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The purpose of the research was to simulate the process of 99Mo production. The most widely used isotope for medical imaging is 99mTc. This radionuclide is produced via 99Mo beta minus decay. A relatively new option is a linac-based way of obtaining 99Mo through a photonuclear reaction 100Mo(γ,n)99Mo with bremsstrahlung irradiation. The purpose of this study was to simulate the process of 99Mo production using a 30 MeV electron linear accelerator with a 100 μA average beam current. The Monte Carlo calculations were used for this purpose. The main goal of the presented work was to optimize the process of irradiation of the 100Mo target with an electron beam in order to produce 99Mo with the highest efficiency. Parameters like FWHM of the beam and thickness of conversion target were investigated. The simulation was carried out using the Monte Carlo method with FLUKA 2011.2x.4 and Flair_2.3-0_all. The study showed that the highest efficiency (photons production) among widely used conversion targets is at an about 3 mm thick round tungsten plate. Results of the executed simulations showed that there is a possibility of obtaining 300 GBq of 99Mo within three days of irradiation of a 99% enriched 100Mo target (φ=3 cm, 5 mm thickness). [ABSTRACT FROM AUTHOR]

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum Δ V capability of 600  ms - 1 . Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes - B1, provided by the Japanese space agency, JAXA, and B2 - that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule., Competing Interests: Competing InterestsThe authors declare no competing interests., (© The Author(s) 2024.)

High pressure variable displacement axial piston pumps are subject to complex dynamic phenomena. Their analysis is difficult, additionally complicated by leakage of the working fluid. Analytically gap flow is calculated with the Reynolds equation which describes the pressure distribution in a thin lubricating layer. The paper presents various approaches to analyze gap flow both in traditional axial piston pump and novel type of hydraulic pump, designed at the Polish Gdansk Institute of Technology. Because of large aspect ratio between the height of the gap and the size of pump elements, the authors present the numerical simulation approach using a local model to define a lubrication gap, linked to a global model of a pump from which boundary conditions were imported. User defined functions implemented in Fluent and Excel were used to calculate the pressure and velocity fields and assess the fluid flow rate., Competing Interests: Compliance with Ethical StandardsThe authors declare that they have no conflict of interest.