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particle accelerators

C

CTho9305

Elite Member
I was talking to my physics friend trying to understand how they work / what limits the speed. What I understood is that if you take two plates, with a 1V difference and shoot a (charged?) particle through them, it will gain 1eV each pass. The reason it doesn't go on forever is that the particle radiates some energy when you force it to turn around to come through again. At a certain, speed/energy, it loses at the same rate it gains, so you can't go any faster.

I was wondering then, if you used gravity to cause the change instead, would you lose energy? because the way I understand it, from earth's frame of reference, it is moving in a straight line - the sun's gravity curves space to cause this.

Soooo... if you conveniently had a "mini black hole" (
rolleye.gif
) and put the accelerator section perpendicular to it, could you theoretically ocntinue to accelerate the particle until its mass becomes siginifcant relative to objects around it (e.g. the black hole) or the orbit gets too big?
 
ok here goes
well that is true for the particle accelerators that are in the shape of a donut (im hungry =P). but there are linear accelerators that use applied electrics fields to maximize particle acceleration in a straight line.
and while it is it true you would no longer have to supply the energy to turn the particle in a donut accelerator, energy is still lost because the energy applied to it isnt in the diretion of the fields acceleration. and eventually, its gravitational potential energy will come to zero (when it hits the black hole or whatever is drawing it). so it has the same problem.
 
I currently use particle accelerators to do research, so I'll let you know how they work and the maximum speed a charged particle can move through it. A particle accelerator can be either a linear or circular accelerator. One of the biggest one's in the world is the circular particle accelerator at FermiLab. This accelerator is the height of a house tall. A particle accelerator will only work on charged particles, i.e. protons, electrons, antiprotons, and positrons, but not neitrons and antineutrons (both are neutral). The particle accelerator itself is in the simplest terminology an electromagnet. The particle is taken from a point in the accelerator, then accelerated to near light speed velocities by using the magnetic fields generated by the electromagnets. Multiple particles with different charges are able to be accelerated in oppsosite direction. One use of the accelerator at FermiLab is they take antiprotons from the antiproton generator, and protons. They accelerate each one in opposite directions. They reach 99.9999% of the speed of light and then an orchestrated collision is performed under one of the sensors. The sensors take a "snap-shot" of the reaction and then the computers analyze the data from the collision. One use of this collsion is the search for "The God particle" or Higg. This particle is what is believed to give subatomic particle mass and gravitational fields. The reason for the sub-light speed speed-limit is due to the speed of electricity in the circular movement. Yes, electricity is moving at the speed of light (186,000 miles/second) but in the circular direction, the particle that is being accelerated is constantly changing direction. It is unable to reach the speed of light due to the constant velocity change. (the definition of velocity is speed in a given direction, in this instance the direction is constantly changing).

Theoretically in a black hole, matter is converted into energy, then from the spewing "burb" from the black hole energy is reconverted back into matter. In the center of a black hole is what is known as a quantum singularity. This is a point in space that has an infinite gravitional field that will "suck" any matter into and compress it under extremely large loads. Currently some physicists believe that a black hole may be the entrance to an Eintein-Rosen bridge (wormhole in lamens terms). An Eintein-Rosen bridge is beleived to connect 2 distant points in space so that when you go through the bridge the distance is shortened dramatically. Space is not a flat plane as many people perceive it to be. Space actually has indentations from gravity fields, such as stars, planets, moons, black holes, etc... All of the stress on the space-time continuum is believed to cause it to go around in a circle. An Einstein-Rosen bridge connects point A on top to point B on the bottom and allows you to go straight through the space-time continuum. In traditional space flight you would have to go around the entire circle to go from point A to point B.

To get back to a particle accelerator, when collisions between different particles occurs many different sub-atomic particles are formed. Bottom quarks are usually produced between collisions of protons and anti-protons. The sub-atomic world is much more complicated than we can ever believe. A few years ago we thought the smallest things were, protons, neutrons, and electrons. We now know that these particles are made up of different particles, such as the many different types of quarks, muons, tau particles, neutrinos, etc... Particle accelerators give us insight to these particles because as we destroy the bigger ones, they break apart into their smaller counterparts.
 
