?? just checking
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mummymanson
Can someone just make sure I'm doing this right please? Is this a '2' just to the left hand side of the centre? Thanks
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markbakovic
no, but nearly:
although the computer does sometimes try to draw back tracks from off centre vertices to the centre of the beamline, the result is usually that the crossing point (the actual vertex) is more or less "in the middle" of the bunch, relative to the beamline (ie in this case if you split the angle between the 2 tracks, through the point where they cross, that line passes well to the left of the centre, so they're probably not being extended artificially by the computer).In situations like this marking it as an ocv is fine, and afterwards you can click "yes" to discuss and have access to the other views. In this instance it's a bit unclear, but if you look at slice view you can see straight away that none of the 4 white lines intersect, so the other view just indicates that their paths only appear to overlap when viewed down the beamline, and in reality lie some distance apart.
If you do that a few times (look at the other views after you've classified an object), you get an idea of what's what, but remember that several people get shown each image and their classifications are collectively analysed, so it's actually much less important (statistically) to be "correct" than it is to be consistent, although of course you'll start seeing things pretty quickly that make you go "oh, that's definitely a [insert feature], i was obviously wrong that other time" and get the hang of it that way.
I'm new to this too, by the way, and look I'm already offering advice 😉
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Whoandwhatitis
moderator
Based on the Normal and Zoom views and the information in the FAQ, I would typically not mark this as an off-center vertex:
Q: Are all line crossings OCVs? - A: No. Remember that we are looking at a 2d representation of a 3d picture (+time). Sometimes the paths of some particles just seem to cross in one of the views. Use your own judgement and don't worry, if it's unclear in one view the data for the other view will make up for it!
However, in Slice view it looks like a muon or something near it did possibly interact with the first detector and caused what I would consider a #wideangle interaction (around 90 degrees). See this discussion: http://talk.higgshunters.org/#/boards/BHH0000001/discussions/DHH00000bd
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DZM
admin
in response to markbakovic's comment.
I'm new to this too, by the way, and look I'm already offering advice 😉
You all learn so fast, and are so eager to help each other out! I'm so proud. 😃
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