Error: Surface Normal returned by Solid is not a Unit Vector

Hi all,

I am trying to simulate a complex geometry and have relied heavily on GEANT’s visualization tools to ensure that my shapes are in the right place. I mostly use OGL however OGL fails to properly display several of my smaller volumes. In an attempt to visualize these volumes I have turned to RayTracer however, when I run RayTracer I encounter a runtime error which causes a breakdown. The error in questions is:

 Point for surface = (-50.1946,58.8054,3.0478)
Surface Normal returned by Solid is not a Unit Vector.

*** Fatal Exception *** core dump ***
G4Track (0x7fc6c9f79bc0) - track ID = 1, parent ID = 0
 Particle type : geantino - creator process : not available
 Kinetic energy : 1 GeV - Momentum direction : (-0.852869,-0.150384,-0.5)
 Step length : 1 Ang - total energy deposit : 0 eV 
 Pre-step point : (-50.1946,58.8054,6.3978) - Physical volume : World (Vacuum)
 - defined by : Transportation - step status : 1
 Post-step point : (-50.1946,58.8054,6.3978) - Physical volume : MountPhys (G4_Al)
 - defined by : Transportation - step status : 1
 *** Note: Step information might not be properly updated.

-------- EEEE -------- G4Exception-END --------- EEEE -------

The point at which this error occurs is close to, but not exactly on, any surface in my simulation. The error occurs ~0.7mm away from the nearest surface which belongs to a mount. The mount is, more or less, a rectangular prism with angled corners. Ive attached this image to help:

The mount is made with several subtraction solids and the error occurs just outside one of the corners.

In the event that it is helpful I have also included my full stack trace. You will see that I have many errors warning about a potential volume overlap. I have used the geometry test to unsure that no such overlap exists. I attribute these errors to the many small curved surfaces in my simulation.

I hope someone can provide some insight into why this is happening and what I can do to fix is. Thank you!

OS: Mac OSX Big Sur (11.3.1)
GEANT Version: 10.07
Compiler: Apple Clang 12.0.5

gabrielbridges@Gabriels-MacBook-Pro DetSim_Build % ./detSim ../macro/ray.g4mac

**************************************************************
 Geant4 version Name: geant4-10-07-patch-01    (5-February-2021)
                       Copyright : Geant4 Collaboration
                      References : NIM A 506 (2003), 250-303
                                 : IEEE-TNS 53 (2006), 270-278
                                 : NIM A 835 (2016), 186-225
                             WWW : http://geant4.org/
**************************************************************


Visualization Manager instantiating with verbosity "warnings (3)"...
Visualization Manager initialising...
Registering graphics systems...

You have successfully registered the following graphics systems.
Registered graphics systems are:
  ASCIITree (ATree)
  DAWNFILE (DAWNFILE)
  G4HepRep (HepRepXML)
  G4HepRepFile (HepRepFile)
  RayTracer (RayTracer)
  VRML1FILE (VRML1FILE)
  VRML2FILE (VRML2FILE)
  gMocrenFile (gMocrenFile)
  OpenGLImmediateX (OGLIX, OGLI)
  OpenGLStoredX (OGLSX, OGL, OGLS)

Registering model factories...

You have successfully registered the following model factories.
Registered model factories:
  generic
  drawByAttribute
  drawByCharge
  drawByOriginVolume
  drawByParticleID
  drawByEncounteredVolume

Registered models:
  None

Registered filter factories:
  attributeFilter
  chargeFilter
  originVolumeFilter
  particleFilter
  encounteredVolumeFilter

Registered filters:
  None

You have successfully registered the following user vis actions.
Run Duration User Vis Actions: none
End of Event User Vis Actions: none
End of Run User Vis Actions: none

Some /vis commands (optionally) take a string to specify colour.
"/vis/list" to see available colours.

 hInelastic QGSP_BERT  Thresholds: 
    1) between BERT  and FTF/P over the interval 3 to 6 GeV. 
    2) between FTF/P and QGS/P over the interval 12 to 25 GeV. 
  -- quasiElastic: 1 for QGS  and 0 for FTF
### Adding tracking cuts for neutron  TimeCut(ns)= 10000  KinEnergyCut(MeV)= 0
Issue /vis/viewer/refresh or flush to see effect.
Issue /vis/viewer/refresh or flush to see effect.
Issue /vis/viewer/refresh or flush to see effect.
WARNING: G4RayTracerViewer::DrawView: true orthogonal projection
  not yet implemented.  Doing a "long shot", i.e., a perspective
  projection with a half field angle of 1e-06 radians.

