Integrating science & policy to promote agroforestry in practice - A nature conservation perspective

Presentatio

Studies of superconducting materials with muon spin rotation

The muon spin rotation/relaxation technique was found to be an exceptionally effective means of measuring the magnetic properties of superconductors, including the new high temperature superconductor materials, at the microscopic level. The technique directly measures the magnetic penetration depth (type II superconductors (SC's)) and detects the presence of magnetic ordering (antiferromagnetism or spin-glass ordering were observed in some high temperature superconductor (HTSC's) and in many closely related compounds). Extensive studies of HTSC materials were conducted by the Virginia State University - College of William and Mary - Columbia University collaboration at Brookhaven National Laboratory and TRIUMF (Vancouver). A survey of LaSrCuO and YBaCaCuO systems shows an essentially linear relationship between the transition temperature T(sub c) and the relaxation rate. This appears to be a manifestation of the proportionality between T(sub c) and the Fermi energy, which suggests a high energy scale for the SC coupling, and which is not consistent with the weak coupling of phonon-mediated SC. Studies of LaCuO and YBaCuO parent compounds show clear evidence of antiferromagnetism. YBa2Cu(3-x)CO(x)O7 shows the simultaneous presence of spin-glass magnetic ordering and superconductivity. Three-dimensional SC, (Ba, K) BiO3, unlike the layered CuO-based compounds, shows no suggestion of magnetic ordering. Experimental techniques and theoretical implications are discussed

Electron-Electron Interactions in Transfer and Excitation in F⁸⁺ →₂ Collisions

We have measured projectile Auger electrons emitted after collisions of H-like F with H2. The cross sections for emission of KLL, KLM, KLN, and KLO Auger electrons show maxima as a function of the projectile energy. One maximum in the KLL emission cross section is due to resonant transfer and excitation. A second maximum in the cross section for KLL emission as well as the maxima in the emission cross section for the higher-n Auger electrons are attributed to a new transfer and excitation process. This involves excitation of a projectile electron by one target electron accompanied by the capture of a second target electron

Projectile Energy Loss in Multiply Ionizing Ion-Atom Collisions

The projectile energy loss for 7.5--25-MeV C6+,5+ and F6+ ions was measured for single collisions with He, Ne, Ar, and Kr as a function of the recoil-ion charge state and the projectile scattering. This energy loss was measured for collisions in which the projectile captured an electron and for those involving just direct ionization. We investigated and found a large average energy transfer (100--250 eV/electron) to the continuum electrons. A strong increase of the scattering angle with recoil-ion charge state was observed for both capture and direct ionization. The results imply that, for smaller impact parameters, higher recoil-ion charge states are produced and that higher energy losses are obtained. We observed a weak target-Z dependence of the energy loss. The results are compared with n-body classical-trajectory Monte Carlo calculations by Olson, semiclassical-approximation calculations by Schuch et al. [Nucl. Instrum. Methods Phys. Res. Sect. B 42, 566 (1989)], and the energy-deposition model

Angular Distribution of Auger Electrons Emitted through the Resonant Transfer and Excitation Process Following O⁵⁺+He Collisions

This Letter reports the first measurements of the angular distribution of Auger electrons emitted from the decay of the (1s2s2p2)3D O4+** doubly excited state formed predominantly through resonant transfer and excitation (RTE) in collisions of 13-MeV O5+ projectiles with He. The (1s2s2p2)3D angular distribution is strongly peaked along the beam direction, in agreement with recent calculations of the RTE angle-dependent impulse approximation. Furthermore, interference effects between the RTE and the elastic target direct-ionization channels are observed

Population of Highly Excited Intermediate Resonance States by Electron Transfer and Excitation

Coincidences between two sulfur K x rays were detected from collisions of hydrogenlike S ions with H2 gas in the projectile energy range between 150 and 225 MeV. These K x rays are emitted in the decay of doubly excited states formed in the collisions via transfer and excitation. The excitation function for two coincident Kβ transitions peaks at about 175 MeV, slightly above the expected KMM resonance energy for resonant transfer and excitation (RTE). This demonstrates the occurrence of ΔN≥2 transitions (i.e., KMM and higher resonances) in the RTE process. The cross sections for the population of the very highly excited states are higher than those predicted by theoretical calculations that use dielectronic recombination rates folded with the Compton profile for the bound electrons

The TInnGO Observatory and the DIAMOND toolbox:self-assessment for service operators on fairness and inclusivity.

This paper summarises the contributions of both projects towards bring the community together, as presented in Session IX of the final conference/TDM Symposium 2021. This session featured a series of presentations from both projects on the steps and outputs that together contribute to the legacy ofSession X: Bringing the community together our projects. Both projects addressed the challenge outlined in the call MG-4-3-2018: Demographic change and participation of women in transport. Through our work we have understood the challenges and barriers to creating a fairer transport system. Here we present practical contributions, tools and strategies which can be built on by other researcher

Double Excitation of He by Fast Ions

Autoionization of He atoms following double excitation by electrons, protons, CQ+ (Q=4-6), and FQ+ (Q=7-9) ions has been studied. The electron-emission yields from the doubly excited 2s2(1S), 2s2p(1P), and 2p2(1P) states were measured at the reduced projectile energy of 1.5 MeV/nucleon for observation angles between 10°and 60°. The results indicate excitation to the 2s2(1S) and 2p2(1D) states increases as approximately Q3, while excitation to the 2s2p(1P) state varies as approximately Q2, where Q is the charge of the projectile. These charge dependences are significantly less than the Q4 dependence expected in the independent-electron model, suggesting the interaction between the two target electrons is important in creating the doubly excited states

Resonant Dielectronic and Direct Excitation in Crystal Channels

We have observed dielectronic and direct excitation of H-like S15+ and Ca19+ and He-like Ti20+ ions in silicon channels caused by collision with weakly bound target electrons which behave as a free-electron gas. As in vacuo, relaxation of the doubly excited states can occur radiatively leading to ions of decreased charge, but in a crystal channel collisional effects can cause double ionization. The effects are seen in both the x-ray yields and charge-state fractions, and, in the case of Ti20+, in charge-state x-ray coincidences

Anomalous Quasiparticle Lifetime in Graphite: Band Structure Effects

We report ab initio calculation of quasiparticle lifetimes in graphite, as determined from the imaginary part of the self-energy operator within the GW aproximation. The inverse lifetime in the energy range from 0.5 to 3.5 eV above the Fermi level presents significant deviations from the quadratic behavior naively expected from Fermi liquid theory. The deviations are explained in terms of the unique features of the band structure of this material. We also discuss the experimental results from different groups and make some predictions for future experiments.Comment: 4 pages, 4 figures, submitted PR