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1

Hello, experts,

I was building my detector based on the example B1, and I changed the length unit of cm to nm. When I run the the code, it says as follows. Can you tell me how to figure this out? Thanks a lot.

-------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : GeomSolids0002
issued by : G4GenericPolycone::Create()
Illegal input parameters - head
R/Z cross section is zero or near zero: -1.28e-10
*** Fatal Error In Argument *** core dump ***
-------- EEEE -------- G4Exception-END --------- EEEE -------

*** G4Exception: Aborting execution ***

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_Geant4 Version:_geant4.10.03.p01
_Operating System:_red hat-64bit
_Compiler/Version:_cmake 3.5.1

2

G4GenericPolycone is a body that is constructed by rotating a polygon around Z-axis. The error message says that the area of the polygon is too small, 1.28e-10 mm^2 (negative sign can be ignored)

3

Thank you for your reply, Sir. So, what should I do if I want to build a detector in a size of nm?

4

What shape you defined with G4GenericPolycone?

5

Actually, I am not sure which shape is defined with G4GenericPolycone. I think that I just changed some shape and the length unit of example B1. But as I checked the B1detectorconstruction, it does not show any G4GenericPolycone inside.

6

As far as I knows the example B1 uses G4Box, G4Cons and G4Trd.

Anyway, it’s looks a bit strange to construct a detector in nanometer scale. 1 nm is a size of 10 hydrogen atoms lined up, 1000 nm is a size of a cell.

1 Like
7

I understand. Thank you for your help.

8

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