119553667
THE RHIC AZIMUTH QUADRUPOLE: "PERFECT LIQUID" OR GLUONIC RADIATION?
Large elliptic flow at RHIC seems to indicate that ideal hydrodynamics provides a good description of Au–Au collisions, at least at the maximum RHIC energy. The medium formed has been interpreted as a nearly perfect (low-viscosity) liquid, and connections have been made to gravitation through string theory. Recently, claimed observations of large flow fluctuations comparable to participant eccentricity fluctuations seem to confirm the ideal hydro scenario. However, determination of the azimuth quadrupole with 2D angular autocorrelations, which accurately distinguish "flow" (quadrupole) from "nonflow" (minijets), contradicts conventional interpretations. Centrality trends may depend only on the initial parton geometry, and methods used to isolate flow fluctuations are sensitive instead mainly to minijet correlations. The results presented in this paper suggest that the azimuth quadrupole may be a manifestation of gluonic multipole radiation.
33152244
First capture of antiprotons in a Penning trap: A kiloelectronvolt source.
Antiprotons from the Low Energy Antiproton Ring of CERN are slowed from 21 MeV to below 3 keV by being passed through 3 mm of material, mostly Be. While still in flight, the kiloelectronvolt antiprotons are captured in a Penning trap created by the sudden application of a 3-kV potential. Antiprotons are held for 100 s and more. Prospects are now excellent for much longer trapping times under better vacuum conditions. This demonstrates the feasibility of a greatly improved measurement of the inertial mass of the antiproton and opens the way to other intriguing experiments.
117386684
The positron-electron peak puzzle: results from APEX
I. Ahmad1, S.M. Austin2, B.B. Back1, R.R. Betts1,3, F.P. Calaprice4, K.C. Chan5, A. Chishti5, P. Chowdhury5, C. Conner3, R.W. Dunford1, J.D. Fox6, S.J. Freedman1,7, M. Freer1,8, S.B. Gazes 9,10, A.L. Hallin 11, T. Happ1,12, D. Henderson1, N.I. Kaloskamis5,13,?, E. Kashy2, W. Kutschera1, J. Last1, C.J. Lister1,5, M. Liu 11, M.R. Maier, D.J. Mercer2, D. Mikolas2, P.A.A. Perera10, M.D. Rhein1,12, E. Roa6, J.P. Schiffer1,9, T.A. Trainor 14, P. Wilt1, J.S. Winfield2, M. Wolanski1,9, F.L.H. Wolfs10, A.H. Wuosmaa1, A. Young4, J.E. Yurkon2
107372673
Improved two-loop beam energy stabilizer for an FN tandem accelerator
A detailed analysis of the properties of various elements in a two-loop voltage regulator for a tandem accelerator enabled design of an optimum system which reduces effective accelerating voltage noise below 100 V. Essential features of the new system are high-quality slit preamplifiers, careful attention to removal of extraneous noise sources, and proper shaping of frequency responses to maximize stable gains and ensure compatibility of the two control loops. The resultant beam energy stabilizer system is easy to operate, has well defined indicators for proper adjustment of operating parameters, and recovers reliably from beam interruptions.
108079620
Overview and status of the University of Washington Nuclear Physics Lab booster project
We are in the process of building a superconducting booster LINAC using quarter wave resonators of lead plated copper. In this paper we give a brief description of the overall design of the accelerator and then present a status report on the construction. The overall layout of the Booster is shown. As is the case with many Booster accelerators, there are features of the design which are dictated by space constraints. In our case, the space in the tandem vault that the booster will occupy is part of the existing building.
117892720
Purpose and Physics of Event‐by‐Event Analysis
Event‐by‐event analysis is the study of event‐wise and ensemble correlation structure in the hadronic final state of heavy ion collisions. Statistical and topological techniques are applied to large event populations to reveal fluctuations and correlations deviating from a null hypothesis. Correlations can arise from initial‐state scattering, incomplete equilibration and from critical correlations developed during traversal of the QCD phase boundary. The goal of this analysis is a phenomenological description of full QCD at and above the phase boundary.
121451303
Molecular beam epitaxial growth and properties of CoFe2O4 on MgO(001)
Abstract We have grown single-crystal Co ferrite (CoFe 2 O 4 ) on MgO(0 0 1) by oxygen-plasma-assisted molecular beam epitaxy (OPA-MBE), and have characterized the composition, structure, surface morphology, and magnetic properties by a number of methods. The as-grown OPA-MBE material forms a perfect inverse spinel, in which all Co is in the 2+ formal oxidation state, and occupies octahedral sites within the cation sublattice. The OPA-MBE film surfaces are very flat, with mean roughnesses of only a few A, and exhibit large, stable magnetic domains. The measured moment per unit volume is 250 emu/cm 3 , and the saturation magnetization for films in the 1000 A film thickness range is ∼60% of that of bulk Co ferrite. The material also exhibits strain-dependent magnetic anisotropy that can be understood by considering the various contributions to the total magnetic energy. The overall quality of epitaxial Co ferrite grown on MgO by OPA-MBE is superior in every respect to that obtained using pulsed laser deposition as the growth method.
134906969
Synchrotron-based studies of microbe-metal ion-mineral interactions
97905177
Structure and reactivity of environmental interfaces : Application of grazing angle X-ray spectroscopy and long-period X-ray standing waves
Abstract Chemical processes occurring at environmental interfaces (e.g. mineral–fluid, mineral–organic matter and mineral–biofilm interfaces) have a profound impact on the environmental fate and bioavailability of aqueous metals and other contaminant species. However, the direct analysis of molecular scale structure and properties of environmental interfaces, particularly under “high-pressure” or “wet” conditions is highly challenging. Synchrotron based X-ray scattering and spectroscopic approaches offer numerous advantages, such as the high penetrating power and molecular scale information inherent to X-ray techniques. Yet, the ability to localize information content to environmental interfaces requires challenging experimental configurations. Here, the application of grazing angle X-ray fluorescence techniques is reviewed, including the presentation of a model formalism that allows for quantitative analysis of fluorescent yield profiles and discussion of the experimental setup. Illustrative examples are discussed, particularly in the context of combining results of GI measurements with the results of other complementary interface probes such as crystal truncation rod diffraction and X-ray microprobe spectroscopic studies.