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The High Energy Accelerator Research Organization (高エネルギー加速器研究機構, Kō Enerugī Kasokuki Kenkyū Kikō), known as KEK, is a Japanese organization whose purpose is to operate the largest particle physics laboratory in Japan, situated in Tsukuba, Ibaraki prefecture. It was established in 1997.[1] The term "KEK" is also used to refer to the laboratory itself, which employs approximately 695 employees.[2] KEK's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics, material science, structural biology, radiation science, computing science, nuclear transmutation and so on. Numerous experiments have been constructed at KEK by the internal and international collaborations that have made use of them. Makoto Kobayashi, emeritus professor at KEK, is known globally for his work on CP-violation, and was awarded the 2008 Nobel Prize in Physics.

Key Information

36°08′55″N 140°04′37″E / 36.14861°N 140.07694°E / 36.14861; 140.07694

History

[edit]

KEK was established in 1997 in a reorganization of the Institute of Nuclear Study, the University of Tokyo (established in 1955), the National Laboratory for High Energy Physics (established in 1971), and the Meson Science Laboratory of the University of Tokyo (established in 1988).[1] However, the reorganization was not a simple merge of the aforementioned laboratories. As such, KEK was not the only new institute created at that time, because not all of the work of the parent institutions fell under the umbrella of high energy physics; for example, the Center for Nuclear Study, the University of Tokyo, was concurrently established for low energy nuclear physics in a research partnership with RIKEN.

  • 1971: National Laboratory for High Energy Physics (KEK) was established.
  • 1976: The proton synchrotron (PS) produced an 8 GeV beam as designed. The PS achieved 12 GeV.
  • 1978: The Booster Synchrotron Utilization Facility and a Photon Factory (PF) were founded.
  • 1982: The PF succeeded in storing a 2.5 GeV electron beam.
  • 1984: The Transposable Ring Intersecting Storage Accelerator in Nippon (TRISTAN) Accumulation Ring (AR) accelerated an electron beam to 6.5 GeV.
  • 1985: The AR accelerated a positron beam to 5 GeV.
  • 1986: The TRISTAN Main Ring (MR) accelerated both electron and positron beams to 25.5 GeV.
  • 1988: The MR energy was upgraded to 30 GeV with the help of superconducting accelerating cavities.
  • 1989: Accelerator and Synchrotron Radiation Science departments were established in the Graduate University for Advanced Studies.
  • 1994: KEKB B-factory construction began.
  • 1995: TRISTAN experiments (AMY, JADE, TOPAZ, VENUS) finished.
  • 1997: The High Energy Accelerator Research Organization was established.
  • 1998: First beam storage at KEKB (KEK B-factory) ring.
  • 1999: The Long-baseline Neutrino Oscillation experiment (K2K) began. The Belle experiment at the KEKB began operation.
  • 2001: Construction of High Intensity Proton Accelerators (J-PARC) started.
  • 2004: Became the Inter-University Research Institute Corporation High Energy Accelerator Research Organization. K2K experiment ended.
  • 2005: Tokai Campus was opened. Experiments at PS ended.
  • 2006: J-PARC Center was established.
  • 2008: Prof. Makoto Kobayashi won the 2008 Nobel Prize in Physics.
  • 2009: J-PARC construction was completed.
  • 2016: First turns and successful storage of beams in the SuperKEKB electron and positron rings[3]
  • 2017: Completed the 'rolling-in' of the Belle II experiment in Tsukuba, Japan.
  • 2018: First collisions of SuperKEKB beams inside Belle II detector[4]

Organization

[edit]

KEK has four main laboratories

Scientists in KEK conduct training for PhD course students of the School of High Energy Accelerator Science in the Graduate University for Advanced Studies.

