Search found 37 matches

by amiso
Tue Nov 02, 2010 10:34 pm
Forum: The Accelerator
Topic: Scrubbing??
Replies: 6
Views: 6453

Re: Scrubbing??

Because of the large collision cross section of heavy ions, I guess this is very important to have extremely good vacuum here: electrons too.
by amiso
Sun Oct 24, 2010 3:18 am
Forum: The Accelerator
Topic: What to ask the LHC team about its operations or displays
Replies: 25
Views: 5860

Re: What to ask the LHC team about its operations or displays

Yes, the number of bunches for each different detector. This makes sense. Thanks
by amiso
Sat Oct 23, 2010 11:45 pm
Forum: The Accelerator
Topic: What to ask the LHC team about its operations or displays
Replies: 25
Views: 5860

Re: What to ask the LHC team about its operations or displays

Please can someone explain the following message from the Page 1: AFS: Single_2b_1_1_1 (this one (fill 1438) is just a test ramp for checking some LHCb polarization change, but please explain what the 1_1_1 would mean otherwise)
by amiso
Sat Oct 23, 2010 11:03 pm
Forum: The Accelerator
Topic: LHC to shut down for a whole year
Replies: 8
Views: 2850

Re: LHC to shut down for a whole year

At this point (october 23rd), does anyone knows what the plan is for the winter?
by amiso
Sat Oct 02, 2010 3:15 am
Forum: The Accelerator
Topic: *** SQUEEZE ***
Replies: 3
Views: 1891

*** SQUEEZE ***

Can someone explain in a few words what this consists in? It seems that this operation takes about 20 minutes!
by amiso
Sun Sep 26, 2010 10:58 pm
Forum: The Accelerator
Topic: Loss of Luminosity
Replies: 3
Views: 1448

Re: Loss of Luminosity

>>>> "...Over time the beam becomes "blurred"..." your explanation makes a lot of sense, but it is not complete. I would like to understand better. Tell me if I am wrong: TRANSVERSE: During the "stable beam" phase, the deflection dipole magnets, and the focusing quadrupole magnets are held at a cons...
by amiso
Sun Sep 26, 2010 3:23 am
Forum: The Accelerator
Topic: Loss of Luminosity
Replies: 3
Views: 1448

Loss of Luminosity

Hi, It seems that a very important parameter of the LHC is the "Luminosity" hence the "Integrated luminosity over one fill". I can see why: somehow, this must be linked to the number of good collisions that the detectors will record in one shift! Now here is my question: It seems that the measured l...
by amiso
Sat Mar 27, 2010 4:23 am
Forum: The Accelerator
Topic: Vacuum
Replies: 11
Views: 2938

Re: Vacuum and pressure differences

Regarding the degree of vacuum, I can add the following: Achieving a high vacuum is usually a real chalenge in vacuum systems, but not here ! When a surface is at low temperature, the large molecules tends to stick to it (adsorption). The lower the temperature, the smaller the molecules that will st...
by amiso
Sun Mar 21, 2010 10:26 pm
Forum: The Accelerator
Topic: Older Events and discussion 3/22/10
Replies: 156
Views: 30096

What do the displays mean ?2

Today is March 31th. Did they try the "squeze" procedure yet. Did someone see this status displayed? I recall that they go thru the following sequence: x--precycle x--inject x--prepare for ramp x--ramp up x--flat top --squeeze << not done yet --adjust << not done yet --stable beams << DETECTOR INTO ...
by amiso
Sun Mar 21, 2010 10:14 pm
Forum: New Users Start Here
Topic: What do the displays mean ?
Replies: 85
Views: 61279

Re: What do the displays mean ?

Hi, Precycle : I think that this means that they actually ramp the magnetic field up and then down but when the beams are not loaded. doing this ensures that any magnetic hysteresis is at a known "usual" state. Doing this avoids any surprise when the beams are filled and potentially dangerous! "E : ...
by amiso
Sun Mar 21, 2010 8:38 pm
Forum: The Accelerator
Topic: Older Events and discussion 3/22/10
Replies: 156
Views: 30096

Re: ** Current Events and discussion **

I don't think the detectors are ON at this point: just "standby".
by amiso
Sat Mar 20, 2010 7:01 am
Forum: The Accelerator
Topic: Older Events and discussion 3/22/10
Replies: 156
Views: 30096

Re: ** Current Events and discussion **

"RECOVERING FROM RAMP". Now what is that? Too many emotions for one night!

I guess the action is over for tonight.

In any ways: well done guys... I wish I had been there with you.

See you tomorrow.
by amiso
Sat Mar 20, 2010 6:53 am
Forum: The Accelerator
Topic: Older Events and discussion 3/22/10
Replies: 156
Views: 30096

Re: ** Current Events and discussion **

Well, it seems that they have stopped at 300 GEV; well below 450. I guess that are would like to start another cycle very soon !
by amiso
Sat Mar 20, 2010 6:47 am
Forum: The Accelerator
Topic: Older Events and discussion 3/22/10
Replies: 156
Views: 30096

Re: ** Current Events and discussion **

Do they HAVE to do a precycle every time?

Do they have to ramp the field all the way down to zero? They could stop at 450 GEV and start loading again?