**1. NAME AND TITLE**

FERD-PC: Interactive Multichannel Neutron and Gamma-Ray Spectrum Matrix Unfolding Code System.

**AUXILIARY ROUTINE**

PLOTFERD: Interactive Graphics Program for FERD-PC.

**2. CONTRIBUTOR**

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 77 and Basic; IBM PC and compatibles.

**4. NATURE OF PROBLEM SOLVED**

FERD-PC solves the integral equation which relates a measured pulse-height distribution and associated uncertainties to the true energy spectrum of the incident radiation. FERD-PC is a modified version of FERD, which is included in PSR-102. Several changes were made to include an interactive binning code, a flux integration code, and a plotting utility.

**5. METHOD OF SOLUTION**

The FERD method uses 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. The mathematical method of FERD-PC differs from FERD only in that FERD-PC assumes no uncertainty in the response matrix, while FERD allows additional uncertainty by means of an upper and lower response matrix.

**6. RESTRICTIONS OR LIMITATIONS**

FERD requires an accurate estimation of the actual detector response and the idealized detector response (detector resolution). The limit on the size of the response is highly dependent on available computer memory. A 68 x 55 response matrix requires a minimum of 360 kilobytes of computer memory.

**7. TYPICAL RUNNING TIME**

Running time depends most strongly on the size of the response matrix and the number of output files it generates. The sample problem used 212 seconds on an IBM PC/XT with a math co-processor.

**8. COMPUTER HARDWARE REQUIREMENTS**

FERD is operable on IBM PC or compatibles running DOS version 2.1 or later. A minimum of 360 K of available user memory is required, and a math coprocessor must be installed. FERD-PC has been run on DEC VAX II and IBM PS/2 computers. PLOTFERD requires a HP 7475A or equivalent plotter.

**9. COMPUTER SOFTWARE REQUIREMENT**

FERD-PC uses the Microsoft Fortran (Version 4.01) compiler, and the Microsoft Quickbasic compiler was used for PLOTFERD.

**10. REFERENCE**

Brian D. Rooney, *User's Manual For FERD-PC*, ORNL/TM-11028 (April 1989).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one double-sided, double density (360 K) diskette containing the source code and sample problem input, plus output from the sample problem.

**12. DATE OF ABSTRACT**

June 1989.

**KEYWORDS** UNFOLDING; GAMMA-RAY SPECTRUM ANALYSIS