Problem 840

I am modelling energy deposition in a BF3 tube as a result of thermal neutron
capture reactions. What I am expecting is the classic wall effect continuum
with peaks at 2.31 and 2.792 Mev. The peaks are present, but instead of the
continuum I have a set of discrete lower intensity peaks. The most obvious
explanation to me is that the interactions are being claculated taking place at
discrete locations within the detector rather than at random distances from the
wall. I had a look at the tracking information over several hundred events and
of the five capture reactions that took place, three took place at one set of
coordinates and two at another. Based on my knowledge of the stepping process,
I cannot understand why this is happening, so I would appreciate some
suggestions!

Many thanks,


Vaughan Rees