FEL gun. The vacuum chamber, the guard-rings and the support-rod electrode are made of titanium alloy with very low out-gassing and robustness to high voltage performances. The Cockcroft-Walton generator, the ceramic insulator, the vacuum chamber and the guard-rings have been assembled and a high-voltage test has been successfully done with up to 550kV. The high-voltage test and up-to-date status of the gun development will be presented in detail.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1997
Abstract Lasing dynamics in a short-pulse FEL oscillator driven by a high-peak current RF linac i... more Abstract Lasing dynamics in a short-pulse FEL oscillator driven by a high-peak current RF linac is numerically studied. Chaotic lasing due to the nonlinear coupling between electron and laser pulses is observed. We suggest a chaos suppression method using a Michelson resonator having path difference shorter than electron bunch length.
For a free-electron laser application and energy- recovery linac based light source, high-stabili... more For a free-electron laser application and energy- recovery linac based light source, high-stability of accelerator RF amplitude and phase is required. A low- level RF controller of the JAEA-ERL has been improved to ensure high-stability accelerating RF field. The controller is a conventional analog Φ-A type controller. The controller performance is evaluated with a 499.8 MHz superconducting cavity and a 1300 MHz copper cavity. The phase and amplitude stabilities of the 499.8 MHz superconducting cavity within latter half of an RF pulse are 0.0055 deg-rms and 7.64×10-5, respectively. For the 1300 MHz copper cavity, the performance of pulse and CW modes are evaluated. In the case of pulse mode, the phase and amplitude stabilities are 0.011 deg-rms and 7.64×10 -5 , respectively. In the case of CW mode, the phase and amplitude stabilities are 0.011 deg-rms and 6.68×10 -5 , respectively. Therefore, the performance of the analog Φ-A type low-level RF controller is sufficient for a free-ele...
The 35-MeV Compact Energy Recovery Linac (cERL) is a superconducting test accelerator for the fut... more The 35-MeV Compact Energy Recovery Linac (cERL) is a superconducting test accelerator for the future 3-GeV ERL project (PEARL) at KEK. During the past year, we have finished key devices such as a 500-kV DC photocathode electron gun and 1.3-GHz superconducting-cavity (SCC) cryomodules for both an injector and a main linac. We installed these devices into a shielding room of the cERL, and carried out high-voltage or high-power tests successfully. A 5-MeV injector of the cERL has been completed and commissioned.
Third International Symposium on Laser Precision Microfabrication, 2003
The JAERI FEL group has successfully discovered, and realized the brand-new FEL lasing of 255fs u... more The JAERI FEL group has successfully discovered, and realized the brand-new FEL lasing of 255fs ultrafast pulse, 6-9% high-efficiency, one gigawatt high peak power, a few kilowatts average power, and wide tenability of medium and far infrared wavelength regions at the same time. The new lasing was named to be “high-degeneracy superradianct lasing of FEL”. Using the new lasing, we could realize a powerful and efficient free-electron laser(FEL) for industrial uses, for examples, pharmacy, medical, defense, shipbuilding, semiconductor industry, chemical industries, environmental sciences, space-debris, power beaming and so on. In order to realize such a tunable, highly-efficient, high average power, high peak power and ultra-short pulse FEL, we need the efficient and powerful FEL driven by JAERI compact, stand-alone and zero-boil-off super-conducting rf linac with an energy-recovery geometry. Our discussions on the FEL will cover market-requirements and roadmap for the industrial FELs, some answers from the JAERI compact, stand-alone and zero-boil-off cryostat concept and operational experience over these 10 years, our discovery of the new highly-efficient, high-power, and ultra-short pulse lasing mode, and the energy-recovery geometry.
Preface Oral Presentations: Nuclear Science and Applications with the Next Generation of High-Pow... more Preface Oral Presentations: Nuclear Science and Applications with the Next Generation of High-Power Lasers and Brilliant Low-Energy Gamma Beams at ELI-NP (S Gales) New Non-Intrusive Inspection Technologies for Nuclear Security and Nonproliferation (R J Ledoux) Development of Gamma-Ray Nondestructive Detection and Assay Systems for Nuclear Safeguards and Security at JAEA (R Hajima) Photonuclear Reaction Studies at HIgammaS: Developing the Science of Remote Detection of Nuclear Materials (C R Howell) Dipole Strength Around the Particle Threshold (D Savran) Resonant Photonuclear Reactions for Neutrino Nuclear Responses and Nuclear Isotope Detections (H Ejiri) Non-Destructive Testing for Control of Radioactive Waste Package (S Plumeri and F Carrel) Development of First Responders Equipment at RN Incident Sites (K Tsuchiya et al.) Compact Short-Pulsed Electron Linac Based Neutron Sources for Precise Nuclear Material Analysis (M Uesaka et al.) Laser-Driven Plasma Deceleration of Electron Beams for Compact Photon Sources (J-L Vay et al.) Advanced Laser-Compton Gamma-Ray Sources for Nuclear Materials Detection, Assay and Imaging (C P J Barty) Compact Gamma-Beam Source for Nuclear Security Technologies (P Gladkikh and J Urakawa) Developments of Optical Resonators and Optical Recirculators for