Keyword:MCSAMPLE

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MCSAMPLE distrib {1} nsamples {10} lb {-3.0} ub {3.0}


This keyword is used in conjunction with the SENSITIVITY keyword to change the sampling used in the Monte-Carlo calculation. In the Monte-Carlo calculation, values of cross-sections are randomly selected from a distribution with a mean and standard deviation given by the value and uncertainty specified. The first argument, distrib, is an integer that specifies the distribution to be used, of which the allowable values are:

  1. log-normal (default)
  2. normal
  3. uniform
  4. log-uniform

nsamples is the number of Monte-Carlo samples per parent-daughter pair specified by SENSITIVITY. lb and ub give the cutoffs for the log-normal and normal distributions. For the log-normal distribution, these define the range in multiples of the standard deviation from the logarithm of the mean at which the logarithm of the sample is accepted. For the normal distribution, they define the range in multiplies of the standard deviation from the mean at which the sample is accepted. lb and ub are not used for the uniform and log-uniform distributions.

Example usage:

< -- Control phase -- >
...
FISPACT
* Title of the simulation
< -- Initial phase -- >
...
SENSITIVITY SIGMA 0.8 2 1
Ti48 Sc48
Ti49 Sc48
Sc48
MCSAMPLE 2 100 -2.0 2.0
...
< -- Inventory phase -- > 
...

I this case, the sensitivity of the Sc48 inventory to the Ti48(n,p)Sc48 and Ti49(n,np+d)Sc48 reactions are used for Monte-Carlo sampling. 100 samples of each is used with a normal distribution between -2 and +2 standard deviations.