You still have the problem of the mass. The closer you get to c the more energy you need to accellerate the particle. To reach c you would need an infinit amount of energy. 🙁
You might gain a bit more speed but won´t solve the problem....(mini black holes seems to me a bit too much efford 😉 for a small success )
 
You are correct about the mass/energy problem, that is another reason we can only accelerate a particle like a proton up to 99.9999% the speed of light. The energy/acceleration graph for a particle accelerating to the speed of light is an exponential curve. Depending on the resting mass, the energy required to reach 99.9999% the speed of light differs. When the accelerators are in use they use a lot of power, but they are in use for such a short time that a quick burst of a lot of energy is possible. A particle, that if certain numbers are plugged into E=mc^2, is a tachyon. A tachyon is theorizes to be a particle that is native to faster than light speeds. With normal sub-light speed matter, as you increase the energy in the particle, it accelerates and to get it to super-light speeds an infinite amount of energy is required, and when energy is removed, the particle slows down. With a tachyon, as energy is increased, the particle slows down and an infinite amount of energy must be used to slow it to sub-light speeds, and as energy is decreased, the particle accelerates and you must remove an infinite amount of energy to reach infinite velocity.
 
jsang - i thought a circular accelerator was a linear accelerator with a loop around it for many passes through.
krazikid - the idea of using a black hole (or maybe shooting particles around the sun 😉) was to avoid having to accelerate the particles. if they go in a circle because they are orbiting something with a lot of gravity, i was under the impression there woudlnt' be any energy lost.
j.zorg - I understand that. but the idea here is to go faster than whatever the current fastest is (purely theoretical) or use heavier particles, etc.
 
CTho9305, the only way to use a sun to move a particle is to accelerate it first, and then place it in orbit (if it is moving too fast it will leave orbit). As you orbit the sun, you move at a constant speed. The Earth is always orbitting the Sun at a constant rate. The only reason we have a leap year every four years, is because an orbit around the Sun is actually 365.25 days. We use 365 days (or 366 on a leap year) because it is easier, it also keeps the daytime inline with night time. A black hole does not have anything orbitting it in a normal sense. The "things" orbitting a black hole are not in a natural orbit, they are gradually being pulled in to be "fed" on. When you put something in orbit around a black hole, it will only be accelerated as it is being pulled in. If you could put something into a true orbit around a black hole, it would orbit at a constant rate.
 
It seems that a black hole here is being used in the science-fiction sense as a galactic vacuum cleaner (sucking up all matter in nearby regions of space). I may be mistaken but I was taught in my astronomy course that a black hole exhibits the same gravitational properties as a star of equivalent mass.
 


<< It seems that a black hole here is being used in the cience-fiction sense as a galactic vacuum cleaner (sucking up all matter in nearby regions of space). I may be mistaken but I was taught in my astronomy course that a black hole exhibits the same gravitational properties as a star of equivalent mass. >>


no, we just need something really heavy
a star of sufficient gravity would be bigger than earth, so the black hole is more convenient to put at the center of a particle accelerator 😉
 
A black hole is just mass squezzed past the point of no return. The Sun would have to be squezed intot he size of my home town ( 12 mile diameter or so ) for it to become a black hole.

The Problem is, no matter how you add energy to the particle being acceleratied, sooner or later is is going to get to heavy to add any more energy to, weither the black hole is adding the energy or the electormagnets are adding the energy.

<-- lives down the street from Fermilab. Maybe I need a summer job?

<edit>
Ariel View
Looks big doesn't it 🙂
 
KraziKid - I really dont think you're understanding my question.

Lets start out with a simpler question:
Why do particle accelerators have a max speed, and why are bigger accelerators faster?
 
