Old notion of the distribution of charge inside the neutron overturned

Apparently the old notion of the distribution of charge inside the neutron has been overturned:

For two generations of physicists, it has been a standard belief that the neutron, an electrically neutral elementary particle and a primary component of an atom, actually carries a positive charge at its center and an offsetting negative charge at its outer edge.

The notion was first put forth in 1947 by Enrico Fermi, a Nobel laureate noted for his role in developing the first nuclear reactor. But new research by a University of Washington physicist shows the neutron's charge is not quite as simple as Fermi believed.

Using precise data recently gathered at three different laboratories and some new theoretical tools, Gerald A. Miller, a UW physics professor, has found that the neutron has a negative charge both in its inner core and its outer edge, with a positive charge sandwiched in between to make the particle electrically neutral.

This is pretty cool, but I wanted to know how the quarks arrange themselves inside the neutron in order for this to happen. It would seem that the down quarks are at the center and outside and the up quark is in the middle, but that doesn't make much sense (since then the up would be in the middle). But then again I don't know much of anything about quantum chromodynamics, perhaps this does make sense.

One of the reasons I mentioned it here is because it's a good example of something we've believed for a while (in this case 60 years) being suddenly overturned. This was published in PRL, so I doubt it's junk, and it will probably be well-received by the Physics community (again, provided it does have good evidence going for it). It's always good to have examples of when a long-held belief is just overturned; it demonstrates the power, flexibility, and nondogmatic nature of science.

Bad News From Switzerland

This is incredibly bad news.

Let me back up some. The LHC (Large Hadron Collider) in CERN is the next-generation particle accelerator. It will, at the very very least, tell us how correct the Standard Model is. It could show us the Higgs Boson (the so-called God Particle that I'll have to do a post on some time, the short version is that it gives all matter mass), and possibly even mini black holes. It could very well tear our knowledge a new one once it starts smashing protons together.

But in a stress test over the weekend the casing of one of a series of crucial magnets (in an accelerator magnetic fields accelerate and direct the particles) failed and broke (for more technical details see the link above). A press release from Fermi-lab (who designed the magnets) said it could delay the LHC up to three years. However, Scientific American link above cites CERN scientists as saying that it has yet to be determined how long the delay will be.

That is incredibly bad news. There are people working in every branch of physics, from String Theory to Cosmology, and especially particle physics, who have been waiting to see what will fly out when two protons hit at 7 Tera-electron-Volts. It will be a big blow for the LHC to be delayed, when it was so close to yielding the anticipated data. I'm sure that the entire physics community is hoping for some good news in the next few days (or weeks). I know I'll have my fingers crossed that this is only a minor problem. It would be devastating if it weren't.

Discovery From Fermilab

There was some very cool news out of Fermilab a couple of days ago. They found a particle called the B_s Meson (Pronounced B-sub-s). This is particularly strange particle that oscillates back and forth between matter and antimatter state 3 trillion times a second.

It’s a technological triumph, because these particles exist for fractions of a second before disintegrating into a haze of less exotic particles. The analysis needed to find them and determine the oscillation speed was immense, and took many years.

It’s also an unfortunate triumph for the Standard Model, which actually predicted that this particle exists. This wildly successful description of particles and their interactions has become a little bit more successful.

But why do I say “unfortunate triumph”? Well, most particle physicists feel that the Standard Model is no the whole picture, that it’s incomplete somehow. But until we break it, we don’t really know where to go. So each confirmation of a prediction just means that we’re dealing with the same old physics, instead of moving on to new physics. As I’ve said before, scientists (particle physicists especially) like to break their theories to see what’s incomplete.

That’s why the Large Hadron Collider at CERN is so exciting. It will probe energies never before reached, and hopefully break the Standard Model and show us where we need to be looking for future theories. There’s also the hope of observing things like the Higgs particle, which is theorized to give all other particles mass (I might make that a separate post, because it’s a pretty interesting particle). There’s even a chance of making black holes. Don’t worry, they’d be so small that they’d evaporate almost instantly.

But it doesn’t open until 2007, and it will probably take a few years before results start to trickle out. Until then we have to keep using our “outdated” colliders, like SLAC and the Tevatron, to bring us discoveries such as this one.