1. HERMES in 2002 Gerard van der Steenhoven, Dec. ‘02 The origin of proton spin

2. HERMES run II (2002-2006) Transversity: –Spin structure of the nucleon without gluons: Generalized Parton Distributions: –Orbital angular momentum –Parton correlations Transverse magnetic field orienting the spin of the target protons in a direction perpendicular to the e + -beam.

3. The origin of spin: Three leading order distributions: momentum carried by quarks longitudinal quark spin,  lattice QCD:  transverse quark spin,  lattice QCD:  ½ = ½  q +  G + L q [“Traffic Lights” – P.J. Mulders] Spin Physics: Transversity

4. HERMES data taking in ‘02 Goal for March 2003: 1.3 Million DIS events

5. Polarization at HERA 35% e + -polarization observed H.P. Blok, P. van der Nat, B. Zihlmann

6. The HERMES spectrometer e + BEAM Target area ~1.5m Magnet TRD + Calo RICH Lambda Wheels Beam Loss Monitor

7. Lambda Wheels Physics: – –  spin structure –Transverse spin Operations: –Commissioned –Interference with transverse field M. van Beuzekom, V. Mexner, A.J. Reischl, J.J.M. Steijger  Shut down ’03: new capacitive couplings

8. Lambda Wheels results I J.J.M. Steijger Energy loss in ohmic (  ) and junction (j) side of one counter Single Si-strip ADC overflow Energy loss in two counters of one LW silicon module Bethe Bloch

9. Lambda Wheels results II J.J.M. Steijger Hits with E loss > 6 MIP in LW at z = 45 cm Broken bond Normal HERMES detector acceptance Lambda Wheels are operational!

10. Beam Loss Monitor Purpose: –Generate trigger in case of excessive beam losses –Trigger to HERA kicker –Monitor radiation Custom built Operational since Febr ‘02 M. van Beuzekom, V. Mexner, A.J. Reischl, J.J.M. Steijger e+e+

11. Integrated dose from BLM M. Demey Maximum dose HELIX > 200 krad  Lambda Wheels ok

12. Physics Results: 4 PhD’s Higher twist effects in DIS on 1,2 H – J. Visser Flavour decomposition of nucleon spin – M.C Simani Semi-inclusive DIS off 84 Kr – E. Garutti * Hyperon and  C + photo- production – D. Heesbeen *next talk: first evidence for (QCD prediction!)

13. Higher twist effects J. Visser  No evidence for higher twist at low Q 2

14. Gottfried Sumrule J. Visser Isospin asymmetry of the sea is Q 2 -independent!

15. Flavour decomposition I Sea quarks: unpolarized for strange sea? M.C. Simani

16. Flavour decomposition II First data on: Data  zero Calculations: –Instantons (  QSM): –Gas of massless quarks: M.C. Simani (Goeke)

17. f 0 (980) Scalar Meson f 0 (980) structure: – –Glue ball (comp.) E. Garutti f 0 (980) No strong A-dependence: – Q 2 and P t 2 dep.:

18.  C +  photoproduction I First observation of  C + near threshold: D. Heesbeen Charm photoproduction

19.  C +  photoproduction II Spin-dependent  C + production: Partial  C + rec.: D. Heesbeen

20. Outlook What to expect in 03+04: –Lambda Wheel data –Transversity data Beyond 2004: –Recoil Detector (GPDs) –Orbital angular momentum –…. Spin physics @ STAR? Henk Blok, Erika Garutti Michiel Demey, David Heesbeen Willem Hesselink, Louk Lapikas Armen Laziev, Vanessa Mexner Paul van der Nat, Andreas Reischl Chiara Simani, Jos Steijger Gerard van der Steenhoven Jan Visser Gabriel Ybeles Smit Beni Zihlmann The cast: