Geometric shielding calculator

For correcting the production rate at a site that is partially shielded from the cosmic-ray flux, either by the surrounding topography or by a nominally infinite dipping surface surrounding the sample. Simple geometric-shielding calculation only -- does not include particle leakage effects. Based on the 'skyline' function previously available at the UW web site. See below for instructions on proper input format.

Version 1.1. March, 2006. Written by Greg Balco,

Strike and dip of surface:

Degrees. Follow the convention that the strike is 90 degrees less than the direction of dip, that is, if you are facing in the strike direction, the surface dips to your right. For a flat surface, enter zero in both boxes.


Notes on azimuth/elevation input format:

Describe the horizon by entering lists of space-separated values corresponding to the azimuth (0-360 degrees) and angular elevation (0-90 degrees) of points on the horizon. If you have a full 2-pi field of view, i.e. no shielding, leave blank or enter zeros.

This procedure means that in the field you should have approximated the horizon by a series of points with straight lines between them. Note that this is not the same as approximating the horizon by the average elevation angle in a series of equal sectors: the latter procedure is inappropriate because the relationship between rise angle and cosmic-ray shielding is nonlinear, and it will underestimate the actual shielding for heavily shielded sites.

For example, if the horizon around you looked as follows:

You might approximate the horizon like this:

And enter the following series of points:

0 55 115 235 310
3 0 5 0 0
This particular horizon has a shielding factor of 0.99995, that is, pretty darn negligible.

(Thanks to David Metsky at Dartmouth College for the 360-degree panorama of the view from Mt. Avalon that we've borrowed here)

Initial development of this website was supported by the National Science Foundation via the CRONUS-Earth project