β-delayed proton pandemonium: A first detailed Cl31(βpγ)P30 decay scheme

Background: Positron decays of proton-rich nuclides exhibit large Q values, producing complex cascades which frequently involve various radiations, including protons and γ rays. Often, only one of the two is measured in a single experiment, limiting the accuracy and completeness of the decay scheme. An example is Cl31, for which protons and γ rays have been measured separately in detail but never with substantial sensitivity to proton-γ coincidences. Purpose: Provide detailed measurements of Cl31 β-delayed proton decay including β-p-γ sequences, extract spectroscopic information on S31 excited states as well as their β+ feedings, and compare to shell-model calculations. Methods: A fast fragmented beam of Cl31 provided by the National Superconducting Cyclotron Laboratory was deposited in the Gaseous Detector with Germanium Tagging (GADGET) system. GADGET's gas-filled Proton Detector was used to detect β-delayed protons, and the Segmented Germanium Array was used to detect β-delayed γ rays. Results: As many as 20 previously unobserved β-delayed proton transitions have been discovered in the present data, most of which populate excited states of P30. The first detailed Cl31(βpγ)P30 decay scheme is presented, including updated β-delayed proton-decay energies and intensities, as well as several new S31 levels. Improved agreement is found with theoretical calculations of the Gamow-Teller strengths B(GT) for S31 excitation energies 7.5