Probing Ganymede's atmosphere with HST Lyα\alpha images in transit of Jupiter

We report results from far-ultraviolet observations by the Hubble Space Telescope of Jupiter's largest moon Ganymede transiting across the planet's dayside hemisphere. {Within} a targeted campaign on 9 September 2021 two exposures were taken during one transit passage to probe for attenuation of Jupiter's hydrogen Lyman-$\alpha$ dayglow above the moon limb. The background dayglow is slightly attenuated over an extended region around Ganymede, with stronger attenuation in the second exposure when Ganymede was near the planet's center. In the first exposure when the moon was closer to Jupiter's limb, the effects from the Ganymede corona are hardly detectable, likely because the Jovian Lyman-$\alpha$ dayglow is spectrally broader and less intense at this viewing geometry. The obtained vertical H column densities of around $(1-2)\times 10^{12}$~cm$^{-2}$ are consistent with previous results. Constraining angular variability around Ganymede's disk, we derive an upper limit on a local H$_2$O column density of $(2-3)\times 10^{16}$~cm$^{-2}$, such as could arise from outgassing plumes in regions near the observed moon limb

Thermo-mechanical properties of ABS/stainless steel composite using FDM

Fused deposition modelling (FDM) process is the most common and traditional additive manufacturing methods for producing complicated three-dimensional (3D) samples from computer-aided design data at a cheaper cost than alternative methods. However, when compared to other common plastic production processes, such as injection moulding, FDM produced parts results in low mechanical properties. Hence, the objective of this study is to produce composite filament using stainless steel (SS) as filler material to enhance the mechanical properties of ABS. ABS is a petroleum based thermoplastic that commonly used in FDM. The production of metal/polymer composites utilising ABS as the matrix and varied SS powder compositions was studied in this work. ABS/SS composite filaments containing 5, 10 wt% SS powder were developed in this experiment to compare with pure ABS for the FDM process. The result shows that the higher the composition of SS powder the lower the ultimate tensile strength and yield strength where 10 wt% SS shows 38.42 MPa in ultimate tensile strength while for yield strength it shows 24.32 MPa. Meanwhile, 10 wt% SS filament has better elongation which is 18.28 % compare to pure ABS that is 9.89 % and 13.3 % for 5 wt% SS. Thus, the percentage of filler plays an important role in determining the properties of ABS

Effect of process parameter on tensile properties of FDM printed PLA

In recent years, 3D printing has contributed to developing new materials and applications, owing to its technological flexibility and distinct characteristics. Polylactic Acid (PLA) polymer samples have been produced using one of the additive manufacturing (AM) processes called fused deposition modelling (FDM). However, poor mechanical characteristics are the most prevalent problem due to the processing parameter when parts are fabricated with FDM. The research aims to study the tensile properties of PLA by varying the processing parameter. In this study, PLA material was used due to its biocompatibility properties. This research is to analyze and compare the tensile properties of 3D printed samples by varying the infill density and raster angle. The change in the circumstances has a discernible impact on the tensile strength based on varied infill densities and raster angles. The results show that infill density of 100% and 45° raster angle performs better tensile strength than 50% and 75% infill density. Hence, it can be concluded that the tensile strength of the printed samples has a noticeable effect when the processing parameters vary

Callisto's Atmosphere and Its Space Environment: Prospects for the Particle Environment Package on Board JUICE

The JUpiter ICy moons Explorer (JUICE) of the European Space Agency will investigate Jupiter and its icy moons Europa, Ganymede, and Callisto, with the aim to better understand the origin and evolution of our Solar System and the emergence of habitable worlds around gas giants. The Particle Environment Package (PEP) on board JUICE is designed to measure neutrals and ions and electrons at thermal, suprathermal, and radiation belt energies (eV to MeV). In the vicinity of Callisto, PEP will characterize the plasma environment, the outer parts of Callisto's atmosphere and ionosphere and their interaction with Jupiter's dynamic magnetosphere. Roughly 20 Callisto flybys with closest approaches between 200 and 5,000 km altitude are planned over the course of the JUICE mission. In this article, we review the state of the art regarding Callisto's ambient environment and magnetospheric interaction with recent modeling efforts for Callisto's atmosphere and ionosphere. Based on this review, we identify science opportunities for the PEP observations to optimize scientific insight gained from the foreseen JUICE flybys. These considerations will inform both science operation planning of PEP and JUICE and they will guide future model development for Callisto's atmosphere, ionosphere, and their interaction with the plasma environment

