محاسبه طول اندرکنش در mcnpx

 the incident particle is proton.   Look at the end creation and loss tables

Then, use the following formula with the no. of nuclear interactions
 in the column of "proton loss", ie. 1025, in the this case

where N is the no. of particles uninteracted N0 = 1025

        N0 is the no. of incident particles, d is the length of 

the fiducial volume you set and l is the interaction length that we

want

Ref : Click