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A communication resource from the world's particle physics laboratories
Interactions.org - Particle Physics News and Resources
A communication resource from the world's particle physics laboratories
Interactions News Wire
#31-03
5/14/03
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Source: KEK
Content: Press Release - KEKB Records 1034/cm^2s Luminosity
Date Issued: 5/14/03
************************************************************************************
KEK Press Release
KEKB Records 1034/cm^2s Luminosity
May 14, 2003
High Energy Accelerator Research Organization (KEK)
On May 9, 2003, the KEKB accelerator at the High Energy Accelerator Research Organization in Tsukuba, Japan, achieved a major breakthrough by being the first colliding-beam facility to attain a peak luminosity above 1034/cm^2s, a long-sought milestone in accelerator physics. This historic accomplishment highlights KEK’s role as one of the world's premier laboratories for accelerator-based science.
KEKB is an accelerator that produces large numbers of B-meson and anti B meson pairs, which are used to explore fundamental questions surrounding the nature of matter and anti-matter. It comprises a large underground complex of radio-frequency structures that accelerate electrons and positrons (the antimatter counterparts of electrons) to high speeds, and magnets that guide them along a 3-km-circumference circular path. B-meson pairs are formed when counterrotating beams of electrons and positrons are brought into collision. Luminosity is a measure of the rate at which the collisions occur. It depends on how many particles are in the beams being collided and how tightly they are packed together into the “bunches" that circulate in the accelerator. The higher the luminosity, the greater the rate at which B-meson and anti-B-meson pairs are produced.
B-meson pairs are particularly useful for investigating the origin of a tiny difference called CP violation that is known to exist in the behavior of matter and anti-matter. Detailed comparison of B-mesons and anti B-mesons requires a large data sample of B anti-B pairs. Thus, the single-most important factor to a successful investigation is high luminosity. The 1034/cm^2s recently achieved by the KEKB team corresponds to a B-pair production rate of 10 per second. Under normal operating conditions, this would yield approximately 100 million B-meson pairs per calendar year.
KEKB has produced about 150 million B-meson pairs since its operation began in May 1999. The Belle collaboration, a large international team of some 300 researchers, has reported numerous new findings from this data, including a 2001 discovery of CP violation in the B-meson system. The recent success is expected to produce a rapid increase in the size of the data sample in the near future, which will be an important boost not only for further investigation of CP violation, but also for a variety of new findings. Some of these findings are already anticipated by theorists working in the field, whereas others may reveal completely unexpected phenomena.
In order to increase the luminosity, the intensity of both the electron and positron beams must be increased, and each must be squeezed to the smallest possible size. Achieving these two conditions simultaneously presents a considerable technological challenge to the accelerator design team. As the beam intensities increase, so do the problems of heating and arcing of the vacuum pipes where the beams circulate, making the beam orbits progressively more difficult to control.
To tackle these problems, the KEKB group, which started construction of their machine in 1994, incorporated a number of new technologies. The luminosity target set at the time was 1034/cm^2s, which many considered an unrealistically ambitious goal. By comparison, the PEP-II accelerator, which was constructed at the Stanford Linear Accelerator Center in California at about the same time, set a more modest design goal of 3 x 1033/cm^2s.
The commissioning of KEKB was reasonably smooth, and the luminosity reached 20% of its design value in one year. This rapid turn-on was by itself a success in comparison to many past accelerator projects, where progress in the early stages could be laboriously slow. KEKB's luminosity has steadily increased ever since, as a result of heroic
efforts on the part of the KEKB team to solve the many problems they encountered along the way. KEKB reached 30% of its design luminosity in March 2001, surpassing PEP-II. Reaching the 1034design luminosity in four years is considered a truly remarkable achievement among accelerator physicists and particle physicists worldwide.
While KEKB is a sprawling device comprising more than 1000 magnets located inside an underground tunnel some 10 meters below the surface, it is also a high-precision device that controls the beam orbits with a precision of a few microns (one micron is 1/1000 of a millimeter). Even such subtle effects as the tiny distortions of the earth's surface
brought about by the pressure changes associated with a passing typhoon must be carefully monitored and corrected for. To meet these challenges, KEKB makes use of a wide variety of industrial services and products ranging from large-scale civil construction to high-precision computerized controls. The remarkable success of the KEKB project is an indication of the highest level of achievement not only in Japanese accelerator technology but also in numerous branches of Japanese industry.
During the past several years, particle physicists around the world have under- taken discussions of a large new particle accelerator called the linear collider. Scientists in Japan as well as in the United States and Germany are actively refining the design while seeking international support for this project. The experience gained in the KEKB project will be of great value in the development of the linear collider.
