An experiment HERA-tex2html_wrap_inline43 utilising an internal polarized nucleon target in the 820 GeV HERA proton beam would constitute a natural extension of the studies of the nucleon spin structure in progress at DESY with the HERMES experiment. Conceivably, this would be the only place where to study high energy nucleon-nucleon spin physics besides the dedicated RHIC spin program at BNL supposed to start early in the next decade. An internal polarized nucleon target offering unique features such as polarization above 80% and no or small dilution, can be safely operated in a proton ring at high densities up to tex2html_wrap_inline45 atoms/cmtex2html_wrap_inline47. The integrated luminosity which could be accumulated in the experiment is estimated to be tex2html_wrap_inline49 and corresponds to about 3 real years running under present HERA conditions. As long as the polarized target would be used in conjunction with the unpolarized HERA proton beam, the `phase-I' physics programme of HERA-tex2html_wrap_inline43 could be started and focused to measurements of single spin asymmetries. Once having available a polarized proton beam at HERA, all combinations of beam and target polarization (tex2html_wrap_inline53) could be possible and correspondingly double spin asymmetries tex2html_wrap_inline55, tex2html_wrap_inline57 and tex2html_wrap_inline59 would be accessible at HERA-tex2html_wrap_inline43. These `phase-II' measurements would constitute an alternative -fixed target- approach to similar physics which will be accessible to the collider experiments STAR and PHENIX at the low end of the RHIC energy scale (tex2html_wrap_inline63 GeV).

[bullet] Contact:

W.-D. Nowak ( nowakw@ifh.de)

V. Korotkov ( korotkov@ifh.de)

Latest update: February 18, 1998
Page updated by: VK