| 1. |
- Aamodt, K., et al.
(författare)
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The ALICE experiment at the CERN LHC
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08002
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Forskningsöversikt (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries, Its overall dimensions are 16 x 16 x 26 m(3) with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
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| 2. |
- Abazov, V. M., et al.
(författare)
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Evidence for production of single top quarks
- 2008
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; D:78, s. 012005-
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Forskningsöversikt (refereegranskat)abstract
- We present first evidence for the production of single top quarks in the D0 detector at the Fermilab Tevatron p (p) over bar collider. The standard model predicts that the electroweak interaction can produce a top quark together with an antibottom quark or light quark, without the antiparticle top-quark partner that is always produced from strong-coupling processes. Top quarks were first observed in pair production in 1995, and since then, single top-quark production has been searched for in ever larger data sets. In this analysis, we select events from a 0.9 fb(-1) data set that have an electron or muon and missing transverse energy from the decay of a W boson from the top-quark decay, and two, three, or four jets, with one or two of the jets identified as originating from a b hadron decay. The selected events are mostly backgrounds such as W + jets and t (t) over bar events, which we separate from the expected signals using three multivariate analysis techniques: boosted decision trees, Bayesian neural networks, and matrix-element calculations. A binned likelihood fit of the signal cross section plus background to the data from the combination of the results from the three analysis methods gives a cross section for single top-quark production of sigma(p (p) over bar -> tb + X, tqb + X) = 4.7 +/- 1.3 pb. The probability to measure a cross section at this value or higher in the absence of signal is 0.014%, corresponding to a 3.6 standard deviation significance. The measured cross section value is compatible at the 10% level with the standard model prediction for electroweak top-quark production. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa quark mixing matrix element that describes the Wtb coupling and find vertical bar V(tb)f(1)(L)vertical bar = 1.31(-0.21)(+0.25), where f(1)(L) is a generic vector coupling. This model-independent measurement translates into 0.68 <= 1 at the 95% C.L. in the standard model.
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| 3. |
- Genkinger, J. M., et al.
(författare)
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Central adiposity, obesity during early adulthood, and pancreatic cancer mortality in a pooled analysis of cohort studies
- 2015
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Ingår i: Annals of Oncology. - : OXFORD UNIV PRESS. - 0923-7534 .- 1569-8041. ; 26:11, s. 2257-2266
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Forskningsöversikt (refereegranskat)abstract
- positively associated with pancreatic cancer. However, little evidence exists regarding the influence of central adiposity, a high BMI during early adulthood, and weight gain after early adulthood on pancreatic cancer risk. Design: We conducted a pooled analysis of individual-level data from 20 prospective cohort studies in the National Cancer Institute BMI and Mortality Cohort Consortium to examine the association of pancreatic cancer mortality with measures of central adiposity ( e. g. waist circumference; n = 647 478; 1947 pancreatic cancer deaths), BMI during early adulthood ( ages 18- 21 years) and BMI change between early adulthood and cohort enrollment, mostly in middle age or later ( n = 1 096 492; 3223 pancreatic cancer deaths). Multivariable hazard ratios ( HRs) and 95% confidence intervals ( CIs) were calculated using Cox proportional hazards regression models. Results: Higher waist-to-hip ratio ( HR = 1.09, 95% CI 1.02- 1.17 per 0.1 increment) and waist circumference ( HR = 1.07, 95% CI 1.00- 1.14 per 10 cm) were associated with increased risk of pancreatic cancer mortality, even when adjusted for BMI at baseline. BMI during early adulthood was associated with increased pancreatic cancer mortality ( HR = 1.18, 95% CI 1.11- 1.25 per 5 kg/ m2), with increased risk observed in both overweight and obese individuals ( compared with BMI of 21.0 to < 23 kg/ m(2), HR = 1.36, 95% CI 1.20- 1.55 for BMI 25.0 < 27.5 kg/ m2, HR = 1.48, 95% CI 1.20- 1.84 for BMI 27.5 to < 30 kg/ m2, HR = 1.43, 95% CI 1.11- 1.85 for BMI = 30 kg/ m2). BMI gain after early adulthood, adjusted for early adult BMI, was less strongly associated with pancreatic cancer mortality ( HR = 1.05, 95% CI 1.01- 1.10 per 5 kg/ m2). Conclusions: Our results support an association between pancreatic cancer mortality and central obesity, independent of BMI, and also suggest that being overweight or obese during early adulthood may be important in influencing pancreatic cancer mortality risk later in life.
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