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Measurements of Scattering Processes in Negative Ion- Atom Collisions

Description: The main research activity is to study various scattering processes which occur in H{sup -} collisions with atomic (specifically, noble gas and atomic hydrogen) targets in the intermediate energy region. These processes include: elastic scattering, single- and double-electron detachment, and target excitation/ionization.
Date: December 22, 2000
Creator: Kvale, T. J.
Partner: UNT Libraries Government Documents Department

Kinematics of the Relativistic Two-Body Problem

Description: Abstract: "The kinematics of elastic scattering, inelastic scattering, and the two body reaction problem is developed in the relativistic limit and exact expressions obtained for the energies, angles, and solid-angle transformations involved. The results are specialized for zero rest mass of one or more of the particles involved. An outline for the coding of the problem on the I.B.M. Electronic Data Processing Machine, Type 701 is presented."
Date: August 1955
Creator: Blumberg, Leroy & Schlesinger, Stewart I.
Partner: UNT Libraries Government Documents Department

Measurement of the Polarization in Elastic Electron ProtonScattering

Description: We have measured the (illegible) scattering (?-illegible) of electrons (?-illegible) from a polarized proton target. (illegible) between (?-illegible) imaginary part of the two-photon-(illegible) (illegible) photon-exchange amplitude could produce (?-illegible) (illegible) results indicate no asymmetry within (illegible) 1 to 2% at four(?-illegible)-momentum transfer (illegible) (illegible) 0.98 (GeV/c){sup 2}.
Date: March 1, 1970
Creator: Powell, Thomas; Chamberlain, Owen & Borghini, Michel
Partner: UNT Libraries Government Documents Department

Measurements of elastic and quasi-elastic scatterings of pp and -pp from ~ 20 to 40 GeV/c

Description: We propose a systematic study of elastic and quasi-elastic scatterings of pp and {bar p}p in the forward region (|t{vert_bar} {approx}< 1.5 GeV{sup 2}) from {approx} 20 to 40 GeV/c by using the single-arm spectrometer of NAL Exp. 7 without any essential change. The physics interests in this energy region warrant a precise comparison between pp and {bar p}p as a function of s(t) for fixed t(s). Therefore it is essential to use the same experimental apparatus and analysis procedures in order to minimize possible systematic errors. The possible future experiments at Serpukhov will not be able to produce sufficient flux in the secondary {bar p} beams to answer the physics questions raised in this proposal.
Date: July 1, 1971
Creator: Lai, K.W.; Turkot, F.; Gordon, H.A.; Schublein, P.; /Brookhaven; Cords, D. et al.
Partner: UNT Libraries Government Documents Department

Elastic scattering of low-energy electrons by randomly oriented and aligned molecules: Influence of full non-spherical potentials

Description: Elastic scattering of low (10-50 eV) kinetic energy electrons from free diatomic molecules is studied using a single-center expansion of the full molecular potential. Dynamic exchange and polarization are included in a local form. The calculated elastic differential scattering cross-sections (DCS) for electron impact on CO and N2 are in good agreement with available experimental data. The importance of using the full molecular potential instead of a two-center potential approach is pointed out. These corrections are small for energies above 50 eV, but they become increasingly important at lower energies. When discussing the angular distributions of elastically-scattered electrons from oriented molecules (like surface adsorbates), we show that these corrections are particularly significant. The results have implications for other electron scattering problems such as those encountered in low-energy photoelectron diffraction from both core and valence levels.
Date: July 17, 2000
Creator: Rolles, D.; Diez Muino, R.; Garcia de Abajo, F.J.; Fadley, C.S & Van Hove, M.A.
Partner: UNT Libraries Government Documents Department

