EMPIRE: Nuclear Reaction Model Code System for Data Evaluation

Journal Article · Sat Dec 15 00:00:00 EST 2007 · Nuclear Data Sheets

DOI:https://doi.org/10.1016/j.nds.2007.11.003· OSTI ID:21028328

Capote, R ^[1]; Carlson, B V ^[2]; Oblozinsky, P ^[3]; Sin, M ^[4]; Trkov, A ^[5]; Wienke, H ^[6]; Zerkin, V ^[1]

---

1. Nuclear Data Section, International Atomic Energy Agency, Wagramer Strasse, A-1400 Vienna (Austria)
2. Departamento de Fisica, Instituto Tecnologico de Aeronautica, 12228-900, SP, Sao Jose dos Campos (Brazil)
3. National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)
4. Nuclear Physics Department, Bucharest University, P.O. Box MG-11, Bucharest-Magurele (Romania)
5. Jozef Stefan Institute, Reactor Physics Division R-1, Jamova 39, 1000 Ljubljana (Slovenia)
6. Belgonucleaire, Dessel, B2480 (Belgium)

EMPIRE is a modular system of nuclear reaction codes, comprising various nuclear models, and designed for calculations over a broad range of energies and incident particles. A projectile can be a neutron, proton, any ion (including heavy-ions) or a photon. The energy range extends from the beginning of the unresolved resonance region for neutron-induced reactions ({approx} keV) and goes up to several hundred MeV for heavy-ion induced reactions. The code accounts for the major nuclear reaction mechanisms, including direct, pre-equilibrium and compound nucleus ones. Direct reactions are described by a generalized optical model (ECIS03) or by the simplified coupled-channels approach (CCFUS). The pre-equilibrium mechanism can be treated by a deformation dependent multi-step direct (ORION + TRISTAN) model, by a NVWY multi-step compound one or by either a pre-equilibrium exciton model with cluster emission (PCROSS) or by another with full angular momentum coupling (DEGAS). Finally, the compound nucleus decay is described by the full featured Hauser-Feshbach model with {gamma}-cascade and width-fluctuations. Advanced treatment of the fission channel takes into account transmission through a multiple-humped fission barrier with absorption in the wells. The fission probability is derived in the WKB approximation within the optical model of fission. Several options for nuclear level densities include the EMPIRE-specific approach, which accounts for the effects of the dynamic deformation of a fast rotating nucleus, the classical Gilbert-Cameron approach and pre-calculated tables obtained with a microscopic model based on HFB single-particle level schemes with collective enhancement. A comprehensive library of input parameters covers nuclear masses, optical model parameters, ground state deformations, discrete levels and decay schemes, level densities, fission barriers, moments of inertia and {gamma}-ray strength functions. The results can be converted into ENDF-6 formatted files using the accompanying code EMPEND and completed with neutron resonances extracted from the existing evaluations. The package contains the full EXFOR (CSISRS) library of experimental reaction data that are automatically retrieved during the calculations. Publication quality graphs can be obtained using the powerful and flexible plotting package ZVView. The graphic user interface, written in Tcl/Tk, provides for easy operation of the system. This paper describes the capabilities of the code, outlines physical models and indicates parameter libraries used by EMPIRE to predict reaction cross sections and spectra, mainly for nucleon-induced reactions. Selected applications of EMPIRE are discussed, the most important being an extensive use of the code in evaluations of neutron reactions for the new US library ENDF/B-VII.0. Future extensions of the system are outlined, including neutron resonance module as well as capabilities of generating covariances, using both KALMAN and Monte-Carlo methods, that are still being advanced and refined.

• OSTI ID: 21028328
• Journal Information: Nuclear Data Sheets, Vol. 108, Issue 12; Other Information: DOI: 10.1016/j.nds.2007.11.003; PII: S0090-3752(07)00098-1; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0090-3752
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ABSORPTION
ANGULAR MOMENTUM
COMPOUND NUCLEI
COUPLED CHANNEL THEORY
CROSS SECTIONS
DIRECT REACTIONS
ENERGY-LEVEL DENSITY
EVALUATED DATA
EVALUATION
EXCITON MODEL
FISSION
FISSION BARRIER
GAMMA RADIATION
GROUND STATES
HEAVY IONS
KEV RANGE
MEV RANGE 100-1000
MOMENT OF INERTIA
MONTE CARLO METHOD
NEUTRON REACTIONS
NEUTRONS
NUCLEAR DATA COLLECTIONS
NUCLEAR DECAY
OPTICAL MODELS
PHOTONS
PROTONS
STRENGTH FUNCTIONS
WKB APPROXIMATION