Compton X/gamma Ray Machines (A Martens) Low-Lying "Pygmy" Dipole Resonances and Strength Functions (V Werner et al.) NRF-Based NDA of Nuclear Material Using Monochromatic gamma-Ray Beam (T Shizuma et al.) Improving the Assay of 239Pu in Spent and Melted Fuel Using the Nuclear Resonance Fluorescence Integral Resonance Transmission Method (C T Angell et al.) Laser Compton Scattering Gamma-Ray Beam Source at NewSUBARU Storage Ring (S Miyamoto et al.) Energy Calibration of Electron and Gamma-Ray Beams at NewSUBARU-GACKO (T Shima and H Utsunomiya) A Paradigm for the Nondestructive Assay of Spent Fuel Assemblies and Similar Large Objects, with Emphasis on the Role of Photon-Based Techniques (A M Bolind) Medium Modification of alpha Cluster Size in 6Li (T Yamagata et al.) Noninvasive Reactor Imaging Using Cosmic-Ray Muons (H Miyadera et al.) Compton Radiation for Nuclear Waste Management and Transmutation (E Bulyak and J Urakawa) Compact Intense Neutron Generators Based on Inertial Electrostatic Confinement of D-D Fusion Plasmas (K Masuda et al.) NRF Based Nondestructive Inspection System for SNM by Using Laser-Compton-Backscattering Gamma-Rays (H Ohgaki et al.) Development of Measurement Methods for Detection of Special Nuclear Materials Using D-D Pulsed Neutron Source (T Misawa et al.) SOFIA, a Next-Generation Facility for Fission Yields Measurements and Fission Study. First Results and Perspectives (L Audouin et al.) Present Status of Nuclear Data for Nuclear Nonproliferation (M Igashira) Development of the Experimental Photo-Nuclear Reaction Database in Hokkaido University (A Makinaga) Laser-Compton Scattering Photon Beams and Other Gamma-Ray Sources: Project for Coherent Gamma-Ray Source on Basis of Femtosecond Laser at ILC MSU (V G Nedorezov and A B Savelev) Laser Driven Ion Acceleration Study in JAEA (K Kondo) Status of New JENDL Photonuclear Data File (K Kosako et al.) Nuclear Research with Egamma<=15 MeV Photons (C Rangacharyulu) IRIDE: Interdisciplinary Research Infrastructure Based on Dual Electron Linac and Laser (M Ferrario) Poster Presentations: A Study of the Nuclear Resonance Fluorescence Reaction Yield Dependence on the Target Thickness of 208PB (H Negm et al.) Photodisintegration Reactions with Linear Polarized gamma-Ray Beam (T Hayakawa et al.) Test Experiment of gamma-Ray Diffraction for Crystal Monochromators (S Matsuba et al.) Overview of Laser Compton-scattered Photon Source at the cERL (R Nagai et al.) Development of a High-Brightness and High-Current Electron Gun for High-Flux gamma-Ray Generation (N Nishimori et al.) Design of ERL Spoke Cavity for Non-Destructive Assay Research (M Sawamura et al.) Measurements of Cosmic-Ray Muon-Capture X-Rays and Its Application to Nuclear Material Detection (Y Shimbara et al.) Active Neutron-Based Interrogation System with D-D Neutron Source for Detection of Special Nuclear Materials (Y Takahashi et al.) Closing Summary: Summary Comments: Nuclear Physics and Gamma-Ray Sources for Nuclear Security and Nonproliferation (C P J Barty)
Nowadays, generation of energy-tunable, monochromatic γ-rays is needed to establish a nondestruct... more Nowadays, generation of energy-tunable, monochromatic γ-rays is needed to establish a nondestructive assay method of nuclear fuel materials. The γ-rays are generated by collision of laser photons stored in a cavity and relativistic electrons. We propose a configuration of an enhancement cavity capable of performing polarization control fabricated by a combination of a four-mirror ring cavity with a small spot inside a cavity and a three-mirror of reflective optics as an image inverter for polarization-selectable γ-rays. The image inverter introduces a phase shift of specific polarization which can be used to generate an error signal to lock an optical cavity at a resonance condition.
Nuclear resonance florescence (NRF) is a powerful tool for non-destructive assaying of nuclear ma... more Nuclear resonance florescence (NRF) is a powerful tool for non-destructive assaying of nuclear materials. Detection system is a key issue for investigating nuclear materials using this technique. For a long time, Ge detectors were used because they have an excellent energy resolution but also have drawbacks of high cost and slow response time. On the other hand, LaBr3(Ce) detectors have
After extensive discussions on the future light source of the Photon Factory at the High Energy A... more After extensive discussions on the future light source of the Photon Factory at the High Energy Accelerator Research Organization (KEK), it has been concluded that a 5 GeV energy recovery linac (ERL) should be the most suitable candidate to foster cutting-edge experiments, as well as to support a large variety of user needs from VUV to X-rays. On the other hand, the Japan Atomic Energy Agency (JAEA), which has built a low energy (17 MeV) ERL, also proposed another 5-6 GeV ERL as a light source. These two institutes, with a participation of some members of the Institute for Solid State Physics (ISSP) of the University of Tokyo, agreed to promote an ERL-based next-generation synchrotron light source in Japan. Before constructing a 5 GeV ERL, it is necessary to develop several critical components, such as an electron gun and superconducting accelerating structures, and to prove their performance. To this end, we plan to construct a test ERL of 200-MeV class at the KEK site. An R&D team...
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Papers by Ryoichi Hajima