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Would it be theoretically possible to create a hadron collider in space by orbiting particles around a planet?

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How would you ever aim the particles and measure the scattering, at a planetary scale? – McGarnagle Nov 22 '12 at 23:14
theoretically possible, Technically improbable – Prathyush Nov 23 '12 at 16:00

Not by orbiting particles around a planet. The LHC needs a lot pf precision to work. The proton beams need to travel along the exact path we tell them to, and they must collide in a precise area. In space, due to the gravitational field being nonuniform (nearby massive bodies will cause perturbations which will change with time and be impossible to circumvent), we really can't do much about that. Aside from that, there are a lot of high energy particles traveling through space already (solar wind/etc).

That aside, we have no way of accelerating the particles. Particle colliders send the beams on a circular path. They are continuously accelerated, and after some number of laps, they are made to collide with a reverse beam. Orbiting particles can't be easily accelerated, without adding a superconducting ring. And, if we have a superconducting magnet ring, then we don't need the planet in the first place--we can keep the system anywhere.

In short a large particle collider can be built in space if we can amass the necessary resources -- but utilizing a planet's gravity for anything other than keeping the entire collider in orbit is a fools' errand -- so using the orbits is out of the question.

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What sparked this idea was the possibility of needing less equipment to achieve the same result. Obviously I am ignoring how you get it up there in the first place. So would there be any advantage to creating a collider in space, be it linear or circular, or do you create more unwanted variables. Would it be possible to accelerate particles in space where part of their journey is not enclosed? – Paul Johnson Nov 23 '12 at 22:48
@PaulJohnson: I would say the situation goes both ways. On one hand, a lot of interference is removed. On the other hand, Earth's natural shielding against cosmic rays is gone. If the journey isn't enclosed, I highly doubt it can be practically done. Not sure, though. – Manishearth Nov 23 '12 at 22:59

The reason we need a large radius for the colliders, LHC has a perimeter of 27km, is so that we can reach a very high energy in a controlled manner, with the type of magnets and cryogenics our technology can devise.

CERN accelerators

In addition, as the energy goes higher the circulating charged beams start to emit synchrotron radiation to such a large extent that the control of the beam is lost. Note that in the tunnel of the LHC the LEP experiments first ran, which collided electrons on positrons not much over 100 GeV. Radiation is the reason that now the next lepton collider, ILC, is planned as a linear collider.Higher energies for electrons in a circular accelerator are self defeating as the energy fed is lost as synchrotron radiation instead of accelerating the leptons. The LHC ring can accelerate protons to TeV energies because the proton mass is so much larger than the electron one. There is a limit to the energies that can be usefully achieved again because the losses from radiation will not allow high energies to grow effectively.

A large ring in space around the earth would would have the advantage for allowing very high energies to be achieved, with small radiative losses as they scale inversely with radius (this is for electrons) :

enter image description here

Why around the earth?

1) Satellite technology is very advanced and the satellites accurately positioned. One would need to set the quadrupoles and dipoles in satellites to keep the beams in a circular orbit and have them collide at a certain spot.

2) cryogenics would be unnecessary as well as maintaining a vacuum since these are available for free

So, imo, it can be done, but the cost would be prohibitive and then to set up experiments , which would need their own satellite, around the collision point would not be an easy thing considering the number of people who babysit experiments now ( about 3000)

Maybe in the far future when nanotechnology and robotics come into their own one could have such a successful experiment.

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If you want to dispense with the cryogenics you will need very good, actively-pointed shading so that the bits ad piece don't see the sun (and perhaps the planet as well). – dmckee Nov 23 '12 at 18:02
@dmckee Yes, particularly superconducting magnetic elements should not see the sun, but they will be in a "satellite", as I see it. – anna v Nov 23 '12 at 20:03
So would a linear set up in space be more feasible than my original suggestion? A linear set up would be easier shield or keep in shadow. – Paul Johnson Nov 23 '12 at 22:14
It would be less feasible because of kinematics. We do not see satellites lined up, do we? – anna v Nov 24 '12 at 5:27

The energy of a proton orbiting a planet is rather small to speak of a "collider".

Let us see: if $v = 10\;km/s$, then $$\frac{M_p v^2}{2}=\frac{1}{2}M_pc^2(\frac{v}{c})^2=\frac{0.938\cdot10^9\;eV}{2} \cdot (\frac{10^4}{3\cdot10^8})^2 \approx 0.52\; eV$$ Besides, magnetic field will affect charged hadrons and prevent them from "orbiting" a planet.

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