Excited states in the neutron-deficient nuclei {sup 197,199,201}Rn

Excited states of the extremely neutron-deficient radon isotopes with N=111,113,115 have been studied for the first time in a series of in-beam experiments performed at the Accelerator Laboratory of the University of Jyvaeskylae. The reactions used were: {sup 118}Sn({sup 82}Kr, 3n){sup 197}Rn, {sup 120}Sn({sup 82}Kr, 3n){sup 199}Rn, {sup 150}Sm({sup 52}Cr, 3n){sup 199}Rn, and {sup 122}Sn({sup 82}Kr, 3n){sup 201}Rn. The {gamma} rays emitted from excited states in the different isotopes were identified using the recoil-{alpha}-decay tagging technique. The estimated cross section for the production of {sup 197}Rn{sup m} was 7(3) nb, which is the lowest cross section reported so far for an in-beam study. The energies of the (17/2{sup +}) levels built on the isomeric (13/2{sup +}) states in {sup 197,199,201}Rn indicate a transition from an anharmonic vibrational structure toward a rotational structure at low spins for these nuclei. However, the transition is not as sharp as predicted by theory.