**1. NAME AND TITLE**

PREANG: Calculation of Pre-equilibrium Angular Distributions with the Exciton Model.

PREANG is a modified version of PREEQ and PREEQ-ECN.

**2. CONTRIBUTOR**

Netherlands Energy Research Foundation, Energy Center of The Netherlands, Petten (NH), The
Netherlands.

**3. CODING LANGUAGE AND COMPUTER**

Fortran; CDC CYBER 175.

**4. NATURE OF PROBLEM SOLVED**

PREANG calculates cross sections, particle emission spectra and their angular distributions for
reactions of type A(x,y)B where x and y can be n, p, alpha, He-3, d or t.

**5. METHOD OF SOLUTION**

PREANG is based upon the time-integrated master-equation approach of the exciton model. It first
determines the transition and emission rates and the level densities and stores them in the memory.
Next, it calculates the desired cross sections; these contain precompound and compound contributions.
The angular distributions are calculated according to the model of G. Mantzouranis, D. Agassi and
H. A. Weidenmuller.

**6. RESTRICTIONS OR LIMITATIONS**

The validity of the model is restricted to projectile energies of 10 to 50 MeV. Only first-particle
emission cross sections are calculated. The level densities are assumed to be described by continuum
distributions; PREANG accounts for no spin and parity dependences.

**7. TYPICAL RUNNING TIME**

On the CDC CYBER 175 computer, PREANG usually executes in less than 2 seconds.

**8. COMPUTER HARDWARE REQUIREMENTS**

PREANG is operable on the CDC CYBER 175 computers. It requires less than 60,000 words
(octal) of storage.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran compiler is required.

**10. REFERENCES**

**a. Included in the documentation:**

J. M. Akkermans and H. Gruppelaar, "Calculation of Pre-equilibrium Angular Distributions with
the Exciton Model Code PREANG," ECN-60 (May 1979).

**b. Background information:**

G. Mantzouranis, D. Agassi, and H. A. Weidenmuller, *Phys. Lett.* 57B (1975) 220.

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document (10.a) and one (1.2MB) DOS diskette which contains the
source code and sample problem input.

**12. DATE OF ABSTRACT**

April 1984.

**KEYWORD: ** NUCLEAR MODELS