KEK (research center)

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Site of the KEK Research Center at the foot of Tsukuba Mountain . Links is the proton, the East Hall synchrotrons (KEK-PS) and right the experimental hall Oho of KEKB - storage ring to see. In the background is the Tsukuba hall with the Belle experiment .

KEK ( Japanese 高 エ ネ ル ギ ー 加速器 研究 機構 kō-enerugī kasokuki kenkyū kikō " High Energy Accelerator Research Organization" ) is a national research center for high energy physics in Japan . The research center, located about 55 kilometers northeast of Tokyo in Tsukuba , in Ibaraki Prefecture , was established in 1971 as the National Laboratory for High Energy Physics (Japanese 高 エ ネ ル ギ ー 物理学 研究所K ō- E nerugī butsurigaku K enkyūsho "High Energy Physics Research Institute") founded and merged in 1997 with the Institute of Nuclear Study (INS) founded in 1955 and the Meson Science Laboratory founded in 1988 - both from the University of Tokyo ; the Japanese acronym for "high-energy research institute" was retained.

KEK conducts research in the field of particle and nuclear physics as well as materials and life sciences with the help of several large particle accelerators . These include the KEKB and its successor SuperKEKB as well as the J-PARC accelerator complex near Tōkai . In addition, components for accelerator systems are developed, especially in the field of superconducting magnets , particle detectors and cavity resonators . The KEK developed, among other things, components for the ATLAS detector of the LHC at CERN and the crab cavities of the KEKB - with the help of which it was possible to achieve the current (2013) luminosity world record in the Belle experiment in 2009 .

founding

After the end of World War II , research in the field of nuclear physics was banned in Japan until the early 1950s. In 1955 the Institute of Nuclear Study (INS) was founded at the University of Tokyo , which built the first larger particle accelerator, a 750 MeV electron synchrotron , from 1956 to 1961 . From 1966 this reached energies of 1.3 GeV. In order to be able to catch up with international research in experiments with high-energy ions, leading scientists pushed ahead with the plan to build a 40 GeV proton synchrotron in the mid-1960s. At the beginning of the 1970s, however, the Japanese government only approved a reduced budget for the construction of an 8 GeV proton synchrotron, combined with the condition that a national high-energy physics research facility be established. The result was the founding of the KEK in 1971.

Accelerators and Experiments

Proton Synchrotron (KEK-PS)

The KEK-PS, TRISTAN and the Photon Factory at KEK in Tsukuba

As part of the development of Tsukuba into the “City of Science” from 1970, construction of the 8 GeV proton synchrotron began in April 1971 in the north of the city on the grounds of the newly founded KEK, which was completed by the end of 1976. The achievable proton energy could be increased further to 12 GeV in the course of a year, and from 1977 the first experiments at Japan's first large particle accelerator were started. The KEK-PS laid the foundation for further accelerators at the KEK and, with its almost 30 years of operation until December 2005, made a significant contribution to the development of the KEK and high-energy physics in Japan.

The KEK-PS consisted of a linear accelerator (LINAC) - in turn fed by a Cockcroft-Walton accelerator - which accelerated the protons to 40 MeV. These were then further accelerated in a first synchrotron with a circumference of 38 meters to 500 MeV and fed into the main ring with a circumference of 339 m. There the proton packets were brought to their final energy of 12 GeV and made available to the experiments in the north and east halls of the KEK-PS via beam lines . The 500 MeV proton beam from the booster was also used for the neutron and meson laboratories to the south of the main ring , which were built in the late 1970s.

Until the completion of TRISTAN in 1985, the KEK-PS was the only available particle accelerator in Japan for this energy range and was used for a large number of experiments in particle and nuclear physics. After the start-up of the electron / positron accelerator TRISTAN, the KEK-PS was mainly used to investigate strange matter such as hyper nuclei and the decay processes of kaons . Furthermore, with the development activities of KEK for particle detectors, the need for proton beams for test purposes increased. The last phase of operation of the KEK-PS was characterized by the KEK-to-Kamioka experiment (K2K) from the end of the 1990s . For this purpose, a beam line in the direction of the Super Kamiokande experiment was put into operation in 1999 , in which neutrinos were generated with the proton beam and sent in the direction of Kamioka (today Hida ) 250 km away . The aim was to study the neutrino oscillation ; around two thirds of the available operating time of the KEK-PS was used for this.

