What does ... mean?

The place to discuss the LHC. Commissioning, operation, issues, events ....
User avatar
Xymox
Site Admin
Posts: 1022
Joined: Wed Nov 11, 2009 12:55 pm
Location: Phoenix, Az USA
Contact:

Re: What does ... mean?

Post by Xymox » Sun Nov 29, 2009 2:48 am

COOL...

Now if I can ever get off the forum and go put some of this stuff together..

heladepela
Posts: 4
Joined: Tue Dec 01, 2009 2:52 pm

Re: What does ... mean?

Post by heladepela » Tue Dec 01, 2009 3:20 pm

Some really good info here, many thanks for the daily distractions from my day-job :lol:

amiso
Posts: 37
Joined: Tue Dec 01, 2009 11:51 pm

Re: What does ... mean?

Post by amiso » Wed Dec 02, 2009 12:51 am

Let's stay focussed to the LHC1 page accronims:

=================================================
TDI P2 GAPS / mm and TDI P8 GAPS / mm I think are some mecanical slits that are located at point 2 and 8. 19.9 means that they are fully open!

1 - Why would they close those slits? To limit the beam current?
2 - What does TDI means?
3 - upstream / downstream ? Can the beam 1 for example be used in both directions ?

==================================================
About "TED TI2 position", I suppose that this is some system to either dump or inject the beams from the SPS

1 - What means TED ?
2 - What is the difference between TT2 and TI2 ?

==================================================
About "BCT TI2" and "BCT TI8" :

1 - What is this?

User avatar
Tim Bergel
Posts: 29
Joined: Mon Nov 23, 2009 1:31 pm

Re: What does ... mean?

Post by Tim Bergel » Wed Dec 02, 2009 11:43 am

taking some of the information Danny posted:

Point 1: ATLAS
Point 2: ALICE, Beam 1 Entry
Point 3: Beam Cleaning (Momentum)
Point 4: RF (Radio Frequency, meaning..?)
Point 5: CMS
Point 6: Dump
Point 7: Beam Cleaning (Betatron)
Point 8: LHCb, Beam 2 Entry

I would like to know what the two beam cleaning points do, and what the difference is (what is a betatron?) and what the point 4 RF station does.

daavery
Posts: 12
Joined: Sun Nov 29, 2009 3:40 am

Re: What does ... mean?

Post by daavery » Wed Dec 02, 2009 2:22 pm

point 4 (RF) is the RF injection point, the RF energy is what accelerates the beam

beam cleaning basically scrapes the particles of the beam that are spread outside of the core beam away, so that the beam cross-section stays constant

amiso
Posts: 37
Joined: Tue Dec 01, 2009 11:51 pm

Re: What does ... mean?

Post by amiso » Thu Dec 03, 2009 7:43 pm

Hi,
the following document :

http://lhcp.web.cern.ch/lhcp/TCC/PLANNI ... /pb2_4.pdf

is nice.

User avatar
Tim Bergel
Posts: 29
Joined: Mon Nov 23, 2009 1:31 pm

Re: What does ... mean?

Post by Tim Bergel » Fri Dec 04, 2009 10:23 am

beam cleaning basically scrapes the particles of the beam that are spread outside of the core beam away, so that the beam cross-section stays constant
Well, I guessed it was something along those lines - though thanks for the precise description - but what I was really trying to find out was the meaning of the 'Momentum' and 'Betatron' modifiers. I suppose Momentum implies that the unwanted particles are being separated out on the basis of momentum (can't quite see how that would work though) but AFAIK a betatron is an early design of particle accelerator primarily used on electrons. How does one of those get involved in beam cleaning?

Or, I've just thought, do the terms refer to the locations - beam cleaning at a momentum analysis site ans another at a site where the is, or used to be, a Betatron?

gluon
Posts: 28
Joined: Fri Dec 04, 2009 2:40 pm
Location: Lisbon, Portugal

Re: What does ... mean?

Post by gluon » Fri Dec 04, 2009 10:19 pm

I believe "BRAN Count Rate" is related to intensity/luminosity but what does it really mean?

User avatar
Texanguy
Posts: 65
Joined: Sun Nov 15, 2009 7:37 pm
Location: Texas

Re: What does ... mean?

