Toshiba's Technology contributted to the Discovery of the Higgs Boson.

Toshiba's Superconducting Technology that Contributted to the Discovery of the Higgs Boson

For the first of this 3 interview series, Shoichi Mizumaki, Machinery and Equipment Design Group, presents Toshiba's superconducting technology.

Toshiba and the European Organization for Nuclear Research (CERN)

Shoichi Mizumaki
Mizumaki talks about the manufacturing stage and the installation of the devices to CERN.

In a circular tunnel with 27-kilometers in circumference at CERN, the Large Hadron Collider (LHC) was constructed for the discovery of the Higgs boson. The LHC is a facility where the scientists conduct the experiments, making collisions of protons, accelerated at nearly the speed of light.

Since the 1950s, Toshiba has developed equipment for accelerators *1 and supplied them to advanced research institutions, including the High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan. Due to the excellence in its technology and experience, Toshiba supplied two devices to CERN that include “Superconducting Central Solenoid” *2 installed in the ATLAS detector and “Superconducting quadrupole magnets (MQX-A)” *3 that focuses the proton beams.

Using LHC, these devices were installed in it, the CERN scientists succeeded in circulating proton beams and making the collisions of them with each other for the first time in Sept. 2008. Later in July 2012, CERN announced the discovery of a particle, regarded as the Higgs boson. Finally, the discovery of the Higgs boson was officially announced in Oct., 2013. Due to the achievements, the Nobel Prize in Physics 2013 was awarded jointly to Peter W. Higgs and Francois Englert, who first theorized the Higgs boson in 1964.

The ATLAS detector being installed (left); the solenoid in the manufacturing stage at Toshiba's Keihin Product Operations (center); and MQX-A and its cross-sectional cut model (right)

*1 The devices accelerate the electron and proton particles nearly at the speed of light for generating the high-energy state.
*2 The magnets generate magnetic fields, essential for the particle identification.
*3 The magnets focuses proton beams into a single point for effective collisions.

Toshiba's Technological Contributions to the Discovery of the Higgs Boson

Toshiba expertise for precise coil-winding inside a support cylinder.

"Technological aspects for making a solenoid involved superconduction; coil-winding; insulation; fabrication and aluminum welding..." describes Mizumaki.

Various elemental particles are produced in the collision of proton beams that are accelerated to close to the speed of light. Particles are identified by measuring its tracks in magnetic field, energy, etc. in the detector.

A major role of solenoids is to generate magnetic fields, essential for the particle identification. The solenoid should generate an axial magnetic field of 20,000 gauss *4 in a warm bore volume of 2.3 m in daimater and 6.3 m in length. Another requirement was that the solenoid should be as thin *5 as possible for the best performance of instruments installed around the solenoid with minimum interaction of elementary particles in the coil.

To satisfy these requirements, aluminum is selected as a major material for increasing physical transparency. And also, solenoid is designed with single layer winding for increasing structural transparency. An operating current of solenoid is 7,600 amperes to provide an axial magnetic field of 20,000 gausses. Solenoid coil is wound on the inner surface of the support cylinder by using "Inner Winding Method" to withstand strong electromagnetic forces.

While it is relatively easy to wind a conductor outside, it is extremely difficult to wind it precisely inside a support cylinder. This is a manufacturing expertise that only Toshiba provides in the world.

The particles generated by the collisions pass through the solenoid and reach the detectors placed outside.

Major dimension of the solenoid is 2.46 meters in inner diameter, 45 millimeters in thickness and 5.3 meters in length; the total mass is approximately 6 tons. In order to make it in the superconducting state, the solenoid needs to be cooled down to the liquid helium temperature (i.e. minus 273.15 degrees Celsius). This could be achieved by circulating liquid helium in the aluminum pipes installed around the outside surface of support cylinder. In the solenoid installation work at CERN, the pipes should be connected at some places in the ATLAS detector. The pipe connection work areas were so very narrow that Toshiba developed a specialized automatic welding machine to perform the work. While welding of aluminum is very difficult, the work was successfully carried out and passed the test complying with tough regulation. This welding technology is one of our high manufacturing technologies.

Mizumaki installing the solenoid at the site.

"...We delivered the solenoids to CERN. As we went through the acceptance test and alignment survey conducted by the CERN personnel, my heart was full of thanks to those involved in this project. But, at the same time, I was having happy and worrying feelings just like I was seeing my child leaving home... As we waited for the test results, we had 'absolute confidence' in our product because we really devoted so much of our professional life to it over the years..." recalls Mizumaki.

*4 A solenoid with the magnetic force of 20,000 gauss is equivalent to a bar magnet that is capable of lifting an object weighing more than 50 tons (e.g. a diesel locomotive).
*5 Since other instruments were in place around the solenoid, it was necessary to let the particles pass through the solenoid.

The World Acclaimed Technology

Mizumaki holding the CERN Award (right); and the ATLAS Supplier Award Certificate (left).

After the installation work at CERN, Toshiba magnets continued working properly, without any trouble or failure.

"As it was installed in the Atlas detector, the solenoid continued working properly. We received such positive comments from the CERN personnel that 'the solenoid works so reliably and naturally that we forgot the existence of solenoid.' As a leading engineer working for the project, I was honored to see the device functioning so well and making such contributions to this 'monumental' discovery," said Mizumaki.

In recognition of its contribution to CERN and KEK in constructing the LHC, Toshiba received the ATLAS Supplier Award in 2002 and the CERN Award in 2010.

In the future, the scientists will reveal many remaining unknowns through the experiments currently on-going at CERN. Actually, the technology related to the discovery has already been applied to our daily lives.

In the next interview series, "MQX-A" the other device installed in the LHC, will be presented as well as the discussions related to the practical applications already utilized in our lives. We hope that these topics sound interesting to you as well !

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