[d2n-analysis-talk] BB cer ped shifts

Thu Feb 11 14:41:37 EST 2010

Hi Brad,

   Here are the overlaid peds that you wanted.

http://www.jlab.org/~posik/d2n/BB/cer/peds/led_beam_beam.png

http://www.jlab.org/~posik/d2n/BB/cer/peds/led_beam_rhrs.png

Looking at these it seems that only the beamline side peds shifted with
beam.

 I took the "beam on" peds from run 1849 which was a 5-pass He3 8uA run and
overlaid the peds from LED runs 1828(beam line side) and 1834(rhrs side).

The red histos are "beam on"  and the blue histos are "LED" .

I will be happy to show this as well as the peds from the hardware
configurations at the next d2 meeting.

-matt

On Thu, Feb 11, 2010 at 12:34 PM, Brad Sawatzky <brads at jlab.org> wrote:

> Hi Matt,
>
> Please overlay the LED, beam-off, and beam-on pedestals all on the same
> plot.  It's a little hard to compare the plots below since they have
> different x-axis and the png files are reduced enough that the legend is
> illegible.
>
> Your APS stuff takes priority though.  I'll be happy if you can present
> these plots at our next phone meeting.
>
> -- Brad
>
> On Wed, 10 Feb 2010, MATTHEW R POSIK wrote:
>
> > Hi Brad,
> >
> >    Here are the peds from an LED and a fivepass run with ~8uA current,
> both
> > taken on the 1881 ADC.
> >
> > LED beam line side:
> > http://jlab.org/~posik/d2n/BB/cer/peds/led/1829.png<http://jlab.org/%7Eposik/d2n/BB/cer/peds/led/1829.png>
> >
> > LED RHRS side:
> > http://jlab.org/~posik/d2n/BB/cer/peds/led/1834.png<http://jlab.org/%7Eposik/d2n/BB/cer/peds/led/1834.png>
> >
> > fivepass beam line side:
> > http://jlab.org/~posik/d2n/BB/cer/peds/fivepass/1849_beam.png<http://jlab.org/%7Eposik/d2n/BB/cer/peds/fivepass/1849_beam.png>
> >
> > fivepass rhrs side:
> > http://jlab.org/~posik/d2n/BB/cer/peds/fivepass/1849_RHRS.png<http://jlab.org/%7Eposik/d2n/BB/cer/peds/fivepass/1849_RHRS.png>
> >
> > I will get working looking at the peds over all hardware changes as you
> > suggested in the previous email. Been a little slow with the APS talk.
> >
> > -matt
> >
> > On Mon, Feb 8, 2010 at 11:16 AM, Brad Sawatzky <brads at jlab.org> wrote:
> >
> > > On Fri, 05 Feb 2010, posik at jlab.org wrote:
> > >
> > > > So I looked at the Big bite cerenkov ped location for run 1849, which
> > > > is a He3 production run at ~8-9 uA.  I did this by plotting the ADC
> > > > for the first 100,000 events and making a T8 trigger cut (pulser)
> > > > which is "(DBB.evtypebits&1<<8)==(1<<8)". Using this cut, I then fit
> a
> > > > Gaussian to the ped and extract the mean. Then I compared these "beam
> > > > on" ped positions with those of the LED runs. Here is a list of the
> > > > mean ped values:
> > > [ . . . ]
> > >
> > > Interesting.  Good work!  Please generate a couple of slides showing
> the
> > > LED-run pedestals overlaid on top of the beam pedestals for the 20
> PMTs.
> > > I'd like to see how the characteristics of the pedestal change.
> > >
> > > Also, we need to determine if the pedestals change between the LED runs
> > > and what you show here is due to beam loading or something else.  Look
> > > for a cosmics/no-beam run in this period and redo your pedestal checks
> > > (and generate the above plots) for a beam-off run and an adjacent
> > > beam-on run.
> > >
> > > If you can find appropriate runs, here's what would be ideal:
> > >  A) peds with beam-off (cosmics or rest run)
> > >  B) peds at low current (1 uA or so)
> > >  C) peds at full current
> > > Having A-C for each hardware configuration (v792, 1881, with pre-amp on
> > > beamline side, without pre-amp on beamline side).  would help
> > > disentangle configuration from beam-loading effects.
