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200GeV Collisions at RHIC
PHENIX Experiment writes: "Brookhaven Labs has produced for the first time, collisions of gold nuclei at a center of mass energy of 200GeV/nucleon. This is a new energy regime for the high energy nuclear physics relativistic heavy ion program which is now getting underway. We have put together a bunch of nice photos of event displays for some nice central collisions, the collisions where the two nuclei hit head on. Over the next 6 months or so, we are looking to collect on the order of a petabyte of data which will then be analyzed using our VA Linux farm operated by the RHIC Computing Facility."
The figure is 200 GeV/nucleon. Since a gold nucleus has about 250 nucleons this is about 50 TeV/nucleus.
This sort of accelerator explores a different physical regime from something thje LHC or the Tevatron, which use single higher-energy particles. It
By colliding particles at every-increasing energies we can split them into their contituent sub-particles. The sub-particls require lots of energy to be "dissociated" from their parent particles. As new particles are discovered, or their existence is confirmed, new theories are made as to whether they have smaller constituent particles. To see them, if they exist, requires more energy, ie faster collisions.... and so on.
By finding these sub-particles we can figure out how the particles in the "particle zoo" behave, why energy and matter appear as they do, and how the universe formed etc.
I'm out of my tree just now but please feel free to leave a banana.
Mmm...should be looking for lithium flares, then. :)
-- Veni, vidi, dormivi
Emmm...
you're looking for real-life benefits from particle physics?
As someone who has worked in both particle physics and medicine I can point out:
*) development of accelerators for cancer radiotherapy, used routinely in hospitals every day
*) advanced dedicated accelerators for novel cancer therapy, like pion therapy and boron neutron capture therapy
*) synchrotron light sources, used for biomedical and semiconductor materials research
*) detectors developed for Positron Emission Tomography scanners
*) development of high field superconducting magnets, as used both in particle detectors and MRI scanners
I think that's a good few examples!
In a word, no. These energies were reached a long time ago, but the lack of a Higgs is not surprising. Remember that the Higgs is never produced alone, and that other particles produced need energy too. You need a center of mass energy on the order of a few TeV before you look for the Higgs.
- W. Blaine Dowler
http://www.bureau42.com
It doesnt really matter how much mass you have, or gravity to make a black hole, what matters is how compressed that mass is. IIRC, if the earths mass were contained in something the size of a pinhead, it would become a black hole with an event horizon the size of a marble. As you accelerate an object, its mass increases, but its size does not. Accelerate a pinhead so that its mass became that of the earth, and you would have a black hole with the earths mass, wether or not it would be stable if slowed down is another matter, but it would become a black hole for awhile.
There's a lot of discussion of RHIC black holes on everything2. See What if a black hole was created on Earth?.
I've been posting on the net since 1994 and I still haven't come up with a good sig!
Fermilab already has a Tevatron.
- "Hear that?! The percolations are imminent! Cease your ingress!"
count me in as getting it - but not from a computer - Tabletop. SJGames Rawks.
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In relativity, mass and energy are equivalent. We know that E^2 = m^2*c^4 + p^2*c^2 (E=energy, p=momentum, m=mass, c=light speed) where E=MC^2 is the case for a massive particle at rest and E=PC for a massless particle such has a photon, since m=0. As long as you have enough energy in a small enough volume, a black hole can form. This works because, as stated before, mass and energy are equivalent in relativity. Photons are massless but have energy, so in theory one could create a black hole just by having enough light in one place! It's awfully hard to do in practice, though, as the energy density needed is very, very high.
Interestingly enough, one can also generate a black hole by having constructive interference between very strong gravity waves. I saw a video from a simulation that showed this happening at a relativity conference I was at (I'm an astrophysics grad student) and it was very cool. I can't seem to find the link and google is on the fritz, but I believe that it was a simulation done by the Virgo Consortium (a bunch of European universities).
