5,343 research outputs found
Performance Characterization of a Solenoid-type Gas Valve for the Magnetron Source at FNAL
The magnetron-style ion sources currently in operation at Fermilab
use piezoelectric gas valves to function. This kind of gas valve is sensitive
to small changes in ambient temperature, which affect the stability and
performance of the ion source. This motivates the need to find an alternative
way of feeding H2 gas into the source. A solenoid-type gas valve has been
characterized in a dedicated off-line test stand to assess the feasibility of
its use in the operational ion sources. ion beams have been extracted
at 35 keV using this valve. In this study, the performance of the solenoid gas
valve has been characterized measuring the beam current output of the magnetron
source with respect to the voltage and pulse width of the signal applied to the
gas valve.Comment: 4 pp. arXiv admin note: text overlap with arXiv:1701.0175
Implementation of Design Changes Towards a More Reliable, Hands-off Magnetron Ion Source
As the main ion source for the accelerator complex, magnetron ion
sources have been used at Fermilab since the 1970s. At the offline test stand,
new R&D is carried out to develop and upgrade the present magnetron-type
sources of ions of up to 80 mA and 35 keV beam energy in the context of
the Proton Improvement Plan. The aim of this plan is to provide high-power
proton beams for the experiments at FNAL. In order to reduce the amount of
tuning and monitoring of these ion sources, a new electronic system consisting
of a current-regulated arc discharge modulator allow the ion source to run at a
constant arc current for improved beam output and operation. A solenoid-type
gas valve feeds gas into the source precisely and independently of
ambient temperature. This summary will cover several studies and design changes
that have been tested and will eventually be implemented on the operational
magnetron sources at Fermilab. Innovative results for this type of ion source
include cathode geometries, solenoid gas valves, current controlled arc pulser,
cesium boiler redesign, gas mixtures of hydrogen and nitrogen, and duty factor
reduction, with the aim to improve source lifetime, stability, and reducing the
amount of tuning needed. In this summary, I will highlight the advances made in
ion sources at Fermilab and will outline the directions of the continuing R&D
effort.Comment: 4 pp. arXiv admin note: substantial text overlap with
arXiv:1701.0175
Improvements on the Stability and Operation of a Magnetron H- Ion Source
The magnetron H- ion sources developed in the 1970s currently in operation at
Fermilab provide beam to the rest of the accelerator complex. A series of
modifications to these sources have been tested in a dedicated offline test
stand with the aim of improving different operational issues. The solenoid type
gas valve was tested as an alternative to the piezoelectric gas valve in order
to avoid its temperature dependence. A new cesium oven was designed and tested
in order to avoid glass pieces that were present with the previous oven,
improve thermal insulation and fine tune its temperature. A current-regulated
arc modulator was developed to run the ion source at a constant arc current,
providing very stable beam outputs during operations. In order to reduce beam
noise, the addition of small amounts of N2 gas was explored, as well as testing
different cathode shapes with increasing plasma volume. This paper summarizes
the studies and modifications done in the source over the last three years with
the aim of improving its stability, reliability and overall performance.Comment: 8 pages, 19 figure
Experimental study of optimal measurements for quantum state tomography
Quantum tomography is a critically important tool to evaluate quantum
hardware, making it essential to develop optimized measurement strategies that
are both accurate and efficient. We compare a variety of strategies using
nearly pure test states. Those that are informationally complete for all states
are found to be accurate and reliable even in the presence of errors in the
measurements themselves, while those designed to be complete only for pure
states are far more efficient but highly sensitive to such errors. Our results
highlight the unavoidable tradeoffs inherent to quantum tomography.Comment: 5 pages, 3 figure
Quantum state tomography by continuous measurement and compressed sensing
The need to perform quantum state tomography on ever larger systems has
spurred a search for methods that yield good estimates from incomplete data. We
study the performance of compressed sensing (CS) and least squares (LS)
