Production and decay of a W particle in the D0 (D-zero) detector at Fermi National Accelerator Laboratory (Fermilab) near Chicago. The computer display shows D0 in cross-section, outlined in black. A proton and antiproton, accelerated in Fermilab's Tevatron collider, annihilate at centre to produce a jet of particles (coloured blocks pointing down) and a recoiling W, which lives too briefly to be seen but reveals itself by its decay into an electron (red block at right) & a neutrino (the pink line shows its path towards the top). The positive and negative W particles are carriers of the weak nuclear force & members of the family of elementary particles called gauge bosons.