Re: Reading in TGeo objects from file, using geomRootToGeant4 and getting "No elements defined"

Ivana Hrivnacova <Ivana.Hrivnacova_at_cern.ch> writes:

> The problem is in your definition of Vacuum, which seems to be defined
> as a mixture of 0 elements:
> root [1] gGeoManager->GetMaterial("Vacuum")->Print()
> Mixture Vacuum Aeff=0 Zeff=0 rho=0 radlen=0 intlen=0 index=9
>
> Please, change your definition to:
> TGeoMaterial* material = new TGeoMaterial("Vacuum", 0, 0, 0);

I was indeed make an element-less mixture for vacuum. Making a proper material allows the app to progress to tracking. Thanks for catching my mistake!

I now notice another possible inconsistency between using the two options "geomRoot" and "geomRootToGeant4". Using the former my app produces 9 logical volumes and the latter 7 as shown by this logging output diff:

diff -u geomRoot.log geomRootToGeant4.log

--- geomRoot.log        2012-05-03 12:26:40.000000000 -0400
+++ geomRootToGeant4.log        2012-05-03 12:26:32.000000000 -0400

...

-G4 Stat: instantiated 9 logical volumes

-                      9 physical volumes
+G4 Stat: instantiated 7 logical volumes 
+                      9 physical volumes

I've updated the geometry file at:

  http://www.phy.bnl.gov/~bviren/wbls/example-geo.root

to include the vacuum fix. Browsing it, I count 9 logical volumes. The only way I could guess to count 7 is to ignore the two assemblies ("cowbells" and "endcap").

Is this difference to be expected?

Thanks,
-Brett.