Location

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  • Tsukuba Campus: 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
  • Tokai Campus: 2-4 Shirane Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan

Particle accelerators

[edit]

Current complex

[edit]
BELLE detector
KEK e+/e- Linac
  • KEK e+/e- Linac: A linear accelerator complex used to inject 8.0 GeV electrons and 3.5 GeV positrons to KEKB. The linac also provides 2.5 GeV electrons for PF and 6.5 GeV electrons for PF-AR. The Linac has in recent years been upgraded for SuperKEKB.
  • Accelerator Test Facility (ATF): A test accelerator is focused on generating a super low-emittance beam. This is one of the essential techniques for realizing a future electron-positron linear collider. The beam energy of electrons is 1.28 GeV in normal operation.
  • Superconducting RF Test Facility (STF): A test facility to build and operate a test linac with high-gradient superconducting cavities, as a prototype of the main linac systems for International Linear Collider (ILC).
  • Japan Proton Accelerator Research Complex (J-PARC): A proton accelerator complex consisting primarily of a 600 MeV linac, a 3 GeV synchrotron and 50 GeV synchrotron. J-PARC was built with a collaboration between KEK and JAEA, and is used for nuclear physics, particle physics, muon science, neutron science, Accelerator-Driven System (ADS) and a range of other applications.
  • KEK digital accelerator (KEK-DA) is a renovation of the KEK 500 MeV booster proton synchrotron, which was shut down in 2006. The existing 40 MeV drift tube linac and rf cavities have been replaced by an electron cyclotron resonance (ECR) ion source embedded in a 200 kV high-voltage terminal and induction acceleration cells, respectively. A DA is, in principle, capable of accelerating any species of ion in all possible charge states.[5]

Shutdown complex

[edit]
  • Proton Synchrotron (PS): An accelerator complex to accelerate protons up to 12 GeV. PS had consisted primarily of a 750 keV pre-accelerator, a 40 MeV linac, a 500 MeV booster synchrotron and a 12 GeV main ring. PS had been used for nuclear and particle physics. PS also had provided the 12 GeV proton beam to a neutrino beam line in KEK for a KEK to Kamioka (K2K) experiment. PS achieved its design energy of 8 GeV in 1976. PS was shut down in 2007.
  • Neutrino Beam Line: A beam line to drive neutrinos into Super-Kamiokande, which is about 250 km away from KEK, and a neutrino oscillation experiment named K2K had been conducted from 1999 to 2004. A neutrino oscillation experiment named Tokai to Kamioka (T2K) has been conducted using J-PARC since 2009.
  • Transposable Ring Intersecting Storage Accelerator in Nippon (TRISTAN): An electron-positron collider had been operated from 1987 to 1995. The main purpose was detecting top quark. The electron and positron energy were 30 GeV. TRISTAN had three detectors: TOPAZ, VENUS and AMY. KEKB was built through the use of the tunnel of TRISTAN.

Running and future plans

[edit]
  • SuperKEKB: An electron-positron collider, consisting of a 7 GeV electron storage ring and a 4 GeV positron storage ring, to achieve higher luminosity by means of increasing the beam current, focusing the beams at the interaction point and making the electromagnetic beam-beam interactions small. The target luminosity has been set to 8×1035 cm−2 s−1, about 60 times higher than the KEKB's original design value. SuperKEKB has adopted a nano-beam scheme. KEK will build a new damping ring in order to generate the nano scale positron beam. On October, 2010 the Japanese government formally approved the SuperKEKB project, and in June 2010 an initial budget of 100 million dollars (¥100 = $1) for a Very Advanced Research Support Program was assigned for 2010-2012. The total budget is about 315 million dollars (¥100 = $1) by the program. The upgrade will be completed, and the first collisions have been conducted in 2018. The highest luminosity will be achieved in 2021. Belle II experiment will be conducted using SuperKEKB.
  • Compact Energy Recovery Linac (cERL): A test accelerator for a future synchrotron light source named Energy Recovery Linac (ERL). cERL will study the uncertainty of the accelerator physics in the ERL through the beam experiments. The beam commissioning in cERL will be scheduled from 2013 with a 35 MeV electron beam. KEK has a plan that will build 5 GeV ERL, provides ultra-high brightness and ultra-short pulsed synchrotron light, after the cERL experiments.
  • International Linear Collider (ILC): A future electron-positron linear collider consisting of superconducting cavities with a length of approximately 31 kilometers in length and two damping rings, for electrons and positrons, with a circumference of 6.7 kilometers. The electron and positron energy will be up to 500 GeV with an option to upgrade to 1 TeV. Nearly 300 laboratories and universities around the world are involved in the ILC: more than 700 people are working on the accelerator design, and another 900 people on detector development. The accelerator design work is coordinated by the Global Design Effort, and the physics and detector work by the World Wide Study.[6]

