Search NASA⌕ Search

Engineering topics

Gupta, M

Publications and source records attributed to Gupta, M.

Horizons: nuclear astrophysics in the 2020s and beyond

Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Interdiffusion in W/Si Multilayers with Boron Carbide Interlayers

W/Si multilayers with B{sub 4}C as a diffusion barrier were deposited using ion beam sputtering technique. It was found that incorporation of B{sub 4}C at both interfaces of Si enhances the reflectivity of the multilayer. Though the interface of W/Si or W/B{sub 4}C has been studied in literature, what happens at Si/B{sub 4}C interfaces is largely unknown. This is primarily due to absence of contrast between Si/B{sub 4}C for x-rays. For neutrons there is significant contrast between Si and B{sub 4}C, therefore we used neutron reflectivity to study thermal stability of Si/B{sub 4}C multilayers. It was found that up to an annealing temperature of 573 K, the multilayer remains intact however at higher temperature interdiffusion starts.

36 MATERIALS SCIENCE↗

Fe/Au Multilayers: Structure and Magnetoresistance

We have measured the magnetoresistance (MR) in two sets of Fe/Au multilayers, with varying (1) Fe layer thickness, t{sub Fe} = 3-10 nm, and (2) Au layer thickness t{sub Au} = 5-15 nm, grown on Si substrates by sputtering. The multilayer interface structure and magnetic properties were studied by polarized neutron reflectometry (PNR). The study was undertaken to understand the correlation between structure of these multilayers and their magneto-transport properties.

36 MATERIALS SCIENCE↗