[d2n-analysis-talk] T2 timing corrections
MATTHEW R POSIK
tua88437 at temple.edu
Wed Mar 31 12:43:24 EDT 2010
Hi Brad,
So in the previous email you said
>Recall that the first hit in time is
> DBB.t2[Ndata.DB.t2 - 1] for Ndata.DB.t2 >= 1
So then my loop should be something like
for (Int_t hit =Ndata.DBB.t2 - 1; hit>=0 ; hit--)
{
t2_histogram->Fill( DBB.t2[hit] );
}
**Note all runs discussed here are from run 2060**
There is something that is confusing me. When I do a T->MakeSelector(), it
produces a .h file that give the definitions in the TTree and for T2 for
example it gives:
Int_t Ndata_DBB_t2;
Double_t DBB_t2[2]; //[Ndata.DBB.t2]
So according to this, I would expect that DBB.t2 to have two elements
DBB.t2[0,1] since Ndata.DBB.t2 = 2. So I plotted Ndata.DBB.t2 see plot
http://jlab.org/~posik/d2n/BB/trigger/t2_data.png
in the upper left box. There are three bins for Ndata.DBB.t2. Then I
plotted various hits in the T2, starting with DBB.t2[Ndata.DBB.t2] in the
upper right, DBB.t2[Ndata.DBB.t2-1] in the bottom left and
DBB.t2[Ndata.DBB.t2-2] in the bottom right. Since [Ndata.DBB.t2-1] is the
first hit in time and [Ndata.DBB.t2-2] would be the last hit in time since
Ndata.DBB.t2 = 2, then what is showing up when I plot DBB.t2[Ndata.DBB.t2] ?
does it correspond to the 0th or 2nd bin in Ndata.DBB.t2 ?
Also I looked at the Ndata.DBB.BBcerT06 histogram
http://jlab.org/~posik/d2n/BB/cer/nhit.png
and Makeselecter gives the foolowing definition:
Int_t Ndata_DBB_BBcerT06;
Double_t DBB_BBcerT06[16]; //[Ndata.DBB.BBcerT06]
But in the Ndata histogram there are 17 bins.
Also I took another look at the triggers on the BigBite side. Here is the
plot of the DBB.t1 trigger vs the TDC 06
http://jlab.org/~posik/d2n/BB/trigger/2060_t1_tdc.png
I can't see too much from here, so I also plotted the DBB.t1 and DBB.t6 vs
the DBB.t2 (
http://jlab.org/~posik/d2n/BB/trigger/trig_check/2060_t6_t1_t2_mod.png). To
the left is T6 vs T2 and the the right is T1 vs T2. Both of these plots have
a
"(DBB.evtypebits&1<<2)==(1<<2) "
cut applied to them. The T6 vs T2 looks pretty clean, except in the T2 range
~450-500 which is where the T6 carries the T2 timing? And in the T2
histogram this is where a good portion of the events fall
http://jlab.org/~posik/d2n/BB/trigger/t2_data.png
I then plotted the T1 vs the T2 and now there is a lot going on in the plot.
There is a lage block structure centered near chan ~250, as well as at chan
~450-550 and at chan 550-560 there are 2 verticle bands. So does this mean
that the T1 trigger is responsible for most of the structure in the T2
trigger, including the two bands at chan 550-560?
Thanks
Matt
On Tue, Mar 30, 2010 at 9:58 PM, Brad Sawatzky <brads at jlab.org> wrote:
> On Mon, 29 Mar 2010, MATTHEW R POSIK wrote:
>
> > I think my code is plotting the correct thing, I think I am just
> > poorly explaining what I am doing, so let me try this again. So I get
> > the value of Ndata.DBB.t2 from the replayed TTree, in the case of run
> > 2060 Ndata.DBB.t2 = 2.
> > Then to plot the T2 trigger, for each event I loop over the hits
> > this is done using the following for loop:
> >
> > for (Int_t hit =0; hit<Ndata.DBB.t2 ; hit++)
> > {
> > t2_histogram->Fill( DBB.t2[hit] );
> > }
> >
> > So is this same thing as DBB.t2[Ndata.DBB.t2-1] , since I have T2[ ]
> > running from 0 to Ndata.DBB.t2-1, ie( T2[0] and T2[1] ) ?
>
> Not quite... reread the previous email. If you want to plot the hit
> farthest from the common stop in time (ie. the first hit the TDC sees
> after the interaction in the target) then you want to plot the *last*
> hit in your TDC array, not the first.