Okay, the reason there is a speed limit on the particle accelerators is due to the constant change of velocity of the particle. As the particle is being moving by the accelerator, it is going around in a circle. This cause it to be constantly turning in one direction. As it turns some of the speed is lost. The reason larger accelerators are faster is because the particle does not have to slow down as much to make the turn. Try and use this analogy. Using a car going around in a circle. If the turning radius of the car going around in a circel was 5 meters, its speed could only be x k/h. As you increases the turn radius, the faster the the speed could be.
 
I think it may be possible to use a black hole as an accelerator. If you can calculate the exact velocity necessary to slingshot a particle around a black hole, you may be able to get faster speeds than any particle accelerator on Earth. You'd only have one pass, and one would probably be all you need.
The problems would probably include the constantly increasing size of the black hole and the extremely small margin of error. You'd have to be just skimming the event horizon or even touching it at one point to get speeds greater than what we can get now. In essence, your particle accelerator would be a sort of gun aimed at some angle away from the black hole. You'd fire the thing and your particle would get drawn to the black hole, then swing around the other side.
I'd imagine we do not have the capability to do this anytime soon, and by the time we do, we probably wouldn't have a need.

And yes, you can technically have a black hole with the mass of a beach ball, but have fun shrinking it down to the necessary size.

And, no, electricity does not flow at the speed of light. Otherwise, it would be light. The reason for the sub-light speed is due to both the speed barrier and the propagation time for electromagnetic fields.

The subatomic world isn't complex per se. It's actually pretty well organized.
Much like zoology.
Too much like zoology.
I hate bio, I really do.
 
Originally posted by: KraziKid
Okay, the reason there is a speed limit on the particle accelerators is due to the constant change of velocity of the particle. As the particle is being moving by the accelerator, it is going around in a circle. This cause it to be constantly turning in one direction. As it turns some of the speed is lost. The reason larger accelerators are faster is because the particle does not have to slow down as much to make the turn. Try and use this analogy. Using a car going around in a circle. If the turning radius of the car going around in a circel was 5 meters, its speed could only be x k/h. As you increases the turn radius, the faster the the speed could be.
Click to expand...

not really... if you strap a rocket engine to the car directed at the center of the circle around which you're turning, you could probably make a 1 meter radius turn at a few hundred miles per hour. or if you had REALLY good tires....

How does that relate to particle accelerators?

sahakiel: after getting the ansewr this question i'll look at your answer again 🙂
 
Actually you're pretty much correct CTho.

When an object is turning in a circular path, the acceleration that is causing the circular motion is always directed radially inwards. Since the velocity of the object is pointing tangential to the surface of the circle described, it becomes easy to see that the centripetal acceleration vector is everywhere perpendicular to the velocity vector. Therefore, the centripetal acceleration has no affect on the magnitude of the velocity vector, it merely changes the direction. This principle is the basis of the mass spectrometer; particles of varying mass are subject to the same force, thus they accelerate differently giving a different final velocity, and when they are turned they turn with differing radii, this would not work as well if the turning force also accelerated the particles.
 
I was wondering then, if you used gravity to cause the change instead, would you lose energy? because the way I understand it, from earth's frame of reference, it is moving in a straight line - the sun's gravity curves space to cause this.

Ok, let me try this 🙂
This should be possable. The problem with a particle accelerator is the turning of the particle while in the accelerator. The turingin takes energy, and at a certain speed that turning force is more than the accelerator can add to the particle, so you hit the speed limit of that accelerator. If you add a black hole of sorts to the center of the accelerator, the gravity will help to pull the particle in a curved line the problem is, to hit the speeds required the particle would have to be extremly close to the event horizon ( within a diameter of the black hole ) for the effet to be worth harnessing for our purposes.