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'World'
   - at position : (-7.592987981026624,160.73536123037,-22.83115224108178)
     in direction: (-0.8528685476877961,-0.1503835390132696,-0.5000000315587532)
    (local position: (-7.592987981026624,160.73536123037,-22.83115224108178))
    (local direction: (-0.8528685476877961,-0.1503835390132696,-0.5000000315587532)).
  Previous phys volume: 'av_3_impr_1_Pipe_Logical_pv_1'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'World'
   - at position : (-2.379785671687216,161.8992192314643,-22.90566764848796)
     in direction: (-0.8528685461036258,-0.1503835384366788,-0.5000000344343503)
    (local position: (-2.379785671687216,161.8992192314643,-22.90566764848796))
    (local direction: (-0.8528685461036258,-0.1503835384366788,-0.5000000344343503)).
  Previous phys volume: 'av_3_impr_1_Pipe_Logical_pv_1'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'World'
   - at position : (3.103988295097679,163.1107862198767,-22.82155863753266)
     in direction: (-0.8528685445194556,-0.1503835378600881,-0.5000000373099475)
    (local position: (3.103988295097679,163.1107862198767,-22.82155863753266))
    (local direction: (-0.8528685445194556,-0.1503835378600881,-0.5000000373099475)).
  Previous phys volume: 'av_3_impr_1_Pipe_Logical_pv_1'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'World'
   - at position : (-10.1072858032255,160.7812852067228,-30.56675874430345)
     in direction: (-0.8528685445194556,-0.1503835378600881,-0.5000000373099475)
    (local position: (-10.1072858032255,160.7812852067228,-30.56675874430345))
    (local direction: (-0.8528685445194556,-0.1503835378600881,-0.5000000373099475)).
  Previous phys volume: 'av_3_impr_1_Pipe_Logical_pv_1'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'World'
   - at position : (8.803215286136322,161.5856046023567,-23.16750624973193)
     in direction: (-0.8528685422145476,-0.1503835405280888,-0.5000000404390677)
    (local position: (8.803215286136322,161.5856046023567,-23.16750624973193))
    (local direction: (-0.8528685422145476,-0.1503835405280888,-0.5000000404390677)).
  Previous phys volume: 'av_3_impr_1_Pipe_Logical_pv_1'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'World'
   - at position : (5.985752888295306,161.088810606893,-24.81926293101152)
     in direction: (-0.8528685422145476,-0.1503835405280888,-0.5000000404390677)
    (local position: (5.985752888295306,161.088810606893,-24.81926293101152))
    (local direction: (-0.8528685422145476,-0.1503835405280888,-0.5000000404390677)).
  Previous phys volume: 'av_3_impr_1_Nitrogen_Logical_pv_2'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'World'
   - at position : (11.29028063900637,162.2687717368971,-24.84023809591622)
     in direction: (-0.8528685406303773,-0.150383539951498,-0.5000000433146647)
    (local position: (11.29028063900637,162.2687717368971,-24.84023809591622))
    (local direction: (-0.8528685406303773,-0.150383539951498,-0.5000000433146647)).
  Previous phys volume: 'av_3_impr_1_Pipe_Logical_pv_1'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'World'
   - at position : (1.715286432549123,160.580444104695,-30.45364425394817)
     in direction: (-0.8528685406303773,-0.150383539951498,-0.5000000433146647)
    (local position: (1.715286432549123,160.580444104695,-30.45364425394817))
    (local direction: (-0.8528685406303773,-0.150383539951498,-0.5000000433146647)).
  Previous phys volume: 'av_3_impr_1_Pipe_Logical_pv_1'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'av_3_impr_1_Nitrogen_Logical_pv_2'
   - at position : (12.01872538125829,159.8671082501723,-28.10034088081228)
     in direction: (-0.8528685383254693,-0.1503835426194988,-0.5000000464437849)
    (local position: (12.01872538125829,159.8671082501723,0.05965911918772093))
    (local direction: (-0.8528685383254693,-0.1503835426194988,-0.5000000464437849)).
  Previous phys volume: 'World'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'MountPhys'
   - at position : (-50.19460069661336,58.80539930338663,6.397798206616849)
     in direction: (-0.8528685610600907,-0.1503836561017843,-0.4999999735327503)
    (local position: (-50.19460069661336,58.80539930338663,3.047798206616849))
    (local direction: (-0.8528685610600907,-0.1503836561017843,-0.4999999735327503)).
  Previous phys volume: 'World'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------


-------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : GeomNav0003
      issued by : G4Navigator::GetLocalExitNormal()
 Parameters of solid: -----------------------------------------------------------
    *** Dump for Boolean solid - Mount ***
    ===================================================
 Solid type: G4SubtractionSolid
 Parameters of constituent solids: 
===========================================================
-----------------------------------------------------------
    *** Dump for Boolean solid - Mount ***
    ===================================================
 Solid type: G4SubtractionSolid
 Parameters of constituent solids: 
===========================================================
-----------------------------------------------------------
    *** Dump for Boolean solid - holeCut ***
    ===================================================
 Solid type: G4SubtractionSolid
 Parameters of constituent solids: 
===========================================================
-----------------------------------------------------------
    *** Dump for Boolean solid - cornerCut ***
    ===================================================
 Solid type: G4SubtractionSolid
 Parameters of constituent solids: 
===========================================================
-----------------------------------------------------------
    *** Dump for solid - mountBase ***
    ===================================================
Solid type: G4Box
Parameters: 
   half length X: 60 mm 
   half length Y: 60 mm 
   half length Z: 6 mm 
-----------------------------------------------------------
-----------------------------------------------------------
    *** Dump for Displaced solid - placedB ***
    ===================================================
 Solid type: G4DisplacedSolid
 Parameters of constituent solid: 
===========================================================
-----------------------------------------------------------
                *** Dump for solid - Corners ***
                ===================================================
 Solid type: G4MultiUnion
 Parameters: 
-----------------------------------------------------------
    *** Dump for solid - corner *** 
    =================================================== 
 Solid geometry type: G4GenericTrap
   half length Z: 7 mm 
   list of vertices:
    #0   vx = 0 mm   vy = 0 mm
    #1   vx = 0 mm   vy = -13 mm
    #2   vx = -13 mm   vy = 0 mm
    #3   vx = 0 mm   vy = 0 mm
    #4   vx = 0 mm   vy = 0 mm
    #5   vx = 0 mm   vy = -13 mm
    #6   vx = -13 mm   vy = 0 mm
    #7   vx = 0 mm   vy = 0 mm
 Translation is (61,61,0) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - corner *** 
    =================================================== 
 Solid geometry type: G4GenericTrap
   half length Z: 7 mm 
   list of vertices:
    #0   vx = 0 mm   vy = 0 mm
    #1   vx = 0 mm   vy = -13 mm
    #2   vx = -13 mm   vy = 0 mm
    #3   vx = 0 mm   vy = 0 mm
    #4   vx = 0 mm   vy = 0 mm
    #5   vx = 0 mm   vy = -13 mm
    #6   vx = -13 mm   vy = 0 mm
    #7   vx = 0 mm   vy = 0 mm
 Translation is (-61,61,0) 
 Rotation is : 
 
   [ ( 6.12323e-17            -1             0)
     (           1   6.12323e-17             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - corner *** 
    =================================================== 
 Solid geometry type: G4GenericTrap
   half length Z: 7 mm 
   list of vertices:
    #0   vx = 0 mm   vy = 0 mm
    #1   vx = 0 mm   vy = -13 mm
    #2   vx = -13 mm   vy = 0 mm
    #3   vx = 0 mm   vy = 0 mm
    #4   vx = 0 mm   vy = 0 mm
    #5   vx = 0 mm   vy = -13 mm
    #6   vx = -13 mm   vy = 0 mm
    #7   vx = 0 mm   vy = 0 mm
 Translation is (-61,-61,0) 
 Rotation is : 
 
   [ (          -1   -1.22465e-16            -0)
     ( 1.22465e-16            -1             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - corner *** 
    =================================================== 
 Solid geometry type: G4GenericTrap
   half length Z: 7 mm 
   list of vertices:
    #0   vx = 0 mm   vy = 0 mm
    #1   vx = 0 mm   vy = -13 mm
    #2   vx = -13 mm   vy = 0 mm
    #3   vx = 0 mm   vy = 0 mm
    #4   vx = 0 mm   vy = 0 mm
    #5   vx = 0 mm   vy = -13 mm
    #6   vx = -13 mm   vy = 0 mm
    #7   vx = 0 mm   vy = 0 mm
 Translation is (61,-61,0) 
 Rotation is : 
 
