Researchers promoting a project to build a 30-km-long straight linear accelerator aimed at answering questions about the beginnings of the universe, named the International Linear Collider, said Friday they have chosen the Kitakami mountain area in the Tohoku region as a candidate site.

But whether the government will invite the project remains to be seen due to the high cost, forecast at more than ¥1 trillion. About half of that amount is expected to be borne by the host state.

The group of researchers told reporters that they prefer the Kitakami area, which straddles Iwate and Miyagi prefectures, over the other candidate, the Sefuri mountain area in Kyushu.

The Ministry of Education, Culture, Sports, Science and Technology will decide whether to allow the project to go ahead and if so will select a candidate site taking the researchers’ choice as a “reference.”

The Science Council of Japan has said it is “premature” to seek to attract the project, in response to an inquiry from the ministry.

The ILC is a linear accelerator about 30 km long that will be built in an underground tunnel and will hurl electrons and their antiparticles, positrons, toward each other at nearly the speed of light to produce conditions resembling the dawn of the universe right after the Big Bang. In the future, the collider’s length may be extended to 50 km.

The researchers said the Sefuri site was less suitable because the prospective tunnel would run under a reservoir and near geological faults.

Construction costs are estimated at ¥830 billion. Including costs for personnel and land acquisitions and production of necessary equipment, the total project expenses will top ¥1 trillion.

The United States and Europe want Japan to lead the construction of the facility. If the accelerator is built in Japan, the country would need to cover at least half of the costs, sources said.