Cross section of electron - off-shell nucleon interaction

Description: The results of theoretical calculations of the electron-bound nucleon interaction cross section ({sigma}{sub eN}) are given for four theoretical approaches. It is shown that there are significant differences between predictions of these methods, especially for the deeply bound (high internal momentum, high removing energy) nucleons. To test these predictions experimentally the authors study of cross sections obtained for two primary energies or for bound proton and neutron. These ratios will be insensitive to the nuclear spectral function as well as to the off-shell modifications of the bound nucleon form-factors if every pair of measurements are made for the same values of energy and momentum-transfers, removal energy, internal and final momenta of the struke nucleon. It is shown that dependences of the discussed ratios on various kinematical parameters are significantly different in different approaches and can be used to distinguish the theoretical models used.
Date: January 1, 1993
Creator: Egiyan, K. & Sargsyan, M.
Partner: UNT Libraries Government Documents Department

SciNOvA: A Measurement of Neutrino-Nucleus Scattering in a Narrow-Band Beam

Description: We propose to construct and deploy a fine-grained detector in the Fermilab NOvA 2 GeV narrow-band neutrino beam. In this beam, the detector can make unique contributions to the measurement of quasi-elastic scattering, neutral-current elastic scattering, neutral-current {pi}{sup 0} production, and enhance the NOvA measurements of electron neutrino appearance. To minimize cost and risks, the proposed detector is a copy of the SciBar detector originally built for the K2K long baseline experiment and used recently in the SciBooNE experiment.
Date: October 15, 2010
Creator: Paley, J.; Djurcic, Z.; /Argonne; Harris, D.; Tesarek, R.; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

Relic neutrino detector

Description: Probably the most promising way of detecting cosmic neutrinos is measuring the mechanical force exerted by clastic scattering of cosmic neutrinos from macroscopic targets. The expected acceleration is ~10<sup>-23</sup>cm/s<sup>2</sup> for Dirac neutrinos of mass ~10 eV and local density ~10<sup>7</sup>/cm<sup>3</sup>. A novel torsion balance design is presented, which addresses the sensitivity-limiting factors of existing balances, such as seismic and thermal noise, and angular readout resolution and stability.
Date: January 27, 1999
Creator: Hagmann, C.
Partner: UNT Libraries Government Documents Department

Understanding of Neutral Gas Transport in the Alcator C-Mod Tokamak Divertor

Description: A series of experiments on the effect of divertor baffling on the Alcator C-Mod tokamak provides stringent tests on models of neutral gas transport in and around the divertor region. One attractive feature of these experiments is that a trial description of the background plasma can be constructed from experimental measurements using a simple model, allowing the neutral gas transport to be studied with a stand-alone code. The neutral-ion and neutral-neutral elastic scattering processes recently added to the DEGAS 2 Monte Carlo neutral transport code permit the neutral gas flow rates between the divertor and main chamber to be simulated more realistically than before. Nonetheless, the simulated neutral pressures are too low and the deuterium Balmer-alpha emission profiles differ qualitatively from those measured, indicating an incomplete understanding of the physical processes involved in the experiment. Some potential explanations are examined and opportunities for future exploration a re highlighted. Improvements to atomic and surface physics data and models will play a role in the latter.
Date: May 7, 2002
Creator: Stotler, D.P.; Pitcher, C.S.; Boswell, C.J.; LaBombard, B.; Terry, J.L.; Elder, J.D. et al.
Partner: UNT Libraries Government Documents Department

Accelerator related backgrounds in the LHC forward detectors

Description: Detailed Monte Carlo simulations are performed on radiation environment in the LHC IP5 interaction region at the locations of the TOTEM Roman Pots proposed to detect particles produced at very small angles in the elastic scattering and diffraction dissociation processes at the LHC. Radiation loads on these detectors are calculated with the MARS14 code both of the pp-collision origin and beam loss related (beam-gas and tails from collimators).
Date: May 28, 2003
Creator: al., Nikolai V. Mokhov et
Partner: UNT Libraries Government Documents Department

Probing the nuclear medium with the K{sup +} meson

Description: Elastic differential cross sections for K{sup +} mesons scattered from targets of carbon and {sup 6}Li have been measured at an incident momentum of 715 MeV/c. The ratios of scattering cross sections from these targets are not predicted by theory, and are consistent with earlier suggestions that the K{sup +}-nucleon interaction is modified in the nuclear medium.
Date: December 31, 1995
Creator: Chrien, R.E.
Partner: UNT Libraries Government Documents Department

