[d2n-analysis-talk] LHRS Scintillator TDCs

[Brad Sawatzky]

Putting this back on-list.

On Fri, 19 Feb 2010, David Flay wrote:

> I'm currently investigating the nature of the Scintillators, and I've
> decided to start with understanding the histos of their ADCs and TDCs.
> What I'm doing is first looking at elastic runs, and making some PID
> cuts for electrons and see how the resulting plot looks.  Then, I'd
> look at some production runs and do the same thing.
> 
> I have TDCs at p = 1.70 GeV, elastics, and p = 0.60 (5-pass), but p =
> 0.60 (4-pass) has no TDCs -- more precisely, I get ~600k entries at
> 0...  There seems to be nothing in the HALOG about any hardware
> changes (I'm looking at run 20675, 3/14/09) and the db_L.s1.dat (and
> db_L.s2.dat) file for that run and the others are identical... do you
> recall any changes to the scintillating planes at some point??

That is very strange.  Smells like a bad db file for those runs...  What
I would do as a first check is to use the DecData class to look at the
raw data in a few channels.  You can do similar things with the THaScint
class, but using DecData
  a) forces you to manually type in and sanity check reasonable
     crate/slot/channel values, and
  b) bypasses 1--2 layers of processing that exists in the THaScint
     class.

> P.S. -- the trigger for a good electron should be requiring paddle (n) in
> the first plane to fire, along with paddle (n, or n +/- 1) in the second
> plane to fire. I was thinking of using a 2D plot of such paddles, but I
> think this should be something to consider if the ADCs and TDCs don't yield
> anything helpful..

I believe that the LHRS trigger is just simple coincidence between each
plane.  People have fooled with a more complicated geometric overlap
scheme in the past, but that isn't the normal configuration.

-- 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