J/Ψ Trigger Parameter Simulation

Arkadiusz BubakInstitute of Physics

University of Silesia, Katowice

Motivations

Developing the (L1) first level trigger algorithmReduction amount of collected dataSeparation of J/Ψ signal from background

Methods

Suppression hadron and lepton background

Determination of required trigger parameters: rejection factor (RF), J/Ψ detection efficiency, transversal momentum cut (Pt_cut)

Hadron and lepton background

100’000 UrQMD eventsJ/Ψ e+e- pairs taken randomly from a pool of 100’000 pairs generated with PlutoProcedure mixes up events from the two above files at the desired J/Ψ multiplicityJ/Ψ multiplicity assumed to be 10-4 pairs per event (LOI January 2004)

Mixing ProcedureRandom choosing one of the 100’000 Pluto events per 104 UrQMD eventsEach UrQMD event contains only charged pions and protons (~850 hadrons/event)

Particle Restrictions

Angular cut: particles must be in the STS range (~2° < θ < ~26°)Preliminary cut on transversal momentum > 0.5 GeV/cHadron contribution: π+, π-, pLepton contribution: decay of π0, ρ, ω, φ and J/ψ

Definition

J/Ψ detection efficiency

Rejection factor (RF)

Event from range: 3.05 < Inv. Mass < 3.15

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JwitheventAll

triggerafterJwitheventEff

eventAll

triggeraftereventRF

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Invariant mass of electrons and positrons from π0, ρ, ω, φ and J/ψ decays

Invariant mass of electrons and positrons from π0, ρ, ω, φ and J/ψ decays

Conclusions

The J/Ψ L1 hadron trigger simulation works well, but is still too weak for the given parametersLepton background: angular cut is of great importanceHadron background: transversal momentum cut “iogi”The main contribution to the background in the invariant mass spectrum is due to high proton production

Plans for the Future

Use of CBM framework to make the simulations more realistic (e.g. angular cuts)Further study of the hadron and lepton background