Coherent radar reflections from an electron-beam induced particle cascade

Experiment T-576 ran at SLAC in 2018, in development of a new radar-based detection scheme for ultra-high energy neutrinos. In this experiment, the electron beam (N∼109e− at ∼10 GeV) was directed into a plastic target to simulate a 1019 eV neutrino-induced shower in ice. This shower was interrogated with radio frequency (RF) radiation, in an attempt to measure a radar-like reflection from the ionization produced in the target during the particle shower. This technique could be employed to detect the rare interactions of ultra-high-energy neutrinos in dense material, such as polar ice sheets, extending the extant energy range of detected neutrinos up to EeV and beyond. In this proceeding, we detail the experiment and present results from the analysis and the observation of a signal consistent with a radar signal

Grain refinement of magnesium alloys: a review of recent research, theoretical developments and their application

This paper builds on the ‘‘Grain Refinement of Mg Alloys’’ published in 2005 and reviews the grain refinement research onMg alloys that has been undertaken since then with an emphasis on the theoretical and analytical methods that have been developed. Consideration of recent research results and current theoretical knowledge has highlighted two important factors that affect an alloy’s as-cast grain size. The first factor applies to commercial Mg-Al alloys where it is concluded that impurity and minor elements such as Fe and Mn have a substantially negative impact on grain size because, in combination with Al, intermetallic phases can be formed that tend to poison the more potent native or deliberately added nucleant particles present in the melt. This factor appears to explain the contradictory experimental outcomes reported in the literature and suggests that the search for a more potent and reliable grain refining technology may need to take a different approach. The second factor applies to all alloys and is related to the role of constitutional supercooling which, on the one hand, promotes grain nucleation and, on the other hand, forms a nucleation-free zone preventing further nucleation within this zone, consequently limiting the grain refinement achievable, particularly in low solute-containing alloys. Strategies to reduce the negative impact of these two factors are discussed. Further, the Interdependence model has been shown to apply to a broad range of casting methods from slow cooling gravity die casting to fast cooling high pressure die casting and dynamic methods such as ultrasonic treatment

Effect of the degree of crystallinity on the electrochemical behavior of Mg65Cu25Y10 and Mg70Zn25Ca5 bulk metallic glasses

The effect of varying the percent crystallinity on the electrochemical behavior of Mg65Cu25Y10 and Mg70Zn25Ca5 bulk metallic glasses was studied. The alloys were heat-treated to achieve desired microstructures ranging from fully amorphous to fully crystalline, providing a systematic basis for subsequent testing. Potentiodynamic experiments in 0.01 M sodium chloride (NaCl) were used, whereby both the amorphous and partially crystallized samples were observed to have more noble corrosion potentials and lower anodic kinetics. However, this was accompanied by more rapid cathodic kinetics relative to their fully crystalline counterparts, meaning that corrosion rates were not significantly lower in the amorphous state. To describe the electrochemical response as a function of the degree of crystallinity, differential scanning calorimetry (DSC), scanning electron microscopy, x-ray diffraction (XRD), and electrical conductivity measurements were undertaken, where it was found that crystallinity alone is not necessarily the controlling factor and microchemistry that evolves upon devitrification, plays a key role in the electrochemical response of these materials