Abstract:

Spin physics is the main focus of the HERMES experiment. Over the last couple of years, data with a polarised lepton beam and a polarised or unpolarised nuclear target were taken and have been analysed. For Run II of HERMES two main topics involve the scope of the experiment: the study of the transverse spin structure of the nucleon and the measurement of asymmetries in exclusive reactions to access Generalised Parton Distributions (GPDs). In order to study the transverse spin structure, single spin asymmetries in semi-inclusive pion production are measured by the HERMES experiment for the first time. For this purpose the target is since 2001 a transversely polarised hydrogen target. Two different sine dependencies are extracted which can be related to the quark distribution's transversity. In this presentation the first results of this analysis will be discussed. The second part of the presentation will concentrate on the Recoil Detector, a HERMES upgrate which will enable the measurement of exclusive reactions. This three-layer detector is now in the production phase and will be finished by the end of this year. A short overview of the design and status of this project will be given.