   [ ( -1.83697e-16             1             0)
     (          -1   -1.83697e-16            -0)
     (           0             0             1) ]

             
-----------------------------------------------------------
===========================================================
 Transformations: 
    Direct transformation - translation : 
           (0,0,0)
                          - rotation    : 
           
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

===========================================================
===========================================================
-----------------------------------------------------------
    *** Dump for Displaced solid - placedB ***
    ===================================================
 Solid type: G4DisplacedSolid
 Parameters of constituent solid: 
===========================================================
-----------------------------------------------------------
                *** Dump for solid - Cavity ***
                ===================================================
 Solid type: G4MultiUnion
 Parameters: 
-----------------------------------------------------------
    *** Dump for solid - hole ***
    ===================================================
 Solid type: G4Tubs
 Parameters: 
    inner radius : 0 mm 
    outer radius : 47.5 mm 
    half length Z: 6 mm 
    starting phi : 0 degrees 
    delta phi    : 360 degrees 
-----------------------------------------------------------
 Translation is (0,0,0) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - topCavity ***
    ===================================================
 Solid type: G4Cons
 Parameters: 
   inside  -fDz radius: 0 mm 
   outside -fDz radius: 47 mm 
   inside  +fDz radius: 0 mm 
   outside +fDz radius: 51 mm 
   half length in Z   : 2 mm 
   starting angle of segment: 0 degrees 
   delta angle of segment   : 360 degrees 
-----------------------------------------------------------
 Translation is (0,0,4.5) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - botCavity ***
    ===================================================
 Solid type: G4Tubs
 Parameters: 
    inner radius : 0 mm 
    outer radius : 57 mm 
    half length Z: 4 mm 
    starting phi : 0 degrees 
    delta phi    : 360 degrees 
-----------------------------------------------------------
 Translation is (0,0,-3) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

             
-----------------------------------------------------------
===========================================================
 Transformations: 
    Direct transformation - translation : 
           (0,0,0)
                          - rotation    : 
           
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

===========================================================
===========================================================
-----------------------------------------------------------
    *** Dump for Displaced solid - placedB ***
    ===================================================
 Solid type: G4DisplacedSolid
 Parameters of constituent solid: 
===========================================================
-----------------------------------------------------------
                *** Dump for solid - notches ***
                ===================================================
 Solid type: G4MultiUnion
 Parameters: 
-----------------------------------------------------------
    *** Dump for solid - topNotch ***
    ===================================================
Solid type: G4Box
Parameters: 
   half length X: 30 mm 
   half length Y: 35 mm 
   half length Z: 2.75 mm 
-----------------------------------------------------------
 Translation is (-60,0,4.25) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - botNotch ***
    ===================================================
Solid type: G4Box
Parameters: 
   half length X: 4 mm 
   half length Y: 6 mm 
   half length Z: 3 mm 
-----------------------------------------------------------
 Translation is (60,0,-3.5) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

             
-----------------------------------------------------------
===========================================================
 Transformations: 
    Direct transformation - translation : 
           (0,0,0)
                          - rotation    : 
           
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

===========================================================
===========================================================
-----------------------------------------------------------
    *** Dump for Displaced solid - placedB ***
    ===================================================
 Solid type: G4DisplacedSolid
 Parameters of constituent solid: 
===========================================================
-----------------------------------------------------------
                *** Dump for solid - Screws ***
                ===================================================
 Solid type: G4MultiUnion
 Parameters: 
-----------------------------------------------------------
    *** Dump for solid - screw ***
    ===================================================
 Solid type: G4Tubs
 Parameters: 
    inner radius : 0 mm 
    outer radius : 2.65 mm 
    half length Z: 16.325 mm 
    starting phi : 0 degrees 
    delta phi    : 360 degrees 
-----------------------------------------------------------
 Translation is (48,48,0) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - screw ***
    ===================================================
 Solid type: G4Tubs
 Parameters: 
    inner radius : 0 mm 
    outer radius : 2.65 mm 
    half length Z: 16.325 mm 
    starting phi : 0 degrees 
    delta phi    : 360 degrees 
-----------------------------------------------------------
 Translation is (48,-48,0) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - screw ***
    ===================================================
 Solid type: G4Tubs
 Parameters: 
    inner radius : 0 mm 
    outer radius : 2.65 mm 
    half length Z: 16.325 mm 
    starting phi : 0 degrees 
    delta phi    : 360 degrees 
-----------------------------------------------------------
 Translation is (-48,48,0) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

