TARGET

A hadronic interaction model for studying inclusive muon and neutrino fluxes

Ralph Engel (Forschungsze ntrum Karls ruhe , Ge rmany)

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 Enge l, 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 Enge l, 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 Enge l, ICRC 2003

Nucleons: projectile/target fragmentation

old version:

no target fragmentation nucleons

tuned to Eichten et al. data

data converted from double-differential cross sections

Ralph Enge l, ICRC 2003

Nucleons: projectile/target fragmentation

new version:

target fragmentation nucleons

target and projectile nucleons symmetric

Ralph Enge l, ICRC 2003

Nucleons: comparison to other models

large differences between models

inconsistent data

not very important for flux calculations

Ralph Enge l, ICRC 2003

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

Low-energy pion production (1)

Ralph Enge l, ICRC 2003

full phase space measurement

recoil nucleons change energy available for particle production

Low-energy pion production (2)

Ralph Enge l, ICRC 2003

full phase space measurement

slow pions from fragmentation of target nucleons

Low-energy pion production (3)

Ralph Enge l, ICRC 2003

full phase space measurement

pion multiplicity at small x too high?

Baryon-antibaryon pair production

Ralph Enge l, 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 Enge l, ICRC 2003

almost no change of distributions at higher energy

Comparison with p-Be at 24 GeV (2)

Ralph Enge l, ICRC 2003

almost no change of distributions at higher energy

Comparison to L3+C muon measurement

Ralph Enge l, 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 Enge l, ICRC 2003

Summary and outlook

Ralph Enge l, 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 Enge l, 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 progressRalph Enge l, ICRC 2003