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All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Data preservation at the Fermilab Tevatron

The Fermilab Tevatron collider's data-taking run ended in September 2011, yielding a dataset with rich scientific potential. The CDF and D0 experiments each have approximately 9 PB of collider and simulated data stored on tape. A large computing infrastructure consisting of tape storage, disk cache, and distributed grid computing for physics analysis with the Tevatron data is present at Fermilab. The Fermilab Run II data preservation project intends to keep this analysis capability sustained through the year 2020 and beyond. To achieve this goal, we have implemented a system that utilizes virtualization, automated validation, and migration to new standards in both software and data storage technology and leverages resources available from currently-running experiments at Fermilab. Lastly, these efforts have also provided useful lessons in ensuring long-term data access for numerous experiments, and enable high-quality scientific output for years to come.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Data preservation at the Fermilab Tevatron

The Fermilab Tevatron collider's data-taking run ended in September 2011, yielding a dataset with rich scientific potential. The CDF and DO experiments each have nearly 9 PB of collider and simulated data stored on tape. A large computing infrastructure consisting of tape storage, disk cache, and distributed grid computing for physics analysis with the Tevatron data is present at Fermilab. The Fermilab Run II data preservation project intends to keep this analysis capability sustained through the year 2020 or beyond. To achieve this, we are implementing a system that utilizes virtualization, automated validation, and migration to new standards in both software and data storage technology as well as leveraging resources available from currently-running experiments at Fermilab. Furthermore, these efforts will provide useful lessons in ensuring long-term data access for numerous experiments throughout high-energy physics, and provide a roadmap for high-quality scientific output for years to come.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2015

Forward-Backward Asymmetry of Top Quark Pair Productionn at the Fermilab Tevatron

This dissertation presents the final measurements of the forward-backward asymmetry (A FB ) of top quark-antiquark pair events (t t - ) at the Collider Detector at Fermilab (CDF) experiment. The t t - events are produced in proton{anti-proton collisions with a center of mass energy of 1:96 TeV during the Run II of the Fermilab Tevatron. The measurements are performed with the full CDF Run II data (9.1 fb -1 ) in the final state that contain two charged leptons (electrons or muons, the dilepton final state), and are designed to con rm or deny the evidence-level excess in the AFB measurements in the final state with a single lepton and hadronic jets (lepton+jets final state) as well as the excess in the preliminary measurements in the dilepton final state with the first half of the CDF Run II data. New measurements include the leptonic AFB (A l FB ), the lepton-pair A FB (A ll FB ) and the reconstructed top AFB (At t FB ). Each are combined with the previous results from the lepton+jets final state measured at the CDF experiment. The inclusive A l FB , A ll FB , and At t FB measured in the dilepton final state are 0.072 ± 0.060, 0.076 ± 0.081, and 0.12 ± 0.13, to be compared with the Standard Model (SM) predictions of 0.038 ± 0.003, 0.048 ± 0.004, and 0.010 ± 0.006, respectively. The CDF combination of A l FB and At t FB are 0.090 +0:028 -0.026 , and 0.160 ± 0.045, respectively. The overall results are consistent with the SM predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The upgraded data acquisition system for beam loss monitoring at the Fermilab Tevatron and Main Injector

A VME-based data acquisition system for beam-loss monitors has been developed and is in use in the Tevatron and Main Injector accelerators at the Fermilab complex. The need for enhanced beam-loss protection when the Tevatron is operating in collider-mode was the main driving force for the new design. Prior to the implementation of the present system, the beam-loss monitor system was disabled during collider operation and protection of the Tevatron magnets relied on the quench protection system. The new Beam-Loss Monitor system allows appropriate abort logic and thresholds to be set over the full set of collider operating conditions. The system also records a history of beam-loss data prior to a beam-abort event for post-abort analysis. Installation of the Main Injector system occurred in the fall of 2006 and the Tevatron system in the summer of 2007. Both systems were fully operation by the summer of 2008. In this paper we report on the overall system design, provide a description of its normal operation, and show a number of examples of its use in both the Main Injector and Tevatron.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Simulation of Hollow Electron Beam Collimation in the Fermilab Tevatron Collider

The concept of augmenting the conventional collimation system of high-energy storage rings with a hollow electron beam was successfully demonstrated in experiments at the Tevatron. A reliable numerical model is required for understanding particle dynamics in the presence of a hollow beam collimator. Several models were developed to describe imperfections of the electron beam profile and alignment. The features of the imperfections are estimated from electron beam profile measurements. Numerical simulations of halo removal rates are compared with experimental data taken at the Tevatron.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Phase modulation of the bucket stops bunch oscillations at the Fermilab Tevatron

Bunches in the Tevatron are known to exhibit longitudinal oscillations which persist indefinitely. These oscillations are colloquially called 'dancing bunches.' Although the dancing proton bunches do not cause single bunch emittance growth or beam loss at injection, they lead to bunch lengthening at collisions. In Tevatron operations, a longitudinal damper has been built which stops this dance and damps out coupled bunch modes. Recent theoretical work predicts that the dance can also be stopped by an appropriate change in the bunch distribution. This paper describes the Tevatron experiments which support this theory.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Fixed target experiments at the Fermilab Tevatron

This paper presents a review of the study of Exclusive Central Production at a Center of Mass energy of √s = 40 GeV at the Fermilab Fixed Target program. In all reactions reviewed in this paper, protons with an energy of 800 GeV were extracted from the Tevatron accelerator at Fermilab and directed to a Liquid Hydrogen target. The states reviewed include π⁺π⁻, K⁰ s K⁰ s , K⁰ s K ± π ∓ , φφ and D *± . Partial Wave Analysis results will be presented on the light states but only the cross-section will be reviewed in the diffractive production of D *± .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Search for $W'\to t b $ in Events with Large Missing Transverse Energy and Jets with the CDF detector at the Fermilab Tevatron Collider

In the scope of the strong ongoing data analysis efforts of the CDF col- laboration at Fermilab, we present a search for the production of mas sive W1 bosons decaying to a top and a bottom quark in p$\bar{p}$ collisions at √s = 1.96 TeV. To perform this search, we select events with large Missing Transverse Energy plus two or three jets, in which the W generated from top decays leptonically, and either the e or µ is lost or the τ is reconstructed as a jet. A complete study of the selected sample is discussed, including the creation and subsequent optimization of a Neural Network-based multivariate tool to reject the QCD multijet background from the signal region. Finally, we perform a likelihood-based multichannel Bayesian fit procedure on the invariant transverse mass of the Missing Transverse Energy and jets to extract 95% CL limits on σ(p$\bar{p}$ . → W') × B(W' → tb) for M W' = 200 GeV/c 2

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

New Measurements with Photons at the Tevatron

With the recent completion of Run II at the Fermilab Tevatron, the CDF and D0 experiments are publishing results based on challenging measurements that probe quantum chromodynamics (QCD) and are sensitive to next-to-leading-order (NLO) and next-to-next-to-leading-order (NNLO) effects and non-perturbative physics. A superior understanding of parton distribution functions and QCD backgrounds will improve the sensitivity of searches for new phenomena at the LHC and reduce uncertainties in a multitude of future measurements. We present three recent photon analyses from data collected at the Fermilab Tevatron: measurements of the direct photon pair production cross section at CDF and D0, measurements of azimuthal decorrelations and multiple parton interactions in {gamma} + 2 jet and {gamma} + 3 jet events at D0, and an observation of exclusive diphoton production at CDF.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

\ttbar and single top cross sections at the Tevatron

We present a summary of the latest measurements of the top pair and single top cross sections performed by the CDF and D0 collaborations at the Fermilab Tevatron collider. The Fermilab Tevatron collider ended its run on September 30, 2011 after delivering more than 10 fb{sup -1} of p{bar p} collision data per experiment at {radical}s = 1.96 TeV. A large sample of top quarks collected by the CDF and D0 experiments allows to perform precision measurements of their production which is predicted to occur within the standard model (SM) either in pairs via strong interactions or as single top events via electroweak interactions. Such measurements represent an important test of the theoretical calculations which predict the t{bar t} and single top production cross sections with a precision of 6% to 8% and 5%, respectively. Precise measurements of top pair cross section ({sigma}{sub t{bar t}}) in different t{bar t} final states and single top production via different production mechanisms are highly desirable as they are sensitive to the non-SM particles that may appear in top quark production or decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Search for pair production of the scalar top quark in muon plus tau final states

