Nuclear structure of the odd-neutron radon isotopes radon-203,205,207

High-spin states in the odd-neutron nuclei 203,205,207Rn have been investigated following heavy-ion fusion evaporation reaction experiments at Yale University, the University of Jyvaskyla, and Argonne National Laboratory. The emitted gamma rays were measured at each location using the Jurosphere, YRAST Ball and Gammasphere detector arrays, respectively. Fusion products were detected at Jyvaskyla using the gas-filled recoil separator RITU and at Argonne with the Fragment Mass Analyzer. Internal conversion electrons were measured at Argonne using the ICE Ball array of mini-orange spectrometers. Experiments that were carried out include excitation function measurements, multi-gamma coincidences, angular distribution measurements, polarization measurements, and internal conversion electron spectroscopy.; No gamma-ray transitions above the 13/2+ state had been reported for any of these isotopes prior to this work. Nuclear decay schemes were constructed for 203,205,207Rn up to a spin of ∼29/2h and an excitation energy of ∼4 MeV. The states built on the 13/2 + isomers feature strongly in the decay of these nuclei. A roughly harmonic DeltaI = 2 sequence assigned the nu( i13/2-1) configuration was observed in each odd-A nucleus. The energy level spacing of the 17/2+, 21/2+ and 25/2+ states relative to the 13/2 + state is similar to the 0+, 2+, 4 +, 6+ spacing observed in the neighboring even-even isotopes. The decreasing E(17/2+) energies and increasing R212 /172 values with decreasing neutron number reflect the increasing collectivity in the lighter isotopes as more neutron holes are added to the system.; In contrast to the even-even neighbors, no evidence was found in any of the odd-A isotopes for isomeric states with lifetimes of tens of nanoseconds. An unobserved isomer in 205Rn with a lifetime of a few nanoseconds is suggested to exist near the top of the most intense cascade to account for the essentially isotropic angular distributions of the transitions in this sequence. A possible explanation for the lack of such long-lived isomers in the odd-A isotopes is the deformation-driving effects of the odd neutron, allowing additional configuration mixing and leading to increased collectivity at higher spin.; A cascade of magnetic dipole transitions was observed in 205Rn and interpreted in terms of the shears mechanism. Its assigned configuration is the nu(i13/2-1) ⊗ pi( i13/22). A short cascade of low-energy transitions was observed in 203Rn, but the shortness of the cascade and lack of other evidence precludes a shears band assignment for this sequence at this time. Such a band was not observed in 207Rn, which may be due to the fact that its core is not sufficiently polarized to allow the perpendicular coupling of the proton and neutron angular momentum vectors required for the manifestation of a shears band structure.; A series of IBM and IBFM calculations were carried out in order to interpret the structure of the light radon nuclei in terms of a collective model. Excitation energies for the low-lying levels in the series of even-even isotopes 198--206Rn are well reproduced by the IBM predictions. Good agreement is also obtained between the IBFM calculations and the data obtained during the course of this work for the DeltaI = 2 sequence built on the 13/2+ states in 203Rn and 205 Rn.