MCNP Simulation of NaI scintillation detector
c     diameter 1.5 " = 3.81 cm 
c     length      2" = 5.08 cm
c
c    Cells
c
c     cel   mat     rho        geom    
    10       1    -3.667     -1          $ NaI crystal
    20       2    -2.7       -2 1        $ Al around detector   
    30       2    -2.7       -10         $ Al for PMT 
    70       20   -10.34     -7          $ UO2 pellet
    40       10 -1.205e-3    -100 
                   (2.1:10.2:2.3) (7.1:7.2:7.3)  $ Air
   100       0 100

c   Surfaces
c
1    RCC   0 0 0.05   0 0  5.13  1.905  $ NaI crystal
2    RCC   0 0 0      0 0  5.18  1.955  $ Al housing
7    RCC -.5 0 -1.45  1 0  0     0.45   $ UO2 pellet  
10   RCC   0 0 5.18  0 0  0.10   1.955  $ PMT behind the crystal
c
100    SO 100

c   Methods
c
nps 1e8
mode p e
imp:p 1 1 1 1 1 0  $ 
imp:e 1 1 1 1 1 0  $ 
c
c      Materials
c       
M1      11000   1           $ Na    NaI, rho = -3.667 g/cm3
        53000   1           $ I
c
c
M2      13000   1           $ Al    Aluminum, rho = -2.70 g/cm3
c
M10      6000 -0.000124     $ C  Dry Air, rho = -1.205E-3 g/cm3
         7000 -0.755268     $ N     
         8000 -0.231781     $ O
        18000 -0.012827     $ Ar
c
c     
m20     92000 1             $ for gamma simulation, all U
                            $ rho=-10.34 g/cm3 
         8000 2             $ O
c
c 
c    Tally Section
c
FC8  NaI  Pulse Height Tally                                        
F8:p 10                           $ Pulse Height Tally 
E8 0 1.e-5  1e-3 1023I 0.512      $ energy bin, 0.5 keV bins
FT8 GEB 0.0 0.031196 4.6141       $ FWHM resolution
c
c
c
sdef PAR=p POS= 0 0 -1.45 RAD=D1 EXT=D2 AXS = 1 0 0  ERG=D3 
c
SI1 0  0.45  $ radius, r
SP1 -21 1    $ sampling prop to r
c
SI2 -0.5 0.5 $ length
SP2 -21  0   $ default radius constant with x
C
C the # below indicates vertical formatting (MCNP6.2 manual 2.8.2)
#   SI3    SP3                  $ U-235  
     L       D
  0.1438    7800                $  
  0.1634    3700                $                         
  0.1857   43000
  0.2021     800
  0.2053    4000
