The LHCb Vertex Locator performance and Vertex Locator upgrade

TL;DR

This paper discusses the current performance and upcoming upgrade of the LHCb Vertex Locator, highlighting new pixel and micro-strip detector solutions designed to withstand higher radiation levels and improve precision in a trigger-less, high-rate environment.

Contribution

It presents the development and testing status of a new pixel detector based on Timepix/Medipix chips and a micro-strip solution for the upgraded VELO at LHCb.

Findings

Current VELO achieves 4 μm hit precision.

New pixel detector prototypes show promising testbeam results.

Micro-strip solutions offer finer granularity and lower mass.

Abstract

LHCb is an experiment dedicated to the study of new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The Vertex Locator (VELO) is the silicon detector surrounding the LHCb interaction point. The detector operates in a severe and highly non-uniform radiation environment. The small pitch and analogue readout result in a best single hit precision of 4 $\rm \mu$m. The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a trigger-less system operating at 40 MHz event rate. The vertex detector will have to cope with radiation levels up to 10$^{16}$ 1 MeV$\rm n_{eq}/cm^2$, more than an order of magnitude higher than those expected at the current experiment. A solution is under development with a pixel detector, based on the Timepix/Medipix family of chips with 55 x 55 $\rm \mu m$ pixels. In addition a micro-strip solution is also under development, with finer pitch, higher granularity and lower mass than the current detector. The current status of the VELO will be described together with recent testbeam results.