# S

## Sandbox

A small collection of files passed along with your job. The sandboxes are stored on the DIRAC server and removed after a limited time. The files they contain must be small.

## Scientific Linux CERN (SLC)

Former "default" Linux operating system at CERN (SLC6 default operating system on lxplus until end of 2018).

## SciFi: Scintillating Fibre Tracker

Large area detector of the Upgraded LHCb experiment, located between the magnet and the downstream PID detectors.

## SE: Storage Element

A service at a grid site that stores data. For example: CERN-USER, GRIDKA_MC-DST.

## Site (Grid)

A computing centre hosting grid computing services. For example: IN2P3-LAPP.

## SMOG: System for Measuring the Overlap with Gas

The System for Measuring the Overlap with Gas is a gas injection system designed to increase the pressure inside the LHCb VELO beam vacuum. Only noble gases are injected. The gas spreads out +/- 20 m around the nominal proton-proton interaction point and the pressure is approximately $$10^{-7}$$ mbar. Originally designed for precise luminosity measurements, SMOG injections are also used for specific data takings, allowing LHCb to be operated in fixed target mode.

The SPD consists of scintillating pads and is placed before the PS. The joint purpose of the SPD and PS is to reduce the background for the L0 electron trigger. The SPD, in conjunction with the ECAL, helps distinguish between electrons and neutral particles like photons and neutral pions.

## ST: Silicon Tracker

A term that collectively refers to the TT and IT.

## Starterkit

One week introduction course into computer usage at LHCb for young students. With no prerequisites on Linux usage, teaching basic survival skills including Grid usage and ntuple production.