Re: Radiation length plots

[David Lawrence <davidl@jlab.org>]

Hi Richard,

    I think I just figured out the issue. When I set the "AUTO" key to 0 
in control.in, it does not take the big steps. I also set the maximum 
step size to 1mm instead of the default of 0. I had to do this via a 
global search and replace in hddsGeant3.F. It looks like from the 
comments in hdds-geant.cpp as well as in the hdds schema that I should 
be able to do this in the region tag somehow, but I could quite figure 
it out.

    Now I just need to understand the discrepancy between the overall 
scale of your  plot with mine.

Regards,
-David

David Lawrence wrote:
>
> Hi Richard,
>
>    I am trying to reproduce some of the plots you showed at the last 
> collaboration meeting on the integrated material in radiation lengths 
> as a function of z. I am doing this using the mcTrajectoryPoint 
> structures which includes the radiation length of the current material 
> in the current step (RADL from GCMATE common) and the step size (STEP 
> from GCTRAK common).
>
>    One problem that I'm having is that, I do no see any gradual slope 
> in areas with air such as between the FDC packages. In your plots, I 
> can see some slight slope as one would expect.
>
>    I'm also a little confused that on your plot of 0 to 0.5 degrees, a 
> single FDC package looks to be right about 1% of a radiation length. 
> Looking at the HDDS files for the geometry used at the time of the DC 
> review (which I think is the geometry you used for these plots) I get 
> 1.32% of a radiation length per package.
>
>    My questions for you are:
>
> 1.) Exactly how did you produce the plots you showed at the 
> collaboration meeting?
>
> 2.) What geometry did you use to produce those plots? (Was it the 
> current one in SVN at the time of the collaboration meeting?)
>
> Thanks.
>
>
> Regards,
> -David
>

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