Old Breaking news 11/30-12/2/09

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Xymox
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Re: *** Breaking news ***

Post by Xymox » Tue Dec 01, 2009 6:26 pm

The 7TeV is a number that seems to come up when nothing is programmed into the machine. Its just some random default number. Its meaningless.

Yes,,,, Page 1 will change radically when the LHC is in different modes. Thats normal. We will work to make "Info" links that describe things when the pages appear.

LHC_Insider,
At the end of the day, we just run C++ applications on a shedload of data.
hahahah... wow... "just" run C++ apps on THE GRID. Wow.

Danny252
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Re: *** Breaking news ***

Post by Danny252 » Tue Dec 01, 2009 7:02 pm

daavery wrote:Page1 format has also changed: the beamTV images are not showing now and the whole mid-page area is different ( blank for now). I also noticed the "Page 1" and "LHC Operations" " Beam Current"(I) values were very different since yesterday. The "LHC Operations" I values seemed to match the Intensity plots while the "Page 1" values were moving around and dropping to 0.
Page 1 does supposedly have different modes depending on what state the LHC is in - I believe earlier it was set in precycling mode. We've been asking around to see if we can get descriptions of these - but the same basic data is there.

Page 1 Beam Current numbers have never seemed reliable so far - I think I was told that this is due to the low intensity of the current beams, which make it hard for the detectors Page 1 references to pick it up accurately. However, Status Op's Beam Current numbers seem to be reliable, and when shown on the graph there, display the sort of shapes you'd expect (injecting, dumping, slowly decreasing in intensity over time, etc.).

Hela - if you try the "info" link on the portal site (in the LHC section) there's an image explaining that, and if the most current version is there it should state that the number you pointed out is the setting - but not the measured energy. But I do know they have used software simulations to model things before, and this can give odd numbers on the screens.

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Xymox
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Re: *** Breaking news ***

Post by Xymox » Tue Dec 01, 2009 7:40 pm

Yes the very latest page 1 and status-op help images are up.. With clickable bigger versions.

heladepela
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Re: *** Breaking news ***

Post by heladepela » Tue Dec 01, 2009 8:28 pm

Great stuff Danny, Xymox, been digging around a bit more !!

Danny252
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Re: *** Breaking news ***

Post by Danny252 » Tue Dec 01, 2009 8:51 pm

heladepela wrote:Great stuff Danny, Xymox, been digging around a bit more !!
Got a JCB we can borrow? It's getting quite hard to dig further with just these spades :(

Hopefully we may be getting information on some of the other VISTARs - such as the SPS and LINAC screens.

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Re: *** Breaking news ***

Post by pcatom » Tue Dec 01, 2009 9:24 pm

The other machines in the injector chain (Linac2, PSB,PS and SPS) are pulsed machines - that is they execute a repetitive set of cycles of injection, acceleration and extraction of various beams to several different users. However, at the moment the complex is running principally for the LHC - most of the other physics programmes are stopped.

The SPS Page 1 shows 2 traces. The white one is the energy and the blue/yellow one is the beam intensity. The repetition rate (supercycle length) is given on the page (presently 32 seconds). The large cycle is the one that is used to accelerate the LHC beam ready for injection into the LHC itself. For this cycle the injection energy is 26GeV and the extraction energy is 450GeV. The smaller pulse in front of the LHC is not used for beam - it is there to set correctly the magnetic hysteresis in the LHC.

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