Solving Fatal Error in MCNP6 Particle Alpha Mode

In summary, "Solving Fatal Error in MCNP6 Particle Alpha Mode" addresses a specific issue encountered when running MCNP6 simulations in alpha particle mode. The article outlines the nature of the fatal error, potential causes, and provides troubleshooting steps to resolve the issue. It emphasizes the importance of correctly setting up the input files and parameters to ensure successful execution of simulations. The guidance aims to help users effectively navigate and fix the error to achieve accurate simulation results.
  • #1
physmcnp6
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TL;DR Summary
Hello everyone here,

I do need your help in this matter, please kindly help me solve this problem. I am new to this forum and now am seeking for help.

I'm new to MCNP code, and I ran the MCNP6 code with particle alpha mode a and it gave me a fatal error saying "source particle type not on mode card". This causes fatal errors for mesh tally and sdef.


please kindly help, and i couldn't find the problem at all.
the whole input are below
warning. Physics models enabled.
1- c Created on: Saturday, January 13, 2024 at 19:20
2- 1 1 -0.998207 -1 2 -3
3- 2 1 -0.998207 -1 3 -4
4- 3 1 -0.998207 -1 4 -5
5- 4 2 -0.001205 (-2 :1 :5 :(1 -3 ):(4 1 ))-6
6- 5 0 6
7-
8- 1 cx 1
9- 2 px -2
10- 3 px -1
11- 4 px 0
12- 5 px 1
13- 6 so 7
14-
15- mode n h a
16- m1 1000. -0.111894 $MAT1
17- 8000. -0.888106
18- m2 6000. -0.000124 $MAT2
19- 7000. -0.755268 8000. -0.231781 18000. -0.012827
20- imp:h 1 3r 0 $ 1, 5
21- imp:n 1 3r 0 $ 1, 5
22- imp:a 1 3r 0 $ 1, 5
23- vol 1408 3r 29.33 0 $ 1, 5
fatal error. too many entries: 6 were read, 5 are required.
24- sdef pos=-5 0 0 axs=1 0 0 ext=-8 rad=d1 par=4 erg=50 vec=1 0 0 dir=1
warning. ext is constant. in most problems it is a variable.
25- si1 1 5
26- sp1 -21 1
27- f6:a 1 2 3 4
28- nps 1000

comment. total nubar used if fissionable isotopes are present.

fatal error. source particle type not on mode card.
1source print table 10

values of defaulted or explicitly defined source variables

cel 0.0000E+00
sur 0.0000E+00
erg 5.0000E+01
tme 0.0000E+00
dir 1.0000E+00
pos -5.0000E+00 0.0000E+00 0.0000E+00
x 0.0000E+00
y 0.0000E+00
z 0.0000E+00
ext -8.0000E+00
axs 1.0000E+00 0.0000E+00 0.0000E+00
vec 1.0000E+00 0.0000E+00 0.0000E+00
ccc 0.0000E+00
nrm 1.0000E+00
ara 0.0000E+00
wgt 1.0000E+00
eff 1.0000E-02
par 4.0000E+00
tr 0.0000E+00
bem 0.0000E+00 0.0000E+00 0.0000E+00
bap 0.0000E+00 0.0000E+00 0.0000E+00
loc 0.0000E+00 0.0000E+00 0.0000E+00
dat 0.0000E+00 0.0000E+00 0.0000E+00
probability distribution 1 for source variable rad
power law 21: f(x)=c*abs(x)**k k = 1.0000E+00 order of sampling source variables.
par axs rad ext pos vec dir erg tme

fatal error. sdef or si source particle type not on mode card.

1tally 6 print table 30
tally type 6 track length estimate of heating.
particle(s): alphas
cells 1 2 3 4

warning. use models for the following missing data tables:
1000. c
7000. c
8000. c
1000. h
6000. h
7000. h
8000. h
18000. h
1material composition
 
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  • #2
Hi, welcome to physicsforums,

"mode n h a" is neutrons, protons, alphas.
"par=4" on your sdef card is negative muons. 34 is alphas, so maybe this is a typo.
 