Photon Factory (PF) and TRISTAN

The linear accelerator (LINAC) at KEK in Tsukuba

In the mid-1970s, the KEK was planning two new particle accelerators at the same time. On the one hand, a 2.5 GeV electron storage ring for the generation of synchrotron radiation for materials and life sciences was to be created, and on the other hand, a large electron-positron collider , with energies of 60 GeV, for high-energy physics. Although these were intended for different research areas, they were both based on the acceleration of electrons, which enabled the joint use of a LINAC for pre-acceleration (the positrons are generated by bombarding special targets with electrons and are also accelerated in the LINAC). At the beginning of 1979, construction work began on the LINAC complex, which was continuously expanded in the following years and, with the exception of KEK-PS, served as a pre-accelerator for all other large particle accelerators at the KEK site in Tsukuba. It is currently (2013) being converted for the SuperKEKB, which is currently under construction. In 1982 the electron beam reached 2.5 GeV. This was then available to the Photon Factory's storage ring, which was also completed , as well as the TRISTAN Accumulation Ring (AR) completed in 1983 . The TRISTAN-AR was another pre-accelerator for the later main ring and brought electrons and positrons to 6 and later to 8 GeV.

TRISTAN
The particle accelerator TRISTAN consisted of several pre-accelerators and a main ring (Main Ring, MR) with a circumference of three kilometers for the simultaneous acceleration of electrons and positrons and their collision with center of gravity energies of up to 64 GeV. The motivation for the construction was the theory put forward by Makoto Kobayashi and Toshihide Maskawa in 1973 to explain the CP violation by means of a third generation of quarks (bottom and top quarks). This should be confirmed experimentally. At the end of the 1970s, plans to build a particle accelerator to search for the remaining top quark (the bottom quark was detected at Fermilab in 1977 ) were pushed forward at KEK and construction began in 1981. It was in operation from 1986, but by the end of the 1980s it became apparent that the energy to produce the top quark would not be sufficient. Thereupon planning for the follow-up project KEKB was started and in 1994 the renovation started; The operation of TRISTAN was finally stopped in 1995.
Photon Factory (PF)
Since 1982, a 2.5 GeV electron storage ring with a circumference of 187 m has been producing synchrotron radiation of high brilliance . The spectrum of radiation ranges from vacuum UV (VUV) to high-energy X-rays . The electrons are already provided with their final energy by the LINAC complex and stored in up to several hundred packets over 30 hours (beam lifetime) in the PF ring. With the conversion of the TRISTAN accelerator to the KEKB, the former pre-accelerator ring TRISTAN-AR was no longer required and in 1998 it was converted for the targeted generation of synchrotron radiation in the field of high-energy X-rays and renamed the Photon Factory Advanced Ring (PF-AR). Electrons with an energy of 3 GeV are fed into the PF-AR by the LINAC and further accelerated to 6.5 GeV in a circulating package, with a beam lifetime of around 20 hours.
With their steel lines, both storage rings serve over 50 experiment stations, two thirds of which with hard X-rays and one third with VUV radiation and soft X-rays. The experiments range from structural analysis by means of X-ray diffraction , through various spectroscopic methods, to medical applications.

KEKB and SuperKEKB

The KEKB particle accelerator ( B-Factory ) at the KEK in Tsukuba
The Belle detector at KEKB

The KEKB , designed as a B-factory with asymmetrical energies, was created in 1994 from the particle accelerator TRISTAN, making maximum use of the existing infrastructure and technology. It was put into operation in 1998 and consisted of two separate storage rings for electrons (8 GeV) and positrons (3.5 GeV), which were built by TRISTAN in the existing 3 km long tunnel. Furthermore, the former linear accelerator had to be upgraded and extended by 200 meters, since it was supposed to feed the particles into the storage rings with their maximum energy.

The aim of the accelerator was the generation of B mesons , whose decay - according to theoretical predictions based on the CKM matrix - would have to have a pronounced CP violation and thus be easily observable. With the BaBar experiment of the PEP-II ( SLAC ) in the USA and the Belle experiment of the KEKB, the CP violation in the system of the B mesons could be observed for the first time, which led to the Nobel Prize in Physics 2008 for the Japanese physicist Makoto Kobayashi and Toshihide Maskawa led. After more than ten years of successful operation, KEKB ceased operations in June 2010.

