Tuesday, July 07, 2009


With a few minor quibbles, such as the phrase "... machine fires electronics that reach nearly the speed of light ...", this is a quick news summary of the Jefferson National Accelerator Facility, one of the DOE's National Laboratories.

The Energy Department's Thomas Jefferson National Accelerator Facility, or Jefferson Lab, was created to study nuclear physics — the most basic pieces that make up our universe.

It takes a massive machine to study the smallest particles known to man. That machine, the centerpiece of the lab's work, is the Continuous Electron Beam Accelerator Facility.

I always wonder whenever we have accounts like this, that someone eventually will get confused into wondering the difference between high energy physics and nuclear physics. For example, the Tevatron and LHC are "high energy physics" machines, while CEBAF and RHIC are "nuclear physics" machines. Most of us in physics kinda understand the energy range and even the type of studies being done in those machines that vaguely separates "nuclear" from "high energy/elementary particles". However, the general description we give to the public (see this news article, for example, doesn't have any distinguishing features that separates one from the other. I mean, saying something like:

"...created to study nuclear physics — the most basic pieces that make up our universe...."


"... a massive machine to study the smallest particles known to man... "

would be an accurate description of high energy physics endeavor as well. If I were a very astute layman, I could have easily noticed the "non-difference" and ask "OK, so how is this any different than high energy physics?"

I would have been a tremendous service to the public if news articles like this emphasize why this is specifically a "nuclear physics" facility.


1 comment:

john said...

I'm not sure you have to answer the question "how is this different from high energy physics". As someone working at Jefferson Lab, I think it's fair to say that a lot of the work going on there falls in the broad category of "high energy physics", especially when talking to people outside of the field.

Experts can of course identify some differences in the focus of medium energy and HEP research, but in a broad sense, I don't think there's a clear cut separation (especially when you start talking about things like neutrino scattering measurements).

In fact, I'd say that the clearest differentiation between medium energy and high energy physics is on the funding side, not the physics side (and similarly for the differences between low energy and medium energy nuclear physics). The facilities are different, and some of the physics goals are unrelated, but other aspects are studies in both areas.