Computers

[edit]
Blue Gene

KEK has computers which are fastest class in Japan, and Computing Research Center in KEK manages the computer systems. The theoretical operation performance of SR16000, a super computer made by Hitachi, is 46 TFLOPS. The theoretical operation performance of Blue Gene Solution, a super computer made by IBM, is 57.3 TFLOPS. These super computers had been used to study quantum chromodynamics and numerical accelerator physics mainly, and these super computers have been shut down in order to introduce a next super computer in the future. Computing Research Center also manages the other computer systems: KEKCC, B-factory Computer System and Synchrotron Light Computer System.[7]

KEK hosted the first web site in Japan on September 30, 1992. The original web site can still be seen.[8]

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

KEK

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from Grokipedia
The High Energy Accelerator Research Organization (KEK) (Japanese: 高エネルギー加速器研究機構; Hepburn: Kō Enerugī Kasōki Kenkyū Kikō) is a national inter-university research institute in focused on advancing accelerator-based science to explore fundamental questions in , , , and related fields. Established in 1997 through the reorganization of the Institute of Nuclear Study (, founded 1955), the National Laboratory for High Energy Physics (established 1971), and the Meson Science Laboratory (, 1988), KEK operates as one of the world's leading facilities for high-energy accelerator research, with campuses in (Ibaraki Prefecture) and Tokai (Ibaraki Prefecture). KEK's core infrastructure includes major accelerators such as the SuperKEKB electron-positron collider, which achieved a instantaneous of 5.1 × 10^{34} cm^{-2} s^{-1} as of December 2024 to enable precise studies of decays and search for ; the Photon Factory synchrotron radiation source for materials structure analysis using and beams; and collaborative facilities like the Proton Accelerator Research Complex (J-PARC) for , , and experiments. The institute supports diverse experiments, including the Belle II detector at SuperKEKB for investigating and rare particle decays; the T2K long-baseline experiment, which spans 295 km from J-PARC to the detector, and recent joint analyses like the 2025 T2K-NOvA collaboration; and international collaborations like the at CERN's to probe the and new particles. KEK's research has yielded landmark contributions to physics, such as the Belle experiment's confirmation of in B mesons, which underpinned the 2008 awarded to KEK professor emeritus (shared with and ) for theoretical insights into and the matter-antimatter imbalance; additionally, KEK's involvement in T2K contributed to the 2016 for discoveries. Beyond , KEK facilitates applications in (e.g., cryo-electron labs), environmental safety, and industrial collaborations, fostering innovations through shared resources and programs like the initiative for young female researchers in the region.

Overview

Introduction

The High Energy Accelerator Research Organization (KEK) is Japan's national laboratory dedicated to and research. Established on , 1997, it resulted from the merger of the National Laboratory for High Energy Physics (established 1971), the Institute for Nuclear Study of the (established 1955), and the Meson Science Laboratory of the (established 1988). As an inter-university corporation, KEK operates under the oversight of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). Its current is Shoji Asai, who assumed the role on , 2024. KEK's core mission involves operating high-energy accelerators to conduct experiments in fundamental physics, developing advanced accelerator technologies, and advancing nuclear science alongside materials research. The laboratory employs over 600 staff members and supports extensive collaborative efforts with thousands of visiting researchers annually. Primary research areas encompass elementary particle physics, nuclear physics, materials structure science, and the innovation of accelerator systems, all aimed at elucidating the laws of nature and the universe's origins. On the international stage, KEK plays a pivotal role through collaborations such as the Japan Proton Accelerator Research Complex (J-PARC), a joint project with the Japan Atomic Energy Agency that facilitates cutting-edge experiments in particle and . The organization has also made significant contributions to landmark discoveries, including experimental validations of the Kobayashi-Maskawa theory on via the Belle experiment, which supported the 2008 awarded to and .