The analysis of a large number of particle collisions is necessary for the precise determination of the CP violation. A measure of the collision rate that can be achieved with an accelerator at the point of interaction is the luminosity . By installing the crab cavities developed at KEK, the Belle experiment succeeded in achieving the luminosity world record of 2.1 · 10 34  cm −2  s −1 , double the originally planned value.

In order to further increase the luminosity, the KEKB has been converted into the SuperKEKB accelerator with the follow-up experiment Belle-II since the end of 2011 . The first tests of the accelerator took place in spring 2016 and the detector was brought into its final position at the collision point in April 2017. Completion is planned for 2018 [obsolete] . The aim is to increase the luminosity by a factor of 40 by 2021, up to 8 · 10 35  cm −2  s −1 . This should be achieved by better focusing the rays at the point of interaction and by increasing the number of particles circulating in the storage rings. Furthermore, a reduction in the asymmetry of the energies is planned; there should be collisions of the electrons with 7 GeV and the positrons with 4 GeV.

J-PARC

The particle accelerators (3 and 50 GeV protons - synchrotron ) and experimental halls at the Japanese research complex J-PARC, about 120 km north of Tokyo on the Pacific coast

The J-PARC is from KEK in cooperation with the Japan Atomic Energy Agency JAEA -driven research complex at Tōkai in Ibaraki Prefecture . Built between 2001 and 2008, it is the successor to KEK-PS, which was operated in Tsukuba until 2005. The J-PARC has three particle accelerators, which one after the other accelerate protons up to 50 GeV.

A multi-stage LINAC brings the protons to an energy of 181 MeV. In a further expansion stage, it should reach 400 MeV for feeding into the first synchrotron with a circumference of 348 meters, as well as 600 MeV for planned separate experiments on the transmutation of radioactive waste . The first synchrotron accelerates the protons of the LINAC to 3 GeV. About 96 percent of the particles are passed through a beam line in the experimental hall of the materials and life sciences, where with the help of spallation - Targets muons and - neutron rays are generated. The hall is located within the 50 GeV main ring , into which the remaining 4 percent of the 3 GeV protons are introduced approximately every 3 seconds. The main ring has a circumference of 1568 m and accelerates the protons to currently (2013) 30 GeV; a further increase to 50 GeV is planned. This serves the beam lines to the hadron experiment hall and to the Tōkai-to-Kamioka experiment (T2K). The T2K experiment is the successor to the K2K experiment, which was operated at KEK-PS until the end of 2005. It sends a neutrino beam to the Super Kamiokande detector, 295 km away , where the first neutrino was registered in February 2010.

The J-PARC generates high-power secondary beams and, along with the Spallation Neutron Source (SNS) of the Oak Ridge National Laboratory in the USA and the ISIS of the British Rutherford Appleton Laboratory, is one of the world's most powerful systems for generating muon and neutron beams. By 2011, the two proton synchrotrons had achieved stable beam powers of 100 to 200 kilowatts, up to one megawatt is planned.

organization

General Directors
Surname Period Life dates
Shigeki Suwa 1971-1977 1920-1997
Tetsuji Nishikawa 1977-1989 1926-2010
Hirotaka Sugawara 1989-2003 * 1938
Yōji Totsuka 2003-2006 1942-2008
Atsuto Suzuki 2006-2015 * 1946
Masanori Yamauchi since 2015

The KEK is under the supervision of the Japanese Ministry of Education, Culture, Sport, Science and Technology (MEXT), which also provides funding. The KEK is headed by the eleven-member board of directors chaired by the general director. Masanori Yamauchi has held this position since 2015. It employs around 700 people. Between 2008 and 2011 it recorded an average of 80,000 person- days in use of the approximately 1,000 experiments; about a quarter of them by foreign scientists. The KEK's expenditures averaged 45 billion yen (about 340 million euros) per year during this period .

