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McStas: Virtual_mcnp_input Component

[ Identification | Description | Input parameters | Output parameters | Links ]

The Virtual_mcnp_input Component

This component uses a filename of recorded neutrons from the reactor monte carlo code MCNP as a source of particles.

Identification

  • Author: Chama Hennane and E. Farhi
  • Origin: ILL
  • Date: June 28th, 2006
  • Version:(Unknown)
  • Modification history:
    • EF, July 25th 2006: bug fixes.

Description

This component generates neutron events from a filename created using the
MCNP Monte Carlo code for nuclear reactors. It is used to
calculate flux exiting from hot or cold neutron sources.
Neutron position and velocity is set from the filename. The neutron time is
left at zero.

Note that axes orientation may be different between MCNP and McStas.
The component has the ability to center and orient the neutron beam to the Z-axis.
It also may change the coordinate system from the MCNP frame to the McStas one.
The verbose mode is highly recommended as it displays lots of useful informations.
To obtain absolute intensity, set 'intensity' and 'nps' parameters.
The source total intensity is 1.054e18 for LLB/Saclay (14 MW) and 4.28e18 for
ILL/Grenoble (58 MW).

Format of MCNP events are :

  position_X position_Y position_Z dir_X dir_Y dir_Z Energy Weight Time

energy is in Mega eV, time in shakes (1e-8 s),
positions are in cm and the direction vector is normalized to 1.

%BUGS
We recommend NOT to use parallel execution (MPI) with this component. If you
need to, set parameter 'smooth=1'.

EXAMPLE:
To generate PTRAC files using MCNP/MCNPX, add at the end of your input file:
  f1:n          2001              // tally
  (...)
  ptrac         filename = asc
                max  = -1000000   // number of neutrons to generate and stop
                write = all
                event = sur
                filter = 2001,jsu // surface tally id
To create a 'source' from a MCNP simulation event file for the ILL:
COMPONENT source = Virtual_mcnp_input(
   filename = "H10p", intensity=4.28e18, nps=11328982,
   verbose = 1, autocenter="translate rotate rescale")

WARNING: This is a contributed Component.

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
filename str Name of the MCNP PTRAC neutron input file. Empty string "" unactivates component 0
autocenter str String which may contain following keywords. "translate" or "center" to center the beam area AT (0,0,0) "rotate" or "orient" to center the beam velocity along Z "change axes" to change coordinate system definition "rescale" to adapt intensity to abs. units. with factor intensity/nps. Other words are ignored. 0
repeat_count 1 Number of times the source must be generated. 0 unactivates the component 1
verbose 0|1 Displays additional informations if set to 1 0
intensity n/s Intensity multiplication factor 0
MCNP_ANALYSE 1 Number of neutron events to read for file pre-analysis. Use 0 to analyze them all. 10000
surface_id 1 Index of the emitting MCNP surface to use. -1 for all. -1
nps 1 Number of total events shot by MCNP to generate the PTRAC as indicated at the end of the MCNP 'o' file as 'source particle weight for summary table normalization' or alternatively 'nps = '. 0
smooth 0/1 Smooth sparsed event files for file repetitions. 1

Output parameters

Name Unit Description Default
hfile  
head char header buffer  
rep  
begin_neutrons  
do_rotate  
do_translate  
bx  
by  
bz  
angle2z rad rotation angle required to orient beam along Z axis  
mean_x m source center coordinates  
mean_y m source center coordinates  
mean_z m source center coordinates  
old_surface  
surface  
informed_event  
informed_surface  
min_x  
min_y  
min_z  
max_x  
max_y  
max_z  
min_vx  
min_vy  
min_vz  
max_vx  
max_vy  
max_vz  
mean_dx  
mean_dy  
mean_dz  
n_count_extrapolated  
repeat_cnt  

Links

  • Source code for Virtual_mcnp_input.comp.
  • MCNP
  • MCNP -- A General Monte Carlo N-Particle Transport Code, Version 5, Volume II: User's Guide, p177

[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Mon Jun 26 12:27:17 2017


Last Modified: Monday, 26-Jun-2017 14:27:17 CEST
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