The first step is to create a list of reflections to be used for 
the averaging of the powder neutron cross section. 
just type: powdermagnon 0.3 2 0.1 80
meaning take file mcphas.j, generate a reflection list and put it to 
file mcdisp.par. Parameters in the above command are 
- 0.3 ....qmin   [1/A] minimal q vector
- 2   ....qmax   [1/A] maximal q vector
- 0.1 ....deltaq [1/A] step width in q
- 80  ....number of steps in polar coordinate  (steps in polar angle (steps in polar angle are  then calculated in module
        powdermagnon by are  then calculated in module
        powdermagnon by