1. NAME AND TITLE

NX1-NX2: Code System to Calculate Excitation Functions for (n,charged particle) Reactions.

2. CONTRIBUTORS

Institute of Atomic Energy, Beijing, China, through the International Atomic Energy Agency, Vienna, Austria, and the NEA Data Bank, Gif-Sur-Yvette, Cedex, France.

3. CODING LANGUAGE AND COMPUTER

Fortran 77; VAX family.

4. NATURE OF PROBLEM SOLVED

NX1 calculates excitation functions for (n,p) and (n,alpha) reactions. NX2 calculates excitation functions for (n,d) and (n,3He) reactions.

5. METHOD OF SOLUTION

The formulas for the excitation functions are analytical expressions. Therefore, no numerical techniques are required. They have been derived based on an evaporation model considering pre-equilibrium emission. Some primary approximations are:

1. Pre-equilibrium emission only occurs at the state of exciton number n = 3.

2. There is only one competing reaction of (n,n').

3. The (n,pn) and (n,alphan) reactions are primary channels for secondary particle emission.

4. A complex particle such as d, t, 3He, or alpha is regarded as an exciton which is previously formed in the target nucleus with a probability P(g).

5. The penetration factor of a rectangular-well potential is used to describe the effects of Coulomb barrier.

6. The energy level density of the compound nucleus is taken in the form of constant temperature.

6. RESTRICTIONS OR LIMITATIONS

The incident neutron energy must be less than or equal to 20 MeV. The target mass number is between 23 and 197.

7. TYPICAL RUNNING TIME

The sample input took only a few seconds on a VAX 6000 under the VAX/VMS operating system.

8. COMPUTER HARDWARE REQUIREMENTS

The code will run on the VAX family of computers.

9. COMPUTER SOFTWARE REQUIREMENTS

The code was written in Fortran 77 and uses the VAX/VMS Fortran compiler.

10. REFERENCE

ZHAO Zhixiang and ZHOU Delin, Systematics of Excitation Function for (n,charged particle) Reactions, INDC(CPR)-8/L (June 1986).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one DS/HD (1.2 Mb) 5.25 inch diskette, including source files and sample cases.

12. DATE OF ABSTRACT

January 1992.