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- TL;DR Summary
- How to calculate the gamma dose rate from MCNP results ?

Hi there,

I have a very simple question about MCNP (6.2 to be precise) ... maybe someone here might enlighten me ...

Based on the (more than simple) MCNP input file below, which describes a sphere with R=200cm, filled with air and a point source in the center. There's a single ring tally on the X axis in a distance of 100 cm from the source, which should give the results in mSv/h/particle. The source is Co-60 with its 3 gamma photons defined.

When I run that file, the tally F15 gives me a value of 1.4657E-15 mSv/h/particle (error is 0.0008).

Question: How do I calculate the correct dose rate for a source with i.e. 1E+6 Bq from that tally result ?

Greetings and may that not too boring a question ... but that topic seems to be a bit neglected in the manuals and lectures ... :(

Takvorian

I have a very simple question about MCNP (6.2 to be precise) ... maybe someone here might enlighten me ...

Based on the (more than simple) MCNP input file below, which describes a sphere with R=200cm, filled with air and a point source in the center. There's a single ring tally on the X axis in a distance of 100 cm from the source, which should give the results in mSv/h/particle. The source is Co-60 with its 3 gamma photons defined.

When I run that file, the tally F15 gives me a value of 1.4657E-15 mSv/h/particle (error is 0.0008).

Question: How do I calculate the correct dose rate for a source with i.e. 1E+6 Bq from that tally result ?

Greetings and may that not too boring a question ... but that topic seems to be a bit neglected in the manuals and lectures ... :(

Takvorian

MCNP input:

```
MCNPX Visual Editor Version X_25
c Created on: Wednesday, February 23, 2022 at 19:58
1 304 -0.001205 -1 imp:p=1
2 0 1 imp:p=0
c Welt
1 so 200 $Welt
mode p
m304 6000 -0.000124 $Air (Dry, Near Sea Level) Density: -0.001205
7014 -0.7525 7015 -0.0027668 8016 -0.23123
8017 -8.7866e-005 18036 -4.2793e-005 18038 -8.0671e-006
18040 -0.012776
sdef pos=0 0 0 ERG=D1
c
c source energies (Co-60)
si1 L 0.6938 1.1732 1.3325
sp1 D 1.6312e-4 1 1
c
f15x:p 100 1 -0.125
df15 IU 2 ic 10
stop F15 0.0005
```