Appropriate importance function and sampling scheme facilitates the application of the Monte Carlo method to problems involving the deep penetration of radiation

Armstrong, T. W.

Stevens, P. N.

English

NASA Technical Reports Server

April 1968
	
.I.,	 Brief 68-10143 
NAS\TECH BRIEF 
NASA Tech Briefs are issued to sumn rjiqecifie.innovations derived from the U.S. space program, 
to encourage their commercial appiiadn. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scicntic and Technical Information, Springfield, Virginia 22151. 
Deep Gamma Ray', Penetration in Thick Shields 
ment was contributed approximately equally by the 
spatial and polar angle biasing; essentially no im-
provement was provided by the azimuthal angle 
biasing. 
Note: 
Complete details of this study may be obtained 
from:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B68-10143 
The results of an analytical study show thatthe 
successful application of the Monte Carlo method to 
problems involving the deep penetration of radiation 
requires the specification of an appropriate impoi-
tance function and sampling scheme. Such a function 
(the V0 importance function), based on the first term 
of the series solution of the value function equation,\ 
has been formulated. For the case of I Mev gamma 
rays incident normally on thick homogeneous slabs 
of lead and water, use of the V importance function 
provides considerable improvement over the conven-
tional exponential transform method, in which only 
the spatial dependence of the value-function is con-
sidered. For the same computation times, the variance 
of the dose buildup factor for slabs having a 2 I-mean-
free-path thickness was reduced by a factor of 
approximately 125 for a lead medium and approxi-
* I r5n for a utr merlium Pr the nqrtir'iikir iiia..ij .	 •. u	 . •......	 Marshall Space Flight Center 
Patent status: 
No patent action is contemplated by NASA. 
Source: T. W. Armstrong and P. N. Stevens 
of the University of Tennessee 
under contract to 
source geometry configuration studied the improve	 (M FS- 14388) 
.IE.
Category 02 
This document was prepared under the sponsorship of the National 	 G . nment assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000143 2020-03-12T05:28:47+00:00Z
a.


Deep gamma ray penetration in thick shields

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server