Internal lecture | LEP II era/precision physics (1994-2004) | Main Auditorium | 25 July

LEP II era/precision physics, by Lydia Fayard, Roberto Tenchini, and Steve Myers.


3.30 p.m. - 3.45 p.m.: coffee

3.45 p.m. - 4.30 p.m.: The quest for the direct CP Violation in the Kaon System at CERN: The NA31 & NA48 experiments by Lydia Iconomidou-Fayard (Université de Paris-Sud 11 (FR)).

After years of studying kaon properties at CERN, the hunt for direct CP violation in this system started in the 1980s and lasted about two decades. While expected to be small, this component is a probe into the validity of the Standard Model and its precise measurement was the main goal of two experiments at CERN, namely NA31 and NA48.

In this talk, we will review the two collaborations in their historical contexts. The challenging detectors and beams, the analyses, the innovative methods and tools, and the first non-zero evidence of Re(epsilon'/epsilon) that resulted in the evolution from NA31 to NA48 in order to increase accuracy and further squeeze the systematics.

Career summary
Lydia Iconomidou-Fayard was born and grew up in Greece. She obtained her Master’s Degree from the Université Paris-XI at Orsay, located in the south of Paris. After her PhD with the UA2 collaboration on the first collected samples of W and Z bosons, she joined the NA31 experiment at CERN in 1986 and NA48 in 1994. Since 2002 she has been working for the ATLAS experiment. Her study topics are: detector commissioning, calibrations, performances and data analysis. She participates in the Programme Committees of various conferences (Moriond Electro-weak, Physics at the LHC and beyond). From 2002 to 2004 she was the head of the CERN Summer School for Students.

4.30 p.m. - 5.15 p.m.: Operational performance of LEP and LEP2 by Steve Myers (CERN).

The Large Electron Positron collider LEP at CERN was commissioned in 1989 and finished operation in November 2000. During this period it was operated in different modes, with different optics, at different energies, and with varied performance. In the end, LEP surpassed all relevant design parameters and provided a large amount of data for the precision study of the Standard Model, first on the Z0 resonance, and then above the W pair threshold.  A brief history of the main modes of operation, associated performance, the highlights and the challenges met over the 12 years of running is presented with emphasis on the high energy upgrade (LEP2).

Career summary
Many significant personal contributions to the field of accelerator science. Crucial role in the performance achievements of the CERN Intersecting Storage Rings (ISR).

LEP: member of the small initial design team. Took responsibility for beam commissioning and performance of LEP. Project leader for the upgrade (LEP2). Overall responsibility for exploitation of the machine.

LHC:  Jointly authored (1983) the first report proposing a Large Hadron Collider in the LEP tunnel. Led the department (AB) responsible for major LHC systems including the acceleration system, controls, beam instrumentation, accelerator physics, power converters, injection and extraction, collimation and beam studies.  Editor-in-chief of the LHC design Report (2004). As Director of Accelerators and Technology, responsible for the repair and re-commissioning of the collider following the accident of 2008. By 4 July 2012 LHC produced enough events to allow ATLAS and CMS to discover a “Higgs-like”  boson. Currently Head of Medical Applications at CERN.

5.15 p.m. -  6 p.m.: LEP II era/ precision physics by Roberto Tenchini (Sezione di Pisa (IT)).

In five years of operation at and above the WW production threshold, the Large Electron-Positron collider (LEP) delivered about 600 inverse picobarns of integrated luminosity to each of the four experiments (ALEPH, DELPHI, L3 and OPAL), reaching, in the year 2000, the highest centre-of-mass energy ever reached at a lepton collider, 209 GeV. The seminar recalls the remarkable jump in precision obtained with LEP data in the realm of W physics, with several examples related to precision measurements of W mass and properties, and to the investigation of the gauge structure of the standard model of electroweak interactions. The new territory explored for physics beyond the Standard Model, leading to long-lasting legacy results, will be revisited. There will also be a reminder of the exciting hunt for the Higgs boson at LEP, which ended only 10 GeV below the actual target.

Career summary
Roberto Tenchini was physics coordinator and spokesperson of one of the four experiments at LEP (the ALEPH experiment). At LEP he worked on electroweak and heavy quarks physics. He started his career at the CERN SPS in the early eighties, where he measured the pion electromagnetic form factor (NA7 experiment) and contributed to the first measurements of charm mesons and baryon lifetimes (NA1 experiment). After the LEP he was physics coordinator deputy and chair of the publication committee of the CMS experiment and, more recently, convener of the top-quark physics group of CMS.

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