-----------------------------------------------------------
    *** Dump for solid - screw ***
    ===================================================
 Solid type: G4Tubs
 Parameters: 
    inner radius : 0 mm 
    outer radius : 2.65 mm 
    half length Z: 16.325 mm 
    starting phi : 0 degrees 
    delta phi    : 360 degrees 
-----------------------------------------------------------
 Translation is (-48,-48,0) 
 Rotation is : 
 
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

             
-----------------------------------------------------------
===========================================================
 Transformations: 
    Direct transformation - translation : 
           (0,0,0)
                          - rotation    : 
           
   [ (           1             0             0)
     (           0             1             0)
     (           0             0             1) ]

===========================================================
===========================================================
 Point for surface = (-50.1946,58.8054,3.0478)
Surface Normal returned by Solid is not a Unit Vector.

*** Fatal Exception *** core dump ***
G4Track (0x7fc6c9f79bc0) - track ID = 1, parent ID = 0
 Particle type : geantino - creator process : not available
 Kinetic energy : 1 GeV - Momentum direction : (-0.852869,-0.150384,-0.5)
 Step length : 1 Ang - total energy deposit : 0 eV 
 Pre-step point : (-50.1946,58.8054,6.3978) - Physical volume : World (Vacuum)
 - defined by : Transportation - step status : 1
 Post-step point : (-50.1946,58.8054,6.3978) - Physical volume : MountPhys (G4_Al)
 - defined by : Transportation - step status : 1
 *** Note: Step information might not be properly updated.

-------- EEEE -------- G4Exception-END --------- EEEE -------


*** G4Exception: Aborting execution ***
zsh: abort      ./detSim ../macro/ray.g4mac

I have a small but potentially useful update on this problem.

After reading some of the GEANT4 papers I enabled the navigator check_mode (command: /geometry/navigator/check_mode true) and ran a few test particles to see what information I could gather. Sure enough I received many warnings which all look something like this:

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1001
      issued by : G4VoxelNavigation::ComputeStep()
Conflicting response from Solid.
          Inaccurate solid DistanceToIn for solid Mount
          Solid gave DistanceToIn = 0 yet returns -kInside- for this point !
          Original Point     = (-49.86691371250938,-59.13308628749062,5.513390734780415)
          Original Direction = (-0.5131383574190744,-0.6084887254426478,-0.6053350288513266)
          Intersection Point = (-49.86691371250938,-59.13308628749062,5.513390734780415)
            Safety values: 
          DistanceToOut(p) = 0
 Solid Parameters: -----------------------------------------------------------

or

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1001
      issued by : G4VoxelNavigation::ComputeStep()
Conflicting response from Solid.
          Inaccurate solid DistanceToIn for solid cuLeads
          Solid gave DistanceToIn = 57.70023560751226 yet returns -kOutside- for this point !
          Original Point     = (29.03326131223548,-0.06113290833270819,61.02)
          Original Direction = (0.06470980019379149,-0.05970147813276804,-0.9961166474201916)
          Intersection Point = (32.76703202953229,-3.505922262710166,3.543834751289729)
            Safety values: 
          DistanceToIn(p)  = 1.303834750289729

My run ultimately reaches a fatal error and quits:

-------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : GeomNav0003
      issued by : G4VoxelNavigation::ComputeStep()
Zero from both Solid DistanceIn and Out(p,v).
  Identified point for which the solid cuLeads
  has MAJOR problem:  
  --> Both DistanceToIn(p,v) and DistanceToOut(p,v) return Zero, an equivalent value or negative value.
    Solid: 0x7fb24e72c200
    Point p= (16.3915,-13.8092,0.8)
    Direction v= (-0.595618,0.693931,0.404597)
    DistanceToIn(p,v)     = 0
    DistanceToOut(p,v,..) = 0
    Safety values: 
      DistanceToIn(p)  = 0
      DistanceToOut(p) = 0
*** Fatal Exception *** core dump ***

The volumes for which I experience these errors appear to be ones which involve a G4MultiUnion in some way. Could this be the source of my problems?