Published on MHI Graph (October 2012 Issue)
INNOVATIVE TECHNOLOGY[ INDUSTRIAL MACHINERY ]
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]
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.
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.
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.
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)
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.
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.
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.
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.