[d2n-analysis-talk] Scintillator Paddle Time Differences

[Brad Sawatzky]

On Wed, 07 Apr 2010, David Flay wrote:

> On Wed, Apr 7, 2010 at 1:40 PM, Brad Sawatzky <brads at jlab.org> wrote:
> 
> > Watch your binning.  Each bin in the plots you sent appears to be 4--5
> > nsecs wide.  You'll never see what you're trying to see on these histos.
> > I would start with the raw histos to do this initial paddle-to-paddle
> > calibration rather than the _c histos (even if you do null out the
> > coefficients).
> >
> > I will also admit I don't understand the other spikes at -60 and +60
> > on the rt_c[0]-rt_c-[1] plot, never mind the multi-spike structure on
> > the rt_c[4]-rt_c-[5] plot...  The only thing that is that periodic that
> > we might see here is the 2ns beam structure...  Do you know what the
> > real units on your x axes are?
> >
> 
> I was multiplying by 1e+9 -- however, the analyzer source code for
> THaScintillator says that the resolution is 0.1e-9 seconds/channel.   So
> maybe I should multiply by that number instead of 1e+9

There are two separate problems listed above.  You don't solve the
first one by changing a scaling factor.

Any resolution that is hardcoded into the THaScintillator is a mistake
since it assumes a particular TDC.  I don't believe we used an 1875 for
our LHRS config since that module is really slow.  Check your
db_cratemap and/or detector map to see what was really used.  Any
calibration must match the TDC in use.

-- 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