> > >
> > > > You can see that there is a significant ped drift with the beam line
> > > > side pmts (1-10) from the LED peds, and the RHRS side (pmts 11-20)
> are
> > > > fairly close to the LED peds. I also calculated the rates for this
> > > > run, using TDC hits and cutting away beam trips, here are the
> results:
> > > [ . . . ]
> > > Rate for cell 05:    0.9315 MHz
> > > ------------------------
> > > Rate for cell 06:    0.4108 MHz
> > > ------------------------
> > > Rate for cell 07:    1.0756 MHz
> > > ------------------------
> > > Rate for cell 08:    0.7693 MHz
> > > ------------------------
> > > Rate for cell 09:    0.9036 MHz
> > > ------------------------
> > > Rate for cell 10:    0.7387 MHz
> > > ------------------------
> > > Rate for cell 11:    0.1087 MHz
> > > ------------------------
> > > Rate for cell 12:    0.0224 MHz
> > > ------------------------
> > > Rate for cell 13:    0.0802 MHz
> > > ------------------------
> > > Rate for cell 14:    0.0816 MHz
> > > [ . . . ]
> > >
> > > > pmt 6 and 12 seem to be much lower than the rest of the pmts on that
> > > > side.  This was also seen in run 1848.
> > >
> > > There was some Pb shielding installed at the beamline height on the
> > > beamline side.  The shadow should have been cast over more than PMTs 6,
> > > 12 though...  I'm not sure what's going on there.
> > >
> > > I don't think I beleive the 20kHz number associated with cell 12.
> > > There's either a bug in the calculation, or the hardware is doing
> > > something really strange.
> > >
> > > > Using these ped values as well as mirror and TDC cuts I plotted the
> > > > ADC for mirror 3 (1849_mir3_pe.png) and 12 (1849_mir12_pe.png) for
> run
> > > > 1849.  Please note that the x-axis is in #p.e. The red histo is the
> > > > signal and blue histo is an off mirror background. Mirror 3 shows
> > > > about 4-6 p.e and mirror 12 7-8 p.e. I am thinking about including
> > > > these two images in my APS talk.
> > >
> > > Using PMT 12 as a 'representative' histogram probably isn't a good
> idea.
> > > What do 11 and 13 look like?
> > >
> > > > So since the ped were stable with beam on/off with the v792 ADC, then
> > > > that means the 1881 ADC is responsible for the ped shift. I assume
> > > > then is has to do with the electronic differences between the 792 and
> > > > 1881. I was wondering what exactly this difference is that results in
> > > > the ped location shifting with beam on/off?
> > >
> > > I did the with/without beam pedestal stability test before
> Transversity.
> > > All I can say is that it was stable then.  That was with the v792s and
> > > with no extra amplification on the beamline side PMTs...
> > >
> > > I suspect/hope that the difference you see is due to some other change
> > > that happened at the same time.  The tests mentioned at the top of the
> > > email should clarify things.
> > >
> > > -- 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
> > > _______________________________________________
> > > d2n-analysis-talk mailing list
> > > d2n-analysis-talk at jlab.org
> > > https://mailman.jlab.org/mailman/listinfo/d2n-analysis-talk
> > >
> >
> >
> >
> --
> 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
> _______________________________________________
> d2n-analysis-talk mailing list
> d2n-analysis-talk at jlab.org
> https://mailman.jlab.org/mailman/listinfo/d2n-analysis-talk
>

-- 
Matthew Posik
Email: posik at temple.edu
Temple University Physics Dept.
Office: BA-319
Office #:  215-204-1331
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/d2n-analysis-talk/attachments/20100211/4598503e/attachment-0001.html 