Powerful catalysts may be produced from gas atomized Al–Ni powders. The efficiency of these catalysts depends on the amount of the different phases formed during solidification. The present paper ...reports on the analysis of these transformations by combining experiments and simulations. Firstly, the volume fractions of phases in gas atomized Al–Ni powders are determined for several compositions and size ranges using neutron diffraction analysis. Additionally, solidification paths are simulated with a model previously validated for concurrent dendritic, peritectic and eutectic phase transformations in binary alloys. The measurements demonstrate a strong dependence of phase fractions on particle size, as well as an inversion of trends with composition. The predictions of the model show good agreement with the measurements. Details of the simulations clarify the combined roles of the kinetics of cooling, the solute diffusion in phases as well as the growth kinetics of microstructures. These advanced interpretations should open the way to the production of further optimized catalysts.
Analysis of inelastic neutron scattering data recorded for the rare earth intermetallic compound TmV2Al20 yields a cubic crystal field Hamiltonian with parameters x = −0.63(1) and W = +0.43(1) K ...(Lea, Leask & Wolf notation). This result is supported by a strong electron paramagnetic resonance signal that is consistent with magnetic splitting of the first excited (Γ5(1)) state. Using this crystal field Hamiltonian, single crystal magnetisation and specific heat data are then interpreted in terms of a model that involves partial Al flux substitution of an approximately 10% depleted Tm “cage” site.
•TmV2Al20 is a skutterudite with Tm located at the centre of spacious 16xAl cages.•The TmV2Al20 cage sites are ≈10% Tm depleted with partial Al replacement.•CF for the Tm3+ J = 6 ground state is characterised by x = −0.63 and W = 0.43 K.•Low temperature TmV2Al20 specific heat dominated by “rattling” and CF contributions.
—
SIKA, a new cold neutron triple-axis spectrometer, was built on the CG4 beam port at the OPAL reactor, ANSTO. Here we report the capabilities and current status of SIKA. A versatile instrument, ...SIKA, provides sample environments with temperature capacities from the dilution temperature below 50 mK to the 750 K; magnetic fields of up to 12 T, the well-developed control and analysis software based on SPICE. Several scientific examples demonstrating the proficiency of SIKA are reported, such as: observation of higher harmonics in the helical magnetic phase of MnP as an example of elastic magnetic scattering; measurement of the aluminum phonon dispersion with the estimated slope of the transverse acoustic phonon at 32.4 meV; the spin-wave dispersion in MnF
2
along the
c
axis enabled determination of exchange parameters
J
1
= 0.0305 meV,
J
2
= –0.1534 meV and
D
= 0.1427 meV; and observation of one of the crystal field excitations from Pr
3+
in the PrFeO
3
powder.
L1 track finding for a time multiplexed trigger Cieri, D.; Brooke, J.; Grimes, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
Odprti dostop
At the HL-LHC, proton bunches will cross each other every 25ns, producing an average of 140 pp-collisions per bunch crossing. To operate in such an environment, the CMS experiment will need a L1 ...hardware trigger able to identify interesting events within a latency of 12.5μs. The future L1 trigger will make use also of data coming from the silicon tracker to control the trigger rate. The architecture that will be used in future to process tracker data is still under discussion. One interesting proposal makes use of the Time Multiplexed Trigger concept, already implemented in the CMS calorimeter trigger for the Phase I trigger upgrade. The proposed track finding algorithm is based on the Hough Transform method. The algorithm has been tested using simulated pp-collision data. Results show a very good tracking efficiency. The algorithm will be demonstrated in hardware in the coming months using the MP7, which is a μTCA board with a powerful FPGA capable of handling data rates approaching 1Tb/s.
PDF
