Charge exchange processes from the collisions of alpha particles with water molecules

Collisions of multiply charged solar wind ions with cometary molecules lead to infrared and far ultraviolet photon emissions [1]. As it was shown in previous work by [2-4] the resulting spectra of the emission yields have astrophysical implications and can be used for testing such properties of the solar wind as velocity, density, and chemical composition. In present work experimental data for the state selective electron capture by He²⁺ ions from water molecules are presented. Three complimentary experimental techniques: Translational Energy Spectroscopy, Photon Emission Spectroscopy and Fragment Ion Spectroscopy were used for measuring state selective electron capture cross sections [5]. Experimental data are compared to the theoretical calculations. Theoretical calculations were carried out using basis approach which is proven to provide a good agreement with the experimental measurements.Зіткнення багаторазово іонізованих зарядів сонячного вітру з нейтральними частинками комет призводять до емісій в рентгенівській і ультрафіолетовій областях [1]. Як було показано раніше [2–4], результуючий спектр перезаряджених іонів може бути використаний для тестування таких властивостей сонячного вітру як швидкість, концентрація частинок та хімічний склад. У роботі представлено експериментальні дані для вибіркового захоплення електрона при зіткненнях альфа-частинок з молекулами води. Для вимірювань поперечних перерізів захоплення електрона було використано три незалежні та взаємодоповнюючі методики – трансляційно-енергетична спектроскопія, фотонно-емісійна спектроскопія та фрагментарно-іонна спектроскопія [5]. Експериментальні дані порівнюються з результатами теоретичних розрахунків. З цією метою нами запропоновано метод базисного підходу до опису таких зіткнень і показано, що теоретичні розрахунки виконані з використанням цього методу добре узгоджуються з експериментальними даними.Столкновения многократно заряженных ионов солнечного ветра с нейтральными частицами комет приводят к эмиссиям в рентгеновской и ультрафиолетовой областях [1]. Как было показано ранее [2–4], исходящий спектр перезаряженных ионов может быть использован для тестирования таких свойств солнечного ветра как скорость, концентрация и химический состав. Представлены экспериментальные данные для частичного захвата электрона при столкновениях альфа-частиц с молекулами воды. Для измерений сечений захвата электрона было использовано три независимые и взаимодополняющие методики – трансляционно-энергетической спектроскопии, фотонно-эмиссионной спектроскопии и фрагментарно-ионной спектроскопи [5]. Экспериментальные данные сравниваются с результатами теоретических расчетов. С этой целью нами предложен метод базисного подхода к описанию таких столкновений и показано, что используемый метод хорошо согласуется с экспериментальными данными

Material informatics driven design and experimental validation of lead titanate as an aqueous solar photocathode

Materials informatics is a rapidly emerging data- and knowledge-driven approach for the identification of novel materials for a range of applications, including solar energy conversion. Despite significant experimental effort, the development of highly efficient, stable, and cost-effective photovoltaic materials remains a challenging scientific problem. The quest for precisely defined semiconductor properties revolves around an immensely broad landscape of structural parameters. Here, we have resolved this challenge by applying material informatics to design a novel photocathode material for dye-sensitized solar cells (DSSCs). By conducting a virtual screening of 50,000 known inorganic compounds, we have identified lead titanate (PbTiO3), a perovskite, as the most promising photocathode material. Notably, lead titanate is significantly different from the traditional base elements or crystal structures used for photocathodes. The fabricated PbTiO3 DSSC devices exhibited the best performance in aqueous solution, showing remarkably high fill factors compared to typical photocathode systems. The results highlight the pivotal role materials informatics can play in streamlining the experimental development of materials with the desired properties

Milagrito: a TeV air-shower array

Milagrito, a large, covered water-Cherenkov detector, was the world's first air-shower-particle detector sensitive to cosmic gamma rays below 1 TeV. It served as a prototype for the Milagro detector and operated from February 1997 to May 1998. This paper gives a description of Milagrito, a summary of the operating experience, and early results that demonstrate the capabilities of this technique.Comment: 38 pages including 24 figure