Measurements of the D{sub onon} and K{sub onno} observables in np elastic scattering between 0.80 and 1.10 GeV

Description: We present results of the rescattering observables D{sub onon}(np) and K{sub onno}(np) measurements at eight energies between 0.80 and 1. 10 GeV. The SATURNE II polarized beam of free neutrons obtained from the break-up of polarized deuterons was scattered on the polarized Saclay frozen-spin proton target. Part of the data was obtained with a CH{sub 2} target where only the polarization transfer parameter K{sub onno} was determined. The present results are the first existing measurements of these observables above 0.80 GeV. They provide an important contribution to any future theoretical or phenomenological analysis.
Date: March 1, 1993
Creator: Ball, J.; Chesny, P. & Combet, M.
Partner: UNT Libraries Government Documents Department

Nonlinear elastic wave interaction in a sandstone bar: A summary of recent pulse-mode experiments

Description: We have performed nonlinear pulse propagation experiments in a 3.8 cm diameter rod of Berea sandstone 1.8 m long at ambient conditions. Unlike earlier studies, we measured acceleration and not displacement. Moreover, we detected 2nd and 3rd harmonic growth at smaller strain amplitudes than were observed previously (10{sup {minus}7}). Harmonic growth at identical strain amplitudes has also been noted in resonance studies using the same rock type. Current measurements are underway with the rod in vacuum where the wave attenuation is less and the conditions can be carefully controlled. Ultimately, we wish to test the validity of current analytic and numerical models for nonlinear propagation in microcracked materials.
Date: March 1, 1995
Creator: Johnson, P.A.; TenCate, J.A.; Cherry, R.; McCall, K.; Van Den Abeele, K.; Kadish, A. et al.
Partner: UNT Libraries Government Documents Department

Electron dynamics in the strong field limit of photoionization

Description: High precision photoelectron energy and angular distributions in helium and neon atoms for a broad intensity range reflect the change in the continuum dynamics that occurs as the ionization process evolves into the pure tunneling regime. Elastic rescattering of the laser-driven free electron from its parent ion core leaves a distinct signature on the spectra, providing a direct quantitative test of the various theories of strong field multiphoton ionization. We show that it takes a relatively complete semi-classical rescattering model to accurately reproduce the observed photoelectron distributions. However, the calculated inelastic rescattering rate fails to reproduce the measured nonsequential double ionization yields.
Date: December 31, 1998
Creator: Sheehy, B.; Walker, B.; Lafon, R. & Widmer, M.
Partner: UNT Libraries Government Documents Department

THERMAL: A routine designed to calculate neutron thermal scattering

Description: THERMAL is designed to calculate neutron thermal scattering that is isotropic in the center of mass system. At low energy thermal motion will be included. At high energies the target nuclei are assumed to be stationary. The point of transition between low and high energies has been defined to insure a smooth transition. It is assumed that at low energy the elastic cross section is constant in the center of mass system. At high energy the cross section can be of any form. You can use this routine for all energies where the elastic scattering is isotropic in the center of mass system. In most materials this will be a fairly high energy.
Date: February 24, 1995
Creator: Cullen, D.E.
Partner: UNT Libraries Government Documents Department

Development of global medium-energy nucleon-nucleus optical model potentials

Description: The authors report on the development of new global optical model potentials for nucleon-nucleus scattering at medium energies. Using both Schroedinger and Dirac scattering formalisms, the goal is to construct a physically realistic optical potential describing nucleon-nucleus elastic scattering observables for a projectile energy range of (perhaps) 20 meV to (perhaps) 2 GeV and a target mass range of 16 to 209, excluding regions of strong nuclear deformation. They use a phenomenological approach guided by conclusions from recent microscopic studies. The experimental database consists largely of proton-nucleus elastic differential cross sections, analyzing powers, spin-rotation functions, and total reaction cross sections, and neutron-nucleus total cross sections. They will use this database in a nonlinear least-squares adjustment of optical model parameters in both relativistic equivalent Schroedinger (including relativistic kinematics) and Dirac (second-order reduction) formalisms. Isospin will be introduced through the standard Lane model and a relativistic generalization of that model.
Date: August 1, 1997
Creator: Madland, D.G. & Sierk, A.J.
Partner: UNT Libraries Government Documents Department

