Search for flavour-changing neutral current top quark decays t → Hq in pp collisions at √s=8 TeV with the ATLAS detector

A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb¯¯, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at s√=8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb−1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt¯→WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t → Hc and t → Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H → γγ and H → WW *, ττ decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |λ tcH | and |λ tuH | couplings are 0.13 (0.10) and 0.13 (0.10) respectively. These are the most restrictive direct bounds on tqH interactions measured so far.

Z boson production in p plus Pb collisions at root S-NN=5.02 TeV measured with the ATLAS detector

The ATLAS Collaboration measures the inclusive production of Z bosons via their decays into electron and muon pairs in p+Pb collisions at sNN−−−√=5.02TeV at the Large Hadron Collider. The measurements are made using data corresponding to integrated luminosities of 29.4 and 28.1 nb−1 for Z→ee and Z→μμ, respectively. The results from the two channels are consistent and combined to obtain a cross section times the Z→ℓℓ branching ratio, integrated over the rapidity region ∣∣y∗Z|<3.5, of 139.8±4.8(statistical)±6.2(systematic)±3.8 (luminosity) nb. Differential cross sections are presented as functions of the Z boson rapidity and transverse momentum and compared with models based on parton distributions both with and without nuclear corrections. The centrality dependence of Z boson production in p+Pb collisions is measured and analyzed within the framework of a standard Glauber model and the model's extension for fluctuations of the underlying nucleon-nucleon scattering cross section.

Measurement of the branching ratio Γ(Λ0b→ψ(2S)Λ0)/Γ(Λ0b→J/ψΛ0) with the ATLAS detector

An observation of the Λ0b→ψ(2S)Λ0 decay and a comparison of its branching fraction with that of the Λ0b→J/ψΛ0 decay has been made with the ATLAS detector in proton--proton collisions at s√=8TeV at the LHC using an integrated luminosity of 20.6fb−1. The J/ψ and ψ(2S) mesons are reconstructed in their decays to a muon pair, while the Λ0→pπ− decay is exploited for the Λ0 baryon reconstruction. The Λ0b baryons are reconstructed with transverse momentum pT>10GeV and pseudorapidity |η|<2.1. The measured branching ratio of the Λ0b→ψ(2S)Λ0 and Λ0b→J/ψΛ0 decays is Γ(Λ0b→ψ(2S)Λ0)/Γ(Λ0b→J/ψΛ0)=0.501±0.033(stat)±0.019(syst), lower than the expectation from the covariant quark model.

Measurements of the top quark branching ratios into channels with leptons and quarks with the ATLAS detector

A measurement of the inclusive cross section for top quark pair production in pp collisions using events with an isolated lepton (muon or electron) and a τ lepton decaying to hadrons (τhad) is reported. Measurements of the branching ratios of top quark decays into leptons and jets using events with tt¯ (top antitop) pairs are also reported. Events were recorded with the ATLAS detector at the LHC in pp collisions at a center-of-mass energy of 7 TeV. The collected data sample corresponds to an integrated luminosity of 4.6 fb−1. The inclusive cross section measured using events with an isolated lepton and a τhad is σtt¯=183±9(stat.)±23(syst.)±3(lumi.)pb. The measured top quark branching ratios agree with the Standard Model predictions within the measurement uncertainties of a few percent.

Characterisation of neutron spectra in mixed high energy fields in lineal accelerators: response functions validation

Actualment, la resposta de la majoria d’instrumentació operacional i dels dosímetres personals utilitzats en radioprotecció per a la dosimetria neutrònica és altament dependent de l’energia dels espectres neutrònics a analitzar, especialment amb camps neutrònics amb una important component intermitja. En conseqüència, la interpretació de les lectures d’aquests aparells es complicada si no es té un coneixement previ de la distribució espectral de la fluència neutrònica en els punts d’interès. El Grup de Física de les Radiacions de la Universitat Autònoma de Barcelona (GFR-UAB) ha desenvolupat en els últims anys un espectròmetre de neutrons basat en un Sistema d’Esferes Bonner (BSS) amb un contador proporcional d’3He com a detector actiu. Els principals avantatges dels espectròmetres de neutrons per BSS són: la seva resposta isotròpica, la possibilitat de discriminar la component neutrònica de la gamma en camps mixtos, i la seva alta sensibilitat neutrònica als nivells de dosi analitzats. Amb aquestes característiques, els espectròmetres neutrònics per BSS compleixen amb els estándards de les últimes recomanacions de la ICRP i poden ser utilitzats també en el camp de la dosimetria neutrònica per a la mesura de dosis en el rang d’energia que va dels tèrmics fins als 20 MeV, en nou ordres de magnitud. En el marc de la col•laboració entre el GFR - UAB i el Laboratorio Nazionale di Frascati – Istituto Nazionale di Fisica Nucleare (LNF-INFN), ha tingut lloc una experiència comparativa d’espectrometria per BSS amb els feixos quasi monoenergètics de 2.5 MeV i 14 MeV del Fast Neutron Generator de l’ENEA. En l’exercici s’ha determinat l’espectre neutrònic a diferents distàncies del blanc de l’accelerador, aprofitant el codi FRUIT recentment desenvolupat pel grup LNF. Els resultats obtinguts mostren una bona coherència entre els dos espectròmetres i les dades mesurades i simulades.

Multilayer perceptron with local constraint as an emerging method in spatial data analysis

The use of Geographic Information Systems has revolutionalized the handling and the visualization of geo-referenced data and has underlined the critic role of spatial analysis. The usual tools for such a purpose are geostatistics which are widely used in Earth science. Geostatistics are based upon several hypothesis which are not always verified in practice. On the other hand, Artificial Neural Network (ANN) a priori can be used without special assumptions and are known to be flexible. This paper proposes to discuss the application of ANN in the case of the interpolation of a geo-referenced variable.

Feasibility and electromagnetic compatibility study of the ClearPEM front-end electronics for simultaneous PET-MR imaging

In this work we present a first feasibility study of the ClearPEM technology for simultaneous PET-MR imaging. The mutual electromagnetic interference (EMI) effects between both systems were evaluated on a 7 T magnet by characterizing the response behavior of the ClearPEM detectors and front-end electronics to pulsed RF power and switched magnetic field gradients; and by analyzing the MR system performance degradation from noise pickup into the RF receiver chain, and from magnetic susceptibility artifacts caused by PET front-end materials.

Incremental neural networks for function approximation

A new strategy for incremental building of multilayer feedforward neural networks is proposed in the context of approximation of functions from R-p to R-q using noisy data. A stopping criterion based on the properties of the noise is also proposed. Experimental results for both artificial and real data are performed and two alternatives of the proposed construction strategy are compared.

ng Tooeoe oeoe Naênêng Löïcïc Laømøm Vieäcäc Cuoeoeaoeoea Baïnïn Chöùng Tooe Naêng Löïc Laøm Vieäc Cuoea Baïn Nôi xuaát baoen

Baïn muoán coù moät vieäc laøm. Vaø baïn cuõng coù caoem giaùctin raèng ôoe moät nôi naøo ñoù coù moätngöôøi chuoechuû nhaân ñang caàn moät ngöôøi laømchính xaùc coâng vieäc baïn muoán - moät coâng vieäcñoøi hooei ñuùng kieán thöùc vaø caùc khaoe naêng cuoea baïn, cuõng nhö ñöa ra nhöõng thaùch thöùc vaø côhoäi thaêng tieán. Ñeå tìm ñöôïc coâng vieäc aáy, baïn caàn phaoei laäpkeá hoaïch tìm vieäc moät caùch kyõ caøng vaø thöïc hieän ñuùng keá hoaïch ñoù. Baïn coù theå baùn ñi moätthöù - ñoù laøcoi nhöõng kieán thöùc, kyõ naêng, vaøkinh nghieäm cuoea baïn - töùc - laø chính baïn! - nhölaø moät saûn phaåm caàn “baùn” cho caùc chuû nhaân!.Ñieàu baïn caàn bieát laø laøm theá naøo ñeå chöùng tooenaêng löïc cuoea mình moät caùch coù hieäu quaoe nhaát. Cho duø baïn môùi ra tröôøng hay vaø ñang chuaånbò baét ñaàu moätböôùc ñaàu trong söï nghieäp cuûa mình hay ñang tìm moät coâng vieäc môùi sau 20naêm kinh nghieäm, moät soá phöông phaùp ñöôïctrình baøy trong taäp thoâng tin naøy coù theå giuùpích cho baïn. NOTE: Vietnamese Translation

A steroidomic approach for biomarkers discovery in doping control.

Anti-doping authorities have high expectations of the athlete steroidal passport (ASP) for anabolic-androgenic steroids misuse detection. However, it is still limited to the monitoring of known well-established compounds and might greatly benefit from the discovery of new relevant biomarkers candidates. In this context, steroidomics opens the way to the untargeted simultaneous evaluation of a high number of compounds. Analytical platforms associating the performance of ultra-high pressure liquid chromatography (UHPLC) and the high mass-resolving power of quadrupole time-of-flight (QTOF) mass spectrometers are particularly adapted for such purpose. An untargeted steroidomic approach was proposed to analyse urine samples from a clinical trial for the discovery of relevant biomarkers of testosterone undecanoate oral intake. Automatic peak detection was performed and a filter of reference steroid metabolites mass-to-charge ratio (m/z) values was applied to the raw data to ensure the selection of a subset of steroid-related features. Chemometric tools were applied for the filtering and the analysis of UHPLC-QTOF-MS(E) data. Time kinetics could be assessed with N-way projections to latent structures discriminant analysis (N-PLS-DA) and a detection window was confirmed. Orthogonal projections to latent structures discriminant analysis (O-PLS-DA) classification models were evaluated in a second step to assess the predictive power of both known metabolites and unknown compounds. A shared and unique structure plot (SUS-plot) analysis was performed to select the most promising unknown candidates and receiver operating characteristic (ROC) curves were computed to assess specificity criteria applied in routine doping control. This approach underlined the pertinence to monitor both glucuronide and sulphate steroid conjugates and include them in the athletes passport, while promising biomarkers were also highlighted.

