1. NAME AND TITLE
FERDO/FERD: Multichannel Neutron and Gamma-Ray Spectrum Matrix Unfolding Code
Oak Ridge National Laboratory, Oak Ridge, Tennessee.
3. CODING LANGUAGE AND COMPUTER
Fortran IV; IBM 3033.
4. NATURE OF PROBLEM SOLVED
FERDO and FERD solve the integral equation which relates a measured pulse-height distribution
and associated uncertainties to the true energy spectrum of the incident radiation.
5. METHOD OF SOLUTION
FERDO uses the method of constrained least-squares and biased estimation to solve a discretized
representation of the integral unfolding problem and to compute a 2-sigma confidence interval for the
true energy spectrum. FERD improves the FERDO solution by iteratively modifying the biased
6. RESTRICTIONS OR LIMITATIONS
FERDO/FERD require accurate estimations of the actual detector response and the idealized
detector response (normally the detector energy resolution). In-core memory requirements are roughly
three times the size of the response matrix (number of rows times the number of columns) for FERDO
and four times the size of the response matrix for FERD. Additionally, a scratch storage device must
be specified for both FERDO and FERD.
7. TYPICAL RUNNING TIME
Running time depends most strongly on the size of the response matrix. An 87 x 88 matrix problem
required 4.5 s of IBM 3033 CPU time for FERDO and 15.2 s for FERD.
8. COMPUTER HARDWARE REQUIREMENTS
FERDO/FERD is operable on the IBM 3033 computer.
9. COMPUTER SOFTWARE REQUIREMENT
FERDO/FERD uses the proprietary DISSPLA graphics software package available from ISSCO,
San Diego, California. It has been successfully run on the IBM 3033 computer under control of the
MVS-JES2 Operating System. A Fortran IV compiler is required.
B. W. Rust, D. T. Ingersoll, and W. R. Burrus, "A User's Manual for the FERDO and FERD
Unfolding Codes," ORNL/TM-8720 (September 1983).
11. CONTENTS OF CODE PACKAGE
Included are the referenced document and one (1.2MB) DOS diskette which contains the source
code and sample problem input and output.
12. DATE OF ABSTRACT
KEYWORDS: UNFOLDING; GAMMA-RAY SPECTRUM ANALYSIS