Physics Colloquium Series - Spring 2019

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Since he has successfully attained employment in academia, industry and the government, Dr. DeAntonio has a lot of tips to help you get a job. He has worked as a post-doc and professor, as well as an engineer, research scientist, test equipment developer, incoming inspection designer, computer programmer and manager. He had jobs that require top secret clearance and even been self-employed. He has several patents and trade secrets and worked in the fields of fiber optics, CADD software design, global warming, atmospheric science and future combat systems. He has even been in the predicament of unemployment. In the presentation, Dr. DeAntonio will cover the basics of networking, searching for a job, creating a good resume or CV and doing a successful interview. The presentation will be very informal. So, come with your questions and concerns and he will be ready to give you his best advice.

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Finding new materials with targeted properties with as few experiments as possible has been a key goal of the materials genome initiative, now expanding in several countries. The enormous complexity due to the interplay of structural, chemical and microstructural degrees of freedom in materials makes the rational design of new materials rather difficult. Machine learning and optimization, used in industry for solving complex problems, are increasingly being adapted for the design of new materials by rapidly learning from past data and making smart decisions. However, the number of well characterized samples available as sources of data to learn from is often typically small. I will review some of the examples we have examined, including guiding experiments for more desirable alloys and ceramics and the use of high throughput electronic structure calculations to find new perovskites.

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Acoustic tomography of the atmosphere is similar to that in medicine where ultrasound or x-rays probe an organ of a human body resulting in an "image" of that organ. In the case of acoustic tomography of the atmosphere, acoustic pulses are used to measure the travel times of sound propagation between different pairs of speakers and microphones, which are arranged so as to create propagation paths through the region to be sampled. Then, the temperature and wind velocity fields inside the tomographic region are reconstructed by inverting the travel times. This presentation overviews general principles and concepts of tomography, a historic perspective of acoustic tomography of the atmosphere, and tomography arrays which have been used in the past. A forward problem in acoustic tomography of the atmosphere is formulated. Inverse algorithms for reconstruction of the temperature and wind velocity fields from the travel times are reviewed. The instrumentation and principle of operation of a tomography array at the Boulder Atmospheric Observatory (BAO) are explained. The array enabled horizontal-slice tomography at a height of 8 m above the ground, in an 80 m × 80 m region. Results in numerical simulations of the BAO tomography array and reconstruction of turbulence fields in tomography experiments are presented. Acoustic tomography can also be performed at other spatial scales, ranging from a size of an ultrasonic anemometer/thermometer to the height of the atmospheric boundary layer. Future developments in acoustic tomography of the atmosphere are discussed.

Several accelerator-based and reactor-based neutrino experiments suggested the existence of a new fundamental particle, the sterile neutrino. Sterile neutrinos, unlike the electron, muon, and tau neutrinos in the standard model, do not interact via weak interaction. In this talk, I will present the latest MiniBooNE oscillation results with 12.84×10²⁰ protons on target (POT) electron neutrino appearance data and 11.27×10²⁰ POT electron antineutrino appearance data. A total electron neutrino and antineutrino charged-current quasi-elastic event excess of 460.5±99.0 events (4.7σ) is observed. The observed excess is consistent in energy and magnitude with the excess reported by the LSND experiment with a combined significance of 6.0σ. Future and current experiments, especially the Coherent Captain Mills experiment at Los Alamos, to test this excess will be discussed.

Acoustic tomography of the atmosphere is similar to that in medicine where ultrasound or x-rays probe an organ of a human body resulting in an "image" of that organ. In the case of acoustic tomography of the atmosphere, acoustic pulses are used to measure the travel times of sound propagation between different pairs of speakers and microphones, which are arranged so as to create propagation paths through the region to be sampled. Then, the temperature and wind velocity fields inside the tomographic region are reconstructed by inverting the travel times. This presentation overviews general principles and concepts of tomography, a historic perspective of acoustic tomography of the atmosphere, and tomography arrays which have been used in the past. A forward problem in acoustic tomography of the atmosphere is formulated. Inverse algorithms for reconstruction of the temperature and wind velocity fields from the travel times are reviewed. The instrumentation and principle of operation of a tomography array at the Boulder Atmospheric Observatory (BAO) are explained. The array enabled horizontal-slice tomography at a height of 8 m above the ground, in an 80 m × 80 m region. Results in numerical simulations of the BAO tomography array and reconstruction of turbulence fields in tomography experiments are presented. Acoustic tomography can also be performed at other spatial scales, ranging from a size of an ultrasonic anemometer/thermometer to the height of the atmospheric boundary layer. Future developments in acoustic tomography of the atmosphere are discussed.

In November 2018 I became the Leader of Los Alamos National Laboratory's Nuclear Engineering and Nonproliferation Division (NEN). NEN Division develops nuclear safeguards concepts and instruments and techniques used to monitor and measure nuclear materials, trains IAEA inspectors, operates the Nation's only capability for nuclear criticality experiments, and develops unique nuclear reactor concepts. In this talk I will provide a contextual overview of our work and discuss some of the physics and engineering challenges of nonproliferation, nuclear safeguards, small modular nuclear reactors and criticality safety.

Until recently, few areas of scientific research demanded the processing power of large supercomputers. Today, high performance computing (HPC) has become ubiquitous. In fact, it is difficult to identify research areas that do not harness the power of parallel and scalable computing. The first part of this presentation will highlight the use of HPC in several important areas of physics that are of particular interest within the Department of Energy (DOE) mission space. Specific problems and their HPC-enabled solutions within the neutron, materials and fusion sciences will be introduced. High-level descriptions of parallel methods designed for high-speed high-resolution computations at precedented scales will be presented. Application-specific scientific milestones resulting from computational speedups of over 100× on leadership class supercomputers will be highlighted. The introductory part of the talk will be followed by a deeper dive into the problem of designing efficient parallel solvers for block-tridiagonal systems of equations that emerge in a number of engineering and scientific applications. Merits and demerits of two different parallel algorithms for such tridiagonal systems will be discussed. The talk will end with a presentation of recent efforts in scaling these solvers for more efficient parallel execution.

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