TARGET

A hadronic interaction model for studying inclusive muon and

neutrino fluxes

Ralph Engel (Forschungszentrum Karlsruhe, Germany)

Giles Barr, Thomas K. Gaisser, Simon Robbins and Todor Stanev

Motivation and outline

TARGET 3D (old version: 2.1, current version: 2.4)

very flexible and tunable hadronic interaction model

simple and fast Monte Carlo code

optimization for inclusive muon/neutrino fluxes

event generation structure and recent improvements

comparison to data

application: L3+C muon flux Ralph Engel, ICRC 2003

Event generation in TARGET simulation of one proton-air interaction

event type

leading particle (projectile)

nucleons from target nucleus

fast pions and kaons (correlated with leading particle)

slow pions and kaons (correlated with target nucleons)

baryon-antibaryon pair production

central pion and kaon production

multiplicity determined by energy conservation

cross sections: PDG data and Glauber approachRalph Engel, ICRC 2003

Event generation in TARGET simulation of one proton-air interaction

event type

leading particle (projectile)

nucleons from target nucleus

fast pions and kaons (correlated with leading particle)

slow pions and kaons (correlated with target nucleons)

baryon-antibaryon pair production

central pion and kaon production

multiplicity determined by energy conservation

cross sections: PDG data and Glauber approachRalph Engel, ICRC 2003

Nucleons: projectile/target fragmentation

old version:

no target fragmentation nucleons

tuned to Eichten et al. data

data converted from double-differential cross sectionsRalph Engel, ICRC 2003

Nucleons: projectile/target fragmentation

new version:

target fragmentation nucleons

target and projectile nucleons symmetric

Ralph Engel, ICRC 2003

Nucleons: comparison to other models

large differences between models

inconsistent data

not very important for flux calculations

Ralph Engel, ICRC 2003

(Gaisser & Honda, Ann. Rev. Nucl. Part. Sci. 52 (2002) 153)

Low-energy pion production (1)

Ralph Engel, ICRC 2003

full phase space measurement

recoil nucleons change energy available for particle production

Low-energy pion production (2)

Ralph Engel, ICRC 2003

full phase space measurement

slow pions from fragmentation of target nucleons

Low-energy pion production (3)

Ralph Engel, ICRC 2003

full phase space measurement

pion multiplicity at small x too high?

Baryon-antibaryon pair production

Ralph Engel, ICRC 2003

no data for nuclear targets

scaled p-p cross sections and distributions used

production of anti- protons, neutrons and lambdas

Comparison with p-Be at 24 GeV (1)

Ralph Engel, ICRC 2003

almost no change of distributions at higher energy

Comparison with p-Be at 24 GeV (2)

Ralph Engel, ICRC 2003

almost no change of distributions at higher energy

Comparison to L3+C muon measurement

Ralph Engel, ICRC 2003

TARGET predictions: good description of L3+C data

SIBYLL gives similarly good description

QGSjet: too few fast pions

(see talks by M. Unger, HE 2.1.10 and T. Stanev, HE 2.4.9)

Comparison of high-energy models

inclusive charged pion spectra

p-air collisions, Elab = 500 GeV

fast pions very important

Ralph Engel, ICRC 2003

Summary and outlook

Ralph Engel, ICRC 2003

TARGET: simple and very flexible event generator

version 2.4:

implementation of processes needed for comparison to forthcoming HARP/NA49 data

improved description of low-energy data

minor changes at high energy

plans: additional fine-tuning and release of new version

Pions: comparison to other models

large differences between models at low and high x

some data sets inconsistent

very important for flux calculations

Ralph Engel, ICRC 2003

(Gaisser & Honda, Ann. Rev. Nucl. Part. Sci. 52 (2002) 153)

Muon flux charge ratio

charge ratio very sensitive to leading particle production

slightly too many fast neg. pions in new version of TARGET

fine-tuning in progress

Ralph Engel, ICRC 2003