What do the displays mean ?

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Danny252
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Re: What do the displays mean ?

Post by Danny252 » Wed Nov 25, 2009 11:57 pm

And yet, even with no beams running (as of right now, apparently), dots and bars are everywhere...

I'm sure it makes sense to the boffins!

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Re: What do the displays mean ?

Post by jepson » Thu Nov 26, 2009 4:33 am

SMP means "Safe Machine Parameters". EDMS 883620 lists (in a very roundabout way) the conditions under which each is true (except for Global Beam Permit, I guess that's a human decision). EDMS 810607 contains them too, along with other info (such as the locations of the detectors).

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Xymox
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Re: What do the displays mean ?

Post by Xymox » Thu Nov 26, 2009 4:44 am

Wow you guys are really finding great stuff...

Ive been watching this stuff for a long time.

The bars and dots and all that are just strange noise and weirdness..

NORMALLY these show very clearly a bright red dot close to center showing the beam location. They can choose the location along the ring.

I have no idea why recently they have been showing this junk. Also the text above the windows gets garbled.

I have asked that they show the real beam. That it would be cool to see it.

Alas they are busy... There might be something minor wrong too. I don't know..

Yoy got me on the Status-op background.

I am hoping we will get a CERN guy/girl who might take the time to explain these things for us..

Once we know what all this is. I will use photoshop and also create a page with screen shots and arrows pointing to section of the displays showing what the function is and what to watch for.

You guys are awesome locating this info... Thanks..

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photino
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Re: What do the displays mean ?

Post by photino » Thu Nov 26, 2009 3:47 pm

Re the BTV displays on page 1: it appears the BTV images are produced by lowering a scintillating screen into the beam. Since this somewhat degrades the beam itself, the screen is only lowered into the beam when measurement is required. I suspect some of the images we are seeing are artifacts of BTV being on but the screen being in its retracted position.

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Xymox
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Re: What do the displays mean ?

Post by Xymox » Thu Nov 26, 2009 9:08 pm

O.... well that explains it.. :)

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Re: What do the displays mean ?

Post by morgad » Thu Nov 26, 2009 10:41 pm

A couple of interesting changes on the lhc_operations screen

* the graphs now show 20 hours of info, not 2hrs

* the energy label at the top of the screen is now in TeV, not GeV

is longer beam duration, higher energy testing planned soon ??
(is Xymox right again?)

Dave

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Xymox
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Re: What do the displays mean ?

Post by Xymox » Fri Nov 27, 2009 5:19 am

The scales on all the pages auto adjust. For some reason it seems that when the input is missing weird things occur.

Once the beam is back all the instrumentation will show correct scales. Both level and time.

Dont consider any of those display valid unless there is beam.

IMHO...

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Xymox
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Re: What do the displays mean ?

Post by Xymox » Fri Nov 27, 2009 5:20 am

When they go to high powers.... What that really means is that they will ramp up the beam. It means they will circulate the beam and push it faster each time around. This will be very obvious on the screens. All the SMP flags on the lower right corner will be green for the beam they are ramping.

Going to higher powers will be very obvious and take time to get there. Constant ramping for a while..

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Xymox
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Re: What do the displays mean ?

Post by Xymox » Fri Nov 27, 2009 9:41 pm

From a different thread... PCollier provided some important insight.
Page 1 is dynamically configured depending on the mode of the machine so the information available will vary.

Here are a few definitions to be going along with:

TI 2 - is the transfer line between the SPS and the LHC for the clockwise beam. It is 2943m long.
TI 8 - is the anticlockwise transfer line from the SPS to LHCand is 2694m long

TED - stands for 'Target Extraction Dump' There are stoppers that can be put into the transfer lines there is one at the top and one at the bottom of each line (upstram and downstream) . Each one weighs about 20 tonnes.

TDI - this is an injection protection element just downstream of the injection point. It has upper and lower jaws that can be moved into the beamline. If the injection kickers fire correctly the beam will be fired through the gap between the jaws. If the kickers do not fire - for example when we are setting up injection - the beam hits one of the jaws and is absorbed.

BKG1,2,3 - These are figures of merit provided by the experiments to the machine. Each one is derived from a specific part of the detector (and are therefore experiment specific). They are normalized to a number between 1 (good) and 5 (bad) - 0 means it is not yet active.

Hope this helps.

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Re: What do the displays mean ?

Post by Danny252 » Fri Nov 27, 2009 10:01 pm

Wonder what all CERN's acronyms mean on those displays? They made a list!

http://lhccwg.web.cern.ch/lhccwg/Biblio ... ronyms.htm

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Xymox
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Re: What do the displays mean ?

Post by Xymox » Fri Nov 27, 2009 11:40 pm

W O W....

Ok Danny you need some sort of LHCPortal forum title.. I gotta figure one out...

Impressive work..

Danny252
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Re: What do the displays mean ?

Post by Danny252 » Sat Nov 28, 2009 12:42 am

UPDATED VERSION OF PAGE 1 IMAGE POSTED

See page 3 of thread
Last edited by Danny252 on Sat Nov 28, 2009 6:58 pm, edited 2 times in total.

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Xymox
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Re: What do the displays mean ?

Post by Xymox » Sat Nov 28, 2009 12:47 am

wow.....

just O M G... Ok so lets see what people think of this, any corrections and then i will use it on on a new page linked from http://www.lhcportal.com/Portal/how_to_ ... portal.htm

I did create a special group called LHCPortal Guru and I added you. But I dont see the title under your name... Weird... Must investigate..

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Re: What do the displays mean ?

Post by Xymox » Sat Nov 28, 2009 1:08 am

There you are now the first LHCPortal Guru..

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photino
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Re: What do the displays mean ?

Post by photino » Sat Nov 28, 2009 1:15 am

Neat summary of the basic "LHC operations" sequence:

After re-cycling, the machine is ready for injection of 450 GeV protons
This should take ~15 minutes

The beams are ramped to nominal energy (3.5 TeV in 2010)
This takes about ½ hours

Beams are prepared for physics:
Squeeze to make them smaller at the interaction point
Put in collision
Collimators adjusted to minimize the background

“Stable Beams” is declared.
We then [...] start physics

Physics (useful part): ~ 10 hours (eventually...)

(Then dump beam and ramp down.)
https://lbtwiki.cern.ch/pub/Operation/T ... course.pdf

Also:

interaction point (IP): Middle of the insertion region (except for IP8). In the insertions where the two LHC beams cross over the IP indicates the point where the two LHC beams can intersect.

Re page 1:
"Save Machine parameters (SMP) flags show if the beam is allowed in the machine (Global beam permit), if they setting up the beam (Setup beam), if beam above the certain level (Beam presence), if Castor and other movable devices are allowed to move in, and if beam is stable and sensitive devices are allowed to turn on (stable beam). On the bottom left the screen also gives you a phone numbers that you can use to vent your frustration."

To understand the information on backgrounds displayed on the LHC page1 check this logbook entry
http://cmsonline.cern.ch/portal/page/po ... d%3D126573
http://cmsonline.cern.ch/portal/page/po ... d%3D126581

I could not access the last 2 links unfortunately...

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