岩手と宮城にまたがる「北上山地」が候補地になっている次世代型の大型実験施設、ＩＬＣ＝国際リニアコライダーの誘致を進める協議会の会合が１２日開かれ、今年度が誘致に向けた重要なタイミングだとして、国への働きかけを強化することを確認しました。（A meeting of the council promoting the ILC, a next-generation large-scale experimental facility proposed for the Kitakami Mountains spanning Iwate and Miyagi prefectures, was held on the 12th. At the meeting, participants confirmed that this fiscal year represents a crucial time for advancing the project and agreed to strengthen their efforts to engage with the national government.）

At the heart of the discussions were current and future flagship projects in fundamental physics: from the Future Circular Collider to the International Linear Collider, from the global network of gravitational wave detectors — LIGO, Virgo, and KAGRA — to the Einstein Telescope, from major experiments on neutrino physics and dark matter searches at Gran Sasso National Laboratories to neutrino studies in the T2K, Super-Kamiokande, and Hyper-Kamiokande experiments.

Inputs for an electron–positron LCF cover potential starting configurations based on Compact Linear Collider (CLIC) or International Linear Collider (ILC) technologies. It is proposed that the latter LCF could be upgraded using CLIC, Cool Copper Collider, plasma-wakefield or energy-recovery technologies and designs. Other proposals outline a muon collider and a possible plasma-wakefield collider, as well as potential “bridging” projects to a future flagship collider.

岩手、宮城両県にまたがる北上山地が建設候補地の超大型加速器「国際リニアコライダー（ILC）」を巡り、達増拓也岩手県知事、伊藤哲也宮城県副知事ら両県関係者が１３日、文部科学省などを訪れ…（有料記事）（On June 13, officials from both Iwate and Miyagi prefectures — including Iwate Governor Takuya Tasso and Miyagi Vice Governor Tetsuya Ito — visited the Ministry of Education, Culture, Sports, Science and Technology (MEXT) .(a paid article.)

岩手県は7日、国際リニアコライダー（ILC）推進本部会議を開き、大阪・関西万博の機会を捉えて誘致機運を醸成する方針を確認した。万博では周辺交通機関への広告出稿などに取り組む。　(On the 7th, Iwate Prefecture held a meeting of its ILC Promotion Headquarters, where it confirmed a policy to use the opportunity of the Osaka-Kansai Expo to build momentum for attracting the ILC. As part of this effort, the prefecture plans to place advertisements on surrounding transportation networks during the Expo.）

欧州の素粒子物理学の研究指針となる次期戦略への反映に向けて、国内外の研究者組織などが国際リニアコライダー（ＩＬＣ）に関する意見書を提出したことが分かった。日本での実現へ「グローバルプロジェクト」としての推進を強調する内容で、加速器建設費の最新試算も示した。今回の戦略更新は、次世代大型加速器の方向性が焦点。欧州、中国でも建設が計画される中、ＩＬＣがどう位置付けられるか注目される。(Research groups from Japan and abroad have submitted statements to the upcoming European particle physics strategy, emphasizing the promotion of the ILC as a global project based in Japan. The submissions include updated cost estimates for construction, and the positioning of the ILC is expected to be a key focus as the future direction of next-generation large-scale accelerators is considered.)

Although there are many novel proposals for new particle colliders, including in China, at CERN, and at Fermilab, the question of whether to build a circular machine, a linear lepton collider, or to pursue a novel muon collider all remain options on the table. In an ideal world, we’d get a linear machine to study the Higgs and the electroweak phase transition with great precision, and then a circular machine to collide hadrons at even higher energies. But funding, political realities, and popular opinion will also play a major role in determining what decisions get made.

The FCC is not the only major particle physics project under consideration.
Another is a proposed 20-kilometre machine called the International Linear Collider, which would likely be built in Japan.
The US has several projects on the go, mainly detectors of various kinds. It also supports an “offshore Higgs factory”, located in Europe or Japan.

The accelerator that could theoretically come on line the soonest, would be the International Linear Collider (ILC) in Iwate, Japan. The ILC would send electrons and positrons down straight tunnels where the particles would collide to produce Higgs bosons that are easier to detect than at the LHC. The collider’s design is technically mature, so if the Japanese government officially approved the project, construction could begin almost immediately.

Instead, researchers have suggested that linear accelerators – which would fire particles in straight lines – might prove to be cheaper, more flexible and more likely to achieve results than a circular collider. This point was backed by Jenny List, a researcher based at the German accelerator centre Deutsches Elektronen-Synchrotron (DESY) in Hamburg.
“There are other technologies on the horizon that could be used to accelerate particles like the proton without needing huge magnets or tunnels,” she said. “Plasma wave technology is one of these. Current devices are small, but within 20 years or so we could find they are ready to use to run a big collider.”

PR動画は、普段なじみのない素粒子物理学やILCを若い世代に身近に感じてもらうとラップやダンスを取り入れ、ILCの特徴である「衝突」を、食パンをくわえた高校生や相撲取りがぶつかり合うシーンで印象的に表現している。動画は２月現在、YouTubeで4万7千回以上、TikTokで200万回以上再生された。(The PR video incorporates rap and dance to help younger generations feel closer to particle physics and the ILC—fields that are usually unfamiliar to them. It highlights the ILC’s defining feature, “collision,” through memorable scenes such as a high school student with a slice of bread in their mouth and sumo wrestlers bumping into each other. As of February, the video has been viewed over 47,000 times on YouTube and more than 2 million times on TikTok.）

Advocates of a linear Higgs factory modelled on the International Linear Collider say it would do all the Higgs studies of the circular version, but be cheaper and faster. Jenny List, a physicist at the German Electron Synchrotron (DESY) in Hamburg, says that a machine with a 21–33-kilometre tunnel could cost less than half as much as the first stage of the FCC. It could also study how two Higgs particles interact with each other.

We can currently observe and measure this force at the CERN’s Large Hadron Collider (CHC) in Switzerland. As China builds its Circular Electron-Positron Collider and Japan builds its International Linear Collider, with Switzerland’s new Future Circular Collider and the Compact Linear Collider, we hope scientists will arrive at the long sought-after Grand Unified Field Theory. And if you add gravity, we will get the complete “Theory of Everything.”