NEA-1043 GRAPE.

1. NAME OR DESIGNATION OF PROGRAM:  GRAPE.

3. DESCRIPTION OF PROGRAM OR FUNCTION

The GRAPE code system for the calculation of precompound and compound nuclear reactions. The main  code in this system is GRYPHON. The statistical exciton model following the master-equation approach has been improved and extended for application as an evaluation tool of double- differential reaction cross sections at incident nucleon energies of 5 to 50 MeV. For this purpose the code system GRAPE has been developed, which combines a number of interesting features such as:  unified treatment of pre-equilibrium and equilibrium processes, renormalized exciton state-densities summing up to the back-shifted  Fermi-gas formula, a new model for the internal transition rates based upon the nucleon mean free path in nuclear matter, angle-energy distributions based on intra-nuclear scattering in nuclear matter, account of discrete-level excitations, a new model for gamma-ray competition, inclusion of multi-particle emission, and various sorting options with code output in the new ENDF-VI format.  An important characteristic of the proposed model is that consistency with equilibrium models has been demanded for the summed exciton-state densities as well as for the particle and gamma-ray emission cross sections. Consistency with the adopted state densities has also been imposed upon the internal transition rates.  A survey of the theory is given and structure of the GRYPHON code is described. This report also contains a user' manual for GRYPHON.

4. METHOD OF SOLUTION

The master equations are solved with a fast algorithm, without approximations.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

- exciton model without spin-parity conservation.
- incoming or outgoing particles: a, p, alpha, 3He, d, t, and   gamma-rays
- the code has been tested for incoming neutrons only
- not more than 5 multi-particle emissions
- not more than 100 energy points (variable grid)
- no calculation of full gamma-ray cascade
- maximum energy of composite state not more than 60 MeV at present

6. TYPICAL RUNNING TIME:  17.8 CP seconds for sample problems given.

NEA-DB executed the test case included in this package  on a CDC CYBER 740 computer in 100 seconds of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM

- interactive operation possible
- multi-particle emission (inclusive and exclusive)
- precompound effects in each stage of the multi-particle emission
- angular distribution calculation
- unified treatment of compound end precompound parts of the
  reaction
- gamma-ray competition included
- default parameters included (in the simplest mode of operation
  only Z and A is needed)
- variable, non-equidistant energy grid

8. RELATED AND AUXILIARY PROGRAMS

The GRAPE code system contains the  following programmes:
GRYPHON* Double-differential reaction cross sections with account  of pre-equilibrium and eliquibrium effects, using the           unified exciton model
PSORT* Simple sorting routine to print double-differential cross  sections for total particle emission from the GRYPHON  output file SPECTR (same function as MCFRLN, without           format conversion to MacFarlanne format)
SPSRT1* Sorts and prints energy-angle integrated cross sections,  last-ejectile emission spectra and angular distributions  for all possible reactions from the GRYPHON output file  SPECTR. In addition the total emission spectra are           printed.
WDILG* Fits level-density parameters g and delta to the  experimental level scheme data and observed level spacing,  using the Williams formula [12] renormalized to the back-           shifted Fermi-gas formula of Dilg et al. [17].
LEG* Angular distribution from Legendre coefficients given on           the GRYPHON output file SPECTR.

10. REFERENCES:

- H. Gruppelaar and J.M. Akkermans:
  The GRAPE Code System for the Calculation of Precompound and
  Compound Nuclear Reactions - GRYPHON Code Description and Manual
  ECN-164  (February 1985)
- H. Gruppelaar:
  Export version of GRAPE Code System for the Calculation of
  Precompound and Compound Nuclear Reactions.
  ECN Memo FYS-FUS-85-18  (September 1985)
- H. Gruppelaar:
  GRAPE Code System: Corrections in PRANG Subroutine
  (November 1986)

11. MACHINE REQUIREMENTS

High speed memory: 100K words, disc file storage, interactive terminal.
NEA 1043/01: To run the test case on a CDC CYBER 740, 220K (octal) words were required.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  NOS/BE.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

Correction: insert in GRYPHON after GRY 5370: if (KERNEL.EQ.2) EIG3(J)=DEIG3(J)

15. NAME AND ESTABLISHMENT OF AUTHORS

         H. Gruppelaar
         Stichting Energieonderzoek Centrum Nederland
         Postbus 1
         NL-1755 ZG Petten

        J.M. Akkermans
        Nuclear Consultant
        Urlusstraat 4
        NL-3533 SN Utrecht

File name	File description	Records
NEA1043_01.001	GRAPE Information file	69
NEA1043_01.002	GRAPE Job Control instructions	33
NEA1043_01.003	GRAPE Source program (Fortran-V)	4513
NEA1043_01.004	SLATEC modules and interface source program	1486
NEA1043_01.005	Inverse cross section input file	35
NEA1043_01.006	Sample input for GRYPHON	19
NEA1043_01.007	Sample input for SPSRT1	4
NEA1043_01.008	Printed output for sample case	1278