One of the main reasons that RHIC was developed was to study the quark-gluon plasma. Though there are more energetic acclerators (Fermilab's Tevatron, for example), RHIC is unique because it collides gold nuclei together instead of single atoms or leptons. Even so, most of a gold nucleus is empty space, so when they collide, the nuclei basically pass through each other, but at such a high energy that the bonds that hold the quarks together are temporarily broken, creating a very hot, dense quark-gluon plasma. (BTW, gluons are the carriers of the 'strong' force and hold quarks together to make hadrons such as protons and neutrons). This allows physicists to study the properties of very hot, dense matter, such as the stuff that existed shortly after the big bang, before the era where protons and neutrons were formed. A paper describing the potential physics of it can be found here.
- Dan I.
The known quantity for looking at melting J-psi, or creating the quark-gloun plasma is energy in, the measured quantity is temperature, avg kinetic energy. There will be a region where energy increases but temperature does not, this is the temperature at which the phase transistion takes place.
--Jimmy has fancy plans; and pants to match.
The gold ions don't collide as such and shatter. IANAHEPPOAFYOLE (I am not a high energy plasma physicist or 15 year old leagal expert), but because they're traveling at relativistic speeds they pancake and pass through each other inelastically imparting some of their lost energy to the vacuum behind them. The vacuum, being unstable with this extra energy spots forth a soup of primordial particles. Particles, who's composition depends on its temperature, which in turn comes from the enegry imparted to the vacuum in the collision. One interesting particle to look at is J-psi. They could simply graph detections of J-psi artifacts vs temperature or energy density (variable the researchers control). It should look just like any phase transition diagram, such as one might do for ice to water. At a certain critical temperature J-psi should essentially 'melt' and then we would know our quark gluon soup is done. And if my hamerster is right, that should be at about 2 trillion degrees K. Careful, the soup's hot.
In a way, what is being done is looking, in extreamly fine detail, at what came before the cosmic background by something like 300,000 thousand years when our universe was about the size of the solar system.
I think someone published a paper that a device like this might impart enough energy to the local vacuum, that it might settle back down to a lower energy state and trigger a big bang giving birth to a new universe. (Now that would be the weapon of an evil genious worthy of James Bond.) Supposedly something like 5,000 similar lead - lead collisions take place every year in the universe, so it's probably pretty unlikely. But it would be pretty funny if they had to state man wouldn't destroy the universe from Long Island for the EPA. Of course it'd probably be even funnier if they were wrong.
--Jimmy has fancy plans; and pants to match.
Don't you get the impression they resented having to write this?
--Jimmy has fancy plans; and pants to match.
The real worry was some new type of exotic matter (a reconfiguration of the quarks that make up protons) that was a lower energy state than normal subatomic particles like protons, and that the transition to such a state would release enough energy to coerce nearby particles into it, or it would simply be a catalyst to induce nearby particles to change over.
The argument against was that far higher energy collisions happen constantly in the high atmospher, on the moon, other planets, for billions of years and they haven't fallen prey to such a situation.
The other theory, that it would create a black hole, never held much water because it would radiate away its mass instantly, far more rapidly than any nearby particles falling into it could replenish it. It requires being at the core of a massive gravity well to keep feeding it to overcome this (presumably, and that assumes black holes actually exist.) In one story I read, it was estimated a black hole would have to be about the size of a marble before it could feed itself fast enough on (or in) a planet (at which point, you'd only have a few seconds left to live anyway. You'd probably die a fraction of a second before being pulled in because your body was torn apart, atom-by-atom, by the tidal force difference in the gravity between your feet and your head.)
I am for the complete Trantorization of Earth.
But then again, they have those Linux'es to handle that, so i guess they'll manage. One doesn't start something like this unless you are quite sure you'll learn something.
Yours Yazeran
Plan: To go to Mars one day with a hammer.
Michael Faraday talking to Benjamin Disraeli, Chancellor of the Exchequer and later Prime Minister, after a demonstration of various projects including induction:
Dizzy: What good are all these things? Faraday: One day, Sir, you may tax them.
Alternative: Faraday: What use is a baby?
Soon they'll be able to make gold-pressed latinum.
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Whew... at least it wasn't 200 Ogre Mk IV's. (someone had to say it)
Lose = not win