[en] The study of nuclei far from beta stability is hampered greatly when the nuclide of interest decays in a manner identical to that of a nuclide produced in greater yield in the same bombardment. Attempts to observe the protons associated with the decay of the A = 4n, T/sub z/ = -2 series of beta-delayed proton emitters failed because of the large number of protons arising from the strong beta-delayed proton decay of the A = 4n + 1, T/sub z/ = -3/2 nuclides. One solution to this problem is through the use of an on-line mass separator. Development of the Berkelely helium-jet fed on-line mass separator RAMA is discussed as applied to studies of the A = 4n, T/sub z/ = -2 nuclides. RAMA (Recoil Atom Mass Analyzer) has typical efficiencies of 0.1% for approx. 75 elements with melting points less than or equal to 2000⁰C. This efficiency permits decay studies to be readily performed on nuclei with production cross sections greater than or equal to 500 μb for γ-ray spectroscopy and greater than or equal to 1 μb for discrete energy charged particle spectroscopy. The mass range on the normalized RAMA focal plane is +- 10%. The quoted efficiency is for a mass resolution of M/ΔM approx. 300. RAMA has been used to observe two members of the A = 4n, T/sub z/ = -2 series of beta-delayed proton emitters, ²⁰Mg and ²⁴Si. Observation of beta-delayed protons from a mass-separated sample of ²⁰Mg(t/sub 1/2/ approx. 95 ms) establishes the mass-excess of the lowest T = 2 (0⁺) state in ²⁰Na (13.42 +- .05 MeV), thereby completing the mass twenty isospin quintet. A similar measurement of the decay of ²⁴Si (t/sub 1/2/ approx. 100 ms) establishes the mass-excess of the lowest T = 2 (0⁺) state in ²⁴Al (5.903 +- 0.009 MeV). The mass 24 isospin quintet is incomplete because the mass of ²⁴Si remains unknown