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First Neutron Pulse from SNS
kebes writes "The $1.4 billion Spallation Neutron Source is nearing completion, and has produced its first neutron pulse. The SNS is a scientific instrument that generates beams of neutrons, which can be used to probe anything from minuscule samples to industrial materials. When fully operational, the facility is expected to host up to 2,000 international scientists annually."
We've had one of those for a while now, on this side of the pond. http://www.isis.rl.ac.uk/ They are building a second target at the site, due to open in 2008.
'The machine is so powerful that in one year it will use about the same amount of electricity as a town of 30,000.'
If we assume that the average person has an electric bill of $1000/yr, that would be $30,000,000/yr, or about $82,200/day just in electricity costs.
I imagine that lots of scientists would want to play around with this- I would certainly have fun with it given the chance. At that price, though, only extremely well-funded researchers could afford to use this machine.
You are reading a copy of my copyrighted post.
so I have nothing to say
"...which can be used to probe anything from miniscule samples to industrial materials."
Sure, it starts out that way, but before you know it you've opened up a gateway to another dimesion.
Please, do us all a favor and keep plenty of weapons and ammo around the facility. Oh, and make sure whoever's wearing the hazmat suit has a crowbar with them at all times.
Demented But Determined.
...I've got to say it anyhow:
First Atom: I just lost an electron
Second Atom: Are you sure?
First Atom: Yeah, I'm positive.
This ain't rocket surgery.
So, what's the point of this thing?
The purpose of a "neutron beam" is *neutron scattering.* You can either use a continuous beam from a nuclear reactor, or a neutron pulse from a spallation source (which the SNS is). The idea is that you sent the beam at your (scientifically interesting) sample, and measure the directions and energies of the neutrons that are scattered/reflected/diffraction from the sample. This is a huge field, but here are some ideas of what it can be used for:
1. Neutron diffraction can be used for crystallography: to determine the crystal structure (hence molecular structure) of some novel material, drug, protein, etc. This can be done with x-rays also, but for some samples neutrons give better results.
2. Neutron reflectivity can be used to study thin films: to analyze coatings applied to electronics, or anti-abrasive coatings, or membranes used in medical applications, and so on.
3. Neutrons can be used to study industrial materials: for instance, a neutron beam can be used to probe a weld joint and map out the 3-dimensional arrangment of microsocpic stress patterns in the material. This has been used to design better welding processes, better aircraft components, engine parts, and so on.
4. A neutron beam can be used for "imaging" similar to an x-ray... except that neutrons can pass through dense materials (like lead) quite easily and can image organic materials with better sensitivity than x-rays.
5. Neutron beams can be used for the study of nuclear physics and chemistry, the properties of neutrons, and other particle-physics questions.
There are of course many other things you can do with a neutron beam, but hopefully that gives you an idea of the diversity of research that goes on at a neutron scattering facility.
I doubt that would attract 2,000 international scientists annualy
Well there is quite a bit of demand for neutron beam-time. Since the SNS will take the flux up a notch (8 times higher than anything we have now), researchers will be able to complete their experiments faster (or conversely complete more experiments in a given timeslot), and will also be able to detect things that perhaps went unnoticed before. So yes, there will quite a bit of demand for this installation.
IANAPP (I am not a Particle Physicist) but I *DO* work at the SNS site. I'm a software engineer in their Beam Diagnostics group, and was in the contorol room on Friday when we met this milestone. My basic understanding is that here we use our Linac to accelerate protons (H-). A minipuse sent down the linac is approx 700 ns long. They first go into an accumulator ring, and are "stacked" to increase the intensity of the pulse to target. On Friday we accumulated for around 180 pulses, design specs are for around 1000. Finally the the pulse is extracted from the ring and hits a target vessel filled with mercury. Again, IANAPP, but my understanding is that this intense pulse of protons only 700 ns long, hits the mecury, and "spalls" neutrons from the mercury atoms. Then as others have mentioned the neutrons are columnated and fly down different beam lines to be used in different refraction experiments (or they will be once this source is fully operational ;-) . Bottom line is that the particles that we acclerate are not the ones that contribute neutrons. Once more, IANAPP, but it helps me to think of it as we're accelerating cue balls, and hitting a (3D) rack of billard balls.
Firstly, they're neutral, so the charge of electrons or lattice ions they scatter off of won't give any extra Coulomb repulsion, as it would if they used proton or electron beams for scattering.
Additionally, they're massive, so the interaction will be different than X-Ray scattering.
But one of the most important characteristics is that neutrons have a spin of 1/2, and this spin looks like a small magnetic moment. So the neutrons can give useful information about magnetic interactions in the sample. Many people are studying interesting ferromagntic or anti-ferromagnetic interactions of whole new classes of materials with neutron scattering. This is also important for spintronics, where the neutrons will scatter differently off of a particle if that particle is spin-up vs spin-down.
The neutrons interact nicely with the lattice in a crystal, and with the energies involved they are a great tool for looking directly at phonon modes of the sample.
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