[d2n-analysis-talk] APS talk (Cerenkov pedestals)

[MATTHEW R POSIK]

 These are the "with beam values"  pedestal subtracted signals. If I do not
do any ped subraction you can see that the Blue histo on mirror 3 does fall
off on both sides. I attached that plot below (aps_mir3_no_cor.png).

 Both the red and blue histos have the following cuts on them:

     "BB.tr.n==1 && abs(BB.tr.vz[0]<0.2) && BB.tr.p[0]>0.4 && BB.tr.p[0]<2.0
&& ((DBB.evtypebits&1<<2)==(1<<2)) "

I then go ahead and plot lets say the corrected (1pe aligned to chan 30 and
ped subtracted from " with beam ped" ) ADC 13.

For the red histo I then apply a TDC and mirror cut that apply to mirror 13.
Where as for the blue histo I apply to mirror 13(ie. ADC 13 ) a cut on the
TDC and mirror associated with mirror 17.

But if I replay the first 100,000 with a T8 cut
("DBB.evtypebits&1<<8)==1<<8") the peds I get for both sides are below
(1849_beam.png and 1849_rhrs.png) for the beam line and rhrs sides.

Since when I make that "background" cut (blue histo) on mirror 13 and have a
non zero centered peak, does that mean there is some correlation between
mirror 13 and 17?


On Tue, Feb 9, 2010 at 2:17 PM, Brad Sawatzky <brads at jlab.org> wrote:

> On Mon, 08 Feb 2010, MATTHEW R POSIK wrote:
>
> > Yes, the plots in slide 10 are pedestal subtracted.
>
> Are those pedestals the "LED" pedestal, or the "with beam" values?
>
> On Mirror 13, if the blue is truely uncorrelated signal then it is, by
> definition, the 'with beam' pedestal.
>
> For Mirror 3, it's hard to tell if the blue peaks at zero and then falls
> off, which would be consistent with a (wide) pedestal, or if keeps
> climbing, which would suggest the pedestal subtraction isn't quite
> right.
>
> -- Brad
>
> --
> Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C / C111
>  Ph: 757-269-5947 -<>- Pager: 757-584-5947 -<>- Fax: 757-269-7848
> 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
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