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Title: Pion physics in the Liege intranuclear cascade model

Abstract

The implementation of {pi} production in the Liege intranuclear cascade model (INCL4) for spallation reactions is revisited to alleviate the overestimate of the {pi} yield. Three modifications are proposed for this purpose: a better {pi}N cross section at high energy, the introduction of a {pi} average potential, and the modification of the average mass of the {delta} resonance. The {pi} potential is determined from a global fit of a set of data bearing on {pi} production in proton-induced reactions, on {pi}-nucleus and absorption cross sections, and on proton production in {pi}-induced reactions. The resulting {pi} potential is poorly determined in the nuclear interior and agrees with the phenomenological optical-model potentials in the surface region. With these modifications, the predictions of the INCL4 model concerning {pi} production cross sections in proton-induced reactions are considerably improved. Predictions of the improved version for {pi}-nucleus reaction and absorption cross sections and for proton, residue, and fission cross sections in {pi}-induced reactions are also presented and shown to give reasonably good agreement. Neutron production and some aspects of fission in {pi}-induced reactions are also investigated and reasonably well predicted. Effects on the modifications on observables, which are not directly linked with {pi}'s, such as themore » neutron yield and the residue mass and charge spectra in proton-induced reactions are also investigated and shown to improve the description of these observable quantities. Several results on {pi} production and the relative insentivity to the {pi} potential in the nuclear interior are shown to be consistent with the fact that most {pi}'s are not produced in early collisions. Importance of rescattering in {pi} absorption on nuclei is also pointed out. A comparison is made with the so-called {delta}-hole model. Residual discrepancies are identified and are interpreted as due to the lack of {pi} interaction with two nucleons at low energy, to the neglect of quantum motion effects, and to a possible underestimate of rescattering.« less

Authors:
 [1];  [2];  [3]
  1. SCK-CEN, Boeretang 200, B-2400 Mol (Belgium)
  2. (Belgium)
  3. University of Liege, Physics Department, allee du 6 Aou circumflex t 17, bat. B5, B-4000 Liege 1 (Belgium)
Publication Date:
OSTI Identifier:
20864212
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 74; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevC.74.064607; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ABSORPTION; CROSS SECTIONS; FISSION; NEUTRONS; NUCLEAR CASCADES; NUCLEAR REACTION YIELD; NUCLEI; OPTICAL MODELS; PARTICLE-HOLE MODEL; PIONS; POTENTIALS; PROTON REACTIONS; PROTONS; RESCATTERING; RESONANCE; SPALLATION

Citation Formats

Aoust, Th., University of Liege, Physics Department, allee du 6 Aou circumflex t 17, bat. B5, B-4000 Liege 1, and Cugnon, J. Pion physics in the Liege intranuclear cascade model. United States: N. p., 2006. Web. doi:10.1103/PHYSREVC.74.064607.
Aoust, Th., University of Liege, Physics Department, allee du 6 Aou circumflex t 17, bat. B5, B-4000 Liege 1, & Cugnon, J. Pion physics in the Liege intranuclear cascade model. United States. doi:10.1103/PHYSREVC.74.064607.
Aoust, Th., University of Liege, Physics Department, allee du 6 Aou circumflex t 17, bat. B5, B-4000 Liege 1, and Cugnon, J. Fri . "Pion physics in the Liege intranuclear cascade model". United States. doi:10.1103/PHYSREVC.74.064607.
@article{osti_20864212,
title = {Pion physics in the Liege intranuclear cascade model},
author = {Aoust, Th. and University of Liege, Physics Department, allee du 6 Aou circumflex t 17, bat. B5, B-4000 Liege 1 and Cugnon, J.},
abstractNote = {The implementation of {pi} production in the Liege intranuclear cascade model (INCL4) for spallation reactions is revisited to alleviate the overestimate of the {pi} yield. Three modifications are proposed for this purpose: a better {pi}N cross section at high energy, the introduction of a {pi} average potential, and the modification of the average mass of the {delta} resonance. The {pi} potential is determined from a global fit of a set of data bearing on {pi} production in proton-induced reactions, on {pi}-nucleus and absorption cross sections, and on proton production in {pi}-induced reactions. The resulting {pi} potential is poorly determined in the nuclear interior and agrees with the phenomenological optical-model potentials in the surface region. With these modifications, the predictions of the INCL4 model concerning {pi} production cross sections in proton-induced reactions are considerably improved. Predictions of the improved version for {pi}-nucleus reaction and absorption cross sections and for proton, residue, and fission cross sections in {pi}-induced reactions are also presented and shown to give reasonably good agreement. Neutron production and some aspects of fission in {pi}-induced reactions are also investigated and reasonably well predicted. Effects on the modifications on observables, which are not directly linked with {pi}'s, such as the neutron yield and the residue mass and charge spectra in proton-induced reactions are also investigated and shown to improve the description of these observable quantities. Several results on {pi} production and the relative insentivity to the {pi} potential in the nuclear interior are shown to be consistent with the fact that most {pi}'s are not produced in early collisions. Importance of rescattering in {pi} absorption on nuclei is also pointed out. A comparison is made with the so-called {delta}-hole model. Residual discrepancies are identified and are interpreted as due to the lack of {pi} interaction with two nucleons at low energy, to the neglect of quantum motion effects, and to a possible underestimate of rescattering.},
doi = {10.1103/PHYSREVC.74.064607},
journal = {Physical Review. C, Nuclear Physics},
number = 6,
volume = 74,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}
  • The Liege intranuclear cascade model has been shown by the HINDAS collaboration to successfully describe spallation-reaction data in the 200-MeV to 2-GeV range. We report here on the recent progress obtained afterwards. They bear on the behaviour of the model at low energy, on the introduction of an energy and isospin dependence of the mean field, on the improvement of the pion-production mechanism, and on the inclusion of composite production in the cascade.
  • A method is presented by which an intranuclear cascade model may be used to obtain pion source parameter predictions which can be directly compared with pion interferometry experiments. This method is applied with Cugnon's intranuclear cascade model to extract predictions for recent pion interferometry measurements, and generally good agreement is found.
  • Prompt ..gamma.. rays from ..pi../sup -/ interactions with /sup 19/F, /sup 27/Al, and /sup 51/V near the ..delta..(1232) resonance were detected. Deexcitation ..gamma.. rays from residual nuclei formed by single and multiple nucleon removal and by inelastic and charge exchange scattering were identified, and cross sections for excitation of residual states were determined. Nuclear recoil momenta were determined from observed Doppler broadening. Where possible, the cross sections were corrected for ..gamma.. feeding from higher states. The results are compared with the results of previous experiments and of intranuclear cascade/evaporation code calculations. (AIP)
  • An extension of the intranuclear cascade model is described. The primary hadrons may be pions, kaons, nucleons, and their antiparticles. Secondary particles produced include hyperons or antihyperons. A large amount of experimental data is described by the model. The model is constructed via the Monte Carlo generation of complete events, based on a model of the nucleus structure and the hadron/nucleon interaction inside the nucleus. Calculated average multiplicities and single and double differential cross sections are compared with experimental data.
  • A single particle intranuclear cascade code has been developed to determine the importance of multiple scattering, various nuclear medium corrections, and pion absorption inputs in medium energy nuclear physics. Reasonable agreement with experimental data for pion production by 740 MeV protons is obtained with all the input parameters taken from experimental free two-body data. Through a detailed study of the pions produced in Pb, it is determined that most of the pions (approx.85%) which exit the nucleus have scattered at most once, and that the results are very sensitive to the nuclear density and the pion absorption models used.