The SLD Vertex Detector

1. The SLD Vertex Detector • The SLAC Linear Collider (SLC) was the world’s first linear collider (high energy electrons colliding with positrons). It started operation in California in the late 1980’s. Making it work was a big challenge, but its eventual outpouring of new physics generated enthusiasm for the next such machine, the International Linear Collider, now being considered for construction as a Higgs Factory. • The SLC physics rested on two special pillars with respect to the ‘rival’ machine LEP; longitudinally polarized electrons, and the world’s first and still the highest performing pixel-based vertex detector at any collider. • This detector comprised 307 Mpixels (still a record) and the material budget was 0.4% radiation length per layer (still a record). • It was built of 48 barrel staves or ‘ladders’, one of which is contained in this box. It comprises a thin beryllium substrate, to which are attached a pair of overlapping CCDs (one above, one below the substrate), each of which contains 3.2 Megapixels. • This vertex detector made point measurements on tracks with precision about 3.5 microns, sufficient to distinguish between tracks from the primary vertex (i.e. the electron-positron collision point) and secondary and tertiary vertices, created by the decay of particles containing bottom or charm quarks, which have lifetimes of typically 0.1 to 1 picosecond – see sketch on next slide

2. The original SLD vertex detector, made with 8 small CCDs per ladder