VELO telescope resolution and efficiency measurements

The 1998 prototypes for the LHCb Vertex Locator were characterised in a beam test. The efficiency of the detectors was studied as a function of bias voltage. For two different strip pitches, the resolution was determined as a function of the incident angle of the particles, with the following best resolutions: 40 micrometer pitch: 3.6 - 3.9 micrometers at 80-120 mrad track angle 60 micrometer pitch: 4.0 - 4.6 micrometers at >=200 mrad track angle The charge sharing fraction between adjacent strips was measured to be 5.3% for 40 micrometer pitch and 4.7% for 60 micrometer pitch, respectively. The results were compared with the LHCb simulation package SICb, and were used to test an improved simulation which is planned to replace the current LHCb Monte Carlo model.