Aplicación de la técnica de espectrometría de fluorescencia de rayos-X en el estudio de la dispersión de metales en áreas mineras

One critical factor for success in characterizing metals polluting mining environments so as to be able to eliminate them and subsequently recover these areas depends upon a speedy and correct response in the analysis of samples. Rapid, simultaneous, multi-element analysis can be undertaken using X-ray fluorescence spectrometry, a versatile, non-destructive analytical technique commonly employed to identify both major and minor elements in samples related to environmental studies. An additional advantage of this technique is the possibility of conducting the analysis directly on solid samples, which is extremely convenient when dealing with environmental samples that are difficult to dissolve, such as soils, sediments and mining wastes. Moreover, in recent years the development of spectrometers equipped with digital-signal processors combined with enlarged X-ray production, using better designs for excitation-detection, has contributed to an improvement in instrumental sensitivity, thus allowing us to detect important polluting elements such as Cd and Pb at trace levels. In this paper the authors describe, on the basis of their own experience, some interesting applications of XRF spectrometry for the analysis of several types of environmental samples related to the study of the dispersion of metals within mining environments: (A) analysis of mining wastes, soils and sediments; (B) analysis of samples of vegetation used as bioindicators or related to phytoremediation studies; and (C) analysis of water samples related to mining operations

Tuotannollisen testerin suunnittelu tiedonsiirtolinkkikortille

Työssä suunniteltiin ja toteutettiin linkkikorttien tuotannollinen testeri. Linkkikortti on osa CERN:iin rakennettavan hiukkaskiihdyttimen Large Hadron Colliderin koeasema Compact Muon Solenoidin luentajärjestelmää. Linkkikortin tehtävänä on muuttaa rinnakkaismuotoinen LVDS-signaali sarjamuotoiseksi optiseksi signaaliksi. Testattaessa testeri ja linkkikortti sijoitetaan kehikkoon, joten testerin liittimien pitää olla linkkikortin liittimien kanssa identtisiä. Testerin lähdöt ovat linkkikortin tuloja ja toisinpäin. Tällöin testattaessa voidaan ohjelmoitavien FPGA-piirien avulla lähettää signaalia kortilta toiselle. Vastaanottavan kortin FPGA-piirin avulla voidaan tarkistaa, onko data tullut perille muuttumattomana. Testin ohjaus tapahtuu tietokoneella, jolla käyttäjä antaa käskyn testin aloittamisesta ja jonne lopulta myös raportoidaan testin tulokset. Testien tulokset näytetään myös testerin ledeillä. Työssä ei pystytä linkkikorttien puuttumisen takia testaamaan testeriä loppukäytössään. Kuitenkin testerin toimivuus pystyttiin suurilta osin testaamaan, jolloin saatiin odotettuja tuloksia.

Optisen 1.6 GHz signaalin monistin

Tässä diplomityössä suunnitellaan CERN:in (Conseil Europëen pour la Recherche Nuclëaire) Compact Muon Solenoid –nimiseen hiukkasilmaisinjärjestelmään laite, joka monistaa 1.6 Gbit/s nopeudella saapuvia optisia signaaleja useaan eri kohteeseen. Aluksi suunnitellaan ja rakennetaan testauslaite, jonka avulla tutkitaan eri komponenttien soveltuvuutta laitteistoon. Lisäksi testauslaitteella haetaan laserohjaimille ja vastaanottimille sopivia säätöarvoja. Testauslaitteesta saatujen kokemusten perusteella suunnitellaan ja rakennetaan signaalinmonistinlaitteisto, johon tuodaan useita satoja erillisiä signaaleja. Jokainen näistä signaaleista monistetaan joko kahdeksi tai neljäksi lähteväksi signaaliksi. Lopuksi testauslaitteella tutkitaan signaalinmonistinlaitteiston toimintaa ja luotettavuutta.

Particle detector link system modifications in RE1/1 sector

The large hadron collider constructed at the European organization for nuclear research, CERN, is the world’s largest single measuring instrument ever built, and also currently the most powerful particle accelerator that exists. The large hadron collider includes six different experiment stations, one of which is called the compact muon solenoid, or the CMS. The main purpose of the CMS is to track and study residue particles from proton-proton collisions. The primary detectors utilized in the CMS are resistive plate chambers (RPCs). To obtain data from these detectors, a link system has been designed. The main idea of the link system is to receive data from the detector front-end electronics in parallel form, and to transmit it onwards in serial form, via an optical fiber. The system is mostly ready and in place. However, a problem has occurred with innermost RPC detectors, located in sector labeled RE1/1; transmission lines for parallel data suffer from signal integrity issues over long distances. As a solution to this, a new version of the link system has been devised, a one that fits in smaller space and can be located within the CMS, closer to the detectors. This RE1/1 link system has been so far completed only partially, with just the mechanical design and casing being done. In this thesis, link system electronics for RE1/1 sector has been designed, by modifying the existing link system concept to better meet the requirements of the RE1/1 sector. In addition to completion of the prototype of the RE1/1 link system electronics, some testing for the system has also been done, to ensure functionality of the design.