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Published on MHI Graph (October 2012 Issue)

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Gigantic Precision Instruments:
Particle Accelerators

Particles Accelerated to the Speed of Light Advance the Progress of Science

Development of the superconducting accelerating cavity is underway for the International Linear Collider (ILC) to search for the origins of the universe and matter and to examine in detail the nature of the Higgs boson that explains how matter attains its mass. After being manufactured from high-purity niobium (a rare metal) materials, it is cooled to an extremely low temperature (-271°C) to induce a "superconductivity" with as little electric resistivity as possible in order to facilitate highly efficient acceleration. At present, MHI is the sole authorized company in Japan to produce the superconducting accelerating cavity for the ILC.
[Cover & Special Feature photos: Unless indicated otherwise, Mihara Machinery Works, Hiroshima Prefecture, Japan]

An Innovative Instrument that Solves Mysteries of the Origins of the Universe and All Other Phenomena

How does matter attain its mass? Why does the cosmos that expands across the heavens exist? Since the distant past, prominent researchers from Galileo to Newton and Einstein have sought solutions to the mysteries of science; today's scientists are aided by the accelerator, an innovative instrument that has substantially contributed to the development of modern science and technology.
The largest of these accelerators are tens of kilometers in total length. Their role is to apply energy from radio frequency waves to charged particles such as electrons and protons and accelerate them to near the speed of light. These extremely fast-moving and high-energy particles are forced to collide with one another. Research into their states can benefit the validation of the laws of physics and more. For example, the origin of the universe is thought to be the Big Bang that occurred approximately 13.7 billion years ago. If an accelerator can be used to re-create the state of the universe immediately following the Big Bang in which there was nothing more than particles flying at high speed, it would provide a significant clue to discovering the origin of the universe.
Also, if the orbit of high-energy electrons is bent, light with extremely short wavelengths in the manner of x-rays is emitted. The use of this synchrotron radiation greatly expands possibilities for observing and understanding nano level phenomena such as the unknown mechanism by which photosynthesis occurs in the nucleus - phenomena that heretofore could not be understood using microscopes. The fruits of research using synchrotron radiation have also recently been put to use in familiar fields. One example of this would be pharmaceuticals with new functions and efficacies that were created thanks to the analysis of three-dimensional structures of proteins.
Accelerators have provided us with a diverse array of benefits in our everyday lives.

Continuing to Evolve with World-Class Japanese Accelerator Development

The accelerator operations of MHI commenced at the beginning of the 1960s when the accelerator development was dawning in Japan. At the time, the foundation for the technology that is essential to the manufacture of accelerators was already in place as the company was using precision processing technology for nonferrous metals such as copper and aluminum that are indispensable to its manufacturing of aircraft components. Thereafter, MHI took part in almost all large-scale accelerator research projects in Japan and continued to refine such technology while gaining the confidence of researchers and research institutions.
Design and manufacturing has now expanded to accelerating structures and accelerating cavities that accelerate particles to near the speed of light, waveguides and radio frequency windows that introduce high-power microwave to the accelerating structure and accelerating cavities, vacuum beam chambers used as passageways for the accelerated particles, and periodical magnetic field generators, so-called undulators or wigglers that generate powerful synchrotron radiation by bending the orbit of particles in tiny increments. Japan has made outstanding discoveries in high-energy physics research, with five of the country's 17 Nobel Prize laureates awarded for their research in the field, to which MHI's accelerator technology has contributed. The KEKB Accelerator (electron-positron collider) of the High Energy Accelerator Research Organization (KEK) was used in the validation of the Kobayashi-Maskawa theory predicting CP violation, for which they were honored with the 2008 Nobel Prize for physics. Amid this effort, MHI designed and produced the injector accelerating structure, vacuum beam chamber, normal conducting ARES cavity, and superconducting crab cavity, thereby contributing to the Japanese scientists being so honored.
MHI's accelerators have continuously supported the successes of researchers from behind the scenes for over 50 years, and MHI continues to support passionately the dreams of researchers in their quest for scientific technology that will benefit mankind and society.

Accelerator Technology, Developed by Giving Concrete Form to Specifications and Functions Sought by Researchers

The superconducting accelerating cavity achieves high efficiency by greatly minimizing the electric resistivity of the cavity in which the particles are accelerated.
MHI has successfully produced many accelerator products that have become famous worldwide, such as the normal conducting C-band accelerating structure that realizes the same acceleration performance as before at about half the length by doubling accelerating frequency.

These and other acceleration related devices are the fruit of untiring endeavors involving the use of all available resources to give a concrete form for the specifications and functions sought by researchers and boldly tackling the challenges posed by extremely difficult demands.