Location and Campuses

KEK maintains two main campuses in Ibaraki Prefecture, Japan, each tailored to distinct aspects of accelerator-based research. The Tsukuba Campus, located at 1-1 Oho, Tsukuba, Ibaraki 305-0801, serves as the organization's primary hub and the original site for high-energy physics investigations. This campus hosts key facilities for particle physics experiments, benefiting from its integration into the Tsukuba Science City, a designated research enclave established in the 1960s to centralize scientific infrastructure and foster interdisciplinary work. The Tokai Campus, situated at 203-1 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1106, emphasizes nuclear and physics . It is the site of the Proton Accelerator Complex (J-PARC), operated jointly with the Japan Atomic Energy Agency (JAEA), and was developed to accommodate advanced proton acceleration capabilities in proximity to established nuclear zones. The two campuses are approximately 80 km apart, enabling coordinated operations while leveraging regional strengths—Tsukuba's urban research ecosystem and Tokai's access to specialized nuclear infrastructure. Infrastructure at the Tsukuba Campus encompasses administrative buildings for organizational management alongside experimental halls that support diverse accelerator-driven studies. In contrast, the Tokai Campus includes underground facilities designed for precise beam delivery, particularly for experiments and muon-based investigations. Accessibility between sites is facilitated by a dedicated service, which covers the 80 km route in about 80 minutes, promoting efficient staff and resource mobility. The Tsukuba Campus's location enhances collaborations with the nearby , including joint events and shared research initiatives in fields like . Both campuses support international partnerships through their strategic positioning in Japan's research network. Environmental management plays a key role in operations, with measures to curb energy use and —such as optimized accelerator scheduling—implemented to mitigate the high power demands of facilities like SuperKEKB.

History

Founding and Reorganization

The Institute for Nuclear Study (INS) was established in 1955 at the as a dedicated center for nuclear and , building on a formed the previous year to advance studies in these fields. This institution played a pivotal role in early Japanese efforts, including the development of facilities like the FF cyclotron in 1957 and the in 1961. In April 1971, the National Laboratory for High Energy Physics—initially referred to as KEK—was founded in Tsukuba as Japan's first inter-university research institute, specifically to develop a proton synchrotron and conduct high-energy physics experiments. This establishment addressed the growing need for centralized, large-scale accelerator infrastructure beyond university capabilities, marking a shift toward collaborative national research in elementary particle physics. Later, in 1988, the Meson Science Laboratory was created at the University of Tokyo to focus on meson-related studies, further expanding the scope of accelerator-based nuclear research. On April 1, 1997, these entities—the National Laboratory for High Energy Physics, INS, and Meson Science Laboratory—were merged under the Ministry of Education, Culture, Sports, Science and Technology (MEXT) to form the High Energy Accelerator Research Organization (), an independent inter-university research institute. The reorganization was driven by the conclusion of TRISTAN experiments in 1995 and the imperative to integrate fragmented high-energy research efforts, particularly accelerator operations, into a unified structure to enhance efficiency and innovation in particle and . This merger incorporated programs from INS into 's broader mandate, transitioning them from university-affiliated operations to a national framework that also encompassed materials and life sciences. As an inter-university , the newly formed KEK received initial budget allocations from MEXT to support accelerator upgrades and facility integration, ensuring sustained operations post-merger. Key early decisions emphasized commitment to international collaborations for global research advancement and to promote industrial applications of accelerator technologies. This foundational structure enabled KEK to build on earlier accelerator projects, such as the initial operations in the 1970s.

Key Milestones and Achievements

In 1976, KEK achieved a significant milestone with the completion of the 12 GeV (PS), which produced its first 8 GeV beam in March and reached full 12 GeV energy by December, enabling Japan's inaugural high-energy physics experiments. This facility marked the beginning of advanced particle acceleration capabilities at KEK, facilitating proton-based research that laid the groundwork for subsequent collider developments. During the 1980s and 1990s, KEK constructed and operated the electron-positron , with key progress including electron acceleration to 6.5 GeV in 1984, positron acceleration to 5 GeV in 1985, and main ring operations reaching 25.5 GeV by 1986, leading to the start of physics experiments in 1987. operated until December 1995, conducting searches for supersymmetric particles and other new physics phenomena in electron-positron collisions up to energies beyond the Z boson mass. In June 1994, construction began on the KEKB B-factory, an asymmetric electron-positron designed for studies, with first beam storage achieved in 1998 and initial collisions enabling observations of in decays by the Belle experiment. The KEKB experiments provided crucial validation for theoretical predictions, culminating in the 2008 awarded to , a former KEK affiliate and director of the Institute of Particle and Nuclear Studies, and for their work on the Cabibbo-Kobayashi-Maskawa (CKM) matrix, which explained and was experimentally confirmed through KEKB's results. In the 2000s, KEK decommissioned the in 2007 to repurpose its infrastructure for the Japan Proton Accelerator Research Complex (J-PARC), a major shift toward higher-intensity proton acceleration. Concurrently, in 2006, KEK established the J-PARC Center in joint operation with the Japan Atomic Energy Agency (JAEA) at the Tokai site, integrating nuclear and particle physics research efforts. Entering the 2010s, KEK upgraded KEKB to SuperKEKB, achieving first beam circulation in February 2016 and initial physics collisions in April 2018, enhancing for precision flavor physics studies. KEK also contributed significantly to physics through the T2K experiment, where the J-PARC facility provided the beam starting from data-taking in 2010, enabling discoveries in s and searches. In recent years, J-PARC's beamline underwent successful upgrades, including enhancements to the main ring accelerator, allowing the T2K experiment to commence a new phase of data collection with increased beam power in December 2023 and stable operations in 2024. In October 2025, the T2K Collaboration published the first joint analysis with the NOvA experiment, combining datasets to constrain parameters and reduce uncertainties on matter-antimatter differences. SuperKEKB set a world record for in electron-positron collisions at 5.1 × 10^{34} cm^{-2} s^{-1} by the end of 2024, with ongoing nanobeam advancements in 2025 further optimizing collision efficiency and data accumulation.

