Re: Linac Neutrons In Maze

["Scott O. Schwahn" <schwahn@CEBAF.GOV>]

>I'm looking for comments on the 2 methods for calculating
>neutron mrem...
>...
>What are other people doing ??
>

Chris,

I am unfamiliar with the NCRP method that you are using, but I would like
to look it up some time.

What I use for neutron scattering is the following reference:

Schopper, H., Shielding Against High Energy Radiation, Group 1, Volume 11
of Numerical Data and Functional Relationships in Science and Technology,
Springer-Verlag, New York, 1990.

On pages 421 and 422, there are good Universal transmission curves for the
first and subsequent legs of labyrinths based on d/A^0.5 where d is the
distance from the tunnel mouth and A is the cross-sectional area of the
tunnel.  In any case, the transmission curves have a low limit, high limit,
and central value.  I have used the central value for many calculations
here, and the measured results are remarkably close.  However, the low
limit and high limit for various calculational methods are up to about a
factor of 10 apart, especially where d/A^0.5 grows larger.

I would be glad to FAX you the Universal Curves if you would like.  The
book itself is about a $600 book!

Scott

Scott O. Schwahn, CHP
Thomas Jefferson National Accelerator Facility
Newport News, VA
schwahn@jlab.org