In writing a km3 scale simulation for the antares detector I've tried to enter
some properties of water for optical photons other than the ones used in ExN06
(I did temporalily use the ones in ExN06 and they worked just fine). Changing
absorbtion length and energy of the photons in the tables PPCKOV[NUMENTRIES]
and  ABSORPTION1[NUMENTRIES] didn't give any problems (the changes were rather
small by the way). However when I changed the RINDEX1[NUMENTRIES] from

 G4double RINDEX1[NUMENTRIES] =
 { 1.33, 1.33, 1.33, 1.33, 1.33, 1.33, 1.33,
   1.33, 1.33, 1.34, 1.34, 1.34, 1.34, 1.34,
   1.34, 1.34, 1.34, 1.34, 1.34, 1.34, 1.34,
   1.34, 1.34, 1.35, 1.35, 1.35, 1.35, 1.35,
   1.35, 1.35, 1.35, 1.35 };

to

  G4double RINDEX1[NUMENTRIES] =
  { 1.3435, 1.344,  1.3445, 1.345,  1.3455,
  1.346,  1.3465, 1.347,  1.3475, 1.348,
  1.3485, 1.3492, 1.35,   1.3505, 1.351,
  1.3518, 1.3522, 1.3530, 1.3535, 1.354,
  1.3545, 1.355,  1.3555, 1.356,  1.3568,
  1.3572, 1.358,  1.3585, 1.359,  1.3595,
  1.36,   1.3608};

and ran a high energy muon (10 GeV) through my km3 scale detector consisting out
of pure H2O and within that the Optical Modules (placed according to the 1999
proposal) which also consisted out of pure H2O I got the following error:


> !!! the global time goes back  !!! :  48.6022 -> -1.79432e+07[ns]
>  !!! the poper time goes back  !!! :  0.00460323 -> -1.21661e+07[ns]
>  G4ParticleChange::CheckIt
>  pointer : 0x8667550
>       -----------------------------------------------
>         G4ParticleChange Information
>       -----------------------------------------------
>         # of 2ndaries       :                    0
>       -----------------------------------------------
>         Energy Deposit (MeV):                    0
>         Track Status        :                Alive
>         True Path Length (mm) :                -35.3
>         Stepping Control     :                    0
>         Event Biasing        :  not used
>         Position - x (mm)   :             -4.9e+08
>         Position - y (mm)   :            -3.61e+09
>         Position - z (mm)   :             1.54e+09
>         Time (ns)           :            -1.79e+07
>         Proper Time (ns)    :            -1.22e+07
>         Momentum Direct - x :                0.124
>         Momentum Direct - y :                0.912
>         Momentum Direct - z :                -0.39
>         Kinetic Energy (MeV):                0.243
>         Polarization - x    :                    0
>         Polarization - y    :                    0
>         Polarization - z    :                    0
>         Touchable (pointer) : 0x86689e8
> G4ParticleChange::CheckIt
>
> *** G4Exception: Aborting execution ***
>

Please correct this problem. I can't get my simulation working properly without
the actual values for the refraction index.

Thanks,
Robbert Mirani
intern for the Antares Project for the NIKHEF