Summary on tau Leptonic Branching Ratios and Universality

The large samples of tau decays available from CLEO and the four LEP experiment have resulted in new, precise measurements of the leptonic branching ratios of the $\tau$. The experimental techniques to obtain these results are reviewed with special emphasis on the DELPHI measurement. World averages are found to be Be = (17.81 +/- 0.06) % and Bmu = (17.36 +/- 0.06) %. These results are consistent with universality in the charged current couplings to a precision of about 0.25 %. The branching ratio measurements can also be used to constrain the "low energy parameter" eta. It is shown that the sensitivity to eta depends on details of the momentum acceptance for muon identification in the different experiments. Assuming universality in the couplings, the estimate eta = 0.012 +/- 0.024 is obtained.Comment: 10 pages, LaTeX, including 9 figures, uses epsf and espcrc2. Invited talk at the Fifth Intl. Workshop on Tau Lepton Physics, 14-17 September 1998, Santander (Spain

A Method to Estimate the Boson Mass and to Optimise Sensitivity to Helicity Correlations of tau+tau- Final States

In proton-proton collisions at LHC energies, Z and low mass Higgs bosons would be produced with high and predominantly longitudinal boost with respect to the beam axis. This note describes a new analysis tool devised to handle this situation in cases when such bosons decay to a pair of tau-leptons. The tool reconstructs the rest frame of the tau+tau- pair by finding the boost that minimises the acollinearity between the visible tau decay products. In most cases this gives a reasonable approximation to the rest frame of the decaying boson. It is shown how the reconstructed rest frame allows for a new method of mass estimation. Also a considerable gain in sensitivity to helicity correlations is obtained by analysing the tau-jets in the reconstructed frame instead of using the laboratory momenta and energies, particularly when both tau-leptons decay hadronically.Comment: 13 pages, method extended with 3D boost finde

Module production of the one-arm AFP 3D pixel tracker

The ATLAS Forward Proton (AFP) detector is designed to identify events in which one or two protons emerge intact from the LHC collisions. AFP will consist of a tracking detector, to measure the momentum of the protons, and a time of flight system to reduce the background from multiple proton-proton interactions. Following an extensive qualification period, 3D silicon pixel sensors were selected for the AFP tracker. The sensors were produced at CNM (Barcelona) during 2014. The tracker module assembly and quality control was performed at IFAE during 2015. The assembly of the first AFP arm and the following installation in the LHC tunnel took place in February 2016. This paper reviews the fabrication process of the AFP tracker focusing on the pixel modules.Comment: PIXEL 2016 proceedings; Submitted to JINS

Tau physics at LEP

This paper gives an overview of some of the more interesting results obtained at LEP in tau physics: precision measurements in neutral and charged currents universality and structure, tau mass, topological and exclusive Branching Ratios.Comment: Invited talk at the Seventh International Workshop on Tau Lepton Physics (TAU02), Santa Cruz, Ca, USA, Sept 2002, 17 pages, LaTeX, 36 eps figure

Kan jeg programmere et verktøy som kan erstatte tradisjonell undervisning? Kan den tradisjonelle undervisningen erstattes av elektroniske løsninger?

I en verden som har utallige elektroniske løsninger, hvorfor blir den samme forelesningen holdt flere ganger over flere år, når den bare kan spilles inn og vises på nytt? Eller bedre, legges inn som en del av et e-læringsverktøy som er spesialisert for at eleven skal tilegne seg kunnskap. Bakgrunnen for oppgaven er påstanden: Hvis en foreleser skreddersyr et elektronisk opplegg for å erstatte forelesningene sine, så vil dette opplegget være bedre enn forelesningene. Videre er det utarbeidet en problemstilling som skal besvares. Kan jeg programmere et verktøy undervisere kan benytte som erstatning for tradisjonell undervisning? Kan den tradisjonelle undervisningen erstattes av elektroniske løsninger? Oppgaven omhandler utviklingen av et program som har til hensikt å kunne fungere som en erstatning for tradisjonell undervisning. Dette programmet blir benyttet av en klasse ved Sjø-krigsskolen. Klassen vil gjennom en spørreundersøkelse gi tilbakemeldinger på problemstil-lingen. Avslutningsvis sammenlignes resultater opp mot relevant litteratur. Utviklingen av programmet gikk som planlagt, det ble utviklet et verktøy som fungerte, om det fungerte bra er derimot diskutabelt. Det var høy korrelasjonen mellom tilbakemeldingene fra klassen ved Sjøkrigsskolen og rele-vant litteratur. Den tilsynelatende største fordelen med elektronisk undervisning er tilgjengelig-heten og friheten til å lære hvor og når man vil. Den tilsynelatende største utfordringen med elektronisk med undervisning er å fremstille en generisk interaktivitet med underviseren. Elektroniske løsninger kan enda ikke erstatte den tradisjonelle undervisningen, da det enda ikke er laget et elektronisk verktøy som godt nok etterligner fordelene med den tradisjonelle under-visningen

Study of the reaction pbar p -> phi phi from 1.1 to 2.0 GeV/c

A study has been performed of the reaction pbar p -> 4K using in-flight antiprotons from 1.1 to 2.0 GeV/c incident momentum interacting with a hydrogen jet target. The reaction is dominated by the production of a pair of phi mesons. The pbar p -> phi phi cross section rises sharply above threshold and then falls continuously as a function of increasing antiproton momentum. The overall magnitude of the cross section exceeds expectations from a simple application of the OZI rule by two orders of magnitude. In a fine scan around the xi/f_J(2230) resonance, no structure is observed. A limit is set for the double branching ratio B(xi -> pbar p) * B(xi -> phi phi) < 6e-5 for a spin 2 resonance of M = 2.235 GeV and Width = 15 MeV.Comment: 13 pages, 13 figures, 2 tables, Latex. To be published in Phys. Rev.

Radiation hard 3D silicon pixel sensors for use in the ATLAS detector at the HL-LHC

The High Luminosity LHC (HL-LHC) upgrade requires the planned Inner Tracker (ITk) of the ATLAS detector to tolerate extremely high radiation doses. Specifically, the innermost parts of the pixel system will have to withstand radiation fluences above 1 × 1016 neqcm-2. Novel 3D silicon pixel sensors offer a superior radiation tolerance compared to conventional planar pixel sensors, and are thus excellent candidates for the innermost parts of the ITk. This paper presents studies of 3D pixel sensors with pixel size 50 × 50 μm2 mounted on the RD53A prototype readout chip. Following a description of the design and fabrication steps, Test Beam results are presented for unirradiated as well as heavily irradiated sensors. For particles passing at perpendicular incidence, it is shown that average efficiencies above 96% are reached for sensors exposed to fluences of 1 × 1016 neqcm-2 when biased to 80 V.publishedVersio