In addition to administration and several smaller departments - responsible for public relations , security and international cooperation, among other things - the research center is divided into two large research institutes and three departments responsible for the operation and development of the current and future accelerator facilities and experiments:

Institute of Particle and Nuclear Studies (IPNS)
The IPNS conducts theoretical and experimental research in the field of particle and nuclear physics . The latter are primarily carried out using the large particle accelerators at the locations in Tsukuba (KEKB or SuperKEKB) and Tōkai (J-PARC), but also as a partner in international collaborations such as the LHC of CERN . It is also involved in the POLARBEAR experiment in the Atacama Desert to measure the polarization of the cosmic microwave background , as well as in the development and planning of the International Linear Collider (ILC), which may be set up in Japan.
Institute of Materials Structure Science (IMSS)
At IMSS , the focus is on researching the structure and functioning of materials with the help of the high-energy photons generated by particle accelerators (synchrotron radiation from the Photon Factory) as well as muon and neutron beams ( Muon Science Laboratory (MSL) and Neutron Science Laboratory (KENS) at J. -PARC, until 2005 at KEK-PS). The broad spectrum of interdisciplinary research is in the field of materials and life sciences .
Accelerator Laboratory
The Accelerator Laboratory operates all of the KEK's particle accelerators and forms the foundation of the research center. In addition to the operation and maintenance of the existing and the construction of the planned facilities, it is involved in the further and new development of components for the accelerator facilities.
Applied Research Laboratory
This laboratory is responsible for radiation and environmental protection, computer and network technology as well as the supply of liquid helium and the support of the systems and experiments with their mechanical workshops. It also conducts its own research in the areas mentioned as well as in cryogenics and superconductivity .
Department of Advanced Accelerator Technologies
The department deals with the development and testing of future particle accelerators and detectors as well as their components, for example for the International Linear Collider or an improved method for generating synchrotron radiation using an Energy Recovery Linac in the GeV range.

The KEK maintains several test facilities for its development activities in the field of accelerator technology and has pioneered pioneering work in the last few decades , especially in the field of superconducting magnets and cavity resonators . So superconducting cavity resonators were as in the 1980s at the TRISTAN Main Ring world's first time as accelerator components used, and the Crab employed at KEKB Cavities presented the first successful implementation of the 30th years earlier by Robert Brian Palmer invented the concept of crab crossings is where By turning the rotating particle packets slightly, a better penetration at the collision point and thus a higher collision rate is achieved.

