[d2n-analysis-talk] Beta Distribution New Binning

[David Flay]

Hey Brad,

I've been doing a lot of staring at these beta plots I've been sending to
you, and I was thinking about how to possibly fix the blips we see in
beta.

Considering that the determination of beta is correlated to the S1 time
offsets and time avg. vs. paddle/track-x, I was thinking about how I was
binning my beta vs. track-x plot.

Previous plots were binned 100 by 100.  However, I think it is more
appropriate to bin the track-x variable to coincide with that of the
binning of the paddles -- so I've plotted the S1 time-related plots with a
binning of 6, and S2m time-related plots with a binning of 16.

Now, in an ideal case, this shouldn't change anything -- in that, we
should still see straight lines across the board for good calibrations,
etc.  My main reason for doing this is that this gives me an idea of where
the paddles would line up in track-x (if I consider the plot of S1
time-avg. vs track-x).  If I then compare this to beta vs. track-x (with
track-x binned as 6, not 100) I can get an idea of which paddles need
tweaking in their time averages.  I'm not too familiar with how much
overlap (if any) there is for the paddles in S1 or S2m (would this
information be in the Hall A NIM Note?), but I think this is a good idea,
at least to first order, so to speak.

If you look at the first plot -- the beta vs. track-x looks fairly
consistent (of course it would, I changed the binning to be less fine). 
But, my argument is that the consistency of beta vs. track-x is dependent
upon how narrow the width of the time averages and, in turn, the time
offsets of S1 are, paddle-by-paddle.  I've also attached the plot with
100-binning for comparison.  I think these blips may be an artifact of
single paddles, which I cannot necessarily correct for further, based on
the width of the time offset plots (see scint_toffs plot -- the binning
hasn't changed, but I've labeled it as new, just because I zoomed in on
S2m -- I've tweaked the time offsets, they're in better agreement now). 
Unless there's a way to 'narrow' the width of these distributions per
paddle?  Vince's calibration script brings all the paddle's time offsets,
time averages to agree with one another, but I don't know about narrowing
the width for each distribution...

My argument above is due to the first hot-spot on the beta vs. track-x
plot in the beta_new_bin plot -- there are two (albeit very hard to see)
bright spots in what I believe to be one paddle... If I look over to the
time offset vs. track-x -- this corresponds to paddle 1 (counting from
zero).  We can see the spread on this time offset is ~2ns centered on
zero.  In short, I think the higher binning of beta tends to reveal the
issues in the time offsets for each paddle -- which themselves seem to
have a width that I at the moment, am unsure of how to fix. (Ideally, for
each paddle, the time offsets and averages would be a very thin straight
line, no?)

I think this seems reasonable (?)

Dave

-------------------------------------------------
David Flay
Physics Department
Temple University
Philadelphia, PA 19122

office: Barton Hall, BA319
phone: (215) 204-1331

e-mail: flay at jlab.org
            flay at temple.edu

website: http://www.jlab.org/~flay
              http://quarks.temple.edu
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