VELO: Vertex Locator

The HEP group is involved in many different areas of the LHCb experiment. One key component in which the group is making large efforts is the Vertex Locator detector, in short called VELO.

The VELO detector consists of two sets of 21 half-moon modules over a distance of one meter, that are separated by 30 millimeters. Upon injection of the proton beams the two sets come together to create 21 full disk-like modules. The modules are only 7 millimeters away from the beams! That's close! Each module consists of two sensors setback to back, one for measurement in the r-direction (radial) and the other for measurement in the phi-direction (angular). This is done by having silicon strips in at constant radial distance away from the beam line (for the r sensor) and strips at almost constant azimuthal angle with respect to the beam line (for the phi sensor).

Below is an image of some VELO detectors lined up. This will be in the LHC tunnel however it will be rotated by 180 degrees when it is inserted.

Connected to the VELO sensors are cables made of a particular substance that is able to withstand very high radiation, since they will be within only a few centimeters of, not only one, but two 7 TeV proton beams! That's some strong stuff.

These cables are connected to a lot of complicated electronics that are in charge of collecting data and sending the data over to computers. Once all the data the physicists want is acquired, analysis begins! This is where the discoveries are made!

This summer there is another side experiment occuring called the VELO FNAL Test Beam. Some of the HEP group will be traveling to Fermilab in Chicago, Illinois to aid in this experiment, where they will be testing selected VELO sensors with a different type of detector, pixel telescope.