Size of particle accelerators

In summary: This could be done using a linear accelerator, but it has some limitations - the beam has to be very tightly focused, and the CLIC has to be very large to achieve a high enough energy.
  • #1
Ryan_m_b
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I have a very lamans understanding of particle accelerators, one of the things I gather is that their large size allows for the particles to be accelerated to higher speeds. This can't be done easily at smaller sizes because a smaller circumference will mean a more extreme angle for the particles to bend round (apologise for probably appalling phrasing on this topic). Is this the case? If so is making progressively larger accelerators the only option or could better technologies achieve the same result?

This question is prompted by hearing a statement that at some point in the future particle physics of this sort would come up against a hard limit; that limit being the circumference of the Earth itself (assuming one build an accelerator along the equator). The statement wasn't said as though this would actually happen but more illustrating the point. I've done a bit of googling but it's hard to find a resource that isn't too popsci that is accessable.
 
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  • #2
You have it approximately correct. The loss of energy in the beam due to bending can be quite substantial the higher the energy (speed) of the beam. Synchrotron losses are always a major problem for such particle accelerators.

Note that circular accelerators aren't the only game in town. The history of high energy physics experiments has always gone circular-linear-circular-linear-etc. The last major linear accelerator was the one at SLAC that has been shut down. So since LHC was the last major accelerator facility constructed, the push right now is for that to be followed by another linear accelerator, thus the push for the ILC. Linear accelerators do not have the energy-loss issues from bending, but of course, it has issues with a finite length and how high of an energy it can achieve for such a finite length.

Zz.
 
  • #3
Ah cool, glad to see I wasn't off base. Did a bit of reading about synchrotron radiation, is there any technology being worked on that could minimise this effect so that a larger circular accelerator could be made more efficient? Regarding linear accelerators I guess the higher efficiency is bought by lower speeds due to the finite length?
 
  • #4
I thought that there is no way to bypass the synchrotron radiation (at least for the circular particle accelerators)?
 
  • #5
Ryan_m_b said:
Ah cool, glad to see I wasn't off base. Did a bit of reading about synchrotron radiation, is there any technology being worked on that could minimise this effect so that a larger circular accelerator could be made more efficient? Regarding linear accelerators I guess the higher efficiency is bought by lower speeds due to the finite length?

We can certainly minimize it by reducing the radius of curvature and thus, making the accelerator larger in diameter, but it will be prohibitively expensive and huge! The LHC is already a beast and expensive.

Not sure what you are asking about linear accelerators. As with the circular accelerator, you get to higher energies by making it longer using current technologies. There are new, exotic schemes of doing particle acceleration (laser/electron/dielectric wakefields, for example), but those won't be practical for several more years since they are still in the R&D stage right now.

Zz.
 
  • #6
You have to distinguish between electron and proton colliders here (antiparticles are always included).

Synchrotron radiation is limiting the energy in synchrotrons for electrons - for a fixed radius, energy loss goes with the 4th power of the energy, at some point you lose as much in the curves as you can add in the straight sections.
Due to this 4th power, going towards even higher energies needs linear accelerators. The Chinese think about a circular collider a bit above the LEP energy (optimized for higgs production), but well below the ILC values.

For protons, synchrotron radiation is something you have to take into account, but it does not limit the energy. For protons, the field strength of the dipole magnets is the limit - for a fixed radius, more energy needs stronger magnetic fields. You can upgrade your magnets a bit, but not by orders of magnitude, so you need larger accelerators. Still way better than linear accelerators.

Linear accelerators have an energy that is roughly proportional to their length - a longer accelerator just allows to put more cavities inside to accelerate particles. As all particles are just used once, they need significantly more power, have just one spot for an experiment (the ILC is planned with movable detectors to have two experiments) and have some other issues (damping, for example - the ILC will have two small synchrotrons to do that).Plasma wakefield acceleration could be game-changing. A factor of 1000 in terms of gained energy per length...
SLAC, DESY and CERN are all building/doing experiments for this, we'll have to see what they can find out.

Another interesting idea is the CLIC concept - use one strong, low-energetic beam to generate electromagnetic oscillations, guide them to another weak, high-energetic beam to accelerate this.

Even more futuristic (in my opinion) is the idea of a muon synchrotron. Muons are heavier than electrons, so they can be accelerated to significantly higher energies (roughly like proton accelerators). The disadvantage? Muons just live for microseconds. No way to use anything similar to the LHC magnets with their 20 minutes to ramp them up.
 

What is the purpose of a particle accelerator?

A particle accelerator is a machine that uses electromagnetic fields to accelerate charged particles to high speeds. The main purpose of a particle accelerator is to study the fundamental properties of matter and the forces that govern them.

How big are particle accelerators?

The size of particle accelerators can vary greatly, depending on their purpose and design. Some accelerators can be as small as a few meters, while others can be several kilometers long.

What is the largest particle accelerator in the world?

The largest particle accelerator in the world is the Large Hadron Collider (LHC) located at the European Organization for Nuclear Research (CERN) in Switzerland. It has a circumference of 27 kilometers and is used for high-energy physics experiments.

Why do particle accelerators need to be so large?

The size of a particle accelerator is directly related to the energy of the particles it can produce. The larger the accelerator, the higher the energy that can be reached. This is necessary for scientists to study the smallest particles and understand their properties and interactions.

Are there any risks associated with particle accelerators?

Particle accelerators are generally safe for both the operators and the environment. However, there is a small risk of radiation exposure for those working in close proximity to the accelerator. Safety protocols are in place to minimize any potential risks.

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