ATLAS

Research group

Research theme

Sub department

About

Related research groups

Combined HERA deep inelastic scattering data and NLO QCD fits

Conference Proceedings - New Trends in HERA Physics 2008 (2008)

Abstract:

Previously published data on inclusive neutral and charged current e +p and e-p deep inelastic scattering from HERA have been combined. The new, model-independent method of combining the measured cross sections takes full account of correlated systematics in a coherent way, leading to significantly reduced uncertainties in the combined measurement across the (x;Q2) plane. The combined cross section data have been used as the sole input for a new next-to-leading order QCD fit to extract the parton distribution functions (PDFs) of the proton. The PDFs extracted have greatly reduced experimental uncertainties, compared to separate QCD analyses on data from H1 and ZEUS. Model uncertainties, including those arising from the parameterisation dependence, have also been carefully considered. The resulting HERA PDFs have impressive precision.

EURECA - The future of cryogenic dark matter detection in Europe

Proceedings of Science (2008)

Authors:

H Kraus, E Armengaud, M Bauer, I Bavykina, A Benoit, A Bento, J Blümer, L Bornschein, A Broniatowski, G Burghart, P Camus, A Chantelauze, M Chapellier, G Chardin, C Ciemniak, C Coppi, N Coron, O Crauste, FA Danevich, M De Jésus, P Marcillac, E Daw, X Defay, G Deuter, J Domange, P Di Stefano, G Drexlin, L Dumoulin, K Eitel, F Von Feilitzsch, D Filosofov, P Gandit, E Garcia, J Gascon, G Gerbier, J Gironnet, H Godfrin, S Grohmann, M Gros, M Hannewald, D Hauff, F Haug, S Henry, P Huff, J Imber, S Ingleby, C Isaila, J Jochum, A Juillard, M Kiefer, M Kimmerle, H Kluck, VV Kobychev, V Kozlov, VA Kudryavtsev, T Lachenmaier, JC Lanfranchi, RF Lang, P Loaiza, A Lubashevsky, M Malek, S Marnieros, R McGowan, V Mikhailik, VM Mokina, A Monfardini, XF Navick, T Niinikoski, AS Nikolaiko, L Oberauer, E Olivieri, Y Ortigoza, E Pantic, P Pari, B Paul, G Perinic, F Petricca, S Pfister, C Pobes, DV Poda, RB Podviyanuk, OG Polischuk, W Potzel, F Pröbst, J Puimedon, M Robinson, S Roth, K Rottler, S Rozov, C Sailer, A Salinas, V Sanglard, ML Sarsa, K Schäffner, S Scholl, S Scorza, A Smolnikov, W Seidel, S Semikh, M Stern

Abstract:

European Underground Rare Event Calorimeter Array (EURECA) will be an astro-particle physics facility in the Laboratoire Souterrain de Modane, aiming to directly detect galactic dark matter. The EURECA collaboration unites CRESST, EDELWEISS and the Spanish-French experiment ROSEBUD, thus concentrating and focussing effort on cryogenic detector research in Europe into a single facility. The aim is to explore WIMP - nucleon scalar cross sections in the 10-9 - 10-10 picobarn region with a target mass of up to one ton. A major advantage of EURECA is the planned use of more than just one target material (multi target experiment for WIMP identification).

Engineering for the ATLAS SemiConductor Tracker (SCT) End-cap

Journal of Instrumentation 3:5 (2008)

Authors:

A Abdesselam, PP Allport, B Anderson, L Andricek, F Anghinolfi, RJ Apsimon, T Atkinson, A Austin, H Band, P Barclay, A Barr, LE Batchelor, RL Bates, JR Batley, G Beck, H Becker, P Bell, WH Bell, A Belymam, J Beneš, P Beneš, E Berbee, J Bernabeu, S Bethke, N Bingefors, JP Bizzell, ZJ Blaszczak, J Blocki, J Brož, J Bohm, R Brenner, TJ Brodbeck, PB De Renstrom, R Buis, G Burton, J Buskop, CM Buttar, JM Butterworth, S Butterworth, E Capocci, C Carpentieri, AA Carter, JR Carter, M Chamizo, DG Charlton, A Cheplakov, A Chilingarov, S Chouridou, D Chren, ML Chu, V Cindro, A Ciocio, JV Civera, A Clark, P Coe, AP Colijn, PA Cooke, MJ Costa, D Costanzo, M Curtis-Rous, C Dabinett, W Dabrowski, J Dalmau, KM Danielsen, S D'Auria, I Dawson, P De Jong, P Dervan, E Dobson, F Doherty, Z Doležal, M Donega, M D'Onofrio, O Dorholt, M Doubrava, IP Duerdoth, C Duisters, R Duxfield, M Dwuznik, S Eckert, L Eklund, C Escobar, DL Evans, V Fadeyev, D Fasching, L Feld, DPS Ferguson, P Ferrari, D Ferrere, J Fopma, P Ford, R Fortin, JM Foster, H Fox, TJ Fraser, J Freestone, RS French, J Fuster, BJ Gallop, M Galuska

Abstract:

The ATLAS SemiConductor Tracker (SCT) is a silicon-strip tracking detector which forms part of the ATLAS inner detector. The SCT is designed to track charged particles produced in proton-proton collisions at the Large Hadron Collider (LHC) at CERN at an energy of 14 TeV. The tracker is made up of a central barrel and two identical end-caps. The barrel contains 2112 silicon modules, while each end-cap contains 988 modules. The overall tracking performance depends not only on the intrinsic measurement precision of the modules but also on the characteristics of the whole assembly, in particular, the stability and the total material budget. This paper describes the engineering design and construction of the SCT end-caps, which are required to support mechanically the silicon modules, supply services to them and provide a suitable environment within the inner detector. Critical engineering choices are highlighted and innovative solutions are presented - these will be of interest to other builders of large-sca e tracking detectors. The SCT end-caps will be fully connected at the start of 2008. Further commissioning will continue, to be ready for proton-proton collision data in 2008. © 2008 IOP Publishing Ltd and SISSA.
More details from the publisher
More details

First measurement of the fraction of top-quark pair production through gluon-gluon fusion

Physical Review D - Particles, Fields, Gravitation and Cosmology 78:11 (2008)

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, M Aoki, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, P Bednar, S Behari, G Bellettini, J Bellinger, A Belloni, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, D Carlsmith, R Carosi, S Carrillo, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, CI Ciobanu

Abstract:

We present the first measurement of σ(gg→tt̄)/ σ(pp̄→tt̄). We use 0.96fb-1 of s=1.96TeV pp̄ collision data recorded with the CDF II detector at Fermilab. Using charged particles with low transverse momentum in tt̄ events, we find σ(gg→ tt̄)/σ(pp̄→tt̄)=0.07±0.14(stat)±0. 07(syst), corresponding to a 95% confidence level upper limit of 0.33, in agreement with the standard model next-to-leading-order prediction of 0.15±0.05. © 2008 The American Physical Society.
More details from the publisher

Including heavy quark production in ZEUS-PDF fits

DIS 2008 - Proceedings of the 16th International Workshop on Deep-Inelastic Scattering and Related Topics (2008)

Abstract:

At HERA heavy quarks may contribute up to 30% of the structure function F2. The potential of including heavy-quark data in the ZEUS PDF fits is explored, using D* double dierential cross-sections as well as the inclusive quantities Fcc2 , Fcc2 . The introduction of heavy quarks requires an extension of the DGLAP formalism. The effect of using different heavy avour number schemes, and different approaches to the running of αs, are compared.