Photo:The C-band choke-mode accelerating structure
Photo:X-ray Free Electron Laser facility SACLA

The C-band choke-mode accelerating structures (left photo) manufactured by MHI are the main components of the X-ray Free Electron Laser (XFEL) facility, SACLA (red box in the photo on the right). The complete system of XFEL tends to be extremely long due to the series arrangement of over 100 accelerating structures, but SACLA is approximately half of the length compared with other XFEL facilities in Europe and the United States. The C-band accelerating structure produced by MHI substantially contributed to shortening the total system length by approximately half of the conventional S-band accelerating structure. (RIKEN Harima Institute, Hyogo Prefecture, Japan)

Photo:The superconducting accelerating cavity

MHI handled the design and production of the superconducting accelerating cavity that was the first in the world to be utilized as a superconducting cavity for the TRISTAN Accelerator constructed in the late 1980s at KEK to search for the top quark. This technology is carried over to the superconducting crab cavity for the KEKB Accelerator and the superconducting accelerating cavity (photo above) for the ILC. The ILC accelerator will be around 40kilometer in total length and will require approximately 16,000 cavities.

Photo:The ACS accelerating cavity for the J-PARC high-energy proton accelerator facility.
The ACS accelerating cavity for the J-PARC high-energy proton accelerator facility. At J-PARC, high-energy proton beams are injected to targets such as mercury or carbon to produce neutrons that are used in a wide range of research fields, including high-energy physics, material science, life science, and more. Mass production of the accelerating cavity for doubling the acceleration energy of the injector proton accelerator is under manufacturing at MHI. This accelerating structure is a special one, called ACS (Annular ring-Coupled Structure) .

Crystallization of Integrated Engineering Technology Produces the Essences of Ultrafine Machining, High Precision Joining, and Precise Measurement Technology

Even with diagrams and procedural manuals which exist, the manufacturing of accelerators is extraordinarily challenging. This is because while high-power radio frequency waves are introduced, all structural components must be highly precise and clean in order to maintain resonance frequency. A wide array of engineering technology and abundant experience involving ultrafine machining of pure oxygen-free copper at micrometer (1/1,000millimeter) levels of precision, vacuum brazing and electron beam welding of machined components at high precision in clean environments, precise measurement and tuning of the resonance frequency, and other expertise and experience are employed.

Photo:Cell components (discs) that have been processed into mirrored surfaces by an ultra-precise lathe sparkle beautifully.
Cell components (discs) that have been processed to mirror-like surfaces by an ultra-precise lathe sparkle beautifully. The roughness of the surface is at sub-micrometer (1/10,000 millimeter) level, or about 1/100 the thickness of a human hair.
Oxygen-free copper cell components (washers) after ultrafine machining. Brazing wires, made from an alloy of gold or silver, are set into the two grooves on the washer surface.
Photo:An ultra-precise lathe is used to put the finishing touches on cell components (washers) that make up a normal conducting accelerating structure.
An ultra-precise lathe is used for finishing touches on cell components (washers) of a normal conducting accelerating structure. Pure oxygen-free copper materials are processed with a diamond cutter so that thin layers are peeled.
Photo:Large vacuum furnace
Approximately 90 sets of disc and washer cell components are stacked cylindrically, placed into a large vacuum furnace, and heated to nearly 900℃. Only the brazing material set between cells melt; this causes the cell to conjoin.
Photo:A normal conducting S-band accelerating structure that has become a single unit by means of brazing in a vacuum furnace.
A normal conducting S-band accelerating structure after brazing. Due to high temperature brazing, the copper softens and the structure is slightly distorted in shape. The amounts of distortion are measured and adjusted after brazing.
Photo:The bowl-shape cell components that form the superconducting accelerating cavity are precisely welded in a high-precision electron beam welding device, while being monitored on a display screen.
The bowl-shape cell components that form the superconducting accelerating cavity are precisely welded in a high-precision electron beam welding device, while being monitored on a display screen. A vacuum is maintained within the device, avoiding contamination by impurities. Because cells themselves are welded, the purity of their materials is maintained.
Photo:The structural components of the proton accelerator for which dimensions are checked=
The structural components of the proton accelerating structure for which dimensions are checked precisely using a three-dimensional measuring instrument. Manufacturing of normal conducting accelerating structure components require fine machining and precise assembly, with nearly all components measured in three dimensions and inspected prior to shipping.
Photo:The resonance frequencies of the coupler components that allow for high output high frequencies within accelerating structure are measured using a high frequency measuring instrument.

The resonance frequency of the coupler components that introduce high-power radio frequency waves into accelerating structures is measured using a radio frequency measuring instrument - a network analyzer. If even the slightest deviation exists in frequency, an ultra-precise lathe is used to process corrections at micrometer level.
Measurement and processing are repeated until the set frequency is obtained.