>
> > I also looked at the shoulder events in TDC 04 from run 2060 (
> > http://jlab.org/~posik/d2n/BB/trigger/t2_walk/2060_tdc04.png<http://jlab.org/%7Eposik/d2n/BB/trigger/t2_walk/2060_tdc04.png>)
> >
> > I plotted the re-timed TDC 04 (Red histo) and the not retimed TDC 04
> (blue
> > histo) on the same plot in log scale. To make these plots I used the
> > following cut on each TDC:
> >
> > "BB.tr.n==1&&(DBB.evtypebits&1<<2)==(1<<2)"
> >
> > I then redid the same plot as above, however this time I did not use the
> > BB.tr.n==1 cut So the cut on each TDC is now
> >
> > "(DBB.evtypebits&1<<2)==(1<<2)"
> >
> > You can now clearly see a well defined shoulder in both the re-timed TDC
> 04
> > (Red histo) and the not re-timed TDC 04 (blue histo). The plot is here:
>
> Interesting.
>
> > http://jlab.org/~posik/d2n/BB/trigger/t2_walk/2060_tdc4_1.png<http://jlab.org/%7Eposik/d2n/BB/trigger/t2_walk/2060_tdc4_1.png>
> >
> > So it seems that the one track cut greatly reduces this shoulder, but
> > that may just be because that cut right now is throwing out a lot of
> > statistics. I also compared the TDC 04 vs the T2 trigger to the
> > re-timed TDC 04 vs the T2 trigger, this can be seen here:
> >
> > http://jlab.org/~posik/d2n/BB/trigger/t2_walk/2060_tdc4_t2.png<http://jlab.org/%7Eposik/d2n/BB/trigger/t2_walk/2060_tdc4_t2.png>
>
> Also a good plot.
>
> > The re-timed TDC looks good against the T2 trigger (right plot),
> > except there seems to be a few events that fall at the two horizontal
> > bands at DBB.t2 = 560 and DBB.t2 = 565 that do not fall in line with
> > the vertical peak at TDC channel ~260. It is these events that
> > contribute to the shoulder events in the TDC histogram. I did verify
> > this by plotting the re- timed TDC 04 and making a cut on the T2
> > trigger, this can be seen here:
> >
> >
> http://jlab.org/~posik/d2n/BB/trigger/t2_walk/2060_tdc04_t2_shoulder_ct.png<http://jlab.org/%7Eposik/d2n/BB/trigger/t2_walk/2060_tdc04_t2_shoulder_ct.png>
> >
> > With that said, I still do not know why these events do not seem to shift
> > with the T2 re-timing of the TDC. Could they some how be correlated with
> the
> > T1, since the T2 trigger is formed from the shower and cerenkov and the
> > shower had two triggeres, the T1 and T6?
>
> Hmm... that's a good thought. If that's what's happening you should see
> it in a plot like this, but with T1.
> http://jlab.org/~posik/d2n/BB/trigger/t2_walk/2060_tdc4_t2.png<http://jlab.org/%7Eposik/d2n/BB/trigger/t2_walk/2060_tdc4_t2.png>
>
> > Also I wanted to check where the structure in the T2 at chan. < 400 were
> > falling in the TDC.
> >
> > http://jlab.org/~posik/d2n/BB/trigger/t2_walk/2060_tdc4_t2selection.png<http://jlab.org/%7Eposik/d2n/BB/trigger/t2_walk/2060_tdc4_t2selection.png>
> >
> > So I plotted for run 2060 the re-timed TDC 04 with T2<400 (red histo,
> > scaled to the blue histo) and the re-timed TDC 04 with T2>400 (blue
> > histo). From this is seems that what ever is generating the T2
> > trigger as chans<400 are events that do not fall into the timing peak
> > of the TDC.
>
> Remember that if you cutting on T2 outside of its self-timing peak means
> (by definition) that some other trigger is carrying the timing. A
> significant fraction of the T6 triggers are good electrons (and would
> have generated a T2 but for prescaling). Events with a T2 well off its
> self timing peak means that the system accepted a trigger pretty far
> away in time from whatever fired the Cerenkov component of the T2
> trigger -- ie. should be dominated by background.
>
> Just FYI, you can get some weird apparent structure when plotting the
> DBB.xxxTnn[0] hit for high rate data. Things might look more reasonable
> if you plot DBB.xxxTnn[Ndata.DBB.xxxTnn-1] instead.
>
> > I am going to take a look at the trigger diagram and see if I can
> > figure anything out.
>
> Very good. All through this email I just about started typing a
> suggestion that you do X, Y or Z only to find in the next paragraph that
> you were one step ahead of me -- excellent.
>
> -- Brad
>
> --
> Brad Sawatzky, PhD <brads at jlab.org> -<>- Jefferson Lab / Hall C / C111
> Ph: 757-269-5947 -<>- Fax: 757-269-5235 -<>- Pager: brads-page at jlab.org
> The most exciting phrase to hear in science, the one that heralds new
> discoveries, is not "Eureka!" but "That's funny..." -- Isaac Asimov
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--
Matthew Posik
Email: posik at temple.edu
Temple University Physics Dept.
Office: BA-319
Office #: 215-204-1331
WebSites:
Temple:
http://quarks.temple.edu/
d2n:
http://hallaweb.jlab.org/experiment/E06-014/
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