IAEA1290 DDCS.

1. NAME OR DESIGNATION OF PROGRAM:  DDCS.

3. DESCRIPTION OF PROGRAM OR FUNCTION

DDCS is a program for calculating the neutron or charged particles (p, d, t, He3, alpha) induced reactions of medium-heavy nuclei in the incident energy range up to 50 MeV including 5 emission processes. For those reaction channels contributed only by 1-4 emission processes the incident energy can go up to 100 MeV. The double differential cross  sections, various cross sections, and spectra can be calculated in this program.

DDCS is constructed within the framework of the optical model, generalized master equation of the exciton model, and the evaporation model. In the first and second particle emission processes, we consider pre-equilibrium emission and evaporation; in  3-5 particle emission processes, we only consider evaporation. The pre-equilibrium and direct reaction mechanisms of gamma emission are also included in this program. The effect of recoil nucleus is taken into account.

Program DDCS includes the first to the fifth particle emission processes.

a+A -> b+B*, a=n, p, alpha, d, t, He3, b=n, p, alpha, d, t, He3,

gamma

B* -> c+C*, c=n, p, alpha, d, t, He3, gamma

C* -> d+D*, d=n, p, alpha, d, t, He3, gamma

D* -> d+E*, e=n, p, alpha, d, gamma

E* -> f+F*, f=n, p, gamma

When a particle is emitted, the residual nucleus may emit another particle or gamma ray continuously if the excited energy is large enough to overcome the binding energy. Generally speaking, the gamma emission cross section is much less than neutron emission cross section when the neutron emission channel is opened. We assume that  after gamma ray is emitted the residual nucleus does not emit any particle except that after the first gamma ray emission process the  particle or gamma are allowed to be emitted. Thus, 7 channels can be opened for the first emission process, 49 channels for the second emission process 252 channels for third emission process, 1080 channels for forth emission process, and 2592 channels for firthemission process.

The following nuclear data can be calculated with the program DDCS:  the double differential emission cross sections of emitted nucleons  (n and p) and composite particle (alpha, d, t, He3) in laboratory or C. M. system, as well as total emission cross sections and spectra of all emitted particles; the partial emission cross sections and spectra of all emitted particles for first to sixth particle emission processes and pick-up configurations (1,m) and (2,m); the various yield cross sections; total and elastic scattering cross sections (only for neutron as projectile); total reaction cross section; nonelastic scattering cross sections; radiative capture cross section; (x, np), (x,n alpha), (x,2n), (x,3n), (x,4n), (x,5n)  cross sections and so on.

4. METHOD OF SOLUTION

The Gilbert-Cameron level density formula was applied in program DDCS. The inverse cross sections of the emitted particles used in statistical theory are calculated from the optical model. The partial widths for gamma-ray emission are calculated based on the giant dipole resonance model with two resonance peaks in both the evaporation model and exciton model.
In the optical model calculation, we usually adopt the Becchetti and Greenlee's phenomenological optical potential, which parameters are  usually given by a program for automatically searching the optimum optical model parameters. We use Neumanove methods to solve the radial equation in optical model. Coulomb wave functions used in optical model are calculated by the continued fraction method. DDCS  does not calculate the direct inelastic scattering and compound nucleus elastic scattering data, but the calculated direct inelastic scattering cross sections and angular distributions by the collective excitation distorted-wave Born approximation and compound nucleus elastic scattering cross sections and elastic scattering angular distributions by Hauser-Feshbach model and optical model can be added in the input data of the program DDCS.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

1) The calculations are restricted to medium-heavy nuclei, for which fission reactions are absent.
2) The incident particle is restricted to n(neutron), p(proton), d(deuteron), alpha(helium-4), t(triton), and He3(helium-3). The outgoing particles only include n(neutron) and the above 5 charged particles as well as gamma photons.