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  • #3
Alex A said:
Hi, welcome to physicsforums,

"mode n h a" is neutrons, protons, alphas.
"par=4" on your sdef card is negative muons. 34 is alphas, so maybe this is a typo.
If I use particle alpha, is the symbol "mode a"? because the result is a fatal error source particle type not on mode card
 
  • #4
When I change the sdef line to have par=a, and I remove an extra entry from the vol line those problems go away for me and the problem tries to run. I then get a geometry error, which is probably down to the definition of cell 4.
 
  • #5
Alex A said:
Hi, welcome to physicsforums,

"mode n h a" is neutrons, protons, alphas.
"par=4" on your sdef card is negative muons. 34 is alphas, so maybe this is a typo.
why the alphas "par=34"?
 
  • #6
The MCNP6.3 manual is public and good, so I will use that. Table 4.3 on page 255 (257 of 1082) lists the particles available, their symbols and their "ipt".

You do not have to use "par=34" you can use "par=a"

Why the number is so high I don't know but though it's very common in nuclear decay it probably isn't very important for most high energy particle transport.
 
  • #7
Alex A said:
Hi, welcome to physicsforums,

"mode n h a" is neutrons, protons, alphas.
"par=4" on your sdef card is negative muons. 34 is alphas, so maybe this is a typo.
why the alphas par=34?
Alex A said:
The MCNP6.3 manual is public and good, so I will use that. Table 4.3 on page 255 (257 of 1082) lists the particles available, their symbols and their "ipt".

You do not have to use "par=34" you can use "par=a"

Why the number is so high I don't know but though it's very common in nuclear decay it probably isn't very important for most high energy particle transport.
may I ask again?
if there is a fatal error with the description "fatal error, 4 tally volumes or areas were not input nor caculated"
what do I have to do?
and what's symbol of areas in mcnpX
 
Last edited:
  • #8
MCNP is not very clever and often needs the volumes of a shape in order to calculate answers. Try attaching the file output file by changing the name to add .txt and then click attach files. If you have used vol correctly I would expect this to work.

"why the alphas par=34?"

I don't seem to understand your question. Why is it not 02004?
 

FAQ: Solving Fatal Error in MCNP6 Particle Alpha Mode

What causes a fatal error in MCNP6 when running in particle alpha mode?

Fatal errors in MCNP6 when running in particle alpha mode can be caused by several factors, including incorrect input file configurations, unsupported physics models, or computational limitations. Ensuring that the input files are correctly formatted and that the necessary physics models are supported for alpha particles is crucial.

How can I identify the specific error causing the fatal error in MCNP6?

To identify the specific error, carefully review the output and error files generated by MCNP6. These files typically provide detailed information on the nature of the error, including line numbers and descriptions. Additionally, using debugging tools and running the code in verbose mode can help pinpoint the issue.

What steps can I take to resolve a fatal error related to geometry issues in MCNP6?

Resolving geometry-related fatal errors involves checking the geometry definitions in the input file for inconsistencies, overlaps, or undefined regions. Using the geometry plotting features in MCNP6 can help visualize and identify problematic areas. Ensuring that all cells and surfaces are correctly defined and properly referenced is essential.

Are there specific settings or parameters that need to be adjusted for alpha particles in MCNP6?

Yes, when working with alpha particles in MCNP6, certain settings and parameters need to be adjusted. This includes specifying the correct particle type, ensuring that the appropriate cross-section libraries are used, and setting relevant physics options like energy cutoffs and transport parameters tailored for alpha particles.

What resources are available for troubleshooting and solving fatal errors in MCNP6?

Several resources are available for troubleshooting and solving fatal errors in MCNP6, including the official MCNP6 user manual, online forums, and user groups. Additionally, reaching out to the MCNP6 support team or consulting with experienced colleagues can provide valuable insights and solutions. Tutorials and example problems provided by the software developers can also be very helpful.

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