Photon-neutrino interactions

Description: The cross sections for the processes {gamma}{nu} {yields} {gamma}{gamma} {yields} {nu}{anti {nu}} are calculated with the aid of an effective Lagrangian derived from the Standard model. These cross sections are shown to be much larger than the elastic cross section {sigma}({gamma}{nu} {yields} {gamma}{nu}) for photon energies {omega} {ge} 1 keV. Possible astrophysical implications are discussed.
Date: December 1, 1997
Creator: Dicus, D.A. & Repko, W.W.
Partner: UNT Libraries Government Documents Department

Electron-atom collision studies using optically state-selected beams. Final report, May 15, 1991--May 14, 1994

Description: As stated in the original proposal, the goal of the project has been to perform electron-scattering experiments on a few model systems with emphasis on resolving all the quantum-state variables possible. The purpose of these experimental studies has been to provide a set of measurements of unprecedented accuracy and completeness that can be used as benchmarks for comparison with theoretical calculations. During the period covered by this report, the work has concentrated on measuring low-energy electron scattering from sodium and chromium. Sodium provides an ideal one-electron test case, since it has a single loosely bound valence electron, making it approachable by even the most complex electron scattering calculations. In addition, the atom has a strong optical transition from the 3{sup 2}S{sub 1/2} ground state to the 3{sup 2}P{sub 3/2} excited state whose wavelength (589 nm) matches the peak output of the laser dye rhodamine 6G. Thus optical pumping techniques can be readily applied in the laboratory, leading to either a population of ground state atoms in which the spin of the valence electron is oriented either up or down in the laboratory, or a spin polarized pure angular momentum state of the excited 3{sup 2}P{sub 3/2} state. Such an excited state makes possible superelastic scattering, where the internal energy of the atom is transferred to the electron during the collision. This turns out to be a very efficient way to study the inelastic scattering process. Unlike sodium, chromium provides an extremely exacting test for theoretical methods because of its very complex electronic structure, not because it is simple. With a valence configuration consisting of five electrons in a half-filled 3d shell, plus another electron in a 4s shell, this atom provides a test case that can challenge even the simplest approximations.
Date: March 15, 1998
Creator: Kelley, M.H. & McClelland, J.J.
Partner: UNT Libraries Government Documents Department

Study of neutron-proton interaction in the 300--700 MeV energy region. Final progress report, July 1991--August 1994

Description: The experimental program supported by the present grant is a continuation of the work supported under DOE Contract DE-AS05-76ER04449. More detailed discussion of the experimental apparatus and earlier activities can be found in annual reports for that contract and this grant. The primary objective of this program is investigation of the nucleon-nucleon (NN) interaction, in the medium-energy region, in both elastic and inelastic channels.
Date: August 1, 1994
Creator: Northcliffe, L.C. & Hiebert, J.C.
Partner: UNT Libraries Government Documents Department

Piston Wetting in an Optical DISI Engine: Fuel Films, Pool Fires, and Soot Generation

Description: Piston-wetting effects are investigated in an optical direct-injection spark-ignition (DISI) engine. Fuel spray impingement on the piston leads to the formation of fuel films, which are visualized with a laser-induced fluorescence (LIF) imaging technique. Oxygen quenching is found to reduce the fluorescence yield from liquid gasoline. Fuel films that exist during combustion of the premixed charge ignite to create piston-top pool fires. These fires are characterized using direct flame imaging. Soot produced by the pool fires is imaged using laser elastic scattering and is found to persist throughout the exhaust stroke, implying that piston-top pool fires are a likely source of engine-out particulate emissions for DISI engines.
Date: March 5, 2001
Creator: Stevens, Eric & Steeper, Richard
Partner: UNT Libraries Government Documents Department