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NASA/TM-1998-208722

Parameterizations of Pion Energy Spectrumin Nucleon-Nucleon Collisions

Francis A. Cucinotta and John W. WilsonLangley Research Center, Hampton, VirginiaJohn W. Norbury

University of Wisconsin, Milwaukee, Wisconsin

October 1998

Since its founding, NASA has been dedicated to the advancement of aeronautics and space

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Since its founding, NASA has been dedicated to the advancement of aeronautics and space

NASA/TM-1998-208722

Parameterizations of Pion Energy Spectrumin Nucleon-Nucleon Collisions

Francis A. Cucinotta and John W. WilsonLangley Research Center, Hampton, VirginiaJohn W. Norbury

University of Wisconsin, Milwaukee, Wisconsin

National Aeronautics andSpace AdministrationLangley Research Center

Hampton, Virginia 23681-2199

October 1998

Since its founding, NASA has been dedicated to the advancement of aeronautics and space

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Since its founding, NASA has been dedicated to the advancement of aeronautics and space

Abstract

The effects of pion (π) production are expected to play an impor-tant role in radiation exposures in the upper atmosphere or on theMartian surface. Nuclear databases for describing pion productionare developed for radiation transport codes to support these studies.We analyze the secondary energy spectrum of pions produced innucleon-nucleon(NN) collisions in the relativistic one-pion exchangemodel. Parametric formulas of the isospin cross sections for one-pionproduction channels are discussed and are used to renormalize themodel spectrum. Energy spectra for the deuteron related channels(NN→dπ) are also described.

1. Introduction

A convenient representation of the differential cross section in energy of particles created in theinteractions of space and atmospheric radiation with materials is required for radiation transport com-puter codes to be efficient for engineering design and risk assessment (refs. 1 through 3). In high-energyreactions, an abundance of mesons is produced through the nuclear force. High-energy reactionsincrease in relative importance in the upper atmosphere due to the Earth’s magnetic field, reducinglower energy ion components which have insufficient energy to overcome the threshold for meson pro-duction. The one-pion production channels dominate the meson production for energies up to about1.5GeV/amu and represent an important contribution at higher energies. The energy region below1.5GeV/amu extends above the galactic cosmic ray (GCR) peak at 0.2 to 0.6 GeV/amu. Also, most ofthe energy range of particles seen in solar particle events (SPE) are dominated by the one-pion exchangeinteractions. The scattering of high-energy protons or neutrons on hydrogen is important because pro-tons and neutrons represent over 90 percent of the particle flu …… 此处隐藏：20739字，全部文档内容请下载后查看。喜欢就下载吧 ……