Imagine this. Space time is somewhat like a mattress ( please guys, don't kill me ) if you put a bowling ball on it, you get a gengle curve to the "face" of the mattress. The problem lies in when a extreeme mass is placed on it. A back hole would basicly tear right through the matress, and leave an impression a little over the diameter of the black hole, and the "sides" of the mattress or space time would be nearly straight up and down, without the gentle curve because all the mass is concentrated in such a small area. The particle we would be accelerating would have to be on that neavr verticle section of space time, which is extremly close to the singlularity. I think the acelrator would be somewhere in the "foot" radius section instead of the mile radius section. It should work, but I don't see how it would be usefull. No testing equipment would be able to fit in that area. As Sahakiel said, we may be able to use the black hole as a sling shot, but more than a pass probably would not be possable as after one pass it would be difficult for the particle to escape the gravity of the black hole.


Back to the size ? of the accelerators. The larger the diameter of the accelerator, the more energy we can add to the particle, therefore the faster it can go.

JSang: Yes, ther are linear accelerators. Fermi Lab has a few. If you look at the pic I posted from mapquest, you can see a few along the "injection" lines on tangent to the main accelerators.

<edit>
I hate that new quote system
</edit>

 
interesting. now another question:
if I take a particle (say, a proton) and shoot it at a few thousand miles per hour around a circular accelerator, then stop accelerating it, will it decelerate as it continues to go around? (few thousand miles per hour so that it is relatively slow, avoiding relativistic effects)

how about if I take that same proton, shoot it in such a way that it is in a stable orbit around a black hole/star, will it decelerate? (I would expect no, otherwise a stable orbit woudln't be possible and earth would currently be spiraling towards the sun, and the moon would be crashing towards the earth instead of drifting away)
 
if I take a particle (say, a proton) and shoot it at a few thousand miles per hour around a circular accelerator, then stop accelerating it, will it decelerate as it continues to go around? (few thousand miles per hour so that it is relatively slow, avoiding relativistic effects)

It would have to decelerate as changing the direction would take some kind of energy. Eiter inputted from outsize, or taken from the particle. The particle wold require energy from the electromagnets to change the direction of said particle.

how about if I take that same proton, shoot it in such a way that it is in a stable orbit around a black hole/star, will it decelerate? (I would expect no, otherwise a stable orbit woudln't be possible and earth would currently be spiraling towards the sun, and the moon would be crashing towards the earth instead of drifting away)

No, it would not decelerate since space time would be curved, so the particle would be "falling" towards the center at the same rate the black hole is rotating away from it. It would not be possable for the particle to take energy from the black hole and spped up while simultainusly pulling away tho. To gain speed it would have to "fall" towards the black hole, or have a "spiraling" in trajectory.

Did that make any sence at all? It is still way to early for this 🙂
 
so a particle accelerator's maximum speed is largely due the speed lost turning the particle. If you build a particle accelerator around a black hole (saturn = black hole, have it be like the planet's rings, completely not to scale), then the black hole would help with the turning, meaning you'd need to spend less energy forcing the particles to go in a circle, decreasing the loss of speed, giving you a faster accelerator, correct?
 
That would be the correct idea, the main thing here is getting the right speed to start with then the particle will remain in an orbit, neither falling towards the black hole or fly away from it. I remember a simplistic example of this from a book, if a tennis player hits the tennis ball horizontally (or perpenticular to the surface) around 7.8 km/s, then the tennis ball will travel around the earth in an orbit. Of crouse this largely depends on the mass of tennis ball and I can't remember the details but at the time it's very reasonable (the book did a calculation)

So there is a right speed for the particle for this to work.
 
As a "physicist" you grasp of the basics continues to amaze me.

As you orbit the sun, you move at a constant speed.
Click to expand...
No
Only for circular orbits, which exist only in textbooks.

The Earth is always orbitting the Sun at a constant rate.
Click to expand...

No
The earth's orbit has an eccentricity of 0.01671022 which means it is moving about 3% faster at perigee then at apogee. Maybe I'm just picking nits here, but your first statement just bugs me.

