Scientific Seminars and Workshops

Starting from a discussion of the smallest constituents of matter to the largest structures in the universe, this 3 lecture series will review the successes of LEP and show how they open the door to an exciting programme of physics at the LHC. These open lectures are targetted at people who have a scientific, engineering or technical background but are not specialists in the field of particle physics. Anyone who is curious about CERN physics and its future will find something of interest.

These open lectures are targetted at people who have a scientific, engineering or technical background but are not specialists in the field of particle physics. Anyone who is curious about CERN physics and its future will find something of interest. Lecture 1 - An introduction to structures on all scales
is now available for viewing on the web at http://wlap.web.cern.ch/

Topics for the LHC workshop, held 19th-21st March in Villars-sur-Ollon, have been chosen to cover a large area of interests and having a character of actuality. The status of the main magnet and an outlook upon the production phase were discussed. The ideas for installation of the finished components in the tunnel, their assembly and the quality assurance were presented. A session was dedicated to interfaces between the accelerator and other systems (experiments, injection, and absorbers, RF). To permit a larger audience to profit from the discussions at the workshop, the chairpersons will present a summary of each session. 14h15 Introduction G.Vandoni 14h25 Main magnets today M.Modena 14h35 Main magnets tomorrow L.Bottura 14h45 From working components towards complete system: installing and assembling P.Proudlock 14h55 From working components towards complete system: did we get it right? R.Schmidt 15h05 Interfaces to experiments and other systems O.Gröbner 15h15 Conclusions and outlook Ph.Lebrun

The main aim of the AMANDA-Experiment at the South Pole is the detection of High Energy (> TeV) Neutrinos of galactic or extra-galactic origin. For this reason large photomultipliers, mounted in pressure spheres, are deployed into the deep (> 1.5km) Antarctic glacier. These photomultipliers detect Cherenkov light emitted by charged secondary particles, which are produced in neutrino interactions inside or close to the detector..

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Deep inelastic electron proton collisions are a straightforward tool to study the QCD dynamics between quarks and gluons in the proton. A recent measurement and QCD analysis of the deep inelastic scattering cross section by the H1 experiment at HERA are presented. In a NLO QCD analysis of H1 structure function data, the gluon distribution in the proton is extracted to typically 3% experimental accuracy at low Bjorken x.. In a combined analysis of H1 and high precision µp data by the CERN muon experiment BCDMS, the gluon distribution at low x and the strong coupling constant as were for the first time extracted simultaneously.The strong coupling constant is determined with about 1% experimental accuracy, and QCD at NLO is confirmed over 5 orders of magnitude of Bjorken x at a new level of precision..

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Les premiers instants de l'univers..

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a land of opulence, tragedy and hope. Rajan Gupta is a theoretical physicist at Los Alamos Laboratory. He has developed lectures on HIV/AIDS awareness and prevention aimed at students, health workers, industrialists parents, and industrial workers in India..

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Ionisation electrons may drift over large distances (meters) in a volume of highly purified liquid argon (O₂ equivalent less than 0.1 ppb!) under the action of an electric field. With an appropriate readout system (i.e. a set of fine pitch wire grids) we have realised a massive, continuously sensitive 'bubble chamber' with multiple readouts of the same, small charge (a minimum ionising track segment, 2 mm long, yields • 10000 electrons). We have developed this technology since 1987, initially with small laboratory devices and later with progressively larger and more sophisticated detectors, the latest being the T600 module (740 ton of liquid Argon), which has been operated in Pavia, as a step toward the ICARUS programme in the Gran Sasso Laboratory (LNGS). With cloning of T600 we aim at a 3000 ton detector by 2005. Argon is a medium with density 1.4 g/cm³, similar in characteristics to the heavy freon used in the famous Gargamelle. With wire pitches of 2-3 mm, it provides an extremely high spatial resolution, with a 'bubble' radius of a little over 1 mm. It is continuously sensitive, self-triggering by its own prompt scintillation light, and it provides an excellent measurement of the local energy deposition, relevant for electron/gamma separation and particle identification by means of dE/dx vs. range measurement. Energies of complex events can be reconstructed by charge integration. Unlike a bubble chamber, it is also an excellent calorimeter: s(E)/E = 3%/•E(GeV) for em showers, s(E)/E = 17%/•E(GeV) + 2% for hadronic cascades and s(E)/E = 7%/•E(MeV) for electrons/g's below transition energy. Multi-GeV muon momenta can be measured by multiple scattering. Possible applications of this technology beyond ICARUS are also part of our R&D programme. In particular we have demonstrated the possibility of extracting ionisation electrons from liquid to gas, where they can be multiplied, in view of a WIMP search in the LNGS, called WARP. Scintillation of slow Ar recoils (• 50 keV) from WIMPs will be distinguished from backgrounds by the absence of ionisation (b < Ar atomic electrons).

Organiser(s): Jasper Kirkby / EP Division

Note: Tea & Coffee will be served at 16:00hrs

At the halfway point in the construction of the LHC, the project is now moving from the design and procurement phase to the installation phase, which officially started on 1st March. An overview of the progress of the project is given and the final schedule for installation and commissioning is discussed. The talk will be given in English but questions can be taken in French..

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Veronique Ducret est consultante en psychosociologie, specialisee dans les cas de harcelement sexuel. Auteur de Pour une entreprise sans harcelement sexuel, elle a donne plusieurs seminaires sur le sujet au CERN..

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We extract the value of the strong coupling constant alpha_s from a single-parameter pointlike fit to the photon structure function F₂(gamma) at large x and Q² and from a first five-parameter full (pointlike and hadronic) fit to the complete F₂(gamma) data set taken at PETRA, TRISTAN, and LEP. In next-to-leading order and the MSbar renormalization and factorization schemes, we obtain alpha_s (m_Z) = 0.1183 ± 0.0050 (exp.) ^+0.0029/_-0.0028 (theor.) [pointlike] and alpha_s (m_Z) = 0.1198 ± 0.0028 (exp.) ^+0.0034/_-0.0046 (theor.) [pointlike and hadronic]. We demonstrate that the data taken at LEP have reduced the experimental error by about a factor of two, so that a competitive determination of alpha_s from F₂(gamma) is now possible.

Organiser(s): Ariane FREY / EP Division

Note: Tea and coffee will be served at 15:00 hrs. Please note unusual day and place.

A theoretical underpinning of the standard model of fundamental particles and interactions is CPT invariance, which requires that the laws of physics be invariant under the combined discrete operations of charge conjugation, parity and time reversal. Antimatter, the existence of which was predicted by Dirac, can be used to test the CPT theorem experimental investigations involving comparisons of particles with antiparticles are numerous. Cold atoms and anti-atoms, such as hydrogen and anti-hydrogen, could form the basis of a new precise test, as CPT invariance implies that they must have the same spectrum. Observations of antihydrogen in small quantities and at high energies have been reported at the European Organization for Nuclear Research (CERN) and at Fermilab, but were not suited to precision comparison measurements. Here we demonstrate the production of antihydrogen atoms at very low energy by mixing trapped antiprotons and positrons in a cryogenic environment. The neutral anti-atoms have been detected directly when they escape the trap and annihilate, producing a characteristic signature in an imaging particle detector. The ATHENA experiment at the Antiproton Decelerator (AD) has recently observed the production of large numbers of cold antihydrogen atoms. The talk will give an overview about the key ingredients of the apparatus and the first results obtained on antihydrogen production, followed by a short outlook on future developments..

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