Here, we present a search for the pair production of scalar top quarks ($\sim\atop{t}$ 1 ), the lightest supersymmetric partners of the top quarks, in $p\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of 7.3fb -1 collected with the D0 experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a b quark, a charged lepton, and a scalar neutrino (ν˜). We investigate final states arising from$\sim\atop{t}$ 1 $≂\atop{t}$ 1 →$b\bar{b}$ μτ$\sim\atop{v}$$\sim\atop{v}$ and $\sim\atop{t}$ 1 $≂\atop{t}$ 1 →$b\bar{b}$ ττ$\sim\atop{v}$$\sim\atop{v}$. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the (m$\sim\atop{t}$ 1 , m$\sim\atop{v}$) plane.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Forward-backward asymmetry in top quark-antiquark production

We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a data set corresponding to an integrated luminosity of 5.4 fb{sup -1}, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t{bar t} forward-backward asymmetry to be (9.2 {+-} 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 {+-} 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 {+-} 4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Top-Quark Mass Measurement Using Events with Missing Transverse Energy and Jets at CDF

We present a measurement of the top-quark mass using a sample of tt events in 5.7 fb{sup -1} of integrated luminosity from pp collisions at the Fermilab Tevatron with {radical}(s)=1.96 TeV and collected by the CDF II Detector. We select events having large missing transverse energy, and four, five, or six jets with at least one jet tagged as coming from a b quark, and reject events with identified charged leptons. This analysis considers events from the semileptonic tt decay channel, including events that contain tau leptons. The measurement is based on a multidimensional template method. We fit the data to signal templates of varying top-quark masses and background templates, and measure a top-quark mass of M{sub top}=172.32{+-}2.4(stat){+-}1.0(syst) GeV/c{sup 2}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurement of the B s 0 Lifetime in Fully and Partially Reconstructed B s 0 →D s - (Φπ⁻)X Decays in pp̄ Collisions at √s=1.96 TeV

We present a measurement of the BB s 0 lifetime in fully and partially reconstructed B s 0 →D s - (Φπ⁻)X decays in 1.3 fb⁻¹ collected in pp̄ collisions at √s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. We measure τ(B s 0 )=1.518±0.041(stat)±0.027(syst) ps. The ratio of this result and the world average B⁰ lifetime yields τ(B s 0 )/τ(B⁰)=0.99±0.03, which is in agreement with recent theoretical predictions.

Aaltonen, T.↗
DOE OSTI2011

W{gamma} Production and Limits on Anomalous WW{gamma} Couplings in pp Collisions at {radical}(s)=1.96 TeV

We measure the cross section and the difference in rapidities between photons and charged leptons for inclusive W({yields}l{nu})+{gamma} production in e{gamma} and {mu}{gamma} final states. Using data corresponding to an integrated luminosity of 4.2 fb{sup -1} collected with the D0 detector at the Fermilab Tevatron Collider, the measured cross section times branching fraction for the process pp{yields}W{gamma}+X{yields}l{nu}{gamma}+X and the distribution of the charge-signed photon-lepton rapidity difference are found to be in agreement with the standard model. These results provide the most stringent limits on anomalous WW{gamma} couplings for data from hadron colliders: -0.4<{Delta}{kappa}{sub {gamma}<}0.4 and -0.08<{lambda}{sub {gamma}<}0.07 at the 95% C.L.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurements of single top quark production cross sections and |V tb | in pp̄ collisions at √s=1.96 TeV

We present measurements of production cross sections of single top quarks in pp̄ collisions at √s=1.96 TeV in a data sample corresponding to an integrated luminosity of 5.4 fb⁻¹ collected by the D0 detector at the Fermilab Tevatron Collider. We select events with an isolated electron or muon, an imbalance in transverse energy, and two, three, or four jets, with one or two of them containing a bottom hadron. We obtain an inclusive cross section of σ(pp̄→tb+X,tqb+X)=3.43± 0.73 0.74 pb and use it to extract the CKM matrix element 0.79<|V tb |≤1 at the 95% C.L. We also measure σ(pp̄→tb+X)=0.68±0.380.35 pb and σ(pp̄→tqb+X)=2.86± 0.69 0.63 pb when assuming, respectively, tqb and tb production rates as predicted by the standard model.

Abazov, V. M.↗