**RSIC COMPUTER CODE PSR-097**

**1. NAME AND TITLE**

PAPER 1: Monte Carlo Calculation of Solid Angle and Self-Absorption Factors for an Inclined
Cylindrical Source Viewed by a Cylindrical Detector.

**2. CONTRIBUTOR**

Department of Physics, Ben Gurion University of the Negev, Beersheva, Israel.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; CDC 6600.

**4. NATURE OF PROBLEM SOLVED**

PAPER 1 calculates the self absorption of gamma radiation in an inclined cylindrical source and,
also, the solid angle of the source subtended by a cylindrical detector. It can be used in any situation
in which a transformation composed of a translation and a rotation between the source and detector
coordinate systems is required.

**5. METHOD OF SOLUTION**

PAPER 1 uses the Monte Carlo method for determining self-absorption and solid-angle correction
factors in the inclined cylindrical geometry. The Monte Carlo method used in PAPER 1 is extremely
flexible and many geometric configurations can be treated with only trivial modifications of the
computer program.

**6. RESTRICTIONS OR LIMITATIONS**

No weighting factor was assigned to the gamma ray as a function of its angle of incidence on the
detector.

**7. TYPICAL RUNNING TIME**

The Monte Carlo method for determining self-absorption and solid-angle correction factors in the
inclined cylindrical geometry requires fairly large amounts of computer time to acquire statistical
accuracy of the order of 1%. A total of 1000 s of computer time was used to run 40,000 case histories
per point on the CDC-6000 computer.

**8. COMPUTER HARDWARE REQUIREMENTS**

PAPER 1 is operable on the CDC 6600 computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCES**

"User's Instructions," Informal Note.

Y. S. Horowitz, S. Mordechai and A. Dubi, "Solid-Angle and Self-Absorption Factors for an
Inclined Cylindrical Source Viewed by a Cylindrical Detector," *Nucl. Instr. and Meth.* 123 (1975) 551-555.

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source
code input.

**12. DATE OF ABSTRACT**

March 1984.

**KEYWORDS: ** GAMMA-RAY SOURCE ANALYSIS; SELF ABSORPTION