Browsing by Author "Fearick, R W"

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    From the Langevin model to the diffusion model of axial channeling
    (Elsevier, 2003) Fearick, R W
    The Langevin model provides a description of axial channeling that is intermediate between a full Monte Carlo treatment and that of a statistical equilibrium treatment. Quantities are readily interpreted in terms of useful variables such as the transverse energy. We show that with appropriate averaging, the usual diffusion model of dechanneling is recovered from the Langevin description. This places the Langevin model more firmly in context.
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    Low-energy magnetic dipole response in 56Fe from high-resolution electron scattering
    (2003) Fearick, R W; Hartung, G; Langanke, K; Martínez-Pinedo, G; Von Neumann-Cosel, P; Richter, A
    The 56Fe(e, e ) reaction has been studied for excitation energies up to about 8 MeV and momentum transfers q 0.4–0.55 fm−1 at the Darmstadt electron linear accelerator (DALINAC) with kinematics emphasizing M1 transitions. Additional data have been taken for q 0.8– 1.7 fm−1 at the electron accelerator NIKHEF, Amsterdam. A PWBA analysis allows spin and parity determination of the excited states. For M1 excitations, transition strengths are derived with a DWBA analysis using shell-model form factors. The resulting B(M1) strength distribution is compared to shell-model calculations employing different effective interactions. The form factor of the prominent low-lying M1 transition at 3.449 MeV demonstrates its dominant orbital nature. It represents a major part of the scissors mode in 56Fe.