1,721,108 research outputs found
Si(lll)/Gd: A fast and high-resolution thermal neutron detector
No full textRecent developments in design and production of thermal neutron detectors based on a crystalline Si diode coupled to a Gd converter are reviewed. The most significant results of neutron test measurements carried out on prototype systems and pointing out the performances of the device are reported. Progress through various detection schemes and technological solutions for the production of a real time neutron counter for routine operation are outlined
A simple model of local density approximation in nonconducting systems. Application to argon and silicon
No full textA new simple model within the local density approximation (LDA) is presented for the exchange potential in systems with an energy gap in their excitation spectrum. APW band structure calculations are performed for silicon and argon and the width of the fundamental gaps is evaluated, employing the so-developed local-exchange-only potential. The results are compared with those obtained by using in the calculation the standard LDA and the exchange-only potential of Levine and Louie. A better qualitative agreement with the experiment is found by employing the presently proposed exchange potential in comparison with the other potentials we considered
Possibility of electron-neutron emission spectroscopy
No full textThe possibility of exciting electrons in crystalline solids by means of energetic neutrons is examined. As expected, the electron-neutron emission is not competitive with respect to familiar photoemission; however, it could be useful in studying special cases, like (for instance) the indirect gap of nonconducting systems
Spin-dependent correlations in electron liquids: Feasibility of magnetic x-ray scattering experiment
No full textThe inelastic magnetic X-ray scattering is analysed and discussed in terms of spin-dependent electron-electron correlation functions. The relevance of the correlation functions is also discussed and the possibility of an experimental determination of the spin-dependent correlations by means of X-ray magnetic scattering is investigated
Temperature dependence of spin density in FeCo alloy: Magnetic response function
No full textThe magnetic structure factor of the equiatomic FeCo alloy has been measured in the disordered phase at 1000K by polarized neutron diffraction. A comparison with the data collected in the ordered phase at room temperature [E. Di Fabrizio et al., Phys. Rev. B40, 9502 (1989) shows marked variations that can be ascribed to the thermal motion of nuclei. From the complete set of data vs temperature, the experimental ion-electron linear response function has been deduced and compared to a theoretical Random Phase Approximation model
Electron-gas self-energy at metallic density
No full textThe self-energy of the uniform electron gas is analyzed within the lowest order in the screened potential, using different approximations for the dielectric function. The present numerical analysis reveals that a rather simple approximation for the dielectric function can be used to derive a good estimate for the self-energy
Neutron excitation of bulk luminescence
No full textThe possibility of producing luminescence by using high-energy neutrons in a doped semiconductor is investigated. It is found that the analysis of the luminescence spectrum could allow for a measure of the spectral function of the excited electron within the bulk of the sample
High-temperature spin density of FeCo: effect of lattice vibrations on the electron distribution
No full textThe magnetic structure factor of equi-atomic FeCo in the disordered phase has been measured at 1000 K by coherent scattering of polarized neutrons. The overall shape of the magnetization distribution exhibits marked variations when compared with the room-temperature distribution. The analysis of the spin density asphericity shows that such an effect cannot be ascribed to a change in the electron distribution in the disordered phase, whereas a correct treatment of the thermal motion of nuclei, inducing a deformation of the electron distribution, takes into account the observed behaviour
Calculated dispersion and lifetime of one-electron states in copper
No full textThe effect of the electron-electron self-energy on the single-particle states lying above the chemical potential is calculated in copper, within the slowly-varying-density approximation. The general trend is found to be in agreement with the available experimental data, though the magnitude of the lifetime broadening appears to be smaller than that deduced from a photoemission experiment
Electron-electron correlations in diamond: An x-ray-scattering experiment
No full textThe inelastic-scattering cross section integrated over the energy has been measured in diamond from an x-ray-scattering experiment. The static structure factor and the exchange and correlation energy of the electrons in diamond have been determined. From the static structure factor, the electron-electron pair correlation function has been deduced. Comparisons have been carried out with both recent quantum Monte Carlo calculations in diamond and calculations for the jellium model
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