Minor detour from the South Pole

This week I'm headed to Puebla, Mexico for the joint NSF-DoE (National Science Foundation and Department of Energy, the two main US funding sources for science that isn't related to your congressman's liver (that would be the National Institutes of Health, funding whatever the congressfolks are scared of medically)) review of the HAWC experiment. This is a science and management review to make sure that we're spending the taxpayer money well, and that the project is progressing reasonably.

HAWC is the High Altitude Water Cherenkov experiment. That means it's being built at high altitude, 4100 meters or about 14000 feet above sea level, in order to get higher up into the cascade (or shower) of energetic particles produced when cosmic rays or gamma rays hit the top of the atmosphere. The detector technology is Water Cherenkov, that is, we observe the light emitted from fast-moving particles traversing through a water tank. The light is detected with photomultiplier tubes (PMTs) capable of seeing single photons with nanosecond (billionth of a second) resolution. It's the gamma rays at energies at the top of the atmosphere of near 1 TeV (10^12 electron volts) that are of particular interest.

One of the main goals of HAWC is to observe the whole sky (rather than like an optical telescope, just the small patch of the sky one is aimed at) in these TeV gamma rays (which are super-high energy photons) for transient sources. The main goal is to observe gamma ray bursts (GRBs, very energetic astronomical explosions much of the way across the universe) at higher energies than previously seen. This would enable us to better understand the physics of the GRB sources and the propagation (travel) of the photons from those sources to the Earth.

To one specific high altitude valley in Mexico to be precise. It's a beautiful site, so look for photos in the next couple of days...