[d2n-analysis-talk] Scintillator Time Offset Checks/Beta Correction

[David Flay]

On Sat, Mar 6, 2010 at 4:19 PM, Brad Sawatzky <brads at jlab.org> wrote:

> That looks a lot better.  I hope I didn't come on too aggressively with
> the stuff about beta :-)  I know you didn't have time to read or respond
> to any of my posts as I wrote them.
>

No problem, I should've known better.


> Cutting on beta is 'OK', but _only_ because it is convenient.  The
> actual logic is something like this:
>  A)  S2m < S1 implies that the particle hit the back plane first, then
>      the front plane,
>  B)  The abs(S2m - S1) is about the same as for particles traveling
>      with speed c between the two planes,
>  *C)  The only class of particles that can reasonably satisfy A and B
>      are cosmics illuminating the detector stack from above,
>  D)  We can remove those (declared) cosmic events either by cutting on
>      S2m < S1 (with some reasonable margin) or, since
>         1/beta == const * (s2m - s1),
>      it is equivalent to apply a cut on the derived quantity beta.
>

This makes sense (using D) -- keeps the logic of the cosmics up front

I'll have a bunch of slides of everything for the talk as well

Also -- I've been looking at the ADCs (for each paddle, so a sum of L & R)
and considering GC > 0 (red), and GC == 0 (blue) cuts.  I can 'pick out' a
peak using GC > 0, but the whole spectrum is unaffected by GC ==0 ... I
tried using this result to 'clean up' my 2D PR plot (OR-ing together all
these histos, choosing events for < 400 in the scintillators)... doesn't
change anything.  I attached the *.pdf of the paddle ADCs.

I'm not absolutely certain of this being the right way of doing it...
wouldn't that main peak in the ADC of the scintillators be due to
electronics, setting some threshold?



-- 
-----------------------------------------------------------
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
-----------------------------------------------------------
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/d2n-analysis-talk/attachments/20100306/3995e068/attachment-0001.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: s2m_ADC-sum_pid-cuts_4p06_3_6_10.png
Type: image/png
Size: 38775 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/d2n-analysis-talk/attachments/20100306/3995e068/attachment-0001.png