Abstract
Full text: Achapter of history at CERN's LEP electron-positron collider closed in October when the four big experiments, Aleph, Delphi, L3 and Opal, logged their final data at the Z energy, just over six years after LEP's first Z was detected. The LEP Z era has been one of great success, both in terms of physics results and the advances which have been made with the machine itself. LEP now takes a step towards becoming LEP2, when the energy is wound up from around 45 GeV to about 70 GeV per beam (September, page 6). By the end of LEP's 1995 run, each of the four LEP experiments had seen almost five million Zs. Now the spotlight at LEP shifts to producing pairs of W particles, the electrically charged counterparts of the Z. LEP's first Zs were recorded in August 1989, one month after the machine's first circulating beam. The 30,000 Z decays recorded by each experiment in 1989 confirmed that matter comes in just three distinct families of quarks and leptons. The values of the Z mass and width quoted in 1990 were 91.161 ± 0.031 GeV and 2.534 ± 0.027 GeV. By the beginning of 1995, these had
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Anon.
CERN: End of LEP's Z era.
CERN: N. p.,
1995.
Web.
Anon.
CERN: End of LEP's Z era.
CERN.
Anon.
1995.
"CERN: End of LEP's Z era."
CERN.
@misc{etde_22556099,
title = {CERN: End of LEP's Z era}
author = {Anon.}
abstractNote = {Full text: Achapter of history at CERN's LEP electron-positron collider closed in October when the four big experiments, Aleph, Delphi, L3 and Opal, logged their final data at the Z energy, just over six years after LEP's first Z was detected. The LEP Z era has been one of great success, both in terms of physics results and the advances which have been made with the machine itself. LEP now takes a step towards becoming LEP2, when the energy is wound up from around 45 GeV to about 70 GeV per beam (September, page 6). By the end of LEP's 1995 run, each of the four LEP experiments had seen almost five million Zs. Now the spotlight at LEP shifts to producing pairs of W particles, the electrically charged counterparts of the Z. LEP's first Zs were recorded in August 1989, one month after the machine's first circulating beam. The 30,000 Z decays recorded by each experiment in 1989 confirmed that matter comes in just three distinct families of quarks and leptons. The values of the Z mass and width quoted in 1990 were 91.161 ± 0.031 GeV and 2.534 ± 0.027 GeV. By the beginning of 1995, these had been fine-tuned to the extraordinary accuracy of 91.1884 ± 0.0022 GeV and 2.4963 ± 0.0032 GeV, and when data from this year's run is included, will be even better. These results, combined with precision data from neutrino experiments and from Fermilab's Tevatron protonantiproton collider, have put the Standard Model of quarks and leptons through its most gruelling test yet. Right from the start, collaboration between LEP experiments and the accelerator team has been close, with frequent scheduling meetings determining how the machine is run. For the first few years, LEP ran on a diet of four bunches of electrons and four of positrons, but by the end of 1992, a way had been found to increase the luminosity by squeezing in more bunches. In 1993, the 'pretzel' scheme (October 1992, page 17), so called because of the shape traced out by the circulating beams, was running with eight bunches per beam, and helped LEP to further tighten the precision of the Z fix. As new skills were mastered, the 27-kilometre circumference machine became a remarkable precision instrument. 1992 saw the LEP beam energy measurement become sensitive to the moon (January 1993, page 4). Later, LEP was found to react to heavy rainfall. These phenomena cause slight movements in the surrounding rock and are amplified by the machine. In 1995, LEP machine physicists opted for the bunch train approach (September, page 14) to further increase the luminosity. The basic idea was to split each bunch of particles into a string of smaller 'bunchlets' - the bunch train - which holds more particles than the bunch it replaces. In this way, LEP2 will be able to supply the increased event rates needed for W physics.}
journal = []
issue = {8}
volume = {35}
journal type = {AC}
place = {CERN}
year = {1995}
month = {Nov}
}
title = {CERN: End of LEP's Z era}
author = {Anon.}
abstractNote = {Full text: Achapter of history at CERN's LEP electron-positron collider closed in October when the four big experiments, Aleph, Delphi, L3 and Opal, logged their final data at the Z energy, just over six years after LEP's first Z was detected. The LEP Z era has been one of great success, both in terms of physics results and the advances which have been made with the machine itself. LEP now takes a step towards becoming LEP2, when the energy is wound up from around 45 GeV to about 70 GeV per beam (September, page 6). By the end of LEP's 1995 run, each of the four LEP experiments had seen almost five million Zs. Now the spotlight at LEP shifts to producing pairs of W particles, the electrically charged counterparts of the Z. LEP's first Zs were recorded in August 1989, one month after the machine's first circulating beam. The 30,000 Z decays recorded by each experiment in 1989 confirmed that matter comes in just three distinct families of quarks and leptons. The values of the Z mass and width quoted in 1990 were 91.161 ± 0.031 GeV and 2.534 ± 0.027 GeV. By the beginning of 1995, these had been fine-tuned to the extraordinary accuracy of 91.1884 ± 0.0022 GeV and 2.4963 ± 0.0032 GeV, and when data from this year's run is included, will be even better. These results, combined with precision data from neutrino experiments and from Fermilab's Tevatron protonantiproton collider, have put the Standard Model of quarks and leptons through its most gruelling test yet. Right from the start, collaboration between LEP experiments and the accelerator team has been close, with frequent scheduling meetings determining how the machine is run. For the first few years, LEP ran on a diet of four bunches of electrons and four of positrons, but by the end of 1992, a way had been found to increase the luminosity by squeezing in more bunches. In 1993, the 'pretzel' scheme (October 1992, page 17), so called because of the shape traced out by the circulating beams, was running with eight bunches per beam, and helped LEP to further tighten the precision of the Z fix. As new skills were mastered, the 27-kilometre circumference machine became a remarkable precision instrument. 1992 saw the LEP beam energy measurement become sensitive to the moon (January 1993, page 4). Later, LEP was found to react to heavy rainfall. These phenomena cause slight movements in the surrounding rock and are amplified by the machine. In 1995, LEP machine physicists opted for the bunch train approach (September, page 14) to further increase the luminosity. The basic idea was to split each bunch of particles into a string of smaller 'bunchlets' - the bunch train - which holds more particles than the bunch it replaces. In this way, LEP2 will be able to supply the increased event rates needed for W physics.}
journal = []
issue = {8}
volume = {35}
journal type = {AC}
place = {CERN}
year = {1995}
month = {Nov}
}