LHCb Logfile

[Allan]

Hi everyone;

Is anyone able to explain this log entry?http://lhcportal.com/Forum/posting.php?mode=post&f=4#

The filling scheme has changed in order to inject a pilot bunch in Bunch ID 1 for both beam. The corrected
values for Bunch ID are:
Bunch ID 1 : beam 1 pilot (5e^9) - beam gas
Bunch ID 101 : beam 1 high intensity - gas
Bunch ID ~102.5 : displaced beam1-beam2 high intensity (+11.25m)
Bunch ID 104 : beam 2 high intensity - beam gas
Bunch ID 895 : beam 2 pilot - beam gas
Bunch ID 995 : beam 2 high intensity - beam gas
Bunch ID 1883 : beam 1 high intensity - beam gas
Bunch ID 2209 : beam 1 - beam 2 colliding high intensity
Bunch ID 2774 : beam 1 - beam 2 colliding high intensity

FYI, the Beam Phase and Intensity Monitor now shows the BunchID as measured in LHCb IP8 and the measured
intensity (in ADC counts just for tonight...).

>
> New filling scheme for this evening to avoid problem with the injection kicker:
>
> Bunch ID 1 : beam 1 - gas
> Bunch ID ~2.5 : displaced beam1-beam2 (+11.25m)
> Bunch ID 4 : beam 2 - gas
> Bunch ID 895 : beam 2 - gas
> Bunch ID 1783 : beam 1 - gas
> Bunch ID 2109 : beam 1 - beam 2
> Bunch ID 2674 : beam 1 - beam 2

Thank you

Allan

[Danny252]

As you may know, the protons aren't a constant beam, but are split into "bunches". In the end the LHC intends to run [some number over 1000] bunches at once.

If you imagine the LHC as a circle split into quite a few sections, each section being called a "bucket", a bunch can be in any bucket theoretically.

However, you want to be able to put the bunches in position such that they hit the other beam's bunches - so you put them in a specific bucket. You might also want to reserve other bunches/buckets, as they seem to be doing below.

It sounds like they're just changing a few settings, to make things work better

[Anitusar]

To add some more information: All the electronic components of the experiment have implemented a counter which basically counts the number of these buckets that have passed the experiment. This information is send out with the measured data by the electronics upon a trigger (command to read out the electronic).

So if you want to find some collision data, you only have to look at data with the corresponding bunch IDs.