Geant4 User's Guide for Application Developers - Geant4 - CERN

Detector Definition and ResponseTube Section Twisted along Its Axis:A tube section twisted along its axis can be defined as follows:G4TwistedTubs(const G4String& pName,G4double twistedangle,G4double endinnerrad,G4double endouterrad,G4double halfzlen,G4double dphi)In the picture:endinnerrad = 10, endouterrad =15, halfzlen = 20, dphi = 90*Degree,twistedangle = 60*DegreeG4TwistedTubs is a sort of twisted cylinder which, placed along the z-axis and divided into phi-segments isshaped like an hyperboloid, where each of its segmented pieces can be tilted with a stereo angle.It can have inner and outer surfaces with the same stereo angle:twistedangleendinnerradendouterradhalfzlendphiTwisted angleInner radius at endcapOuter radius at endcapHalf z lengthPhi angle of a segmentAdditional constructors are provided, allowing the shape to be specified either as:• the number of segments in phi and the total angle for all segments, or• a combination of the above constructors providing instead the inner and outer radii at z=0 with different z-lengths along negative and positive z-axis.4.1.2.2. Solids made by Boolean operationsSimple solids can be combined using Boolean operations. For example, a cylinder and a half-sphere can be combinedwith the union Boolean operation.Creating such a new Boolean solid, requires:• Two solids• A Boolean operation: union, intersection or subtraction.• Optionally a transformation for the second solid.The solids used should be either CSG solids (for examples a box, a spherical shell, or a tube) or another Booleansolid: the product of a previous Boolean operation. An important purpose of Boolean solids is to allow the descriptionof solids with peculiar shapes in a simple and intuitive way, still allowing an efficient geometrical navigationinside them.78