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LHC-EXPERIMENTS TIMING COORDINATION

COGGING FIRST BEAMS

Cogging Blog

REPORT OF WEEK 1

Report on timing of week 1 (cogging + phase jumps) to LPC

Timing log using TTCpage1

VERTICES Day 3: experiments reported Vertices within 1.5cm from the IP!!!!

ALICE

 

ATLAS

CMS

Vertex collision fit.jpg

LHCb (beam gas & collisions)

 

PLANNING

PARAMETER DEFINITION

ΔT will be the delay in ns between calculated crossing point (one value from BPTX and one from trackers if available) versus theoretical crossing point. ΔT will be positive when the calculated collision point is ahead of the theoretical IP clockwise. Inversely, if the calculated IP is behind the theoretical IP, then the sign of ΔT will be negative.

For example, if ATLAS BPTXs give an estimated crossing point 6ns far from the theoretical crossing point in the direction of ALICE, ΔZ will be +6ns.

To ease the interpretation of ΔT shared by the 4 experiments, it should have comparable values for the 4 experiments, regardless of the bucket number used during the run.

BUCKET NUMBER

To know which bucket(s) is(are) actually used, check on DIP the parameter:

Circulating Bunch Configuration : dip/acc/LHC/RunControl/CirculatingBunchConfig/* (Beam1 and 2)

Contains an array which encodes mapping of circulating bunches to RF buckets i.e. the first element contains the RF bucket number of the bunch 1 etc. If the value is 0 then there is no corresponding bunch.

More info about DIP : https://twiki.cern.ch/twiki/bin/view/Leade/WebHome

 

FIRST MEASUREMENTS

You can:

- post your measurements on the cogging blog : https://espace.cern.ch/cogging-data-exchange/default.aspx (preferred solution)

To post the message, just click on 'create a post', write your comments and select your category. One category has been created by experiment (for example "LHCb DeltaT"), plus one for General messages and one for RF/Operation messages and logs. Do not hesitate to post intermediate values if you want - just specify it.

- publish them on DIP (please send a path to Sophie with the refresh rate)

- send them to Sophie by SMS (I will post them to the blog asap) 160494 - (the full number may be required for sms: 0764870494)

- give a call to Sophie 160494