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Abstract We present stellar parameters and chemical abundances of 47 elements detected in the bright (V= 11.63) very metal-poor ([Fe/H] = −2.20 ± 0.12) star 2MASS J22132050−5137385. We observed this star using the Magellan Inamori Kyocera Echelle spectrograph as part of ongoing work by theR-Process Alliance. The spectrum of 2MASS J22132050−5137385 exhibits unusually strong lines of elements heavier than the iron group, and our analysis reveals that these elements were produced by rapid neutron-capture (r-process) nucleosynthesis. We derive a europium enhancement, [Eu/Fe] = +2.45 ± 0.08, that is higher than any otherr-process-enhanced star known at present. This star is only the eighthr-process-enhanced star where both thorium and uranium are detected, and we calculate the age of ther-process material, 13.6 ± 2.6 Gyr, from the radioactive decay of these isotopes. This star contains relatively large enhancements of elements that may be produced as transuranic fission fragments, and we propose a new method using this characteristic to assess ther-process yields and gas dilution in samples ofr-process-enhanced stars. Assuming a canonical baryonic minihalo mass of 10⁶M_⊙and a 1% metal retention rate, this star formed in a cloud of only ∼600M_⊙. We conclude that 2MASS J22132050−5137385 exhibits a high level ofr-process enhancement because it formed in an environment where ther-process material was less diluted than average.