Instruments that will Change the World Continues to Evolve

MHI has always served an important role among the Japanese corporations taking part in national accelerator research projects. Its achievements and technical capabilities can be used in places around the world. In the future, MHI plans to develop operations globally by taking part in the preparations of the ILC. Recently the ILC has become the focus of attention because of the discovery of the Higgs boson-like particle by CERN (European Organization for Nuclear Research). MHI is also participating in research projects for synchrotron radiation in Taiwan and South Korea and is also applying accelerators to other fields such as medical use.
Sales of the "Vero 4DRT," an x-ray cancer treatment device equipped with a compact normal conducting C-band accelerating structure are now expanding. Furthermore, development of the small-scale proton accelerating structure for Boron Neutron Capture Therapy (BNCT) through joint cooperation with universities and national organizations is underway. Accelerators have many possibilities for making contributions to mankind throughout the world and beyond generations. MHI will continue to challenge future developments.

Photo:The X-ray Free Electron Laser (XFEL) facility SACLA
The XFEL facility, SACLA, for which operations began this March. The mammoth facility, nearly 700 meters in length, is expected to contribute greatly to many fields of science and technology in Japan as a facility capable of observing movements at the atomic and molecular level.
(RIKEN Harima Institute, Hyogo Prefecture, Japan)

MHI Principal Accelerator Products and Customers

  • Some are Undergoing Production

Superconducting accelerating cavity

Research and development for the ILC/International Linear Collider (High Energy Accelerator Research Organization(KEK))
This is an international project for investigating in detail the nature of the Higgs boson-like particle discovered by CERN using the LHC by colliding high-energy electrons and positrons. In Japan, KEK plays an important role in research and development. MHI is preparing production of the superconducting accelerating cavity that accelerates electrons and positrons.
Taiwan Photon Source Project (National Synchrotron Radiation Research Center(NSRRC))
This is the only high-brightness synchrotron radiation facility in Taiwan. It is currently upgrading its facility. The three superconducting accelerating cavities are now under manufacturing at MHI and are planned to be installed in a new synchrotron radiation ring.

Superconducting crab cavity

KEKB (High Energy Accelerator Research Organization(KEK))
The superconducting crab cavities were installed in the main ring of the KEKB accelerator that collides highenergy electrons and positrons to produce massive quantities of B mesons and anti-B mesons. By passing them through this special crab cavity, beams can be properly oriented, achieving the highest beam collision frequency in the world.

Normal conducting C-band accelerating structure

Accelerating electrons are injected into a periodic magnetic field called an undulator and produces a powerful short wavelength x-ray free electron laser that can facilitate the observation of movement at the atomic level. It is expected to be utilized in basic research such as structural analysis of membrane proteins as well as applied fields. The C-band choke mode accelerating structure manufactured by MHI is used as the primary linear accelerator of SACLA and contributes to the compactness of facilities and their stable operation.

Normal conducting S-band accelerating structure

SPring-8 (RIKEN)
A large-scale synchrotron radiation facility that uses the world's highest energy level (8GeV) and conducts research into nanotechnology, biotechnology, industrial applications, and so on. It can produce synchrotron radiation including x-rays, gamma rays, and infrared rays. The S-band accelerating structure is used in the 1.5GeV injector that accelerates electrons.
Pohang Accelerator Laboratory X-ray Free Electron Laser Project (Pohang Accelerator Laboratory (PAL))
This is a new project for construction of an x-ray free electron laser facility adjacent to Pohang Light Source, the only high-brightness synchrotron radiation facility in South Korea. The project has just started, and the S-band accelerating structures of MHI have been employed as a part of the main linear accelerator.

Proton accelerators (RFQ, DTL, SDTL)

J-PARC (High Energy Accelerator Research Organization(KEK)/ Japan Atomic Energy Agency)
A high-energy proton accelerator facility that produces the world's highest intensity proton beam. Proton beam is injected to the targets to produce neutrons, muons, K-mesons, and neutrinos for high-energy physics, material science, life science, and so on. MHI manufactured the injector proton accelerating structures such as DTL and SDTL.
Base technology development for selective noninvasive cancer cell treatment devices (New Energy and Industrial Technology Development Organization(NEDO))
This project employs compact proton accelerators to produce a neutron beam that can destroy targeted cancer cells for the next generation cancer therapy. At present, testing facilities are being prepared. A small-scale proton accelerating structure consists of RFQ and DTL based on J-PARC injector proton accelerating structure manufactured at MHI for Boron Neutron Capture Therapy (BNCT).

ACS accelerating cavity

J-PARC (High Energy Accelerator Research Organization(KEK)) / Japan Atomic Energy Agency)
MHI is producing an ACS accelerating cavity for injector proton accelerator upgrade.