[d2n-analysis-talk] retimed TDCs

Tue Apr 6 13:39:37 EDT 2010

Hi Brad,

  I had thought that there may be a correlation between the T2 and the T1
and/or T6. Last week I made two plots DBB.t2:DBBt1 and DBB.t2:DBB.t6

http://jlab.org/~posik/d2n/BB/trigger/trig_check/2060_t6_t1_t2_mod.png

There seems to be more correlation between the T2 and the T1.

I also looked at a first hit in the T2 re-timed TDC for run 2060 vs
different trigger bits.

 http://jlab.org/~posik/d2n/BB/trigger/2060_tdc_bit_lin_Ndata.png

In the above plot the upper left box is the T2 re-timed TDC with no trigger
bit cut, the upper right is re-timed TDC with T1 trigger bit cut, the bottom
left is re-timed TDC with T2 trigger bit cut and the bottom right is the
re-timed TDC with a T6 trigger bit cut. For the T1 and T6 bit cut the self
timing peak is clear (~560) but it is hard to see any other structure so I
made the same plot on log scale

http://jlab.org/~posik/d2n/BB/trigger/2060_tdc06_bits_log.png

Looking at the T2 structure there is still a peak near chan 300 and some
structure at chan <100. Comparing to the T1 and T6 you can see similar
structure at same chans.

I am not too sure where I should be going from here with the study of the T2
trigger?

I was looking at the trigger diagram here

https://hallaweb.jlab.org/wiki/index.php/DAQ_Diagrams

Am I correct in thinking that the signal at the BB weldment (T1,T2, ect) has
a time that is determined from when the detectors got a start signal? For
example say a particle comes in and hits the shower causing a TDC signal.
This TDC signal then triggers the shower trigger ( T1 ). The newly created
T1 signal then arrives at the BB weldment and is then sent off to the
trigger supervisor?  I also remeber you mentioning that there should be a
diagram of the trigger time gates. I was looking on the wiki but did not see
them up there.

I am also confused on why the structure of the retimed TDCs are so much
different depending on if I plot the first hit
DBB.BBcerTxx[Ndata.DBB.BBcerTxx-1] or it I plot the last hit
DBB.BBcerTxx[0]. Here is the same re-timed TDC plot I did above but using
[0] array rather than [Ndata.DBB.BBcerTxx-1] array. Does this seem correct?

http://jlab.org/~posik/d2n/BB/trigger/2060_tdc_bits_0.png

I also checked with Kalyan about how many tracks he saw for his d2n 1pass H2
run 1258 and he said he got ~25% one track events, he did mention that this
was looked at near the d2n running and may have used old mwdc software. I
looked at the same run I replayed and got ~56% one track events.

Thanks
Matt

On Mon, Apr 5, 2010 at 10:44 AM, Brad Sawatzky <brads at jlab.org> wrote:

> On Wed, 31 Mar 2010, posik at jlab.org wrote:
>
> >    I followed up on your suggestion to use
> > DBB.BBxxxTnn[Ndata.DBB.BBxxxTnn-1] instead of DBB.BBcerTnn[0]. I first
> > just plotted TDC 04 from run 2060 with an (DBB.evtypebits&1<<2)==(1<<2)
> > cut (t4.png). This is fine, but I then tried to plot the re-timed TDC
> > by doing
> >
> > "DBB.BBcerT04[Ndata.DBB.BBcerT04-]-DBB.t2[Ndata.DBB.t2-1]+560"
> >  with (DBB.evtypebits&1<<2)==(1<<2) cut and I get this (retimed_tdc.png).
> >
> > This seems like an odd TDC structure.
>
> Hmm...  It almost looks like there are two copies of the same structure
> in the second plot with and amplitude ratio of about 5:1.  Are the two
> structures correlated with different "secondary" triggers?  You're
> cutting on T2s so they all have that trigger bit set -- I'm wondering if
> there's a correlation between the structure and when the event is a T2
> and a T1, vs. T2 and T6, etc...
>
> Just a thought.
>
> -- 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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