Probing the limit on nuclear existence:

Proton emission from ¹⁵⁹Re

D.T. Joss et al.,

Physics Letters B641 (2006) 34

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A new isotope, ¹⁵⁹Re, at the extremes of nuclear existence has been discovered. This nuclide, 26 neutrons away from the nearest stable rhenium isotope, was synthesised and identified via its proton radioactivity using the ritu gas-filled separator and the great focal-plane spectrometer.

The observation of the new nuclide ¹⁵⁹Re provides important insights into the evolution of single-particle structure and the mass surface in heavy nuclei beyond the proton drip line. Comparisons of the measured proton energy (E_p=1805 +/- 20keV) and decay half-life (t_1/2 =21 +/- 4 ms) with values calculated using the WKB method indicate that the proton is emitted from an h_11/2 state. The implications of these results for future experimental investigations into even more proton unbound nuclei using in-flight separation techniques are considered.

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