PDA

View Full Version : Largest safe particle collider



Tom Mazanec
2012-Apr-18, 10:32 PM
There was some concern about the LHC creating a black hole, strange matter, a"true" vacumn, or some other world destroying phenomenon. The proof that this would not happen was cosmic rays. The 14 Tev beams would have the relativistic equivalent of a 100 Pev (10^17) cosmic ray particle hitting the upper atmosphere, and there have been cosmic rays three orders of magnitude stronger.
I forget the formula to calculate how high the beams must be to exceed this cosmic ray equivalence. What energy of colliding particles is equivalent to the strongest cosmic rays?

cjameshuff
2012-Apr-19, 04:27 PM
There was some concern about the LHC creating a black hole, strange matter, a"true" vacumn, or some other world destroying phenomenon. The proof that this would not happen was cosmic rays. The 14 Tev beams would have the relativistic equivalent of a 100 Pev (10^17) cosmic ray particle hitting the upper atmosphere, and there have been cosmic rays three orders of magnitude stronger.
I forget the formula to calculate how high the beams must be to exceed this cosmic ray equivalence. What energy of colliding particles is equivalent to the strongest cosmic rays?

I can't think of any rationale for equating 14 TeV accelerator collisions to 100 PeV natural ones. 14 TeV is 14 TeV.

And in any case, there are vastly more violent events than the collisions of those cosmic rays. Pair production supernovas that fuse most of the core of a supergiant star in a few seconds, hypernovas of even larger stars that collapse directly into black holes, collisions between compact objects like white dwarfs, neutron stars, and black holes, etc.

Tom Mazanec
2012-Apr-19, 04:42 PM
Those are not on nuclear particle scales.
I found the answer on the Wikipedia page for Ultra-high-energy cosmic ray.
The OMG particle's 300 Pev was equivalent to 50 times the LHC energy, or about 750 Tev for colliding particles.

cjameshuff
2012-Apr-19, 06:08 PM
Those are not on nuclear particle scales.

You don't think some pretty energetic things might happen on those scales when neutron stars merge or supergiants collapse directly into black holes?



I found the answer on the Wikipedia page for Ultra-high-energy cosmic ray.
The OMG particle's 300 Pev was equivalent to 50 times the LHC energy, or about 750 Tev for colliding particles.

No, it was roughly 21 thousand times the LHC energy. 300 PeV/14 TeV. The Wikipedia article mentions something about the energy available to the collision as a function of the kinetic energy, but the very same function would apply to the LHC particles. To equal the collision of a 300 PeV particle you need a 300 PeV particle.

Ara Pacis
2012-Apr-19, 06:14 PM
You don't think some pretty energetic things might happen on those scales when neutron stars merge or supergiants collapse directly into black holes?

No, it was roughly 21 thousand times the LHC energy. 300 PeV/14 TeV. The Wikipedia article mentions something about the energy available to the collision as a function of the kinetic energy, but the very same function would apply to the LHC particles. To equal the collision of a 300 PeV particle you need a 300 PeV particle.
Perhaps what he's suggesting is that the larger giga-scale effects subsume and mask the nano-scale effects as distinguishable from thousands to billions of lightyears away..

Tom Mazanec
2012-Apr-19, 06:44 PM
One is a 300 Pev particle hitting a 0 Pev particle (some near-mostionless atomic nucleus in the atmosphere). The other is a 750 Tev particle hitting a 750 Tev particle (two intersecting beams in a hypothetical hyper hadron collider)). In the frame of the collision, the energy available to do stuff is the same. Since there have been 300 Pev cosmic rays, a 750 Tev collider should be safe, but I would not want to risk building bigger ones.

Nereid
2012-Apr-19, 06:57 PM
IIRC, the highest energy cosmic rays - "seen" to date - have energies > 10^21 eV.

What's not yet known, with any certainty, is whether they were protons (so the same as the LHC) or Fe nuclei (or something else). HOwever, as I understand the OP's question, it wouldn't matter, one way or the other.

10^21 is somewhat greater than 10^17 :p

Tom Mazanec
2012-Apr-19, 07:40 PM
10^21 is somewhat greater than 10^17
Yes, Nereid, so our colliders are still safe.
At least till we enlarge them 50 fold!

Jens
2012-Apr-20, 06:39 AM
One thing that comes to mind. As long as you accept the big bang theory, then it appears that there was a colossally energetic event which gradually gave way to the fairly mild conditions we are experiencing. So I would assume that no matter how powerful a collision you make, it's always going to go downhill from there, so there really isn't any way to make anything dangerous in the sense you mean. Of course, you can make something that is locally dangerous if there is insufficient shielding. But nothing leading to an out-of-control reaction. Otherwise the universe wouldn't be here in the first place.

But that's just my layperson's guess.

Shaula
2012-Apr-20, 07:22 AM
Well, there is the whole possibility of false vacuums. Could be some rather nasty effects with these at lower energies than the initial conditions. Last time that possibly happened was around the strong/electroweak unification energy.

publiusr
2012-Apr-21, 07:52 PM
10^21 is somewhat greater than 10^17
Yes, Nereid, so our colliders are still safe.
At least till we enlarge them 50 fold!

How'd you know I was working on a heavy lift collider? ;)