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

[MATTHEW R POSIK]

Ok found where I went wrong. Since the peds changed I am using a variable
from my older replays which plot the ADC without ped subtraction but applies
the gain correction factor. So in order for me to make the photoelectron
plots, I have to subtract the ped with this gain correction factor
multiplying it. Since I have to check all the peds, and needed just these
two plots for the APS I did the ped*gain_correction_factor directly in my
script. Turns out I used the wrong gain coeficent, using the correct one
fixes it all (see below)



On Tue, Feb 9, 2010 at 8:38 PM, MATTHEW R POSIK <tua88437 at temple.edu> wrote:

> Checked up on what you had asked and here is the plot of the electron
> signal (red histo) and the background(blue histo). The background peak is at
> chan 510, which is consistent with my ped runs I did. I'll recheck my plot,
> maybe I subtracted the wrong ped or using the wrong gain constant.
>
>
> On Tue, Feb 9, 2010 at 4:37 PM, Brad Sawatzky <brads at jlab.org> wrote:
>
>> On Tue, 09 Feb 2010, MATTHEW R POSIK wrote:
>>
>> [ . . . ]
>> > 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.
>>
>> The center of the pedestal for Mirror 3 from the T8 cut is consistent
>> with the rough centroid of the blue background shown in
>> aps_mir3_no_cor.png.  That makes sense.
>>
>> > 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?
>>
>> I'd double check that the pedestal you're subtracting is really the one
>> you're showing in 1849_rhrs.png -- I'll bet it isn't.  (I should be able
>> to see the pedestal start to rise up in the lowest bins of your mirror13
>> ped-subracted plot in your talk, but there's nothing there.)
>>
>> That is, make the same kind of non-ped-subtracted plot for mirror 13 as
>> you did for aps_mir3_no_cor.png.  If there really is a pedestal below
>> the blue peak, we should see it.
>>
>> -- 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
>
>


-- 
Matthew Posik
Email: posik at temple.edu
Temple University Physics Dept.
Office: BA-319
Office #:  215-204-1331
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