The error says there is something wrong with the material of your (logic) world but the code for the world definition looks fine to me…?!
I think it’s the line
G4Material *worldMat = nist->FindOrBuildMaterial("G4_Air");
as the key for the material is “G4_AIR”. So worldMat gets set to nullptr and hence the error. A full list of builtin material definitions and the keys to pass to FindOrBuildMaterial can be found in the Appendices of the Application Developer Guide
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now what should i do?
its difficult for me how to resolve it?
I guess @bmorgan highlighted that the material has to be written as “G4_AIR” and not as “G4_air”.
I’ve to admit I didn’t notice that.
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Yes, I should have made that clearer, the line should be
G4Material *worldMat = nist->FindOrBuildMaterial("G4_AIR");
sir i need this type of geometery but after removing the error which you have mentioned G4_AIR but i could not get required light shower .After removing error i got geometery which which consist of only one beam.
i attach below an other geometery which i got.
I think there is no way around following the well-written instructions in this post: Beginner at geant4 - #2 by John_McFee
Well, but this means it is working in general now.
What you’re describing now is a specific issue as there is no shower produced. We would need further information for this to resolve, especially the code.
Out of the blue I assume the box the beam passes through has no material so it also consists of air? Could you check that? And also show us the code?
I agree with weller, at this point you need more knowledge on C++ or Geant4 in general or else you will come back to this thread at every error.
As for your specific problem, it looks like you are generating a proton, is that what you intend? Do you expect a 100 GeV proton to interact with your material? Did you define your material correctly? You say you expect a light shower, did you implement optical photons in your physics list? (if that is what you want?).
There are a number of reasons why you are not getting what you expect, and you first must understand what you want to do and how you can do it using Geant4
sir i follow this tutorial but i do not know where i do mistake , geant4 can not show the light shower
The code you’re looking for is shown in the video, you basically “only” have to copy that.
I did the same tutorial and I also stumbled over a lot of issues but most of them were mistakes on my side and some solutions you can find in the comments of the tutorial.
Hello
I downloaded Geant 4.10.7 Vesrion. I created a build and install directory. My question is: could you give me the commands to install and build, then run this code?
For future reference, please start new threads rather than reviving an old one/or interjecting your own question!
All the information on installing Geant4 can be found in the Installation Guide, which is part of the documentation listed on the Geant4 website