Discovery of beta-delayed two-proton radioactivity in 22Al and 26P

22Al(tau/sub 1/1/ approx. 70 ms) and 26P(tau/sub 1/2/ approx. 20 ms) were produced via the (3He,p4n) reaction on 24Mg and 28Si targets, respectively, using 110 MeV 3He+2 beams of 3 to 7 μA from the 88-inch Cyclotron at the Lawrence Berkeley Laboratory: the effective cross section for their observation as high energy (7 to 8 MeV), beta-delayed single proton emitters was approx. a few nb. A helium jet system and a high geometry, three-element particle telescope (ΔE1,ΔE2,E) were used to search for two-proton decay events. Symmetrically divided, circular ΔE1 (24 μm for 22Al, 14 μm for 26P0 and ΔE2 (155 to 170 μm) detectors were employed to observe coincident, low-energy protons with each telescope subtending 4.5% of 4π sr. A standard 500 μm E detector placed behind and in coincidence with either of these two-counter telescopes observed the high energy groups from beta-delayed single proton decay as a monitor of the reactions. Results are presented