[Halld-physics] current Ckov response in hdgeant

[Richard Jones]

Nathan and all,

I found a bug in my hdds-geant.cpp translator program that was failing to return the polish factor for the Cerenkov mirrors correctly.  When built for 32bit targets, the buggy code seems to have always produced perfect polish (which is why I never noticed it) but the 64bit binary was always returning 7e-9 and giving diffuse scattering by the mirrors (which is why you noticed it).

I have verified that the fix leads to consistent results between 32bit and 64bit executables.  Please check out the changes in your hdds working directory, do "make" in hdds, followed by "make" in the HDGeant directory.  After that, you should find that running with the control.in file I shared with you generates an average of 10 or so pe per event in sector 1.

-Richard J.





On 4/11/2011 9:30 PM, Nathan Sparks wrote:
> Hi all,
>
> Richard and I went over the problems I have been having with the Cerenkov simulation earlier. Here is a quick summary.
>
> I had observed that the number of photoelectrons for Cerenkov hits is too small, but when he checked the simulation, he found a reasonable distribution for photoelectrons and also that the optics are working as expected (see previous email). We verified that I have the Cerenkov enabled in the geometry correctly and I use the same gustep.F. Then, I did the simulation using the same control.in file as Richard, but was still not able to reproduce the same results as Richard.  We realized that we were using different types of the code: He was using 32-bit code and I 64-bit. Next, Richard demonstrated that for the 64-bit code, the optics do not work correctly: light is not focused onto the PMT, and he is investigating further.
>
> Regards,
> Nathan
>


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