Post by Texanguy » Fri Dec 04, 2009 10:45 pm

The most i can find on the BRAN is that it's what they call a "Luminometer", so you were correct in your assessment that it has something to do with measuring Luminosity :)

**EDIT: Found the more precise answer. :) http://ab-dep-bi-pm.web.cern.ch/ab-dep- ... ities.BRAN
BRAN=Beam RAte of Neutrals (which i suppose translates to Luminosity.. ._. )

JTC
Posts: 3
Joined: Sat Dec 05, 2009 2:07 pm

Re: What does ... mean?

Post by JTC » Sat Dec 05, 2009 2:30 pm

Here is an older but still relevant document:

http://lhccwg.web.cern.ch/lhccwg/Meetin ... 0Modes.ppt

It explains the various accelerator, beam, operations modes so that you can track where the LHC is overall. Snip of some of the early Beam Modes we are in now or will soon be in:

Injection Probe Beam: If either ring 1 or ring 2 will be injected with or have safe beam circulating. In this mode a number of checks will be done for the different accelerator sub-systems before injecting higher intensities. The aim will be to establish a circulating safe beam with a given lifetime.

Injection Setup Beam: During the INJECTION PROBE BEAM we will be able to make measurements with very limited precision. In order to make more precise measurements before filling for physics, a SETUP BEAM will be used. This beam will be wholly representative of the physics beam to follow, just with fewer bunches to stay below the damage threshold.

Injection Physics Beam: At this stage the machine has been optimized. It proved to be able to have circulating beam with appropriate lifetime and it is ready to accept higher intensities needed for physics. Within this mode, prior to high intensity beam injection, a pilot beam will be injected since the accelerator will be empty when this mode is reached.

Prepare Ramp: Injection complete, preparing for ramp.

Ramp: Ready to ramp or ramping or immediate post ramp.

Flat Top: Ramp finished - pre-squeeze checks.

Squeeze: Preparing for or squeezing.

Adjust: Preparing for collisions or adjusting beams after the squeeze. Possible to enter this mode from STABLE BEAMS. Possible to enter this mode at the end of STABLE BEAMS without the intention of going back into physics.

Stable Beams: Stable conditions with collisions in the experiments, backgrounds and life time under control. Small adjustment of beam parameters permitted. In case of slow degradation all the experiments are warned and the ADJUST mode is entered when all the experiments have confirmed they are ready.

The various modes are followed all the way from shutdown to collisions for physics, with good descriptions at each step. Includes a good graphic chart of the cycle, which, if made into an image, may be suitable for posting here.

JTC

JTC
Posts: 3
Joined: Sat Dec 05, 2009 2:07 pm

Re: What does ... mean?

Post by JTC » Sat Dec 05, 2009 3:49 pm

At the lower-right of "LHC Page 1" is the SMP, or Safe Machine Parameter section. These are status flags from the control system. The SMP system is a highly redundant hardware/software safety system, operating sort of as safety interlocks across the entire control system. They are in place to ensure coordination across the system as far as status and safety. The SMP system is redundant, cross-checks its own results, and operates low-level with physical detector signals and high-level with the control system itself. This is accomplished through software but the SMP system also has its own dedicated electronics to execute the SMP system. The SMP is one of the reasons we are operating at an energy of 450GeV; we are able to 'ignore' some of these flags for testing and special procedures, giving us a little less stringent set of operating parameters for these early runs. You should be able to Google : LHC "Safe Machine Parameter" : for more detailed information.

JTC

User avatar
DCWhitworth
LHCPortal Guru
Posts: 581
Joined: Mon Nov 30, 2009 8:13 am
Location: Norwich, UK

Re: What does ... mean?

Post by DCWhitworth » Sat Dec 05, 2009 4:09 pm

I've noticed the SMP 'beam presence' sometimes says 'false' even when there is a low intensity beam present (>3e9)
DC

The LHC - One ring to rule them all !

JTC
Posts: 3
Joined: Sat Dec 05, 2009 2:07 pm

Re: What does ... mean?

Post by JTC » Sat Dec 05, 2009 4:24 pm

Beam presence for Beams 1 and 2 do have a threshold limit of 3e9, so should be negative for anything below that value. Beam presence shouldn't go TRUE until protons meet or exceeds 3e9. Not sure if this threshold is ever altered though.

JTC

Celladoor
Posts: 21
Joined: Sun Mar 14, 2010 4:52 pm

Re: What does ... mean?

Post by Celladoor » Sun Mar 14, 2010 4:59 pm

The progress leading to the first collisions was amazing, as he told it. For example, they were able to obtain the “beta beat” of the machine on the first try – it took five years to obtain this with LEP.

http://muon.wordpress.com/2009/11/26/

What is the "beta beat"?

Post Reply