192 research outputs found
Estudio no destructivo del interior de piezas de valor histórico mediante gammagrafías
La tecnología de Tomografía de Hormigón Armado desarrollada por THASA ha sido aplicada al estudio de piezas ornamentales y otras de valor histórico con el objeto de examinar el interior de las mismas e investigar, en algunos casos, la existencia, configuración y condición de refuerzos metálicos y en otro caso, la existencia de huecos producidos por termitas en vigas de madera. En este trabajo se discuten detalles metodológicos y resultados alcanzados en los casos de las estatuas ubicadas en el coronamiento del Palacio de Tribunales en la Ciudad Autónoma de Buenos Aires, en dragones colgantes de las torres de la Basílica de Luján y en las vigas del techo de la Capilla Doméstica, construida en 1660 y declarada patrimonio de la humanidad por la UNESCO, ubicada en la manzana jesuítica en la Ciudad de Córdoba. El carácter pionero de la investigación de oquedades en madera realizada en este último caso hizo necesario la construcción de modelos de simulación que resultan de utilidad para otras aplicaciones similares
Fast readout algorithm for cylindrical beam position monitors providing good accuracy for particle bunches with large offsets
A simple, analytically correct algorithm is developed for calculating pencil
beam coordinates using the signals from an ideal cylindrical particle beam
position monitor (BPM) with four pickup electrodes (PUEs) of infinitesimal
widths. The algorithm is then applied to simulations of realistic BPMs with
finite width PUEs. Surprisingly small deviations are found. Simple empirically
determined correction terms reduce the deviations even further. The algorithm
is then used to study the impact of beam-size upon the precision of BPMs in the
non-linear region. As an example of the data acquisition speed advantage, a
FPGA-based BPM readout implementation of the new algorithm has been developed
and characterized. Finally,the algorithm is tested with BPM data from the
Cornell Preinjector.Comment: 21 pages, 17 figure
High energy Coulomb-scattered electrons for relativistic particle beam diagnostics
A new system used for monitoring energetic Coulomb-scattered electrons as the
main diagnostic for accurately aligning the electron and ion beams in the new
Relativistic Heavy Ion Collider (RHIC) electron lenses is described in detail.
The theory of electron scattering from relativistic ions is developed and
applied to the design and implementation of the system used to achieve and
maintain the alignment. Commissioning with gold and 3He beams is then described
as well as the successful utilization of the new system during the 2015 RHIC
polarized proton run. Systematic errors of the new method are then estimated.
Finally, some possible future applications of Coulomb-scattered electrons for
beam diagnostics are briefly discussed.Comment: 16 pages, 23 figure
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Interpretation of desorption measurements for high energy beams at RHIC
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Higher order mode damper for low energy RHIC electron cooler SRF booster cavity
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon,
the Low Energy RHIC electron Cooler (LEReC) is currently under commissioning at
BNL. The Linac of LEReC is designed to deliver a 1.6 MeV to 2.6 MeV electron
beam, with rms dp/p less than 5e-4. A 704 MHz superconducting radio frequency
(SRF) booster cavity in this Linac provides up to 2.2 MeV accelerating voltage.
With such a low energy and very demanding energy spread requirement, control of
Higher Order Modes (HOMs) in the cavities becomes critical and needs to be
carefully evaluated to ensure minimum impact on the beam. In this paper, we
report the multiphysics design of the HOM damper for this cavity to meet the
energy spread requirement, as well as experimental results of the cavity with
and without the HOM damper.Comment: 9 pages, 7 figure
Laboratory Measurement of Volatile Ice Vapor Pressures with a Quartz Crystal Microbalance
Nitrogen, carbon monoxide, and methane are key materials in the far outer
Solar System where their high volatility enables them to sublimate, potentially
driving activity at very low temperatures. Knowledge of their vapor pressures
and latent heats of sublimation at relevant temperatures is needed to model the
processes involved. We describe a method for using a quartz crystal
microbalance to measure the sublimation flux of these volatile ices in the free
molecular flow regime, accounting for the simultaneous sublimation from and
condensation onto the quartz crystal to derive vapor pressures and latent heats
of sublimation. We find vapor pressures to be somewhat lower than previous
estimates in literature, with carbon monoxide being the most discrepant of the
three species, almost an order of magnitude lower than had been thought. These
results have important implications across a variety of astrophysical and
planetary environments
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