Fine structure in the beta-delayed proton decay of 33Ar

Low-energy beta-delayed protons from ³³Ar have been measured for the first time. The data reveal states, which, despite unfavourable barrier penetrability values, strongly decay to the first excited 2 ⁺ state in ³²S. The observation is discussed in terms of the standard shell model. A natural explanation is provided by the large spectroscopic amplitudes, involving s _{1}/{2} and d _{3}/{2} orbitals, as well as the l = 0 barrier penetrability, favouring the decay to the 2 ⁺ state.