## RSICC CODE PACKAGE CCC-802

### 1. NAME AND TITLE

SACALC3 - Calculates the Average Solid Angle Subtended by a
Volume.

**2. CONTRIBUTORS**

Ralph Whitcher, Crawley, United Kingdom through the OECD
Nuclear Energy Agency Data Bank, Issy-Les Moulineaux, France.

### 3. CODING LANGUAGE AND COMPUTER

Turbo Delphi,
Microsoft Windows PC (C00802PCX8600).

**4. NATURE OF PROBLEM
SOLVED**

** **SACALC3v1.4 calculates the average solid angle subtended by a
right cylinder detector, a cuboid detector, a plane disc window detector, a plane
rectangular window detector, or a spherical detector to a circular or
rectangular, plane, thick or point source at any position and orientation to
the detector. The program also calculates the number of hits on the detector
sides and the average path length through the detector volume (assuming no
scattering or absorption). The current performance of personal computers makes
it realistic achieve accuracies of solid angle estimates typically better than
0.03 %.

** **The program also
calculates the number of hits on the detector walls and the average path length
through the detector volume (assuming no scattering or absorption).

** **The input data can be
done on screen, or for batch processing, multiple cases can be entered as a
text file.

### 5. METHOD OF SOLUTION

** **The program uses a
Monte Carlo method to calculate the average solid angle for source-detector
geometries that are difficult to analyse by analytical methods. The values of
solid angle are calculated to accuracies of typically better than 0.03%. The
calculated values from the Monte Carlo method agree closely with those produced
by polygon approximation and numerical integration by Gardner and Verghese, and
others.

** **The program models
non-coaxial and non-parallel geometries, and combinations of source and
detector shapes.

### 6. RESTRICTIONS OR LIMITATIONS

The sources are assumed to be uniformly distributed. To
avoid rounding errors, differences less than 1e-12 are assumed to be zero.

### 7. TYPICAL RUNNING TIME

Depends on the number of random events selected by the user.

### 8. COMPUTER HARDWARE REQUIREMENTS

IBM PC.

### 9. COMPUTER SOFTWARE REQUIREMENTS

Microsoft Windows, Windows-9X, or Windows-NT, -2000, -XP, or
-7.

### 10. REFERENCES

**a) Included Documentation**

R. Whitcher: “SACALC3 v1.4 How to Use” (March 2012).

**b) Background Documentation**

R. Whitcher: “A Monte Carlo Method to Calculate the Average
Solid Angle Subtended by a Right Cylinder to a Source that is Circular or
Rectangular, Plane or Thick, at any Position and Orientation,” *Radiation Protection
Dosimetry 2006 118(4):459-474* .

### 11. CONTENTS OF CODE PACKAGE

Included in the SACALC3 package is documentation, readme
files, pre-compiled Windows executables, and sample test input. Note: no
source code is included.

### 12. DATE OF ABSTRACT

December 2012.

**KEYWORDS:** MONTE CARLO METHOD, DETECTORS, SOURCE