Web links

Commons : KEK  - collection of pictures, videos and audio files

literature

Individual evidence

  1. ↑ a b c d e Yoshitaka Kimura, Nobukazu Toge: Pursuit of Accelerator Projects at KEK in Japan. ( Memento of October 4, 2013 in the Internet Archive ) (PDF; 2.9 MB) In: Reviews of Accelerator Science and Technology. Vol. 5, 2012, pp. 333-360.
  2. ^ History - About KEK. Official website of the High Energy Accelerator Research Organization, KEK. Retrieved December 4, 2015.
  3. ^ Historical Background and Perception of the Times. Tsukuba-Science City Network. Retrieved September 8, 2013.
  4. ^ Neutron Science Laboratory and Meson Science Laboratory. KEK News, Vol. 1, No. 2, 1998, ISSN  1343-3547 , pp. 1-6 ( online ).
  5. ^ Satoshi Ozaki: Report of the 2004 KEK PS External Review Committee. (PDF; 329 kB) High Energy Accelerator Research Organization (KEK), External Review Committee, Tsukuba 2004, pp. 2-15.
  6. ↑ a b Yoshitaka Kimura: The Performance of TRISTAN and Accelerator Development at KEK. (PDF; 676 kB) In: Proc. of the 2nd European Particle Accelerator Conference. Nice, France, 12.-16. June 1990, pp. 23-27.
  7. ^ I. Abe et al .: The KEKB injector linac. (PDF; 2.7 MB) In: Nuclear Instruments and Methods in Physics Research Section A. Vol. 499, No. 1, 2003, pp. 167-190, doi : 10.1016 / S0168-9002 (02) 01787-4 .
  8. ^ T. Higo et al .: Linac Upgrade in Intensity and Emittance for SuperKEKB. (PDF; 758 kB) In: Proc. of the IPAC2012. New Orleans, USA, Jan. 20-25 May 2012, pp. 1819-1821.
  9. ↑ a b Hironori Nakao et al. (Ed.): Photon Factory Activity Report 2011 - Part A "Highlights and Facility Report". High Energy Accelerator Research Organization (KEK), Tsukuba 2012, ISSN  1344-6320 , pp. 84-110.
  10. ^ Yoshitaka Kimura: FROM TRISTAN TO B-FACTORY. (PDF; 1.6 MB) In: IPAC'10 - Special Lectures to Commemorate the 120th Anniversary of Birth of Yoshio Nishina. Kyoto, Japan, May 23, 2010.
  11. ↑ a b Akira Yamamoto: Progress in applied superconductivity at KEK. CERN-Courier, October 25, 2011. Accessed September 8, 2013.
  12. ^ Tetsuo Abe et al .: Achievements of KEKB. In: Prog. Theor. Exp. Phys. 03A001, 2013, pp. 1–18, doi : 10.1093 / ptep / pts102 .
  13. ^ Belle II detector rolled-in. Belle II Experiment, updates June 26, 2017. Retrieved September 24, 2017.
  14. ↑ Paul Maurice: BELLE II experiment benefits from GÉANT's global left. In: CONNECT magazine. July 16, 2014, pp. 10-12.
  15. ↑ K. Akai, H. Koiso, K. Oide: Design Progress and Construction Status of SuperKEKB. (PDF; 1.9 MB) In: Proc. of the IPAC2012. New Orleans, USA, Jan. 20-25 May 2012, pp. 1822-1824.
  16. ^ M. Masuzawa: NEXT GENERATION B-FACTORIES. (PDF; 3.1 MB) In: Proc. of the IPAC'10. 23-28 May 2010, Kyoto, Japan, pp. 4764-4768.
  17. ^ A b Yoshishige Yamazaki: FROM KEK-PS TO J-PARC. (PDF; 1.1 MB) In: IPAC'10 - Special Lectures to Commemorate the 120th Anniversary of Birth of Yoshio Nishina. Kyoto, Japan, May 23, 2010.
  18. ↑ Shoji Nagamiya: Introduction to J-PARC. In: Prog. Theor. Exp. Phys. 02B001, 2012, pp. 1–13, doi : 10.1093 / ptep / pts025 .
  19. ^ KEK Executive Board - Officer list. Official website of the High Energy Accelerator Research Organization, KEK.Retrieved December 4, 2015.
  20. ↑ Akihiro Maki et al. (Ed.): 2011 at KEK - Annual Report Vol. 3. ( Memento from September 25, 2013 in the Internet Archive ) (PDF; 1.9 MB) High Energy Accelerator Research Organization (KEK), Tsukuba 2012, ISSN  1344-1299 , Pp. 79-81.
  21. ^ KEK Organization. Official website of the High Energy Accelerator Research Organization, KEK.Retrieved December 4, 2015.
  22. ↑ Akihiro Maki et al. (Ed.): 2011 at KEK - Annual Report Vol. 2. ( Memento from September 26, 2013 in the Internet Archive ) (PDF; 12.0 MB) High Energy Accelerator Research Organization (KEK), Tsukuba 2012, ISSN  1344-1299 , Pp. 5-26.
  23. ↑ Akihiro Maki et al. (Ed.): 2011 at KEK - Annual Report Vol. 2. ( Memento from September 26, 2013 in the Internet Archive ) (PDF; 12.0 MB) High Energy Accelerator Research Organization (KEK), Tsukuba 2012, ISSN  1344-1299 , Pp. 27-48.
  24. ↑ The Accelerator Laboratory provides foundation to scientific research at KEK. Official website of the Accelerator Laboratory at KEK. Accessed August 4, 2016.
  25. ^ KEK Applied Research Laboratory. Official website of the High Energy Accelerator Research Organization, KEK.Retrieved December 4, 2015.
  26. ^ Department of Advanced Accelerator Technologies. Official website of the Department of CEC.Retrieved August 4, 2016.
  27. ↑ KEK Feature Story: KEKB crab cavity may help LHC upgrade. March 9, 2010, High Energy Accelerator Research Organization (KEK). Retrieved December 4, 2015.
This version was added to the list of articles worth reading on October 12, 2013 .

Coordinates: 36 ° 8 ′ 57 ″  N , 140 ° 4 ′ 31 ″  E