High pile-up MD

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High pile-up MD

Post by pjotertje » Mon Oct 10, 2011 10:12 am

Whats means High pile-up???


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Re: High pile-up MD

Post by Harbles » Mon Oct 10, 2011 6:32 pm

From; http://hep.physics.indiana.edu/~luehring/pile-up.html
Pile-up occurs when the readout of a particle detector includes information from more than one primary beam particle interaction - these multiple interactions are said to be "piling-up".

The LHC has had it's instantaneous luminosity increase to a point where they are getting many collisions per bunch crossing which complicates the job of the trackers in finding the vertices of all the events. They will use luminosity levelling to reduce the lumi at the beginning of the run by changing the crossing angle at the interaction points to reduce pileup when the beams are fresh then slowly bring the beams tighter as they loose protons to collisions and collimation to keep the number of interactions relatively constant over the length of a run, hopefully improving the amount of time taking data verses set up.

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Re: High pile-up MD

Post by PhilG » Wed Oct 12, 2011 6:27 am

Hopefully they will not have to use luminosity leveling until much later except for LHCb and ALICE that already use it.

The pile-up MD will collide a small number of high intensity bunches to increase the pile-up. This will give CMS and ATLAS some data to test and improve their reconstruction algorithms and triggers in preparation for the higher pile-up anticipated next year if luminosity can be increased further.

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