6. TYPICAL RUNNING TIME

The running time depends on the incident energies and the kind of target for calculating double differental cross sections.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES

- G. Mantzouranis et al.:

Angular Distribution of Nucleons in Nucleon-Induced Preequilibrium    Reactions, Phys. Lett. 57B, 220 (1975)

- G. Mantzouranis et al.:

  Generalized Exciton Model for the Description of Preequilibrium

  Angular Distribution, Z. Phys. A276, 145 (1976)

- Z. Sun et al.:

Angular Distribution Calculation Based on the Exciton Model Taking    Account of the Influence of the Fermi Motion and the Pauli

  Principle, Z. Phys. A305, 61 (1982)

- K. Kikuchi et al.:

  Nuclear Matter and Nuclear Reaction, North-Holland, Amsterdam,

  1968, p.33

- C. Costa et al.:

  Angle-Energy Correlated Model of Preequilibrium Angular

  Distribution, Phys. Rev. C28, 587 (1983)

- A. Iwamoto et al.:

  An Extension of the Generalized Exciton Model and Calculations of
  (p,p') and (p,alpha) Angular Distribution, Nucl. Phys. A419, 472

  (1984)

- X. Wen et al.:

  A Semi-Classical Model of Multi-Step Direct and Compound Nuclear

  Reactions, Z. Phys. A324, 325 (1986)

- J. Akkermans and H. Gruppelaar:

  #FK Phys. Let., #FH 157B, #FS 95 (1985)

- Zhang Jing-shang and Shi Xiang-jun:

  INDC(CRP)-014/L

- A. Iwamoto et al.:

  Mechanism of Cluster Emission in Nucleon Induced Preequilibrium

  Reactions, Phys. Rev. C26, 1821 (1982)

- K. Sato et al.:

  Preequilibrium Emission of Light Composite Particles in the

  Framework of the Exciton Model, Phys. Rev. C28, 1527 (1983)

- J.Zhang et al.:

  Formation and Emission of Light Particles in Fast Neutron Induced
  Reactions, Commun. in Theor. Phys., 10, 33 (1988)

- J. Zhang et al.:

  The Pick-up Mechanism in Composite Particle Emission Processes,

  Z. Phys., A344, 251 (1992)

- J. Zhang:

  The Angular Distribution of Light Particle based on a

  Semi-Classical Model, Commun. Theor. Phys. 14, 41 (1990)

- J. Zhang et al.:

A Theoretical Method for Calculating the Double Differential Cross    Section of Composite Particles, Chinese J. Nucle. Phys., 13, 129

  (1991)

-J. Zhang:

  A Method for Calculating Double Differential Cross Sections of

  Alpha Particle Emissions, Nucl. Sci. Eng., 116, 35 (1994)

- A. Gilbert et al.:

  Can, J. Phys., 43, 1446 (1965)

- F.D. Becchetti et al.:

  Phys. Rev., 182, 1190 (1969)

- C. M. Perey et al.:

  Atomic Data and Nuclear Data Tables, 17, 3 (1976)

- A. R. Barnett et al.:

  #FK Computer Phys. Commun., 8, 377 (1974)

- P. D. Kunz:

  Distorted Wave Code DWUCK4, University of Colorado, USA

- S. Qingbiao:
  The User's Manual for Program DDCS

11. MACHINE REQUIREMENTS:

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

Modified NDP system in microscopic computer 486. OS system in SUN work station.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

1) The double precision arithmetic is necessary.
2) The unit number is 1 for input and 7 for output.

15. NAME AND ESTABLISHMENT OF AUTHORS

Shen Qing-biao
China Institute of Atomic Energy,
Beijing,
P.R. China

source program   mag tapeDDCS.FOR Source program                    SRCTP
test-case data   mag tapeDDCSI.DAT Main input data                  DATTP
test-case data   mag tapeDDCSE.DAT Input data for elastic scatteringDATTP
test-case data   mag tapeDDCSD.DAT Input data for direct reaction   DATTP
test-case data   mag tapeCENPL.GDR Input for giant resonance param. DATTP
test-case output mag tapeDDCSO.DAT Output data                      OUTTP
user's guide             User's manual                              WRKPT