Doc Lightning
Doc Lightning

HOP Mad Doctor
Location: San Francisco, CA, USA
Member Since: 28th May 2001
Total posts: 13920
Posted:So I have a question for the physics dorks out there.

Why do you need to build a larger and larger accelerator in order to achieve higher speeds?

First, I understand that if a charged particle is traveling perpendicular to a magnetic field that it will experience a force perpendicular to both its direction of travel and the magnetic field, which implies that it will travel in a circle until it leaves the field, unless the field is large enough to contain the entire circle. I also understand that, although the force increases as the particle travels more quickly, that a faster particle will be deflected less by a given magnetic field than a slower particle. Thus, a faster particle in a given magnetic field makes a bigger circle than a slower particle in the same field.

At first it makes sense why you would need a bigger accelerator to move a particle faster; a faster particle needs to make a bigger circle.

But, given a project like CERN, why couldn't you simply retrofit the accelerator to increase the strength of the magnetic field? If you increased the field, then why couldn't you simultaneously increase the speed of the particles without changing the radius of the circle?

I mean, obviously there's a good reason or CERN wouldn't have been built. But I don't understand that reason.


-Mike )'(
Certified Mad Doctor and HoP High Priest of Nutella

"A buckuht 'n a hooze!" -Valura

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pineapple pete
pineapple pete

water based
Location: melbourne
Member Since: 20th Sep 2004
Total posts: 5125
Posted:from what i understand, linear accelerators are more efficient than circular ones, but linear ones have to have an end, or travel off into space for a highly unpractical distance. the bonus of a circular accelerator being that it can continue around the circle a second time, then a third, and so on.. therefore the larger the circle gets, the closer in efficiency it comes to a linear accelerator, but is much more practical..

does that make sence?

hug


"you know there are no trophys for doing silly things in real life yeah pete?" said ant "you wont get a 'listened to ride of the valkyries all the way to vietnam' trophy"

*proud owner of the very cute fire_spinning_angel, birgit and neon shaolin*

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Pink...?
Pink...?

Mistress of Pink...Multicoloured
Location: Over There
Member Since: 6th Apr 2002
Total posts: 6140
Posted:From what I understand the CERN guys did retrofit an existing tunnel... the Large Electron-Positron Collider.

Never pick up a duck in a dungeon...

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MikefromGlos
MikefromGlos

Hitman
Location: Gloucester England
Member Since: 10th Jul 2006
Total posts: 985
Posted:Maybe they just wanted a excuse to not to break the speed of light and have to re-write all of modern physics.....

he he i am mike the amazing gloscircus person who is mike.

Officaly an exception to the Poi Boys are Girls Thing

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Doc Lightning
Doc Lightning

HOP Mad Doctor
Location: San Francisco, CA, USA
Member Since: 28th May 2001
Total posts: 13920
Posted:Mike, I do know that you can make the particles go ever faster and faster. You could accelerate them forever. But as they approach the speed of light, they get more and more massive (at least from our point of view). At a certain miniscule fraction below the speed of light, you could theoretically give a proton the apparent mass of a mountain, or even a star.

What I don't get is why physicists keep saying that you would need an accelerator the size of the circumference of the Earth or the solar system in order to perform certain experiments. Surely stronger magnets could allow you to keep the accelerator smaller, right?


-Mike )'(
Certified Mad Doctor and HoP High Priest of Nutella

"A buckuht 'n a hooze!" -Valura

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MikefromGlos
MikefromGlos

Hitman
Location: Gloucester England
Member Since: 10th Jul 2006
Total posts: 985
Posted:maybe there trying to make up for somthing lol wink

he he i am mike the amazing gloscircus person who is mike.

Officaly an exception to the Poi Boys are Girls Thing

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pineapple pete
pineapple pete

water based
Location: melbourne
Member Since: 20th Sep 2004
Total posts: 5125
Posted:coleman: 'theyre kinda the best magnets in the world'

from the point where you cant do any better with the magnets available, the way i see it, by not having to turn, you decrease the amount of energy wasted in turning. so, the longer it takes to do a full rotation, there will be less wasted energy per unit of distance.. the larger the diameter of the circle, there will be larger total applied force per unit of energy wasted.. the slower the curve (tending towards infinity) the more efficient it will be..

they still cant hit the speed of light with it though

hug


"you know there are no trophys for doing silly things in real life yeah pete?" said ant "you wont get a 'listened to ride of the valkyries all the way to vietnam' trophy"

*proud owner of the very cute fire_spinning_angel, birgit and neon shaolin*

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Eera
old hand
Location: In a test pit, Mackay
Member Since: 29th May 2003
Total posts: 1107
Posted:You can picture it the same way as a car going around a corner; tight corner means having to slow down and lose energy, whereas you can speed through a large, slight corner without touching the brake.

There is a slight possibility that I am not actually right all of the time.

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pineapple pete
pineapple pete

water based
Location: melbourne
Member Since: 20th Sep 2004
Total posts: 5125
Posted:yeah, thats totally a better way to describe it smile

thanks eera

hug


"you know there are no trophys for doing silly things in real life yeah pete?" said ant "you wont get a 'listened to ride of the valkyries all the way to vietnam' trophy"

*proud owner of the very cute fire_spinning_angel, birgit and neon shaolin*

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87wt2gxq7
87wt2gxq7

veteran
Location: Birmingham
Member Since: 12th Apr 2005
Total posts: 1502
Posted:Doc, basically you're right. If you fit more powerful magnets then you'd make the particles faster. If the power of your magnets is limited for technological reasons, the only way you can get the particles to go faster is to increase the size of the accelerator.

In the case of the LHC, the tunnel was already dug, as Pink says. Digging the 'ole is pretty much the most expensive part of a project like this!


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