[G8b_run] Follow up to meeting

[Michael Dugger]

Brian,

Thanks for the plots and estimates of the single particle inefficiencies 
:)

-Michael

On Tue, 26 Mar 2013, Brian Vernarsky wrote:

> Hello all,
>
> I spent some time this afternoon making a few of the plots that were
> requested at the meeting this morning.  I have just added them to the
> pdf from this morning.  You can find it at:
> http://www.andrew.cmu.edu/user/bvernars/2013-03-26_g8b_Meeting.pdf
>
> What I added were the TOF TDCs and ADCs for events with one good TDC
> and one bad TDC (i.e. one below 4096 and one above), as well as ones
> where both TDCs are below 4096.  The first one shows how likely it is
> that we can recover an event if one of the TDCs is bad but the other
> one is ok, and the second one shows that some of the events will
> likely be unsalvagable.  The one caveat to these plots is that all
> events from paddles that given a bad status flag will show up as bad
> (red); the entirely "bad" paddles generally had about half of their
> TDC values above 4096, but half below; unfortunately there was no way
> to account for this.  Please note that I've used the same scale for
> all the TDC plots so you can easily compare how big the contributions
> are.
>
> I also tacked on a slide at the very end that shows the phi
> distribution for single proton and single pi+ events to see the effect
> of the start counter inefficiencies.  These plots are made with events
> from a single amorphous run, 48133, and include both "good" and "bad"
> TOF paddles; in short, this is a separate issue from the TOF problem
> and I'm not compounding things by removing bad TOF paddles and showing
> the start counter inefficiency.  The proton is largely unaffected, but
> sector 3 shows a definite bump in the middle of the sector.  However,
> the pi+ in all sectors shows a marked inefficiency.  Interestingly it
> always seems to be more inefficient on the first two paddles of a
> sector.  Also notice the soft shoulder on the left hand side of each
> sector, compared to the harder fall off on the right hand side; note
> sectors 3, 5 and 6 as good examples of this.
>
> I also added which runs were used in the making of each plot to the slides.
>
> Lastly, Michael and some others were interested in the possible gain
> in statistics in the single particle topologies.  I did just a quick
> counting exercise on a few runs and it looks like a maximum of 2% of
> the single proton events have TOF = 0 and 19% of the single pion
> events have TOF = 0.  This would lead to an increase in statistics of
> almost 25% for the pions if we could recover every event, which we
> can't, but still should yield around a 20% increase.  One caveat on
> those numbers, it is possible that some of the missing protons are in
> fact being labelled pi+s because with no timing info the positive
> tracks with a huge beta are assigned as pions.  I don't think that it
> is a huge issue (mainly because the "good" events don't seem to have a
> dip that is unaccounted for), but it could mean there are "some" more
> protons that are being missed, however I don't expect the increase in
> statistics for the single proton events to be much more than 2-3%.
>
> Were there any other questions this morning that I have not answered?
>
> Brian
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