a couple of questions

Questions / discussions specific to the LHCb experiment or science
Post Reply
seedyjay
Posts: 8
Joined: Fri Nov 13, 2009 3:58 pm

a couple of questions

Post by seedyjay » Fri Dec 11, 2009 2:00 am

There are two or three questions I am having difficulty finding the answers for. Firstly, I have heard the path traveled by the beams described as a spiral, which makes perfect sense, but are they spirals even when kept in a holding pattern for longevity testing? Also, can the beams be held that way indefinitely (I have read that 4 then 10 and now 25 hours was the longest they have been sustained) in theory? Finally, where can I get a LHC blueprint so I can build one of my own?.......just kidding about the blueprint :D

dh2va
Posts: 6
Joined: Wed Dec 09, 2009 6:34 am

Re: a couple of questions

Post by dh2va » Fri Dec 11, 2009 7:55 am

I am no beam physicist, but afaik you can in first order assume a circular reference orbit.

(LHC is no circle but more an octagon.. long straight sections LSS and dipole arcs ARC)

Ok, assume now a protons runs on this reference orbit. It gets disturbed by some external force (kick it!). The guide systems will try to push it back and eventually over-do it which creates some wobbling around the reference orbit. The beam 'rings' just like a bell.

The trick is now to stay away from these beam 'tunes' as when such a tune gets excited ('resonance disaster') part of the beams will eventually hit the collimators and be lost (reduced lifetime). This can be achieved by properly setting the feedback terms for the orbit corrections.

This external force is not even necessary as any imperfection from injection will show up as a tiny wobble already.

All in all, high respect for the beams division. It used to be black magic and maybe still is sometimes.. :D

seedyjay
Posts: 8
Joined: Fri Nov 13, 2009 3:58 pm

Re: a couple of questions

Post by seedyjay » Sat Dec 12, 2009 12:30 am

Thanks for taking the time to give me this information. Hopefully, somebody will be able to expand on it some. At the very least I know a little bit more than before reading it.

josch222
Posts: 78
Joined: Sat Dec 12, 2009 4:10 pm

Re: a couple of questions

Post by josch222 » Sun Dec 13, 2009 1:14 pm

seedyjay wrote: (...) Finally, where can I get a LHC blueprint so I can build one of my own?.......just kidding about the blueprint :D
Why kidding?
There are a lot of blueprints on the web, not only at CERN sites.
Here is an example from a local university:
http://www1b.physik.rwth-aachen.de/~cms ... r/Modules/
Good luck for your DIY collider ;-)

Joerg.

seedyjay
Posts: 8
Joined: Fri Nov 13, 2009 3:58 pm

Re: a couple of questions

Post by seedyjay » Sun Dec 13, 2009 2:37 pm

josch222 wrote:
seedyjay wrote: (...) Finally, where can I get a LHC blueprint so I can build one of my own?.......just kidding about the blueprint :D
Why kidding?
There are a lot of blueprints on the web, not only at CERN sites.
Here is an example from a local university:
http://www1b.physik.rwth-aachen.de/~cms ... r/Modules/
Good luck for your DIY collider ;-)

Joerg.
Thanks. But since my net worth is probably closer to that of a sharecropper than Bill Gates or Warren Buffet, I will be putting off construction for some time yet. :P

User avatar
DCWhitworth
LHCPortal Guru
Posts: 573
Joined: Mon Nov 30, 2009 8:13 am
Location: Norwich, UK

Re: a couple of questions

Post by DCWhitworth » Mon Dec 14, 2009 4:29 pm

seedyjay wrote:Thanks for taking the time to give me this information. Hopefully, somebody will be able to expand on it some. At the very least I know a little bit more than before reading it.
Take a look at this great thread. Info from pcatom in chat that Chris has posted to the forum.

http://lhcportal.com/Forum/viewtopic.php?f=4&t=219
DC

The LHC - One ring to rule them all !

seedyjay
Posts: 8
Joined: Fri Nov 13, 2009 3:58 pm

Re: a couple of questions

Post by seedyjay » Tue Dec 15, 2009 7:32 am

Thanks for the link D C, well worth reading.

Post Reply