1. NAME AND TITLE

FLYSPEC/SHORTSPEC: Neutron Unfolding Code System for Reducing Proton-Recoil Pulse-Height Obtained with NE-213 Liquid Scintillator.

AUXILIARY ROUTINES

FLYINP: Pulse Height Data File for FLYSPEC.

SHORTINP: Pulse Height Data File for SHORTSPEC.

FLYSPEC was developed for the LSI-11 microcomputer and has been modified to run on the CDC 7600 computer. The earliest version of FLYSPEC, NUTSPEC, was written in LRLTRAN for the CDC-7600 computer and includes not only a derivative-unfolding package for NE213 and stilbene pulse height spectra, but also a response matrix calculation and inversion package for proportional counters containing H2, CH4, or 3He. A later version, SHORTSPEC, is a CDC-7600 version containing only the NE213 and stilbene unfolding package from NUTSPEC.

2. CONTRIBUTOR

Lawrence Livermore National Laboratory, Livermore, California.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; CDC 7600, LSI-11.

4. NATURE OF PROBLEM SOLVED

FLYSPEC and SHORTSPEC are neutron unfolding codes used to reduce proton recoil pulse height data obtained with a NE213 liquid scintillation spectrometer. They read the pulse height data file obtained using a NE213 or stilbene spectrometer. Then, using the energy calibration data and detector dimensions contained in the data file and the parameters set by the user during execution, the codes unfold the incident neutron spectrum from the pulse height data.

5. METHOD OF SOLUTION

Data unfolding is accomplished by differentiation of the recoil proton energy distribution and includes compensation for the non-linear relation between detector pulse height and proton energy as well as empirical corrections for proton escape from the detector active volume and multiple neutron scattering in the detector.

6. RESTRICTIONS OR LIMITATIONS

The maximum number of pulse height bins is 256 and maximum number of output sample points for the neutron spectrum is 128.

Since this version uses the full interactive and graphics capabilities of the LLNL and Magnetic Fusion Energy Computer Center networks, it will not run on other computers without modification.

7. TYPICAL RUNNING TIME

Execution time is a few seconds on the LSI-11 microcomputer and is a few milliseconds on the CDC 7600 computer.

8. COMPUTER HARDWARE REQUIREMENTS

SHORTSPEC is written in Fortran IV for the CDC 7600 system at LLNL and will run on either the LLNL OCTOPUS system or the MFECC. FLYSPEC is written in Fortran IV for the LSI-11 microcomputer and runs under the RT-11 operating system.

9. COMPUTER SOFTWARE REQUIREMENTS

SHORTSPEC requires the software libraries FORTLIB and TV80LIB available on the LLNL network. Several LLNL utility routines which are not available are required to run this code. FLYSPEC and SHORTSPEC may be compiled using the CHAT compiler on the MFECC.

10. REFERENCES

D. Slaughter and R. Strout, II, "FLYSPEC: A Simple Method of Unfolding Neutron Energy Spectra Measured with NE213 and Stilbene Spectrometers," Nucl. Inst. & Meth., 198 (1982).

D. Slaughter and R. Stout, II, Informal Notes.

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

April 1983; updated October 1983; revised February 1984, August 1984.

KEYWORDS: UNFOLDING; NEUTRON; MICROCOMPUTER; SCINTILLATION DETECTOR