Double check 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nf6 5.Qd3 e5 6.dxe5 Qa5+ 7.Bd2 Qxe5 8.0-0-0 Nxe4 9.Qd8+ (sacrificing a queen in order to set up a double check) Kxd8 10.Bg5++ and White mates after 10...Ke8 11.Rd8# or 10...Kc7 11.Bd8#. A double check was also seen in the celebrated Evergreen Game, Anderssen–Dufresne, 1852. Anderssen won with 20.Rxe7+! Nxe7 21.Qxd7+!! (a queen sacrifice to set up a deadly double check) Kxd7 22.Bf5++ Ke8 (or 22...Kc6 23.Bd7#) 23.Bd7+ Kf8 24.Bxe7#. In chess with variant rules or fairy pieces, other ways of delivering a double check may be possible. Triple, quadruple and even quintuple checks may
Double beta decay or double beta decay are predicted to be very long; hence, quadruple beta decay is unlikely to be realized. The eight candidate nuclei for quadruple beta decay include Zr, Xe, and Nd capable of quadruple beta-minus decay, and Xe, Ba, Gd, and Dy capable of quadruple beta-plus decay or electron capture. In theory, quadruple beta decay may be experimentally observable in three of these nuclei, with the most promising candidate being Nd. Double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa,