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Looking at today's beam dump, it looks like the B2 "thick line" continues with a thin line for another loop... I wonder what is it?

How accurate is the display ? It looks like an inverted image of the main line. Is it real or some sort of an effect of the monitoring ? The beam 1 display has a bright area to the left, is this part of the beam ? I'd think it unlikely.

Edit - Just noticed the Page 1 PM Comment. It ends with "some debunc" but is cut off. So I guess there were some issues with beam debunching that might explain the shadowing, but I don't know how the effect would manifest itself on the dump. Don't know where else this information could be viewed, it's not in the Op Log Book.

I have slightly enlarged and enhanced the two displays.
1 - debunched beam in a gap
2 and 3 - probably dimmed image of the beam trace, displaced by a glass pane or another optics element
4 - no idea, the beam should not go through there
5 - trail of debunched beam in abort gap
6 - no idea, abort gap is IMO way shorter
7 - gap in B1
8 - no idea but this light has always been there. Background light or IR emission?

Interesting. I'd want to see more dumps to work out what is actual beam effects and what is an effect of the display.

A thought - are the two displays rotationally the same ? If they're not (i.e one display goes clockwise and one anti-clockwise then 1 corresponds roughly with 7)

Could 2 and 3 be a debunching effect ?

DCWhitworth wrote:Could 2 and 3 be a debunching effect ?

Definitely not, debunching is a longitudinal effect. Any beam that diverges too much from beam path is captured by collimators.

any one find any information about the seminar held on dec 2?

Kasuha wrote:...
5 - trail of debunched beam in abort gap
...

The abort gap is there to give the dump kicker time to switch. Any beam which is in the abort gap receives a partial kick and is lost on the collimators somewhere - it can't go down the dump line.

adam_jeff wrote:The abort gap is there to give the dump kicker time to switch. Any beam which is in the abort gap receives a partial kick and is lost on the collimators somewhere - it can't go down the dump line.

Contents of abort gap is not lost on collimators... at least not mostly. Even though the abort gap is cleaned, there is always some small population of particles cycling in its buckets (and note that in this case the beam was partially debunched). When the dumper kicker ramps up (it does so in order of microseconds but for the beam it's a looooong time), it sweeps abort gap population all the way from original beam route to the final beam route, i.e. from beam pipe all the way to the dump pipe. The horizontal line is artifact caused by that sweep.
In fact many beam dump displays have such line, more or less pronounced.

today is the last day of the phyics runs this year. it has been very exciting and alot has been acomplished. congragulations to the LHC team, for such a wonderfull job, and i look forward to next year!

tomey36 wrote:today is the last day of the phyics runs this year.

Is it? the schedule shows physics up to Friday...

B.

BenM wrote:

tomey36 wrote:today is the last day of the phyics runs this year.

Is it? the schedule shows physics up to Friday...

B.

Perhaps, but page 1 says: "No beam", followed by "end of ion run 2010". I would trust the latter=)

Congrats guys

Any one know where i can find any information on what they are doing durring the shutdown? thanks

LHC End-of-year jamboree (talks summarizing the latest results etc)

http://indico.cern.ch/conferenceDisplay ... fId=113139

Anybody know what the schedule is for restarting operations in 2011? Will it be more ions work or will proton experiments be back?