Organization

Administrative Structure

KEK is governed as an inter-university corporation under the oversight of Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT), enabling extensive collaborations with numerous Japanese universities to advance accelerator-based research. The , Shoji Asai, holds ultimate responsibility for overseeing all organizational operations, supported by a team of executive directors managing key areas such as research coordination and administration. Advisory bodies, including the KEK Science Advisory Committee, convene annually to evaluate strategic priorities, including budget allocations, as detailed in the committee's 2025 report. KEK's annual operating budget is approximately ¥19 billion as of 2024, primarily funded through MEXT grants to support core operations and facility maintenance. Supplemental has been allocated in fiscal years 2024 and 2025 specifically for aging countermeasures and efficiency improvements at major facilities like J-PARC and SuperKEKB. Central administration is coordinated via the Administration Bureau, which manages , financial affairs, international collaborations, and research cooperation. and ethics oversight for accelerator operations is ensured through compliance frameworks, including dedicated protocols for and ethical conduct in high-energy experiments. KEK upholds policy frameworks emphasizing through transparent research dissemination and public engagement initiatives; in staffing, as outlined in its 2024 DE&I policy; and to industry via structured industry-academia partnerships.

Research Divisions and Education

KEK's research activities are organized into four primary laboratories, each focusing on distinct aspects of accelerator science and related fields. The Accelerator Laboratory, directed by Tadashi Koseki, is responsible for the design, construction, and operation of particle accelerators to support scientific experiments across various disciplines. The Particle and Nuclear Laboratory, also known as the Institute of Particle and Nuclear Studies and led by Director Naohito Saito, conducts experimental and theoretical research on elementary particles and atomic nuclei, including development and . The Applied Research Laboratory, under Director Yoshihito Namito, provides engineering support through research in radiation safety, computing, , and mechanical technologies, with applications in and beam utilization. Complementing these, the Institute of Materials Structure Science, directed by Nobumasa Funamori, utilizes , neutron, and beams to investigate the structures and functions of materials in , chemistry, and . KEK engages in collaborative frameworks to advance large-scale projects and international research. It jointly operates the Japan Proton Accelerator Research Complex (J-PARC) with the Japan Atomic Energy Agency (JAEA), facilitating high-intensity proton beam experiments in particle and . For the experiment, KEK contributes through the J-PARC neutrino beamline and participates in an international collaboration involving approximately 650 researchers from 23 countries, including partnerships with institutions in , , and . KEK maintains formal ties with global facilities such as , through memoranda of understanding for networking and joint research initiatives, and Fermilab, via collaborations on accelerator technologies and neutrino experiments like the design efforts. Education at KEK is integrated with the Graduate University for Advanced Studies (SOKENDAI), where it offers doctoral programs in Accelerator Science, Materials Structure Science, and Particle and , providing advanced training in theoretical and experimental techniques. These programs emphasize hands-on research using KEK's facilities, preparing students for careers in high-energy physics and related sciences. KEK also hosts the SOKENDAI KEK Tsukuba/J-PARC Summer Student Program, an eight-week internship for undergraduate and master's students from abroad, focusing on accelerator physics through lectures, experiments, and facility tours. Additionally, KEK organizes workshops and summer schools on accelerator physics to foster expertise among emerging researchers. KEK places strong emphasis on developing by training the next generation of scientists, with dedicated programs to support PhD candidates in conducting frontier research. Post-2020, KEK has advanced (DE&I) initiatives to create an environment where diverse talents can contribute equally, including policies to maximize abilities across demographics in research and operations. Outreach efforts at KEK aim to engage the public and students with concepts. The organization hosts public lectures, science cafés, and open campus events to explain accelerator science and its societal impacts. For educational , KEK runs programs like the Physics Program, where high school students participate in lectures, experiments, and facility visits to explore basic principles of the field. These initiatives, including hands-on science camps and masterclasses, promote awareness of high-energy physics among younger audiences.