Ozone Production in Electron Irradiated CO2:O2 Ices

The detection of ozone (O3) in the surface ices of Ganymede, Jupiter's largest moon, and of the Saturnian moons Rhea and Dione, has motivated several studies on the route of formation of this species. Previous studies have successfully quantified trends in the production of O3 as a result of the irradiation of pure molecular ices using ultraviolet photons and charged particles (i.e., ions and electrons), such as the abundances of O3 formed after irradiation at different temperatures or using different charged particles. In this study, we extend such results by quantifying the abundance of O3 as a result of the 1 keV electron irradiation of a series of 14 stoichiometrically distinct CO2:O2 astrophysical ice analogues at 20 K. By using mid-infrared spectroscopy as our primary analytical tool, we have also been able to perform a spectral analysis of the asymmetric stretching mode of solid O3 and the variation in its observed shape and profile among the investigated ice mixtures. Our results are important in the context of better understanding the surface composition and chemistry of icy outer Solar System objects, and may thus be of use to future interplanetary space missions such as the ESA Jupiter Icy Moons Explorer and the NASA Europa Clipper missions, as well as the recently launched NASA James Webb Space Telescope

Mass spectrometry of anions and cations produced in 1-4 keV H^-, O^-, and OH^- collisions with nitromethane, water, ethanol, and methanol

Interactions between 1 and 4 keV anions (H−, O−, and OH−) and gas-phase molecules (nitromethane, water, ethanol, and methanol) have been studied using quadrupole mass spectrometry of the product anions and cations. The low collision velocities (0.07–0.40 vBohr) provide favourable conditions for electron transfer from the anion projectile to the neutral target molecule yielding negative ion formation, while strong competition with cation formation is also observed. Relative production of fragment cations increases with H− impact energy and with projectile mass when energy is constant. Considered together, these results suggest a momentum dependence on collisional energy deposition. As far as negative ion production is concerned, comparisons with previous free electron attachment studies are drawn as a starting point for the interpretation of the anion fragmentation channels. For nitromethane and water, the present anion fragmentation patterns are substantially different to the free electron attachment data. Conversely the fragmentation channels of ethanol and methanol anions only show clear dependence on the electron attachment/transfer process in terms of the relative anion yields

Characterization and recent modification of a compact 10 GHz ECRIS for atomic physics experiments and spectroscopic investigations

A compact 10 ECR ion source (200 mm long, 170 mm diameter) has been developed and tested. The complete magnetic structure made from permanent magnet material is comprised of four ring magnets producing an asymmetric axial magnetic field and a hexapole magnet with a maximum radial field of 0.94 T inside the plasma chamber. The coupling of the microwave to the plasma shows efficient ECR plasma heating at microwave power levels around 10 watts. Charge state distributions for various elements with intensities up to 320 e{mu}A and their dependence on operation parameters will be presented as well as VUV spectra in the wavelength region down to 15 nm

An ultra compact 10 GHz electron-cyclotron-resonance ion source (ECRIS) for the production of multiply charged ions

There is a growing interest in the use of beams of multiply charged ions produced in special environments like high voltage platforms, Dynamitrons, Van-de-Graaff accelerators or on-line production systems for radioactive beam facilities. A compact 10 GHz ECR ion source (200 mm long, 170 mm diameter) has been developed and tested. The complete magnetic structure made from permanent magnet material is comprised of four ring magnets producing an asymmetric axial magnetic field with a mirror ratio of 2.5 and a 24 piece hexapole magnet with a maximum radial field of 0.94 T inside the plasma chamber of 25 mm inner diameter. The coupling of the microwave to the plasma using a resonant transition line from rectangular to circular waveguide shows efficient ECR plasma heating at microwave power levels around 10 watts. Charge state distributions for various elements with intensities up to 320 e{mu}A and their dependence on operation parameters will be presented as well as VUV spectra in the wavelength region down to 15 nm

An ultra compact 10 GHz electron-cyclotron-resonance ion source (ECRIS) for the production of multiply charged ions

There is a growing interest in the use of beams of multiply charged ions produced in special environments like high voltage platforms, Dynamitrons, Van-de-Graaff accelerators or on-line production systems for radioactive beam facilities. A compact 10 GHz ECR ion source (200 mm long, 170 mm diameter) has been developed and tested. The complete magnetic structure made from permanent magnet material is comprised of four ring magnets producing an asymmetric axial magnetic field with a mirror ratio of 2.5 and a 24 piece hexapole magnet with a maximum radial field of 0.94 T inside the plasma chamber of 25 mm inner diameter. The coupling of the microwave to the plasma using a resonant transition line from rectangular to circular waveguide shows efficient ECR plasma heating at microwave power levels around 10 watts. Charge state distributions for various elements with intensities up to 320 e{mu}A and their dependence on operation parameters will be presented as well as VUV spectra in the wavelength region down to 15 nm