Measurement of the neutron proton spin correlation parameter Azz at forward angles

The n-p spin correlation parameter Azz was measured at an energy of 68 MeV and 7 angles in the range of 22.5° - 57.3° CM with a statistical accuracy better than 0.01. In the measured range, Azz is most semsitive to є1, the mixing parameter of the deuteron states 2S1 and 2D1. Therefore the measurement is expected to reduce significantly the uncertainties of the phases in the energy range below 100 MeV, when a new global Phase Shift Analysis (PSA) is performed. This should help to find a more accurate answer to the strength of the tensor force in the NN-interaction. The experiment was performed in the low energy area C (NEC) of the Paul Scherrer Institute )PSI) in Villigen, Switzerland