Accelerator Facilities

Current Accelerators

KEK operates a suite of advanced accelerator facilities that support cutting-edge research in , accelerator technology, and applied sciences as of 2025. These systems include , , test beds, and specialized machines, each optimized for specific scientific and technical objectives while maintaining high reliability and performance. The KEK e⁺/e⁻ Linac functions as the primary for the SuperKEKB collider, accelerating electrons and positrons to an energy of 2.5 GeV. It delivers beams with exceptional stability, achieving bunch charges up to 10 nC and repetition rates of 50 Hz, enabling precise control for low-emittance injection into storage rings. This linac also supplies beams to synchrotron light sources at KEK, demonstrating its versatility in multi-user operations. SuperKEKB is an asymmetric electron-positron collider situated at KEK's campus, comprising a 7 GeV high-energy ring for electrons and a 4 GeV low-energy ring for s, with a of approximately 3 km. Operational since , it utilizes a nanobeam collision scheme to maximize event rates at the Belle II interaction point, focusing on precision measurements of decays and searches for new . In December 2024, SuperKEKB attained a world-record instantaneous of 5.1×1034 cm−2s−15.1 \times 10^{34} \, \mathrm{cm}^{-2} \mathrm{s}^{-1}, facilitated by optimized beam currents exceeding 1.4 A in the positron ring and advanced feedback systems; operations in 2025 continue to pursue luminosities approaching 1×1035 cm−2s−11 \times 10^{35} \, \mathrm{cm}^{-2} \mathrm{s}^{-1} through emittance tuning and injection improvements. The Accelerator Test Facility (ATF) features a 1.3 GeV damping ring that generates ultra-low emittance beams, essential for research and development toward the (ILC). The facility includes an S-band linac and extraction lines for beam diagnostics, routinely achieving vertical emittances below 10−9 m⋅rad10^{-9} \, \mathrm{m \cdot rad} at nominal intensities of 101010^{10} electrons per bunch. Ongoing studies at ATF2, the final-focus test beamline, validate nanometer-scale beam focusing techniques critical for linear collider designs. J-PARC, the Japan Proton Accelerator Research Complex, is a collaborative effort between KEK and the Japan Atomic Energy Agency (JAEA) located at the Tokai site, incorporating a 50 GeV proton synchrotron (Main Ring) that delivers intensities up to 2.6×10142.6 \times 10^{14} protons per pulse. This synchrotron drives the neutrino beamline for long-baseline experiments like T2K and the forthcoming Hyper-Kamiokande, producing muon neutrino beams over 295 km to Super-Kamiokande, as well as feeding the Muon Science Facility for precision measurements of the muon anomalous magnetic moment (g-2) and electric dipole moment (EDM). In June 2024, J-PARC's neutrino facility reached stable beam power of 800 kW, exceeding the original 750 kW design specification and enabling enhanced data collection; as of September 2025, it achieved 830 kW continuous operation, with scheduled runs through December 2025 to support ongoing neutrino oscillation analyses. The KEK Digital Accelerator (KEK-DA) is a compact, fast-cycling induction synchrotron designed for accelerating protons and heavy ions, achieving energies around 1.3 MeV for protons in a ring circumference of 18 m. It serves as a proof-of-principle platform for digital control techniques in accelerator physics and supports industrial applications, including beam irradiation for materials testing and development of compact sources for boron neutron capture therapy (BNCT). Recent enhancements focus on multi-ion beam handling and kicker systems for efficient capture from low-energy injectors. The Superconducting RF Test Facility (STF) evaluates cryomodules and cavities for high-gradient acceleration in prospective linear colliders such as the ILC, operating at 1.3 GHz with niobium-based superconductors cooled to 2 K. It has demonstrated stable beam acceleration to 40 MeV and supports long-pulse operations up to 1.5 ms, with 2025 tests achieving high currents of 10 mA while maintaining gradients exceeding 30 MV/m. STF also integrates low-level RF controls and cavity processing infrastructure to refine fabrication techniques for global collider projects.

