Motivated by the possibility of guiding daughter ions from double beta decay events to single-ion sensors for barium tagging, the NEXT collaboration is developing a program of R&D to test radio frequency (RF) carpets for ion transport in high pressure xenon gas. This would require carpet functionality in regimes at higher pressures than have been previously reported, implying correspondingly larger electrode voltages than in existing systems. This mode of operation appears plausible for contemporary RF-carpet geometries due to the higher predicted breakdown strength of high pressure xenon relative to low pressure helium, the working medium in most existing RF carpet devices. In this paper we present the first measurements of the high voltage strength of xenon gas at high pressure and at the relevant RF frequencies for ion transport (in the 10 MHz range), as well as new DC and RF measurements of the breakdown strengths of high pressure argon and helium gases at small gap sizes. We find breakdown voltages that are compatible with stable RF carpet operation given the gas, pressure, voltage, materials and geometry of interest.

For a sustainable development, chemical processes should be designed around the use of renewable raw materials (RRM). The aim of this study is using limonene, chosen as example of an industrial by-product, to prepare limonene oxides, carvone, carveol, carvacrol and terephthalic acid, all of great industrial interest, with values of one to two orders of magnitude greater than limonene and compare the results obtained with conventional, microwave or solar activation in order to decrease the environmental impact of the process. The reactions were carried using catalysts based on materials of low toxicity, i.e. iron, manganese, titania and sepiolite. A number of techniques were used to characterise the compositional, structural and textural proiperties of the catalysts used. The results of this research indicate that for similar conversions conventional activation requires the highest energy expenditure, related to a negative environmental impact, while the use of microwave heating greatly reduces the reaction times and solar activation proves to be a very competitive and indeed the most environmentally friendly activation method. Furthermore, orange peel oil