A black hole does not have anything orbitting it in a normal sense. The "things" orbitting a black hole are not in a natural orbit, they are gradually being pulled in to be "fed" on. When you put something in orbit around a black hole, it will only be accelerated as it is being pulled in. If you could put something into a true orbit around a black hole, it would orbit at a constant rate.
Click to expand...

No, its angular momentum would be constant, its velocity would not be. And yes, you could put an object in orbit around a black hole. It's just a gravity well, just a point source instead of a distributed source. In fact, a black hole in isolation may be the only place where you might achieve a true circular orbit, contrary to my statement above.

 
One thing I didn't notice anyone point out is that if you accelerate a charged particle it gives off radiation. The harder you accelerate it the more radiation it gives off.

Anything moving in a curved path is being accelerated even if the magnitude of the velocity vector doesn't change (i.e. constant speed but not constant direction still equals acceleration) so a charged particle moving at constant angular velocity around a ring is still being accelerated, even if it isn't going any faster, simply because it's path is curved. This results in radiation being given off (synchotron radiation if you happen to be using electrons).

It actually doesn't require energy input to hold a particle in a curved path it just requires a force such as gravity, electrostatic or electromagnetic. As the particle moves through the field it can trade kinetic energy for potential; a satellite moving slower at apogee (the highest altitude of the orbit) is an example. Unless there is friction or some other mechanism to convert kinetic energy irreversibly into heat, or you are drawing off energy by some other means, a particle can continue in a curved orbit with a constant velocity magnitude indefinitely (the solar system is a good example of this type of perpetual (for all practical purposes) motion). However with charged particles there is a mechanism that draws off energy; the emmission of photons. The harder you accelerate a charged particle the more radiation it gives off until you are accelerating it with all the power you have at your disposal at which point you reach max velocity because you are losing energy as fast as you pump it in.

An interesting historical note is that the "fact" that accelerated electrons give off radiation spelled doom for the Bohr model of the atom (with electrons whirling about a nucleus) since those electons would have to give off radiation and fall into the positively charged core. The quantum theory of radiation helped to resolve this dilemma.

I believe the reason why accelerators are being fashioned as larger and larger rings is to minimize the acceleration losses inherent in moving a charged particle through a curved path. A larger diameter means less acceleration but you still get to circulate the particles through the acceleration coils time and time again, unlike a linear accelerator where you make one pass. This would lead me to belive that the synchrotron radiation losses are the dominant factor in limiting the speed of accelerators, at least for electrons with their small rest mass.

The relativistic effect on mass was mentioned. A fast moving particle has a larger apparent mass (to a stationary reference frame) so it requires more energy to increase its velocity. As it approaches the speed of light the apparent mass becomes infinite. The reason photons can travel at the speed of light is that they have no mass (at least that was the explaination last I checked).

Tachyons have some odd properties that are explained a number of ways. One explaination is that they move backwards in time and so they appear to move faster than light. This is a physical interpretation of a mathematical model and not a descriptive analysis of natural phenomenon so it doesn't necessarily represent physical reality in all it's aspects. In other words, this physical interpretation leaves something to be desired even if the math does work out. It doesn't really portend the invention of time machines or faster than light travel (kind of like learning there is no Santa isn't it 🙁 ). Still some pretty amazing things have come out of seemingly meaningless mathematical side effects of physical models so there is not telling what future technology and science will bring.

Max L.
 
Originally posted by: EmMayEx
This is a physical interpretation of a mathematical model and not a descriptive analysis of natural phenomenon so it doesn't necessarily represent physical reality in all it's aspects. In other words, this physical interpretation leaves something to be desired even if the math does work out.

Max L.
Click to expand...

Reminds me of a quote ussually attributed to Einstein.
As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.

BTW: Here is a nice collection of Einstein quotations I found when googleing for the exact quote above.
 
emmayex - my original question was directly related to your statement about electrons giving off radiation when they are accelerated. So would an electron in an approximately elliptical orbit around a star or black hole give off radiation and lose energy, or not?

The deceleration of an electron in a particle accelerator is largely related to the radiation it gives off, correct?
 
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