Decommissioned Accelerators

The (PS) at KEK, located in , was a 12 GeV proton accelerator that operated from December 1976 until its effective cessation in December 2005. It facilitated pioneering physics experiments, including studies of particle interactions and using high-intensity proton beams. The PS's decommissioning was driven by the reallocation of resources to the Japan Proton Accelerator Complex (J-PARC), which demanded advanced proton acceleration capabilities beyond the PS's design limits. The electron-positron collider, also at , functioned from 1987 to December 1995 with a maximum center-of-mass energy of 64 GeV. It conducted searches for the top quark and evidence of through high-energy collisions, contributing key data to the global understanding of electroweak interactions. Operations ended due to the machine's energy constraints relative to emerging priorities in B-physics and the need to repurpose infrastructure for higher-luminosity experiments. KEKB, the pre-upgrade B-factory collider at , operated from 1998 to June 2010, featuring an 8 GeV ring and a 3.5 GeV ring in an asymmetric configuration. It enabled the Belle experiment to achieve landmark measurements of in B meson decays, providing crucial evidence for the standard model's matter-antimatter asymmetry. Decommissioning occurred to facilitate the upgrade to SuperKEKB, aiming for significantly higher to probe new . The beamline from the PS to , part of the K2K (KEK to Kamioka) experiment, ran from May 1999 to November 2004. It produced a beam over 250 km to study oscillations, confirming atmospheric disappearance and laying groundwork for long-baseline oscillation measurements. The facility was shut down following the experiment's completion, with subsequent efforts shifting to the more intense beams from J-PARC in the T2K experiment. The decommissioned accelerators at KEK have left a lasting legacy through their datasets, which continue to inform global analyses, such as precision electroweak fits and mixing parameters. Infrastructure from these facilities has been repurposed effectively; for instance, the tunnel was reused for KEKB and subsequently SuperKEKB, optimizing resource use in accelerator development.

Future and Upgrade Projects

KEK is actively pursuing several upgrade projects and new facilities to enhance its accelerator capabilities and address key questions in . Central to these efforts is the ongoing optimization of the SuperKEKB electron-positron collider, which employs nanobeam collision technology to achieve higher luminosities. As of early 2025, beam squeezing techniques have shown promising progress, enabling the to record integrated luminosities approaching design goals, with a target of 10 ab⁻¹ by 2032 through phased upgrades, and plans for further detector and accelerator enhancements to achieve higher integrated luminosities in the following decade. The Compact Energy Recovery Linac (cERL) represents another key development, designed as an (IR-FEL) source for applications. This superconducting accelerator, capable of recirculating high-average-current beams up to 1 mA, has demonstrated stable operations in 2025, building on prior mid- FEL commissioning. Full commissioning and user operations for IR-FEL experiments are targeted for post-2025, aiming to provide tunable coherent light for ultrafast and structural studies. A flagship long-term project is the (ILC), a proposed 250–500 GeV electron-positron linear collider for precision Higgs and studies. KEK leads Japanese research and development, including tests at the Superconducting RF Test Facility (STF) to validate cryomodule performance and beam dynamics. 's 2025 strategy positions the ILC as the primary post-SuperKEKB and T2K initiative, with potential siting in and ongoing international discussions for funding and collaboration through frameworks like the ILC Technology Network. Further enhancements at the Japan Proton Accelerator Research Complex (J-PARC) are also advancing, targeting a proton beam power increase to approximately 1 MW by late 2025 and 1.3 MW by 2028 through magnet and RF cavity reinforcements and other improvements. This will support the new / (EDM) facility (E34), which uses low-emittance muon beams to probe beyond-Standard-Model physics with unprecedented sensitivity, as demonstrated in 2025 beam tests. Additionally, integration with the detector will leverage the upgraded beam for enhanced searches of in oscillations. In the broader vision, Japan's input to the 2025 European Strategy for process underscores the ILC as a cornerstone project following SuperKEKB successes, while emphasizing human resource development through international training and education programs to sustain expertise in large-scale collider technologies.

