Search results for "inelastic"
showing 10 items of 700 documents
Magnetic excitations in polyoxometalate tetrameric clusters
1997
Abstract The metal-oxide clusters with formula [M4(D2O)2(PW9O34)2]10− which contain a tetrameric magnetic cluster M4O16 provide an ideal series for the study of magnetic exchange interactions in polymetallic molecular clusters. To get a more direct information on the splitting of the spin states caused by the exchange interactions we have performed inelastic neutron scattering measurements on the Co, Mn and Ni clusters. Magnetic excitations have been observed in the range 0.5–6 meV. A tentative interpretation of these data from a Heisenberg exchange Hamiltonian and a single ion zero-field splitting is presented for Ni cluster.
Flux-flow instability and its anisotropy inBi2Sr2CaCu2O8+δsuperconducting films
1999
We report measurements on voltage instability at high flux-flow velocities in ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\mathrm{\ensuremath{\delta}}}$ superconducting films. Current-voltage $(I\ensuremath{-}V)$ characteristics have been measured as a function of temperature, magnetic field, and angle between the field and the c axis of the sample. Voltage jumps were observed in $I\ensuremath{-}V$ characteristics taken in all magnetic-field directions and in extended temperature and field ranges. An analysis of the experimental data, based on a theory for viscous flux-flow instability with a finite heat-removal rate from the sample, yielded the inelastic scatterin…
Density of Phonon States in Superconducting FeSe as a Function of Temperature and Pressure
2010
The temperature and pressure dependence of the partial density of phonon states (phonon-DOS) of iron atoms in superconducting ${\text{Fe}}_{1.01}\text{Se}$ was studied by $^{57}\text{F}\text{e}$ nuclear inelastic scattering. The high-energy resolution allows for a detailed observation of spectral properties. A sharpening of the optical phonon modes and shift of all spectral features toward higher energies by $\ensuremath{\sim}4\mathrm{%}$ with decreasing temperature from 296 to 10 K was found. However, no detectable change at the tetragonal--orthorhombic phase transition around 100 K was observed. Application of a pressure of 6.7 GPa, connected with an increase in the superconducting temper…
Electromagnetic Processes and Interactions
2011
The electron, the muon, and their neutrinos are important tools in testing the structure of the fundamental electromagnetic and weak interactions. On the other hand, if these interactions are known, they serve as ideal probes for the internal structure of complex hadronic targets such as nucleons and nuclei. Although electroweak interactions should in fact be discussed as a whole and on the same footing, purely electromagnetic interactions play a distinctive role, for obvious experimental reasons: At low and intermediate energies the effective electromagnetic coupling is larger by many orders of magnitude than the weak couplings, so that electromagnetic processes are measurable to much high…
Compton scattering off nucleons near threshold
2008
The energy dependence of the magnetic polarizability β has been evaluated by use of the delta resonance in the s- and u-channel of the Compton scattering amplitude. It was the idea to extract the influence of higher order terms (higher than ω2, ω = |k| being the photon energy) in the analysis of the polarizability. The static paramagnetic polarizability βPara(0) has been substituted by an energy dependent βδPara(k) and the result is compared with experimental data.
New Insight into the Cluster Structure of $^9$Be by Reactions with Deuteron Beam
2018
International audience; Angular distributions of protons, deuterons, tritons, and alpha particles emitted in the reaction 2H+9Be at Elab=19.5, 25, and 35 MeV were measured to study the structure of 9Be, especially to shed light on the internal clusters and possible cluster transfer of 5He. The experiments were performed at sufficiently high energies to ensure suppression of compound nucleus contribution. Thus, the direct reaction mechanism should be mainly responsible for the measured five-nucleon transfer cross section. The analysis suggests a significant contribution of simultaneous five-nucleon transfer in the reaction channel 9Be (d,4He) 7Li.
Elastic constants in RbI, determined by inelastic neutron scattering
1978
Long-wavelength acoustic phonons have been studied in the whole (100)-plane of RbI at 295 K by means of inelastic neutron scattering. The raw data have been corrected for resolution effects taking into account the curvature of the dispersion surface and variations of the mode eigenvectors. The shifts of the neutron groups due to these resolution effects are discussed in detail. The analysis of the experimental results gives for the zero sound elastic constantsc11=28.15±0.5,c12=3.7±0.5 andc44=2.85±0.1 1010 dyn/cm2. A comparison with first sound elastic constants taken from ultrasonic measurements yields significant differences between the high and low frequency elastic constantsc11 andc″=(c1…
Theoretical study of energy transfer in Rb(7S) + Rb(5S) and Rb(5D) + Rb(5S) collisions
2000
We present results of theoretical studies of the non-resonant excitation transfer in Rb(7S) + Rb(5S) and Rb(5D) + Rb(5S) collisions at thermal collision energies. Rb2 adiabatic molecular terms correlating with the 5S+7S, 5S+5D and 5P+5P states of separated atoms were calculated for internuclear distances R > 20 a.u. using asymptotic approximation. Mechanisms of collisional population and quenching of the 5D state were treated on the basis of the computed molecular terms, and the respective cross-sections were calculated. Theoretical cross-sections are in good agreement with the experimental values at thermal collision energies (\(\) K).
Reply to “Comment to ‘Dynamics of supercooled confined water measured by deep inelastic neutron scattering’ by Y. Finkelstein and R. Moreh”
2019
We reply to the comment [Front. Phys. 14(5), 53605 (2019)] by Y. Finkelstein and R. Moreh on our article Front. Phys. 13(1), 138205 (2018). We agree with some of their criticisms about our calculation of the temperature effect on the kinetic energy of hydrogen atoms of supercooled confined water; we also agree with their statement that, in view of the current sensitivity of the technique, possible effects of the liquid-liquid water transition are hardly detected with deep inelastic neutron scattering (DINS). However, we disagree with their use of the translational mass ratio of a single water molecule and, in general, with their underestimation of collective effects.
Small-$x$ Physics in the Dipole Picture at NLO Accuracy
2018
International audience; We review recent progress in NLO calculations for dilute-dense processes in the CGC picture. In particular, we focus here on recent steps in understanding high energy renormalization group evolution (BK/JIMWLK), the total DIS cross section at small x and forward particle production in proton-nucleus collisions at next-to-leading order.