ψ' to J/ψ ratio measurements in PHENIX at RHIC

The ratio of the ψ' over the J/ψ production cross section in the dielectron channel has been measured in √s = 200 GeV p + p collisions with the PHENIX detector at RHIC. The analysis is based on fitting of the dielectron invariant mass spectra in the area around the J/ψ and ψ' signals in order to extract a ratio ψ' over J/ψ of 0.019 ± 0.005 (stat) ± 0.002 (sys) and a fractional feed-down contribution to J/ψ from ψ' of 8.6 ± 2.5%. (author)