arXiv subjects

Bruno Lepetit

Publications and source records attributed to Bruno Lepetit.

4 recordsLinked to original sources

arXiv2014

Field emission from metal surfaces in the Thomas-Fermi-von-Weizsäcker model

We evaluate the electron emission current density from jellium metallic surfaces in the Thomas-Fermi-von-Weizsäcker approximation. We implement the weighted density approximation (WDA) for description of the exchange and correlation energy of interacting electrons. We find the emission mechanism exhibits crossover from quantum to classical over-barrier escape of electrons from the surface. Well below a surface-specific threshold field strength $E_d$, electron tunneling is mainly affected by the change of the metal workfunction, and is less sensitive to the detailed shape of the surface barrier. In particular, since the position of the image charge plane for electrons leaving the surface does not precisely coincide with the centroid of the induced screening charge at the surface in response to the applied electric field, we find an effective increase in the metal workfunction by $ΔW \sim 0.01$ eV, which decreases the dark current.

cond-mat.mtrl-sci↗

arXiv2006

Hyperspherical elliptic coordinates treatment of muon transfer from muonic hydrogen to atomic oxygen

Quantum-mechanical calculations of muon transfer between muonic hydrogen and an oxygen nuclei for $s$ waves and collision energies in the range $10^{-3} - 10^3$ eV, are presented. Close-coupling time-independent Schrödinger equations, written in terms of hyperspherical elliptic coordinates were integrated along the hyper-radius to obtain the partial and total muon-transfer probabilities. The results show the expected Wigner-Bethe threshold behavior up to collision energies of the order of $10^{-2}$ eV and pronounced maxima at $10^2$ eV which can be interpreted in terms of crossings between potential energy curves corresponding to the entrance channel state $(μp)_{1s} + \mO$ and two product channels which asymptotically correlate to $p + (\mOμ)_{n=5,6}$. The population of the final states with different orbital angular momenta is found to be essentially independent of energy in the range considered in this work. This can be attributed to a strong selection rule for the conservation of the quantum number associated to one of the elliptic hyperangles.

quant-ph↗

arXiv2003

Proton Zemach radius from measurements of the hyperfine splitting of hydrogen and muonic hydrogen

While measurements of the hyperfine structure of hydrogen-like atoms are traditionally regarded as test of bound-state QED, we assume that theoretical QED predictions are accurate and discuss the information about the electromagnetic structure of protons that could be extracted from the experimental values of the ground state hyperfine splitting in hydrogen and muonic hydrogen. Using recent theoretical results on the proton polarizability effects and the experimental hydrogen hyperfine splitting we obtain for the Zemach radius of the proton the value 1.040(16) fm. We compare it to the various theoretical estimates the uncertainty of which is shown to be larger that 0.016 fm. This point of view gives quite convincing arguments in support of projects to measure the hyperfine splitting of muonic hydrogen.

quant-ph↗

arXiv2003

Muon transfer from muonic hydrogen to atomic oxygen

The muon transfer probabilities between muonic hydrogen and an oxygen atom are calculated in a constrained geometry one dimensional model for collision between 10^-6 and 10^3 eV. These estimated rates are discussed in the light of previous model calculations and available experimental data for this process.

quant-ph↗