English press release: http://belle.kek.jp/press/14May03/1034.pdf
Japanese page is: http://www.kek.jp/press/2003/kekb02.html
5/14/03
*************************************************************************************
Source: KEK
Content: Press Release - KEKB Records 1034/cm^2s Luminosity
Date Issued: 5/14/03
************************************************************************************
KEK Press Release
KEKB Records 1034/cm^2s Luminosity
May 14, 2003
High Energy Accelerator Research Organization (KEK)
On May 9, 2003, the KEKB accelerator at the High Energy Accelerator Research Organization in Tsukuba, Japan, achieved a major breakthrough by being the first colliding-beam facility to attain a peak luminosity above 1034/cm^2s, a long-sought milestone in accelerator physics. This historic accomplishment highlights KEK’s role as one of the world's premier laboratories for accelerator-based science.
KEKB is an accelerator that produces large numbers of B-meson and anti B meson pairs, which are used to explore fundamental questions surrounding the nature of matter and anti-matter. It comprises a large underground complex of radio-frequency structures that accelerate electrons and positrons (the antimatter counterparts of electrons) to high speeds, and magnets that guide them along a 3-km-circumference circular path. B-meson pairs are formed when counterrotating beams of electrons and positrons are brought into collision. Luminosity is a measure of the rate at which the collisions occur. It depends on how many particles are in the beams being collided and how tightly they are packed together into the “bunches" that circulate in the accelerator. The higher the luminosity, the greater the rate at which B-meson and anti-B-meson pairs are produced.
B-meson pairs are particularly useful for investigating the origin of a tiny difference called CP violation that is known to exist in the behavior of matter and anti-matter. Detailed comparison of B-mesons and anti B-mesons requires a large data sample of B anti-B pairs. Thus, the single-most important factor to a successful investigation is high luminosity. The 1034/cm^2s recently achieved by the KEKB team corresponds to a B-pair production rate of 10 per second. Under normal operating conditions, this would yield approximately 100 million B-meson pairs per calendar year.
KEKB has produced about 150 million B-meson pairs since its operation began in May 1999. The Belle collaboration, a large international team of some 300 researchers, has reported numerous new findings from this data, including a 2001 discovery of CP violation in the B-meson system. The recent success is expected to produce a rapid increase in the size of the data sample in the near future, which will be an important boost not only for further investigation of CP violation, but also for a variety of new findings. Some of these findings are already anticipated by theorists working in the field, whereas others may reveal completely unexpected phenomena.
In order to increase the luminosity, the intensity of both the electron and positron beams must be increased, and each must be squeezed to the smallest possible size. Achieving these two conditions simultaneously presents a considerable technological challenge to the accelerator design team. As the beam intensities increase, so do the problems of heating and arcing of the vacuum pipes where the beams circulate, making the beam orbits progressively more difficult to control.
To tackle these problems, the KEKB group, which started construction of their machine in 1994, incorporated a number of new technologies. The luminosity target set at the time was 1034/cm^2s, which many considered an unrealistically ambitious goal. By comparison, the PEP-II accelerator, which was constructed at the Stanford Linear Accelerator Center in California at about the same time, set a more modest design goal of 3 x 1033/cm^2s.
The commissioning of KEKB was reasonably smooth, and the luminosity reached 20% of its design value in one year. This rapid turn-on was by itself a success in comparison to many past accelerator projects, where progress in the early stages could be laboriously slow. KEKB's luminosity has steadily increased ever since, as a result of heroic
efforts on the part of the KEKB team to solve the many problems they encountered along the way. KEKB reached 30% of its design luminosity in March 2001, surpassing PEP-II. Reaching the 1034design luminosity in four years is considered a truly remarkable achievement among accelerator physicists and particle physicists worldwide.
While KEKB is a sprawling device comprising more than 1000 magnets located inside an underground tunnel some 10 meters below the surface, it is also a high-precision device that controls the beam orbits with a precision of a few microns (one micron is 1/1000 of a millimeter). Even such subtle effects as the tiny distortions of the earth's surface
brought about by the pressure changes associated with a passing typhoon must be carefully monitored and corrected for. To meet these challenges, KEKB makes use of a wide variety of industrial services and products ranging from large-scale civil construction to high-precision computerized controls. The remarkable success of the KEKB project is an indication of the highest level of achievement not only in Japanese accelerator technology but also in numerous branches of Japanese industry.
During the past several years, particle physicists around the world have under- taken discussions of a large new particle accelerator called the linear collider. Scientists in Japan as well as in the United States and Germany are actively refining the design while seeking international support for this project. The experience gained in the KEKB project will be of great value in the development of the linear collider.
English press release: http://belle.kek.jp/press/14May03/1034.pdf
Japanese page is: http://www.kek.jp/press/2003/kekb02.html