n write and link your own 
<code><a href="BeamShape.html" target="page">BeamShape</a></code> class.

<p/><code>flag&nbsp; </code><strong> Beams:allowMomentumSpread &nbsp;</strong> 
 (<code>default = <strong>off</strong></code>)<br/>
Allow the beam momenta to be smeared around their initialization
nominal values. 
  

<p/><code>parm&nbsp; </code><strong> Beams:sigmaPxA &nbsp;</strong> 
 (<code>default = <strong>0.</strong></code>; <code>minimum = 0.</code>)<br/>
The width of a Gaussian distribution of the <i