Computing Resources

Supercomputing Infrastructure

The Computing Research Center (CRC) at KEK oversees the organization's resources, enabling advanced simulations and data processing essential for research. These resources support key experiments including Belle II for B-physics, ATLAS at the LHC, J-PARC for and studies, and R&D for the (ILC). The CRC integrates computational power with storage and networking to handle the intensive demands of simulations, lattice (QCD) calculations, and beam dynamics modeling. Historically, KEK deployed the SR16000 in 2002, achieving a peak performance of 46 TFLOPS to facilitate early large-scale numerical simulations in high-energy physics. This system was complemented by the IBM Blue Gene/P installation in 2007, which delivered 57.3 TFLOPS and focused on parallel processing for theoretical computations. Both systems were decommissioned by the early 2020s as computational needs evolved toward greater and energy efficiency. KEK's current supercomputing infrastructure consists of hybrid clusters incorporating CPU and GPU acceleration. Key systems include the SX-Aurora TSUBASA vector supercomputer with 313.6 TFLOPS peak performance and 128 vector engines, and the KEKCC2024 central system, deployed in 2024, featuring 12,096 cores and 30 PB of combined disk and . Additional systems like Suiren2 (1.082 PFLOPS) and Suiren Blue (0.428 PFLOPS) contribute to the overall capacity. These clusters process from detector experiments, perform simulations for quark-gluon plasma studies, and model beam dynamics for accelerator optimization. Usage is predominantly allocated to ongoing experiments, with over 80% of resources dedicated to collaborative projects; international users access these via cloud-integrated grid frameworks such as WLCG. Looking ahead, KEK is conducting R&D toward and enhanced storage, with KEKCC2024 providing 120 PB tape capacity as of 2025, and AI tools under development for automating in projects like ; major upgrades are planned for KEKCC2028. These developments aim to address the growing computational intensity of physics and applications in particle detection.

Digital Innovations and Networks

KEK played a pioneering role in Japan's adoption of technologies, hosting the country's first on September 30, 1992, through its Computing Research Center. This early implementation served as a platform for disseminating information about the electron-positron project and marked one of the initial web servers in during the nascent stages of the . As an early adopter of TCP/IP protocols in , KEK established international connectivity in 1987 via a 9.6 kbps link, with full TCP/IP adoption and transition from protocols like BITnet and DECnet occurring by 1988; a 56 kbps link to a U.S. site was implemented in , facilitating high-energy physics collaborations and data exchange within the global HEP community. In the , KEK contributed to network infrastructure development by integrating with Japan's Science Information NETwork (SINET), which provided a dedicated academic backbone for high-speed data transfer among research institutions. KEK's network evolution continued into high-capacity systems, with the connected to SINET at 130 Gbps domestically and 400 Gbps for international links via SINET6 as of 2025, including direct paths to for real-time data sharing in experiments like Belle II. These connections enable seamless global collaboration, supporting petabyte-scale data flows essential for analysis. The KEK Digital Accelerator (KEK-DA), operational since 2011, exemplifies advancements in digital control systems for beam acceleration. Its intelligent control framework uses and feedback loops to precisely manage rapid voltage variations in induction acceleration, achieving stable control from low energies without a high-energy . This approach has enhanced techniques for digital beam diagnostics and synchronization, influencing compact accelerator designs. In modern initiatives, KEK addresses cybersecurity challenges for large-scale experiments through robust network protections integrated with SINET, safeguarding sensitive data transfers against threats in environments. For experiments like T2K and Belle II, KEK implements comprehensive data management plans that emphasize long-term preservation and accessibility, including policies for raw data redundancy across multiple sites to mitigate risks from failures or disasters. These plans support controlled within collaborations while adhering to international standards for scientific . Looking ahead, expansions in SINET6 upgraded international lines to 400 Gbps in 2025, enabling KEK to leverage international grids like the Worldwide LHC Computing Grid (WLCG) for enhanced simulations of the (ILC). This infrastructure facilitates for complex ILC detector and beam dynamics models, distributing workloads across global sites to accelerate R&D. KEK's digital innovations have broader impacts through to Japanese industry, where expertise from accelerators like KEK-DA informs high-reliability networking solutions for sectors requiring precise, fault-tolerant data handling. Collaborations with companies have licensed accelerator-derived technologies, promoting applications in and industrial automation.

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