Search results for "Inelastic Scattering"
showing 10 items of 592 documents
Temperature and magnetic field dependent correlations in the singlet ground state system CsFeBr3
1992
The magnetic excitations in CsFeBr3 have been measured with inelastic scattering of cold neutrons to high precision at 80 mK. The fact that the lowest frequency mode softens with decreasing temperature but stabilizes at 0.11 THz below 2.5 K is the indication that CsFeBr3 remains a SGS system forT→0. From dispersion curves measured earlier in a magnetic field along the chain axis experimental intensities were derived and in turn correlation lengths. Correlation lengths were also calculated using the new parameters for exchange and anisotropy. The experimental results and the calculations both show that the correlation lengths increase for increasing magnetic field, flatten off around the pha…
Coherent and incoherent electron transport along a disordered chain
1992
Abstract The Landauer-Buttiker approach is used to describe electron transport along a chain of scatterers which allow elastic as well as inelastic processes. The inelastic scattering takes place via side branches, coupling the chain to electron reservoirs which serve as a heat bath. In this approach, coherent and dissipative transport can be treated in a unified manner, and the suppression of quantum coherence effects for increasing coupling to the heat bath can be described. The influence of disorder on the transmission properties can be characterized by an appropriate coherence length in addition to the decay of the coherence due to dissipation.
Resonant hyper-Raman scattering in semiconductors: Excitonic effects
1999
Abstract A theoretical model of resonant hyper-Raman scattering involving two incident photons of frequency ωL is developed. The model is valid for energies 2ℏωL around the absorption edge of the semiconductor, and takes into account Wannier excitons as intermediate states in the scattering process. Both deformation potential and Frohlich interaction are included in the model: It is found that Frohlich-mediated scattering is a dipole-allowed process, in contrast to one-phonon Raman scattering, where the Frohlich mechanism is dipole-forbidden. We have performed numerical calculations of the resonance profile (hyper-Raman cross-section versus 2ℏωL) and applied our model to materials with dipo…
Spin Dynamics of the Half-Integer-Spin Quasi-One-Dimensional Heisenberg Antiferromagnet CsMnI3
1994
Magnetic excitations of CsMnI 3 , a quasi-one-dimensional Heisenberg antiferromagnet with S =5/2, have been measured by means of inelastic neutron scattering. Magnetic excitations in the low temperature phase are in good agreement with the predictions of the conventional linear spin-wave theory. In particular, in accordance with the linear spin-wave theory, we found three separate modes at Q =(0, 0, 1) instead of a threefold degenerate mode as seen in CsNiCl 3 ( S =1). It confirms that the spin dynamics of the integer spin value system are very different from those of the half-integer spin value system, even in their three-dimensionally ordered phase. Magnetic excitations in the intermediat…
Transmission of electrons through ferromagnetic material and applications to detection of electron spin polarization
1993
The salient features of the total low energy inelastic electron scattering cross section in transition metals are described by a constant term σ 0 plus a term σ d that is proportional to the number of unoccupied d-orbitals. This simple model predicts that low energy electrons transmitted through a ferromagnetic ultrathin film acquire a transport spin polarization a(x). Using the ratio σ 0 /σ d as the only adjustable parameter, the model predicts the enhancement of the spin polarization of the low energy cascade electrons as well as a(x) in reasonable agreement with the existing observations on Fe, Co and Ni. A detector for electron spin polarization P based on the spin dependent transmissio…
Spatial fluctuations of the chemical potential in case of nearly coherent transport along an ordered chain
1991
The Landauer-Buttiker approach is used to describe electron transport along a chain of scatterers which allow elastic as well as inelastic processes. The inelastic scattering takes place via side branches coupling the chain to electron reservoirs which serve as a heat bath. For small inelastic coupling of the scatterers to the heat bath strong interference effects lead to spatial fluctuations of the charge density. The corresponding oscillations of the chemical potential are discussed in view of phase-sensitive experiments measuring the four-probe resistance.
A study of coupled-reaction channel effects in the36S +37Cl system, hybridization between single particle orbits
1996
Elastic and inelastic scattering as well as transfer transitions involving a valence proton in thesd- andfp- shell orbits are studied in the interaction of37Cl +36S at ECM=50 MeV. Experimental angular distributions of single particle states of37Cl (elastic and inelastic transfer) are presented with a CRC analysis. In the CRC calculations the effects of inelastic and transfer couplings are studied using known spectroscopic information. In the CRC analysis six single particle bound states and the collective 2+ excitation of36S are included in the coupling scheme. Higher order coupling effects are found to be important. A distinct effect, the mixing of single particle states (of different pari…
Solving the Balitsky-Kovchegov equation at next to leading order accuracy
2016
We solve the Balitsky-Kovchegov small-x evolution equation in coordinate space. We find that the solution to the equation is unstable when using an initial condition relevant for phenomenological applications at leading order. The problematic behavior is shown to be due to a large double logarithmic contribution. The same problem is found when the evolution of the “conformal dipole” is solved, even though the double logarithmic term is then absent from the evolution equation.
The spin-dependent structure function g1(x) of the deuteron from polarized deep-inelastic muon scattering
1997
We present a new measurement of the spin-dependent structure function $g_{1}^{\rm d}$ of the deuteron from deep inelastic scattering of 190 GeV polarized muons on polarized deuterons. The results are combined with our previous measurements of $g_{1}^{\rm d}$. A perturbative QCD evolution in next-to-leading order is used to compute $g_{1}^{\rm d}(x)$ at a constant $Q^{2}$. At $Q^{2} = 10$ GeV$^{2}$, we obtain a first moment $\Gamma_{1}^{\rm d} = \int_{0}^{1} g_{1}^{\rm d}{\rm d}x = 0.041 \pm 0.008$, a flavour-singlet axial charge of the nucleon $a_{0} = 0.30 \pm 0.08$, and an axial charge of the strange quark $a_{s} = -0.09 \pm 0.03$. Using our earlier determination of $\Gamma_{1}^{\rm p}$, …
dc transport in dissipative disordered one-dimensional systems
1995
We present a numerical study of the dc transport properties of dissipative disordered chains which are described by linear ensembles of interconnected scatterers. The elastic-scattering amplitudes are derived from an Anderson Hamiltonian with diagonal (site) disorder. Inelastic scattering is accounted for by connecting the sites of the Anderson chain to separate external electron reservoirs. The calculated wave-vector-dependent transmission probabilities are discussed for chains with different lengths and for different degrees of dissipation. Using the Landauer-B\"uttiker approach we obtain the dc resistance of the considered samples. Our results demonstrate the rather intricate competition…