Engineering Papers⌕ Search

Engineering topics

Prieto, P.

Publications and source records attributed to Prieto, P..

12 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

In-situ study of the carbon gasification reaction of highly oriented pyrolytic graphite promoted by cobalt oxides and the novel nanostructures appeared after reaction

Cobalt interaction and its effects on carbon-based systems at the nanoscale have recently attracted much attention in different fields, such as catalysis of carbon nanotubes or graphene and graphite nano-patterning taking advantage of its ferromagnetic behavior. Experiments performed in our laboratories show how the re-oxidation process of two equivalent monolayers of CoO deposited on highly oriented pyrolytic graphite at 400 °C leads to the formation of nanochannels at lower temperature than using other methods. Here we present the in-situ characterization of the carbon gasification reaction that drives this process by means of near ambient pressure X-ray photoelectron spectroscopy performed at the ALBA synchrotron facility. The reason why this reaction takes place at such low temperature compared to other methods is due to the weakening of the carbon σ bonds by the initial CoO wetting layer formed at the early stages of growth on the graphite surface. Besides nanochannels, ex-situ atomic force microscopy measurements also show the appearance of two more kinds of nanostructures: nano-strips and nano-rings. The appearance of these nanostructures reveals the impressive modification of the surface after the re-oxidation process mediated by the cobalt oxide.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Thermal Transport Measurements of LaCoO{sub 3} and SrTiO{sub 3}

Thermal conductivity and thermopower measurements as functions of temperature were carried out on SrTiO{sub 3} single crystals below room temperature and compared to those obtained for LaCoO{sub 3} polycrystalline samples. The maximum value of thermal conductivity for SrTiO{sub 3} (110) and Nb-doped SrTiO{sub 3} single crystals was 1.09 and 0.91 W/mK, respectively, at 300 K. The thermopower measurements were − 5.47 and − 41.17 μ V/K, respectively, at 300 K. This indicates the predominance of negative charge carriers or electrons in the material. Measurements on LaCoO{sub 3} polycrystalline samples yielded maximum values of 0.37 W/mK and 620 μ V/K for thermal conductivity and thermopower, respectively. These positive values suggest that positive charge carriers are predominant or that the compound is slightly hole-doped. We studied the effect of Nb doping on the thermopower and thermal conductivity of SrTiO{sub 3} and contrasted the results obtained with similar measurements on LaCoO{sub 3}.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Diagnostics Upgrades for Investigations of HOM Effects in TESLA-type SCRF Cavities

We describe the upgrades to diagnostic capabilities on the Fermilab Accelerator Science and Technology (FAST) electron linear accelerator that will allow investigations of the effects of high-order modes (HOMs) in SCRF cavities on macropulse-average beam quality. We examine the dipole modes in the first pass-band generally observed in the 1.6-1.9 GHz regime for TESLA-type SCRF cavities due to uniform transverse beam offsets of the electron beam. Such cavities are the basis of the accelerators such as the European XFEL and the proposed MaRIE XFEL facility. Preliminary HOM detector data, prototype BPM test data, and first framing camera OTR data with ~20- micron spatial resolution at 250 pC per bunch will be presented.

Lumpkin, A. H.↗
DOE OSTI2017

Commissioning and First Results of the Electron Beam Profiler in the Main Injector at Fermilab

The planned neutrino program at Fermilab requires large proton beam intensities in excess of 2 MW. Measuring the transverse profiles of these high intensity beams is challenging and often depends on non-invasive techniques. One such technique involves measuring the deflection of a probe beam of electrons with a trajectory perpendicular to the proton beam. A device such as this is already in use at the Spallation Neutron Source at ORNL and a similar device has been installed in the Main Injector at Fermilab. Commissioning of the device is in progress with the goal of having it operational by the end of the year. The status of the commissioning and initial results will be presented

Thurman-Keup, R.↗
DOE OSTI2015

Installation Status of the Electron Beam Profiler for the Fermilab Main Injector

The planned neutrino program at Fermilab requires large proton beam intensities in excess of 2 MW. Measuring the transverse profiles of these high intensity beams is challenging and often depends on non-invasive techniques. One such technique involves measuring the deflection of a probe beam of electrons with a trajectory perpendicular to the proton beam. A device such as this is already in use at the Spallation Neutron Source at ORNL and the installation of a similar device is underway in the Main Injector at Fermilab. The present installation status of the electron beam profiler for the Main Injector will be discussed together with some simulations and test stand results.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Operation of an ungated diamond field-emission array cathode in a L-band radiofrequency electron source

We report on the operation of a field-emitter-array cathode in a conventional L-band radio-frequency electron source. The cathode consisted of an array of ∼10{sup 6} diamond tips on pyramids. Maximum current on the order of 15 mA was reached and the cathode did not show appreciable signs of fatigue after weeks of operation. The measured Fowler-Nordheim characteristics, transverse beam density, and current stability are discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Electron Beam Profiler for the Fermilab Main Injector

The long range plan for Fermilab calls for large proton beam intensities in excess of 2 MW for use in the neutrino program. Measuring the transverse profiles of these high intensity beams is challenging and generally relies on non-invasive techniques. One such technique involves measuring the deflection of a beam of electrons with a trajectory perpendicular to the proton beam. A device such as this is already in use at the Spallation Neutron Source at ORNL and a similar device will be installed shortly in the Fermilab Main Injector. The Main Injector device is discussed in detail and some test results and simulations are shown

Thurman-Keup, R.↗
DOE OSTI2012

Mu2e Conceptual Design Report

Mu2e at Fermilab will search for charged lepton flavor violation via the coherent conversion process mu- N --> e- N with a sensitivity approximately four orders of magnitude better than the current world's best limits for this process. The experiment's sensitivity offers discovery potential over a wide array of new physics models and probes mass scales well beyond the reach of the LHC. We describe herein the conceptual design of the proposed Mu2e experiment. This document was created in partial fulfillment of the requirements necessary to obtain DOE CD-1 approval, which was granted July 11, 2012.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