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Proton Beam Focusing and Heating in Petawatt Laser-Solid Interactions (open access)

Proton Beam Focusing and Heating in Petawatt Laser-Solid Interactions

It has recently been demonstrated that femtosecond-laser generated proton beams may be focused. These protons, following expansion of the Debye sheath, emit off the inner concave surface of hemispherical shell targets irradiated at their outer convex pole. The sheath normal expansion produces a rapidly converging proton beam. Such focused proton beams provide a new and powerful means to achieve isochoric heating to high temperatures. They are potentially important for measuring the equation of state of materials at high energy density and may provide an alternative route to fast ignition. We present the first results of proton focusing and heating experiments performed at the Petawatt power level at the Gekko XII Laser Facility at ILE Osaka Japan. Solid density Aluminum slabs are placed in the proton focal region at various lengths. The degree of proton focusing is measured via XUV imaging of Planckian emission of the heated zone. Simultaneous with the XUV measurement a streaked optical imaging technique, HISAK, gave temporal optical emission images of the focal region. Results indicate excellent coupling between the laser-proton conversion and subsequent heating.
Date: August 13, 2003
Creator: Snavely, R. A.; Gu, P.; King, J.; Hey, D.; Akli, K.; Zhang, B. B. et al.
System: The UNT Digital Library
Phase motion of the scalar {pi}{pi} amplitudes in D{sup +}, D{sub s}{sup +} {yields} {pi}{sup -} {pi}{sup +}{pi}{sup +} decays (open access)

Phase motion of the scalar {pi}{pi} amplitudes in D{sup +}, D{sub s}{sup +} {yields} {pi}{sup -} {pi}{sup +}{pi}{sup +} decays

We make a direct and model-independent measurement of the low {pi}{sup +} {pi}{sup -} mass phase motion in the D{sup +} {yields} {pi}{sup -} {pi}{sup +}{pi}{sup +} decay. Our preliminary results show a strong phase variation, compatible with the isoscalar {sigma}(500) meson. This result confirms our previous result [1] where we found evidence for the existence of this scalar particle using full Dalitz-plot analysis. We apply the Amplitude Difference (AD) method [2] to the same Fermilab E791 data sample used in the preceding analysis. We also give an example of how we extract the phase motion of the scalar amplitude, looking at the f{sub 0}(980) in D{sub s}{sup +} {yields} {pi}{sup -} {pi}{sup +}{pi}{sup +} decay.
Date: August 13, 2003
Creator: Bediaga, Ignacio
System: The UNT Digital Library
Systematic uncertainties on Delta m2 from neutrino physics, using calorimetric energy reconstruction (open access)

Systematic uncertainties on Delta m2 from neutrino physics, using calorimetric energy reconstruction

This report describes how uncertainties in neutrino interactions, particularly at neutrino energies of a few GeV, can contribute to uncertainties in measurements of neutrino oscillation parameters for experiments using calorimetric devices. Uncertainties studied include those on final state multiplicities, cross sections, electron-hadron calorimeter differences, and nuclear rescattering.
Date: August 13, 2003
Creator: Harris, Deborah A.
System: The UNT Digital Library
The scalar {kappa} from D{sup +} {yields} K{sup -} {pi}{sup +}{pi}{sup +}: Further studies (open access)

The scalar {kappa} from D{sup +} {yields} K{sup -} {pi}{sup +}{pi}{sup +}: Further studies

We briefly review the recent results obtained by Fermilab experiment E791 on the Dalitz plot analysis of the decay D{sup +} {yields} K{sup -} {pi}{sup +}{pi}{sup +}, where indication for a light K {pi} scalar resonance, the {kappa}, was found. We also present preliminary studies providing further information on the phase behavior of the scalar components at low mass, supporting the previous indication for the {kappa}.
Date: August 13, 2003
Creator: Gobel, Carla
System: The UNT Digital Library
Elastic properties of supported polycrystalline thin films and multilayers: An X-ray diffraction study (open access)

Elastic properties of supported polycrystalline thin films and multilayers: An X-ray diffraction study

Numerous experimental and theoretical studies have shown that thin film elastic behavior may be different from the bulk one due to size effects related to grain boundaries, free surfaces and interfaces. In addition, thin films often present high compressive residual stresses which may be responsible of thin film buckling. These two features will be discussed in this communication through recent x-ray diffraction experiments: in situ tensile testing for elastic constant analysis and scanning x-ray micro diffraction for stress relaxation measurements associated with film buckling.
Date: August 13, 2003
Creator: Goudeau, P.; Villain, P.; Tamura, N.; Renault, P.-O.; Badawi, K.F. & Padmore, H.A.
System: The UNT Digital Library
Relativistic Electron Beam Transport and Characteristics in Solid Density Plasmas (open access)

Relativistic Electron Beam Transport and Characteristics in Solid Density Plasmas

The transport of intense relativistic beams in solid density plasma presently is actively being studied in laser laboratories around the world. The correct understanding of the transport enables further application of fast laser driven electrons to a host of interesting uses. Advanced x-ray sources, proton and ion beam generation and plasma heating in fast ignitor fusion all are owed their eventual utility to this transport. We report on measurements of relativistic transport over the whole of the transport region, via analysis of x-ray emission. Our experiments cover laser powers from Terawatt to Petawatt. Advances in transverse imaging of fluorescent k-alpha x-rays generated along the electron beam path are used to diagnose the electron emission. Additionally the spatial pattern of Bremsstrahlung x-rays provides clues into the physics of electron transport in above Alfven current limit beams. Issues regarding the electron distribution function will be discussed in light of possible electron transport anomalies. The initial experiments performed on the Nova Petawatt Laser System were those associated with determining the nature of the electrons and x-rays in this relativistic regime especially those useful for advanced radiography sources suitable for diagnostic use in dense high-Z dynamic processes or as the driver of a relativistic …
Date: August 13, 2003
Creator: Snavely, R. A.; King, J.; Freeman, R. R.; Hatchett, S.; Key, M. H.; Koch, J. et al.
System: The UNT Digital Library