Double stop Double stop In music, a double stop refers to the technique of playing two notes simultaneously on a stringed instrument such as a violin, a guitar, a cello, or a double bass. In performing a double stop, two separate strings are bowed or plucked simultaneously. Although the term itself suggests these strings are to be fingered (stopped), in practice one or both strings may be open. A triple stop is the same technique applied to three strings; a quadruple stop applies to four strings. Double, triple, and quadruple stopping are collectively known as multiple stopping. Early extensive examples of the
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,