======================================== January 17th 2017 - Luminosity 1: Detectors and formulae ======================================== First meeting of 2018! First session of Luminosity paper, Patrick chairs. ------------ Topics: - basic definitions of luminosity and what we actually try to measure - lumi blocks - BCM and LUCID - Bunch-by-bunch vs integrated measurements - the VanDerMeer scans - beam parameters ----------- Details: - equations 2 and 9 are what are actually used. 9 is the one used in the vanDerMeer scans. - Both Patrick and Greg emphasized that reference 14 of this paper is very good for the basics - Some questions about lumi blocks, why are they a minute? - Bunch-by-bunch lump measurements have to be fast enough but can suffer other problems - BCM and LUCID weren’t invented for high lumi monitoring but have been adapted to cope. BCM wasn’t really made for lump monitoring at all (the clue is in the name) - You can’t just use reconstructed Z’s, despite their clean mass peak and obvious signature, b/c your trigger isn’t always a muon trigger, so you’d need to know your trigger efficiency < 1% - The calo methods for lumi measurement cannot be used during the vanDerMeer scan as v. low lumi is used and they rely on significant differences in baseline current consumption. - CMS uses pixel cluster counting as their main method, which we do not currently do (but which Patrick is working on?) - LUCID, BCM, and track counting are all good for vanDerMeer as they work at low-lumi - the vdm scan let’s you figure out the amount of overlapping surface area in the beams as opposed to the total - as long as both the beams are the same shape they can reco the shape from the convolutions of the beams in the vdm scan - ‘non-factorization' - beta star has to be corrected for significantly if too small, so use larger beta-star ****************************** Next time: Lumi part 2 w/ Patrick ******************************