Japan defers ILC decision (Symmetry magazine)

2019年3月7日

Proponents of building the next big particle collider in Japan expressed their disappointment today at the latest statements on the topic from government officials.

Scientists have proposed building the International Linear Collider, which would be the longest linear collider in the world, in the Kitakami mountains in the Iwate prefecture of northern Japan. Scientists had called on the Japanese government to come to a decision about whether they support hosting the ILC by today’s meeting of the International Committee for Future Accelerators, or ICFA.

Government officials spoke positively about the proposed collider and recommended Japanese research organization KEK approach governments and funding agencies in other countries to discuss options for sharing its associated costs, the chair of ICFA said today in a press conference in Tokyo. But the officials did not go as far as declaring their interest in hosting the ILC.

Scientists set today’s decision deadline in the hopes of having a clearer picture of the future of the ILC as physicists in Europe begin the process of updating their regional strategy for particle physics. “We were hoping that for this strategy discussion that we would know whether Japan was going to be hosting it or not,” said Geoffrey Taylor, chair of ICFA and director of CoEPP in Australia. “We were hoping that there would be a definite statement. We don’t have a positive statement like that.”

However, he said, “the fact that it is not going to be made in time for this discussion in Europe is not the end of the story.”

The ILC would be a tool to study in detail the Higgs boson, discovered at experiments at the Large Hadron Collider in 2012. The ILC is designed to be a precision machine, capable of generating the same type of collisions over and over. This would allow it to mass-produce particles like the Higgs; scientists call it a “Higgs factory.”

Mass-producing Higgs bosons would allow scientists to investigate with great precision the particle’s properties. Any deviations from scientists’ predictions could point the way to new discoveries, such as additional Higgs bosons, supersymmetric particles or dark matter.

The ILC is not the only Higgs factory that scientists have proposed to build, but so far it is the most developed idea, giving it a competitive advantage, said Tatsuya Nakada, chair of ICFA’s Linear Collider Board and a professor at École Polytechnique Fédérale de Lausanne in Switzerland. “If we wait, then the situation will change, but right at the moment, it is the most advanced.”