Physics research interests

A list of the projects I have worked on. Most of my physics work has been in general relativity, gamma-ray burst astrophysics, and nuclear non-proliferation.

General relatitivity and Regge calculus

I did my PhD thesis in general relativity, specifically Regge Calculus, a way of expressing and solving Einstein’s equations for General Relativity on a simplicial grid.

HETE and HETE-2 satellites

I got to work with a remarkable team of experimentalists from MIT, Los Alamos, Riken (Tokyo), CESR (Toulouse), joined by theorists from University of Chicago, U.C. Santa Cruz, and U.C. Berkeley.

HETE and HETE-2 were very small, inexpensive satellites aimed at detecting gamma-ray bursts, localizing them in real time, and transmitting the coordinates to ground immediately.

The first HETE spacecraft was lost when the rocket did not release the two satellites in it. HETE-2 was built from spare parts, launched on 2000-10-09, and was a remarkable succes. (archived)

Swift

Swift is possibly the most successful gamma-ray burst mission. It was a large effort, and my role was quite small, assiting David Palmer and Ed Fenimore in the Los Alamos contribution to the Bat (Burst Alert Telescope) instrument on Swift.

The Raptor telescope and software pipeline

The Raptor telescope complex is a small telescope system installed in the mountains behind Los Alamos. The software pipeline for Raptor was designed to identify transient sources, such as the optical counterparts for untriggered gamma-ray bursts, or near-earth moving objects.

Muon tomography

The Los Alamos muon tomography project …

Three-dimensional backscatter imaging

An ingenious approach to positron emission backscatter imaging, which can be used to do three dimensional imaging of objects behind a wall, when you only have access from one side. The technique is described here.

Los Alamos Lightning Array

My division in Los Alamos has at times maintained an array of lightning detection stations. I worked on rebuilding the data acquisition and the overall softare pipeline for it.

Hurricane prediction from lightning data

I worked on Chris Jeffery’s project which tried to use the Los Alamos lightning detection array to predict hurricane intensification. There is also a popular article on it.

Standoff Radiation Detection System (SORDS)

The SORDS instrument uses both a truck-sized coded aperture and a compton telescope to image radiation sources. Information is in this article.

Integrated Standoff Inspection System

This was an active interrogation system that uses gamma-rays to inspect for nuclear materials. There is not much public material, but there is an article from Raytheon’s public relations feed.

DREAM

DREAM is a project to model how a high altitude nuclear detonation might affect the flux of charged particles in the Earth’s magnetic field. A brief description is here.

Space-based nuclear detonation detection

Los Alamos entered the field of space exploration in the 1960s with the Vela satellites, whose purpose was to look for the radiation signature nuclear tests. This effort continues today.