estimators in a fast protocol based on continuous measurement on an ensemble of
cesium atomic spins. Both efficiently reconstruct nearly pure states in the
16-dimensional ground manifold, reaching average fidelities FCS = 0.92 and FLS
= 0.88 using similar amounts of incomplete data. Surprisingly, the main
advantage of CS in our protocol is an increased robustness to experimental
imperfections
Recent Operation of the FNAL Magnetron Ion Source
This paper will detail changes in the operational paradigm of the Fermi
National Accelerator Laboratory (FNAL) magnetron ion source due to
upgrades in the accelerator system. Prior to November of 2012 the ions
for High Energy Physics (HEP) experiments were extracted at ~18 keV vertically
downward into a 90 degree bending magnet and accelerated through a
Cockcroft-Walton accelerating column to 750 keV. Following the upgrade in the
fall of 2012 the ions are now directly extracted from a magnetron at 35
keV and accelerated to 750 keV by a Radio Frequency Quadrupole (RFQ). This
change in extraction energy as well as the orientation of the ion source
required not only a redesign of the ion source, but an updated understanding of
its operation at these new values. Discussed in detail are the changes to the
ion source timing, arc discharge current, hydrogen gas pressure, and cesium
delivery system that were needed to maintain consistent operation at >99%
uptime for HEP, with an increased ion source lifetime of over 9 months.Comment: 8 p
Effect of botulinum neurotoxins from Mendoza of clostridium botulinum strains on cytoskeletal proteins of mammary tumor cells
The botulinum neurotoxin serotype A (BoNT A) produced by Clostridium botulinum, which causes botulism, is used for the treatment of multiple neurological diseases and its therapeutic action against cancer is currently being evaluated. In previous studies, we have shown that BoNT A from autochthonous soil strains (Su) have different properties than the reference A Hall strain. Among these, its molecular structure, its enzymatic activity against brain SNARE proteins and its greater specific toxic activity (AE) stand out. In cells from human mammary carcinoma (MCF-7) treated with BoNTs for 45 min, we found a marked effect on the expression of cytoskeletal proteins. Therefore, in this work, we delve into the study of the action of autochthonous BoNTs A and prototype A Hall on the distribution of actin and tubulin in these cells. Native forms of autochthonous BoNT (Su strains 1935 and 1891, Tupungato) and prototype A Hall were purified by saline precipitation. Their AE values (LD50 / mg protein) were established and their electrophoretic characteristics were evaluated under non-denaturing conditions. 250 LD50 of the BoNTs were incubated to MCF-7 cell cultures for 10 or 25 min. Later, the cells were fixed and processed for indirect immunofluorescence with the use of specific antibodies that recognize tubulin or actin. The samples were visualized by fluorescence microscopy. At the two times evaluated, the three types of BoNTs produced a marked redistribution of the actin cytoskeleton, patch form, on areas coinciding with the plasma membrane. Tubulin was redistributed to multiple areas with high signal density at 10 min of incubation only in the presence of BoNT 1891. At 25 min of incubation, the cells treated with BoNTs 1891 and 1935 showed this effect, while in those incubated with A Hall, the distribution of these proteins was not modified. The notable alterations in the distribution of components of the tumor cell cytoskeleton by BoNT from native strains of Mendoza soils open new perspectives for therapy against solid tumors.Fil: Chapana, Agostina Lucía. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Guarniolo, D.. Universidad Nacional de Cuyo. Facultad de Cs.médicas. Departamento de Patología. Area de Microbiología; ArgentinaFil: Carvelli, Flavia Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Sosa, E.. Universidad Nacional de Cuyo. Facultad de Cs.médicas. Departamento de Patología. Area de Microbiología; ArgentinaFil: Fernández, R. A.. Universidad Nacional de Cuyo. Facultad de Cs.médicas. Departamento de Patología. Area de Microbiología; ArgentinaFil: Sosa, M. A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Caballero, P. A.. Universidad Nacional de Cuyo. Facultad de Cs.médicas. Departamento de Patología. Area de Microbiología; ArgentinaIV Reunión Conjunta de Sociedades de Biología de la República ArgentinaArgentinaSociedad de Biología de CuyoSociedad Argentina de BiologíaSociedad de Biología de RosarioSociedad Chilena de Reproducción y DesarrolloAsociación de Biología de TucumánSociedad de Biología de Córdob
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