The applicant wants to work in the commissioning, operation and physics analysis of a new double-sided vertex detector, to be installed at the beginning of 1996 in the ALEPH experiment at LEP. The vertex detector is used to identify charged particles coming from the decay of unstable particles, such as b-flavoured hadrons. The use of the new detector will enhance the detection efficiency for b-quarks by about 20%. The advantages of the new vertex detector are most important during the second phase of LEP experiments, in the search for the Higgs boson. The research project is aimed to optimize reconstruction algorithms for the most common final states originating from the Higgs boson production and decay.