In the framework of the gravitational behaviour of antihydrogen at rest (GBAR) experiment, cross sections for the successive formation of Hlogical and, bar above and Hlogical and, bar above super(+) ...from collisions between positronium (Ps) and antiprotons ( plogical and, bar above) have been computed in the range 0-30 keV plogical and, bar above energy, using the continuum distorted wavefinal state theoretical model in its three-body and four-body formulations. The effect of the electronic correlations in Hlogical and, bar above super(+) on the total cross sections of Hlogical and, bar above super(+) production has been studied using three different wave functions for H super(-) (the matter equivalent of Hlogical and, bar above super(+)). Ps excited states up to n sub(p) = 3, as well as Hlogical and, bar above excited states up to n sub(h) = 4, have been investigated. The results suggest that the production of Hlogical and, bar above super(+) can be efficiently enhanced by using either a fraction of Ps(2p) and a 2 keV (plogical and, bar above) beam or a fraction Ps(3d) and antiprotons with kinetic energy below 1 keV.
The aim of the GBAR (Gravitational Behavior of Antimatter at Rest) experiment is to measure the free fall acceleration of an antihydrogen atom, in the terrestrial gravitational field at CERN and ...therefore test the Weak Equivalence Principle with antimatter. The aim is to measure the local gravity with a 1% uncertainty which can be reduced to few parts of 10 -3 .
The production and cooling of the + ion is the key point of the GBAR experiment (Gravitational Behaviour of Antihydrogen at Rest), which aims at performing the free fall of antihydrogen atoms to ...measure , the acceleration of antimatter on Earth. + ions will be obtained from collisions between a positronium cloud and antiprotons delivered by the AD/ELENA facility at CERN, with intermediate formation of antihydrogen atoms. In order to optimise the experimental production of + ions, we computed the total cross sections of the two corresponding reactions, within the same theoretical framework of the Continuum Distorted Wave – Final State (CDW-FS) model. The different contributions of the excited states have been systematically investigated for different states of Ps. The results exhibit an increase of the production toward low kinetic energies, in agreement with experimental data and previous calculations, whereas the largest + production is obtained with low energy ground-state antihydrogen atoms. These theoretical predictions suggest that the overall production of + could be optimal for 2 keV antiproton impact energy, using positronium atoms prepared in the 2p state.
Positron accumulation in the GBAR experiment Blumer, P.; Charlton, M.; Chung, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2022, Volume:
1040
Journal Article
The production and cooling of the H super(+) ion is the key point of the GBAR experiment (Gravitational Behaviour of Antihydrogen at Rest), which aims at performing the free fall of antihydrogen ...atoms to measure g, the acceleration of antimatter on Earth. H super(+) ions will be obtained from collisions between a positronium cloud and antiprotons delivered by the AD/ELENA facility at CERN, with intermediate formation of antihydrogen atoms. In order to optimise the experimental production of H super(+) ions, we computed the total cross sections of the two corresponding reactions, within the same theoretical framework of the Continuum Distorted Wave - Final State (CDW-FS) model. The different contributions of the H excited states have been systematically investigated for different states of Ps. The results exhibit an increase of the H production toward low kinetic energies, in agreement with experimental data and previous calculations, whereas the largest H super(+) production is obtained with low energy ground-state antihydrogen atoms. These theoretical predictions suggest that the overall production of H super(+)could be optimal for 2 keV antiproton impact energy, using positronium atoms prepared in the 2p state.
The independent verification in a forensics context of quartz grain morphological typing by scanning electron microscopy was demonstrated using particle-induced X-ray emission (PIXE) and ...particle-induced ...-ray emission (PIGE). Surface texture analysis by electron microscopy and high-sensitivity trace element mapping by PIXE and PIGE are independent analytical techniques for identifying the provenance of quartz in sediment samples in forensic investigations. Trace element profiling of the quartz grain matrix separately from the quartz grain inclusions served to differentiate grains of different provenance and indeed went some way toward discriminating between different quartz grain types identified in a single sample of one known forensic provenance. These results confirm the feasibility of independently verifying the provenance of critical samples from forensic cases. (ProQuest: ... denotes formulae/symbols omitted.)
We report on the first production of an antihydrogen beam by charge exchange of 6.1 keV antiprotons with a cloud of positronium in the GBAR experiment at CERN. The antiproton beam was delivered by ...the AD/ELENA facility. The positronium target was produced from a positron beam itself obtained from an electron linear accelerator. We observe an excess over background indicating antihydrogen production with a significance of 3-4 standard deviations.
We present a description of the GBAR positron (e+) trapping apparatus, which consists of a three stage Buffer Gas Trap (BGT) followed by a High Field Penning Trap (HFT), and discuss its performance. ...The overall goal of the GBAR experiment is to measure the acceleration of the neutral antihydrogen (H) atom in the terrestrial gravitational field by neutralising a positive antihydrogen ion (H+), which has been cooled to a low temperature, and observing the subsequent H annihilation following free fall. To produce one H+ ion, about 10^10 positrons, efficiently converted into positronium (Ps), together with about 10^7 antiprotons (p), are required. The positrons, produced from an electron linac-based system, are accumulated first in the BGT whereafter they are stacked in the ultra-high vacuum HFT, where we have been able to trap 1.4(2) x 10^9 positrons in 1100 seconds.
For the GBAR (Gravitational Behaviour of Antihydrogen at Rest) experiment at CERN's Antiproton Decelerator (AD) facility we have constructed a source of slow positrons, which uses a low-energy ...electron linear accelerator (linac). The driver linac produces electrons of 9 MeV kinetic energy that create positrons from bremsstrahlung-induced pair production. Staying below 10 MeV ensures no persistent radioactive activation in the target zone and that the radiation level outside the biological shield is safe for public access. An annealed tungsten-mesh assembly placed directly behind the target acts as a positron moderator. The system produces \(5\times10^7\) slow positrons per second, a performance demonstrating that a low-energy electron linac is a superior choice over positron-emitting radioactive sources for high positron flux.
Metal oxide materials have been applied in different fields due to their excellent functional properties. Metal oxides nanostructuration, preparation with the various morphologies, and their coupling ...with other structures enhance the unique properties of the materials and open new perspectives for their application in the food industry. Chemical gas sensors that are based on semiconducting metal oxide materials can detect the presence of toxins and volatile organic compounds that are produced in food products due to their spoilage and hazardous processes that may take place during the food aging and transportation. Metal oxide nanomaterials can be used in food processing, packaging, and the preservation industry as well. Moreover, the metal oxide-based nanocomposite structures can provide many advantageous features to the final food packaging material, such as antimicrobial activity, enzyme immobilization, oxygen scavenging, mechanical strength, increasing the stability and the shelf life of food, and securing the food against humidity, temperature, and other physiological factors. In this paper, we review the most recent achievements on the synthesis of metal oxide-based nanostructures and their applications in food quality monitoring and active and intelligent packaging.
![H[logical and, bar above] s...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1367-2630/small "H[logical and, bar above] super(+) ion production from collisions between antiprotons and excited positronium: cross sections calculations in the framework of the GBAR experiment")
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