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HK: Hadronen und Kerne
HK 32: Structure of Baryons, Mesons IV, HERMES, CHORUS, SELEX
HK 32.1: Talk
Tuesday, March 17, 1998, 14:00–14:15, H
Extraction of Polarised Quark Distributions at HERMES — • Uta Stösslein on behalf of the HERMES Collaboration — DESY-Zeuthen
The HERMES experiment at DESY investigates the spin structure of the nucleon by deep inelastic scattering of longitudinally polarised positrons on polarised internal 1H, 2H, and 3He targets. Since 1995 data on hydrogen and 3He have been collected, for 1998/99 measurements with a polarised deuterium target are planned. Besides the inclusive measurements of the polarised structure functions g1p and g1n, additional informations about the scattering process are accessible based upon the good acceptance and identification capabilities for hadrons within the HERMES spectrometer. Corresponding measurements of semi-inclusive production cross sections asymmetries are sensitive to the polarisation of the valence and sea quarks. Various methods of the extraction of the polarised parton distributions will be discussed and the results will be compared with other experiments. Finally, the upgrade programme for the HERMES spectrometer will be presented taking into account the possible investigation of the contributions of the s-quarks and gluons to the nucleon spin.