249 research outputs found
Progress in Absorber R&D for Muon Cooling
A stored-muon-beam neutrino factory may require transverse ionization cooling
of the muon beam. We describe recent progress in research and development on
energy absorbers for muon-beam cooling carried out by a collaboration of
university and laboratory groups.Comment: 7 pages, 1 figure, presented at the 3rd International Workshop on
Neutrino Factory Based on Muon Storage Rings (NuFACT'01), May 24-30, 2001,
Tsukuba, Japa
Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV
We report the results of a study of color coherence effects in ppbar
collisions based on data collected by the D0 detector during the 1994-1995 run
of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8
TeV. Initial-to-final state color interference effects are studied by examining
particle distribution patterns in events with a W boson and at least one jet.
The data are compared to Monte Carlo simulations with different color coherence
implementations and to an analytic modified-leading-logarithm perturbative
calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters
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Spectra of Heliumlike Krypton From Tokamak Fusion Test Reactor Plasmas
Krypton has been injected into ohmically-heated TFTR plasmas with peak electron temperatures of 6 key to study the effects of krypton on the plasma performance and to investigate the emitted krypton line radiation, which is of interest for future-generation tokamaks such as ITER, both as a diagnostic of the central ion temperature and for the control of energy release from the plasma by radiative cooling. The emitted radiation was monitored with a bolometer array, an X-ray pulse height analysis system, and a high-resolution Johann-type crystal spectrometer; and it was found to depend very sensitively on the electron temperature profile. Satellite spectra of heliumlike krypton, KrXXXV, near 0.95 [Angstrom] including lithiumlike, berylliumlike and boronlike features were recorded in second order Bragg reflection. Radiative cooling and reduced particle recycling at the plasma edge region were observed as a result of the krypton injection for all investigated discharges. The observations are in reasonable agreement with modeling calculations of the krypton ion charge state distribution including radial transport
Coherent Ï0 photoproduction on the deuteron up to 4 GeV
The differential cross section for 2H(Îł,d)Ï0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions
Marketing as a means to transformative social conflict resolution: lessons from transitioning war economies and the Colombian coffee marketing system
Social conflicts are ubiquitous to the human condition and occur throughout markets, marketing processes, and marketing systems.When unchecked or unmitigated, social conflict can have devastating consequences for consumers, marketers, and societies, especially when conflict escalates to war. In this article, the authors offer a systemic analysis of the Colombian war economy, with its conflicted shadow and coping markets, to show how a growing network of fair-trade coffee actors has played a key role in transitioning the countryâs war economy into a peace economy. They particularly draw attention to the sources of conflict in this market and highlight four transition mechanisms â i.e., empowerment, communication, community building and regulation â through which marketers can contribute to peacemaking and thus produce mutually beneficial outcomes for consumers and society. The article concludes with a discussion of implications for marketing theory, practice, and public policy
First Observation of a Upsilon(1D) State
We present the first evidence for the production of Upsilon(1D) states in the
four-photon cascade, Upsilon(3S)-->gamma chib(2P), chib(2P)-->gamma
Upsilon(1D), Upsilon(1D)-->gamma chib(1P), chib(1P)-->gamma Upsilon(1S),
followed by the Upsilon(1S) annihilation into e+e- or mu+mu-. The signal has a
significance of 10.2 standard deviations. The measured product branching ratio
for these five decays, (2.5+-0.5+-0.5)x10^(-5), is consistent with the
theoretical estimates. The data are dominated by the production of one
Upsilon(1D) state consistent with the J=2 assignment. Its mass is determined to
be (10161.1+-0.6+-1.6) MeV, which is consistent with the predictions from
potential models and lattice QCD calculations.
We also searched for Upsilon(3S)-->gammachib(2P),
chib(2P)-->gammaUpsilon(1D), followed by either Upsilon(1D)-->eta Upsilon(1S)
or Upsilon(1D)-->pi+pi- Upsilon(1S). We find no evidence for such decays and
set upper limits on the product branching ratios.Comment: 12 pages postscript,also available through this
http://w4.lns.cornell.edu/public/CLNS/, submitted to PR
Search for electroweak production of single top quarks in collisions.
We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process ppbar->tb+X of 39 pb. The upper limit for the t-channel process ppbar->tqb+X is 58 pb. (arXiv
Helicity of the W Boson in Lepton+Jets ttbar Events
We examine properties of ttbar candidates events in lepton+jets final states
to establish the helicities of the W bosons in t->W+b decays. Our analysis is
based on a direct calculation of a probability that each event corresponds to a
ttbar final state, as a function of the helicity of the W boson. We use the 125
events/pb sample of data collected by the DO experiment during Run I of the
Fermilab Tevatron collider at sqrt{s}=1.8 TeV, and obtain a longitudinal
helicity fraction of F_0=0.56+/-0.31, which is consistent with the prediction
of F_0=0.70 from the standard model
Hard Single Diffraction in pbarp Collisions at root-s = 630 and 1800 GeV
Using the D0 detector, we have studied events produced in proton-antiproton
collisions that contain large forward regions with very little energy
deposition (``rapidity gaps'') and concurrent jet production at center-of-mass
energies of root-s = 630 and 1800 Gev. The fractions of forward and central jet
events associated with such rapidity gaps are measured and compared to
predictions from Monte Carlo models. For hard diffractive candidate events, we
use the calorimeter to extract the fractional momentum loss of the scattered
protons.Comment: 11 pages 4 figures. submitted to PR
Measurement of the View the tt production cross-section using eÎŒ events with b-tagged jets in pp collisions at âs = 13 TeV with the ATLAS detector
This paper describes a measurement of the inclusive top quark pair production cross-section (ÏttÂŻ) with a data sample of 3.2 fbâ1 of protonâproton collisions at a centre-of-mass energy of âs = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electronâmuon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously ÏttÂŻ and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be:
ÏttÂŻ = 818 ± 8 (stat) ± 27 (syst) ± 19 (lumi) ± 12 (beam) pb,
where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented
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