Callisto’s atmosphere: First evidence for H₂ and constraints on H₂O

We explore the parameter space for the contribution to Callisto's H corona observed by the Hubble Space Telescope from sublimated H2O and radiolytically produced H2 using the Direct Simulation Monte Carlo method. The spatial morphology of this corona produced via photoelectron and magnetospheric electron-impact-induced dissociation is described by tracking the motion of and simulating collisions between the hot H atoms and thermal molecules including a near-surface O2 component. Our results indicate that sublimated H2O produced from the surface ice, whether assumed to be intimately mixed with or distinctly segregated from the dark nonice or ice-poor regolith, cannot explain the observed structure of the H corona. On the other hand, a global H2 component can reproduce the observation, and is also capable of producing the enhanced electron densities observed at high altitudes by Galileo's plasma-wave instrument, providing the first evidence of H2 in Callisto's atmosphere. The range of H2 surface densities explored, under a variety of conditions, that are consistent with these observations is ∼(0.4–1) × 108 cm−3. The simulated H2 escape rates and estimated lifetimes suggest that Callisto has a neutral H2 torus. We also place a rough upper limit on the peak H2O number density (≲108 cm−3), column density (≲1015cm−2), and sublimation flux (≲1012 cm−2 s−1), all of which are 1–2 orders of magnitude less than that assumed in previous models. Finally, we discuss the implications of these results, as well as how they compare to Europa and Ganymede

Design and construction of the MicroBooNE Cosmic Ray Tagger system

The MicroBooNE detector utilizes a liquid argon time projection chamber (LArTPC) with an 85 t active mass to study neutrino interactions along the Booster Neutrino Beam (BNB) at Fermilab. With a deployment location near ground level, the detector records many cosmic muon tracks in each beam-related detector trigger that can be misidentified as signals of interest. To reduce these cosmogenic backgrounds, we have designed and constructed a TPC-external Cosmic Ray Tagger (CRT). This sub-system was developed by the Laboratory for High Energy Physics (LHEP), Albert Einstein center for fundamental physics, University of Bern. The system utilizes plastic scintillation modules to provide precise time and position information for TPC-traversing particles. Successful matching of TPC tracks and CRT data will allow us to reduce cosmogenic background and better characterize the light collection system and LArTPC data using cosmic muons. In this paper we describe the design and installation of the MicroBooNE CRT system and provide an overview of a series of tests done to verify the proper operation of the system and its components during installation, commissioning, and physics data-taking

A Deep Neural Network for Pixel-Level Electromagnetic Particle Identification in the MicroBooNE Liquid Argon Time Projection Chamber

We have developed a convolutional neural network (CNN) that can make a pixel-level prediction of objects in image data recorded by a liquid argon time projection chamber (LArTPC) for the first time. We describe the network design, training techniques, and software tools developed to train this network. The goal of this work is to develop a complete deep neural network based data reconstruction chain for the MicroBooNE detector. We show the first demonstration of a network's validity on real LArTPC data using MicroBooNE collection plane images. The demonstration is performed for stopping muon and a $\nu_\mu$ charged current neutral pion data samples

Ionization Electron Signal Processing in Single Phase LArTPCs II. Data/Simulation Comparison and Performance in MicroBooNE

The single-phase liquid argon time projection chamber (LArTPC) provides a large amount of detailed information in the form of fine-grained drifted ionization charge from particle traces. To fully utilize this information, the deposited charge must be accurately extracted from the raw digitized waveforms via a robust signal processing chain. Enabled by the ultra-low noise levels associated with cryogenic electronics in the MicroBooNE detector, the precise extraction of ionization charge from the induction wire planes in a single-phase LArTPC is qualitatively demonstrated on MicroBooNE data with event display images, and quantitatively demonstrated via waveform-level and track-level metrics. Improved performance of induction plane calorimetry is demonstrated through the agreement of extracted ionization charge measurements across different wire planes for various event topologies. In addition to the comprehensive waveform-level comparison of data and simulation, a calibration of the cryogenic electronics response is presented and solutions to various MicroBooNE-specific TPC issues are discussed. This work presents an important improvement in LArTPC signal processing, the foundation of reconstruction and therefore physics analyses in MicroBooNE.Comment: 54 pages, 36 figures; the first part of this work can be found at arXiv:1802.0870

Ionization Electron Signal Processing in Single Phase LArTPCs I. Algorithm Description and Quantitative Evaluation with MicroBooNE Simulation

We describe the concept and procedure of drifted-charge extraction developed in the MicroBooNE experiment, a single-phase liquid argon time projection chamber (LArTPC). This technique converts the raw digitized TPC waveform to the number of ionization electrons passing through a wire plane at a given time. A robust recovery of the number of ionization electrons from both induction and collection anode wire planes will augment the 3D reconstruction, and is particularly important for tomographic reconstruction algorithms. A number of building blocks of the overall procedure are described. The performance of the signal processing is quantitatively evaluated by comparing extracted charge with the true charge through a detailed TPC detector simulation taking into account position-dependent induced current inside a single wire region and across multiple wires. Some areas for further improvement of the performance of the charge extraction procedure are also discussed.Comment: 60 pages, 36 figures. The second part of this work can be found at arXiv:1804.0258