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| SuperKEKB commissioning | |
|---|---|
| Name | SuperKEKB |
| Location | Tsukuba, Japan |
| Affiliation | KEK |
| Type | electron–positron collider |
| Status | Commissioning |
| Energy | 7 GeV / 4 GeV design (leaning ring energies) |
| Circumference | 3016 m |
| Colliding beams | Belle II |
SuperKEKB commissioning SuperKEKB commissioning began as the activation and beam-conditioning program for the SuperKEKB particle accelerator upgrade at KEK in Tsukuba, intended to deliver high-luminosity collisions to the Belle II detector. The commissioning program linked machine physics, accelerator technology, and detector readiness, coordinating efforts among teams from KEK, CERN collaborators, KEK Theory Center, and international partner laboratories such as SLAC, Brookhaven, and DESY. The effort drew on experience from predecessors and projects like KEKB, PEP-II, the LHC injector complex, and facilities including J-PARC, TRISTAN, and SPring-8.
Commissioning objectives were defined to validate the nanobeam scheme developed by Pantaleo Raimondi and collaborators, demonstrate the targeted instantaneous luminosity for the Belle II physics program, and establish reliable operational procedures for machine protection and beam lifetime. Primary goals included achieving design currents in the High Energy Ring and Low Energy Ring, validating the new positron and electron injection systems, and characterizing collective effects such as the electron cloud, intrabeam scattering, and beam–beam interaction phenomena. The program aimed to enable searches for new physics via precision measurements of CP violation, rare decays studied by Belle II and to support global efforts alongside experiments at CERN and Fermilab.
Infrastructure work reused sections of the original KEKB tunnel while installing new arc optics, final-focus magnets, and superconducting components designed with input from KEK engineers and international partners. Upgrades included fabrication and installation of the compressed-beta final-focus system inspired by Final Focus Test Beam concepts, replacement of vacuum chambers with low-secondary-emission materials informed by studies from SLAC and Cornell University, and deployment of new radio-frequency systems similar to those at PEP-II and ALBA. Beam instrumentation integrated hardware from DESY and diagnostics techniques developed at Brookhaven and TRIUMF. Civil works coordinated with Ibaraki Prefecture authorities and procurement partners across Japan and Europe.
Commissioning progressed through staged phases: initial hardware checkout and low-current single-beam tests, energy ramping and optics validation, multi-bunch operation, and collision tuning for luminosity optimization. Early milestones tracked by KEK teams paralleled timelines used at LHC commissioning and lessons from KEKB. Key calendar points included first stored beam, RF conditioning, and first collisions with the Belle II detector in parasitic or off-beam modes before full integrated physics running with partners from University of Tokyo groups, Nagoya University, and international collaborators.
Procedures combined classical accelerator techniques with modern diagnostics: orbit correction using Beam Position Monitor arrays, betatron tune measurement inspired by SPS methods, transverse feedback systems adapted from PEP-II, and beam-size measurements employing synchrotron radiation monitors developed with teams from SLAC and DESY. Diagnostics leveraged devices such as bunch-by-bunch transverse feedback, streak cameras, and synchrotron-light interferometers similar to those at SPring-8 and NSLS-II. Commissioning workflows used routines from CERN’s Accelerator Control systems and timing architectures analogous to XFEL projects. Injection studies coordinated with injector linac groups and injector test stands collaborated with KEK Accelerator Laboratory experts.
Notable milestones included demonstration of stable stored beams, mitigation of the electron cloud effect through coatings and scrubbing procedures informed by Cornell University and SLAC research, and progressive increases in bunch current and number to approach design luminosity. Challenges comprised vacuum conditioning, synchrotron radiation heat loads seen at predecessors like PEP-II, high-order mode heating in RF cavities, and beam instabilities analogous to experiences at SPS and KEKB. Machine tuning used feedback algorithms and optics corrections co-developed with groups from University of Melbourne, Osaka University, and international accelerator laboratories.
Radiation protection strategies followed national regulations coordinated with Ibaraki Prefecture and institutional protocols at KEK, employing interlock systems, beam-loss monitors modeled after LHC and SNS installations, and shielding upgrades. Machine protection systems integrated fast aborts, collimation inspired by LHC designs, and beam dump systems comparable to those at SLAC. Safety reviews engaged external advisory committees with members from Brookhaven, CERN, and Japanese regulatory bodies to ensure compliance with radiological and personnel safety standards.
Commissioning delivered critical data on beam dynamics, validated the nanobeam approach originally proposed by Pantaleo Raimondi, and yielded operational practices that improved uptime for the Belle II physics program. Lessons included improved vacuum treatments drawing on experience from Cornell University and SLAC, refined electron-cloud mitigation strategies, and control-system upgrades informed by CERN and DESY collaborations. The successful commissioning enabled Belle II to pursue precision studies relevant to flavor physics, searches for lepton flavor violation and rare processes complementary to experiments at LHCb, ATLAS, and CMS, strengthening the global particle-physics program through coordinated international collaboration.
Category:Particle accelerators Category:KEK Category:High-energy physics