[d2n-analysis-talk] Investigation of Timewalk Correction Factors & RF Time

[Brad Sawatzky]

On Sat, 13 Mar 2010, David Flay wrote:

Whoops.  Sorry for the long delay.

> To get a feel of by how much the timewalk correction factors that are
> currently in the database correct for, I commented them out of my DB
> (on my machine) to see what the TDC vs. 1/sqrt(ADC) plot would look
> like.  The first 4 plots show the L and R for s1, then S2m.  The last
> four show the same plots, but now with the correction factors
> implemented.  It seems that there is no change in these plots.
> 
> This could mean that either the DB isn't reading the #'s correctly, or
> that these factors are just not right altogether.  I have a feeling it's
> the latter.

Put a big (random) number in and see if you get a change.

> In which case, I notice that Chiranjib has done this study using the
> RF clock.  When I use 'T->Print("DL.rftime*"), I get:
> ****************************************************************************
> *Br    0 :DL.rftime1 : DL.rftime1/D                                       
[ . . ]
> *Br    1 :DL.rftime2 : DL.rftime2/D                                       
[ . . ]
> So, there's two of these guys.  Which one would be the 'right' to use?

They are probably redundant copies of each other.

> Further -- what is the RF clock? I've never gotten a straight answer
> from Chiranjib...

It is the 2ns RF clock that drives the RF in the accelerator.  The JLab
"CW" beam is really pulsed with a 2ns period.

-- Brad

-- 
Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C / C111
        Ph: 757-269-5947        -<>-        Fax: 757-269-5235
The most exciting phrase to hear in science, the one that heralds new
  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov