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Joey Butterworth

Publications and source records attributed to Joey Butterworth.

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STARlight: A Monte Carlo simulation program for ultra-peripheral collisions of relativistic ions

Ultra-peripheral collisions (UPCs) have been a significant source of study at RHIC and the LHC. In these collisions, the two colliding nuclei interact electromagnetically, via two-photon or photonuclear interactions, but not hadronically; they effectively miss each other. Photonuclear interactions produce vector meson states or more general photonuclear final states, while two-photon interactions can produce lepton or meson pairs, or single mesons. In these interactions, the collision geometry plays a major role. We present a program, STARlight, that calculates the cross-sections for a variety of UPC final states and also creates, via Monte Carlo simulation, events for use in determining detector efficiency.

hep-ph

Production of $e^{+}e^{-}$ from U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV and Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6, 27, 39, 62.4, and 200 GeV as measured by STAR

We present STAR's measurement of the $e^{+}e^{-}$ continuum as a function of centrality, invariant mass, and transverse momentum for U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV. Also reported are the acceptance-corrected $e^{+}e^{-}$ invariant mass spectra for minimum-bias Au+Au collisions at $\sqrt{s_{NN}}$ = 27, 39, and 62.4 GeV and U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV. The connection between the integrated $e^{+}e^{-}$ excess yields normalized by charge particle multiplicity ($dN_{ch}/dy$) at mid-rapidity and the lifetime of the fireball is discussed.

nucl-ex