Hi everyone

I have found a significant discrepancy when I use a very simple (i.e.,
PLAN2P-type) geometry versus one using Combinatorial Geometry.  The layers
of W-RE struck by 150-keV electrons are quite thin (0.0001 cm each and using
chard=0.0001 cm).  The two geometries are shown in the attached PDF files.
I am using modified versions of ucsampl5.f and ucsampcg.f and I am finding
that electrons backscatter more from the first layer using CG than they do
using PLAN2P---both using the same EGS5 and input data!  Take a look at the
following results:

>From ucsampl5_x.out:

ENERGY DEPOSITION SUMMARY FOR PARTICLES WITH IQ=-1
                                                       IARG
                   0               1             2              3         4                ROW SUM
   REGION

      1       0.5694778E-01   0.000000      0.7769612E-02   0.000000   0.000000           0.6471739E-01
      2       0.7739501E-01   0.000000      0.1081845E-01   0.000000   0.000000           0.8821345E-01
      3       0.7826126E-01   0.000000      0.1111047E-01   0.000000   0.000000           0.8937173E-01
      4       0.7257108E-01   0.000000      0.1042557E-01   0.000000   0.000000           0.8299665E-01
      5       0.6367305E-01   0.000000      0.9229329E-02   0.000000   0.000000           0.7290237E-01
      6       0.5353554E-01   0.000000      0.7857990E-02   0.000000   0.000000           0.6139354E-01
      7       0.4311949E-01   0.000000      0.6355380E-02   0.000000   0.000000           0.4947488E-01
      8       0.3370415E-01   0.000000      0.5003118E-02   0.000000   0.000000           0.3870727E-01
      9       0.2506897E-01   0.000000      0.3771369E-02   0.000000   0.000000           0.2884034E-01
     10       0.1809285E-01   0.000000      0.2730352E-02   0.000000   0.000000           0.2082320E-01
     11       0.2956366E-01   0.000000      0.4535731E-02   0.000000   0.000000           0.3409939E-01
     12       0.1587969E-02   0.000000      0.2564311E-03   0.000000   0.000000           0.1844400E-02
     13       0.2557094E-03   0.000000      0.4604219E-04   0.000000   0.000000           0.3017516E-03
     14       0.2600498E-03   0.000000      0.4834904E-04   0.000000   0.000000           0.3083988E-03
     15        0.000000       0.000000       0.000000       0.000000   0.000000            0.000000    
     16        0.000000       0.000000       0.000000       0.000000   0.000000            0.000000    
     17        0.000000       0.000000       0.000000      0.3586720   0.000000           0.3586720    
   COL SUM    0.5540366       0.000000      0.7995819E-01  0.3586720   0.000000           0.9926667    

>From ucsampcg_x.out:

ENERGY DEPOSITION SUMMARY FOR PARTICLES WITH IQ=-1
                                                       IARG
                   0               1             2              3         4                ROW SUM
   REGION

      1       0.3091283E-01   0.000000      0.4553527E-02   0.000000   0.000000           0.3546636E-01
      2       0.8510116E-01   0.000000      0.8986106E-02   0.000000   0.000000           0.9408727E-01
      3       0.7539845E-01   0.000000      0.1045807E-01   0.000000   0.000000           0.8585652E-01
      4       0.7138458E-01   0.000000      0.1018348E-01   0.000000   0.000000           0.8156806E-01
      5       0.6353604E-01   0.000000      0.9165792E-02   0.000000   0.000000           0.7270183E-01
      6       0.5364234E-01   0.000000      0.7795454E-02   0.000000   0.000000           0.6143780E-01
      7       0.4389440E-01   0.000000      0.6429661E-02   0.000000   0.000000           0.5032406E-01
      8       0.3437023E-01   0.000000      0.5085933E-02   0.000000   0.000000           0.3945616E-01
      9       0.2628175E-01   0.000000      0.3872993E-02   0.000000   0.000000           0.3015474E-01
     10       0.1606868E-01   0.000000      0.2189591E-02   0.000000   0.000000           0.1825827E-01
     11       0.3450066E-01   0.000000      0.5388663E-02   0.000000   0.000000           0.3988932E-01
     12       0.1785714E-02   0.000000      0.2871495E-03   0.000000   0.000000           0.2072864E-02
     13       0.2528237E-03   0.000000      0.4428248E-04   0.000000   0.000000           0.2971062E-03
     14       0.2343868E-03   0.000000      0.4204600E-04   0.000000   0.000000           0.2764328E-03
     15        0.000000       0.000000       0.000000       0.000000   0.000000            0.000000    
     16        0.000000       0.000000       0.000000       0.000000   0.000000            0.000000    
     17        0.000000       0.000000       0.000000      0.3811779   0.000000           0.3811779    
   COL SUM    0.5373640       0.000000      0.7448275E-01  0.3811779   0.000000           0.9930247    

As you can see from there is almost a factor of two difference in the
fraction of energy deposited in the first 1-micron thick layer of W-RE.