Ultrabroadband pulses exhibit a frequency-dependent mode size owing to the wavelength dependence of free-space diffraction. Additionally, rather complex lateral dependence of the temporal pulse shape has been reported for Kerr-lens mode-locked lasers and broadband amplifier chains and in frequency-domain pulse shapers, for example. We demonstrate an ultrashort-pulse characterization technique that reveals lateral pulse-shape variations by spatially resolved amplitude and phase measurements by use of spectral phase interferometry for direct electric-field reconstruction (SPIDER). Unlike with autocorrelation techniques, with SPIDER we can obtain spatially resolved pulse characterization even after the nonlinear process. Thus, with this method the spectral phase of the pulse can be resolved very rapidly along one lateral beam axis in a single measurement.

Pion energy spectra from the reactions np~nn~+ and np~pp~were measured as a function of the angle at 790 MeV. The angular distribution in the np center-of-momentum system was given by [(123.1+2.7)+(88.3+4.9) cps ()~] pb/sr. The total cross section for each reaction was found to be 1.92+0.20 mb. Evidence for T=0 pion production was observed in shape differences between the positive-and negative-pion spectra. However, it was shown that pions are preferentially produced by nucleons in a o'(T =0)=3crptCoulomb effects, the neutron-proton mass difference, and the m. -~+ -mass difference introduce uncertainties in these relationships. However, the corrections to these relationships are estimated to be no more than a few percent. 'The Mandelstam model has been used to describe single-pion production from threshold to about 800 MeV. One of the basic assumptions of this model is that the outgoing pion and one of the nucleons form the b, (1232) resonant state. In this case, isospin conservation requires that the colliding nucleons be in a T =1 state, which means that the total pion-production amplitudes should be front-back symmetic in the center-of-momentum system (c.m.s.) and that cr(T =0) should be zero.However, results from previous experiments concerning reactions (1) and (2) indicate the existence of T =0 amplitudes. Specifically, Yodh found substantial differences between the~+ and energy spectra and angular distributions at 400MeV, a strong indication of interfering T =0 and T =1 amplitudes. Handler also found differences between the pion angular distributions near 400 24 1736

High-statistics measurements of the absolute differential cross section for n-p scattering have been made over neutron cm.-system scattering angles 9.5°<0* <64.5°. The statistical error is 1.7 to 3.3% for 2°-wide angular bins, and the systematic error is 2.7 to 3.3%. The cross section is fitted by do/dSl**A exp(bt), with A*10.27±0.36 mb/sr, b =5.00 ±0.05, and 0.01<-£<0.39 (GeV/c) 2 . For the ratio of the real to the imaginary part of the forward-scattering amplitude we obtained a"^-0.43 ±0.04, consistent with other less precise determinations of a".Vacuum polarization at long distances for confined heavy-quark-antiquark (QQ) pairs is considered. The vacuum-polarization-corrected static potential is shown to have a radial dependence which should allow interpolation between charmonium, upsilon states, and other heavy QQ systems. It is argued that the static, confining potential cannot grow faster than a linear potential at large distances, within the framework of this analysis.

Abstract. The laser-driven MiniFlyer system is used to launch a small, thin flyer plate for impact on a target. Consequently, it is an indirect drive technique that de-couples the shock from the laser beam profile. The flyer velocity can be controlled by adjustment of the laser energy. The upper limits on the flyer velocity involve the ability of the substrate window to transmit the laser light without absorbing, reflecting, etc.; Le., a maximum amount of laser energy is directly converted into kinetic energy of the flyer plate. We have investigated the use of sapphire, quartz, and BK-7 glass as substrate windows. In the past, a particular type of sapphire has been used for nearly all Miniflyer experiments, Results of this study in terms of the performance of these window materials, based on flyer velocity are discussed,

A full vectorial contrast source inversion scheme for three-dimensional acoustic imaging of both compressibility and density profiles J. Acoust. Soc. Am. 121, 1538 (2007); 10.1121/1.2431333High-resolution three-dimensional reconstruction: A combined scanning electron microscope and focused ionbeam approach